MECP Basic Study Guide
Short Description
Car Audio installation...
Description
Basic Installer Study Guide
The Basic Installer Study Guide is based on carefully documented material and research. Every attempt has been made to relay accurate and up-to-date information. This book is designed to assist Mobile Electronics Installers in passing the MECP Basic Installer Test and can also be used as a reference guide. MECP and/or the Consumer Electronics Association cannot be held responsible for discrepancies or inconsistencies contained in this publication. Copyright © 2000 by Consumer Electronics Association/ First Edition All rights reserved. No part of this work covered by the copyright hereon may be reproduced or used in any form or by any means - graphic, electronics, or mechanical, including photocopying, recording, taping or information storage and retrieval systems - without the written permission of the publisher.
MECP Consumer Electronics Association 2500 Wilson Boulevard Arlington, Virginia 22201-3834 (703) 907-7689
CONTRIBUTORS WRITERS AND CONTRIBUTING EDITORS
Eric Abbiss Wayde Alfarone Paul Baird John Banse Ward Benjamin Bob Bentley Jim Boyte Kris Bulla Dennis Deck Tim Den Hartog Charlie Fox Mark Fukuda Joe Garruba Tom Gazda Doug Giddens Mary Ann Giorgio Lonnie Goddard Mark Gordon Jeff Halkin Homer Hawlins Scott Heidbrink Stan Hoffman Jim Jardin
Dan Jobin Ed Kuehner Derek Lee David Long Martin Marino James Milton Ted Peterson Joe Petreau Todd Ramsey Rudy Sanders Allen Schultz Kerry Shrode Geoff Smith Kenny Snoddy Dave Sprosty Justin Stanley Jerry Sterling Gil Stroud Todd VanZandt Joe Walters Paul Wanders Ken Ward
MECP would like to thank the following manufacturers: Alpine, Code Alarm, Directed Electronics, Kenwood, Metra Electronics Corporation, Pioneer Electronics, Scosche Industries, and Vehicle Security Electronics for their continued support of the program and contributions to this book.
CONTRIBUTING COMPANIES
Alpine Electronics ATX Research Audio Comp Electronics, Inc. Audio Control Audivox Benjamin Consulting Bobit Publishing Car Audio Engineering CMA School of Mobile Electronics Directed Electronics, Inc. Installer Institute JBL Car Audio Listen Up Luzerne County Community College, Advanced Technology Center
Mobile Dynamics Mobile One Auto Sound Mobilworks Ora Electronics Pioneer Electronics Quality Auto Sound Robert Bentley Audio Sherwood South Bay Cellular Telephone Company Stillwater Designs Vehicle Security Electronics Traffic Jams
MANAGING EDITOR
Chris Cook ..............................................MECP DESIGN AND PRODUCTION
Alpha MicroDesigns, Inc. ........................http://www.amdi.com CONTRIBUTORS
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TABLE OF CONTENTS INTRODUCTION
Understanding The Format ............................................................10 What Is MECP…And What Does It Mean To You? ........................11 Why Certification Is Essential: Customer Perceptions ....................11 Botton Line Benefits........................................................................11 Making The Most Of This Study Guide ..........................................12 Understanding The MECP Tests ....................................................13 How The Tests Are Created ............................................................19 Preparing For The Exam ................................................................20 The Day Before The Test ................................................................20 The Day Of The Test ......................................................................21 At The Test Site ..............................................................................21 How To Take The Test ....................................................................22 After The Test ................................................................................23 CHAPTER 1 - BASIC AND ADVANCED ELECTRICAL
Section 1 - Electrical Laws And Formulas For The Mobile Electronics Environment ..................................................................26 Understanding OHM’s Law ............................................................28 Electrical Power ..............................................................................34 Series And Parallel Total Resistance Formulas ................................38 Kirchoff’s Voltage Law ....................................................................42 Kirchoff’s Current Law....................................................................42 Current Flow ..................................................................................43 Section 2 - Electrical Components........................................................................44 Resistors ........................................................................................44 Potentiometers................................................................................46 Inductors ........................................................................................47 Capacitors ......................................................................................48 Fuses And Circuit Breakers ............................................................51 Section 3 - Basic Electrical Troubleshooting..........................................................52 Voltage Drops ................................................................................52 Voltage Drops - Series Circuits........................................................54 Ground Loops ................................................................................55 Short Circuit ..................................................................................57 Open/Closed Circuits ....................................................................58 Clipping ........................................................................................58 Section 4 - Filters ................................................................................................60 Passive Crossovers ..........................................................................60 Bandpass Filters..............................................................................62
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Section 5 - Relays, Batteries And Cable ..............................................................62 Batteries..........................................................................................67 Cable Quality..................................................................................68 Section 6 - Semiconductors ..................................................................................71 Transistors ......................................................................................71 Diodes ............................................................................................72 Section 7 - Automotive, Electrical and Charging Systems ....................................75 Ignition Switch Functions/Power Wiring ........................................76 Section 8 - Troubleshooting Guide ........................................................................77 Overall............................................................................................77 Speakers ........................................................................................78 Sample Test Questions ................................................................................80
CHAPTER 2 - INSTALLATION KNOWLEDGE & TECHNIQUE
Section 1 - Basic Installation Practices ................................................................84 Vehicle Check In ............................................................................84 Bookkeeping ..................................................................................85 Vehicle Disassembly And Reassembly ............................................86 Cable Routing/Lead Dress ..............................................................87 Power Accessing ............................................................................88 Ground Loops/Ground Paths..........................................................89 Finding A Good Ground ................................................................90 Proper Wire Gauges........................................................................91 Proper Connections ........................................................................92 Antennas ........................................................................................94 Fusing And Circuit Breakers ..........................................................95 Section 2 - Noise Troubleshooting ........................................................................96 System Noise ..................................................................................96 Types of Noise Problems ................................................................97 Section 3 -Battery Troubleshooting ......................................................................100 Hydrometer ....................................................................................102 Load Testing ..................................................................................102 Section 4 -Meters And Test Equipment ................................................................103 DMMS And VOMS ........................................................................103 Test Lights ......................................................................................109 Noise Sniffers..................................................................................109 Section 5 General Installation & Equipment........................................................103 Non-Powered Hand Tools ..............................................................111 Powered Hand Tools ......................................................................112 Large Shop Tools ............................................................................113 Specialty Tools ................................................................................113 Cutting Techniques ........................................................................114
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Section 6 - Shop Safety ........................................................................................115 Safety Practices ..............................................................................116 Safety Around Batteries ..................................................................117 Safe Tool Use ..................................................................................117 Fire Extinguishers ..........................................................................118 Cleaning The Shop ........................................................................118 First Aid ........................................................................................119 Section 7 - Troubleshooting Guide ........................................................................119 Overall............................................................................................119 Noise Problems ..............................................................................120 Sample Test Questions ................................................................................125
CHAPTER 3 - INTRODUCTION TO AUTOSOUND, SECURITY, WIRELESS & NAVIGATION
Section 1 - Introduction To Audio - Autosound Basics ..........................................130 Frequency ......................................................................................131 Wavelength ....................................................................................132 Period ............................................................................................132 Amplitude ......................................................................................133 Phase & Polarity ............................................................................134 Resonance ......................................................................................138 Frequency Response ......................................................................138 Octives and Harmonics ..................................................................141 Signal To Noise ..............................................................................142 Dynamic Range Of A Music Recording ..........................................143 Headroom ......................................................................................143 Section 2 - Introduction To Security ....................................................................144 Basic Components Of A Security System ........................................145 Sirens..............................................................................................146 Switch Triggers ..............................................................................146 Sensors ..........................................................................................147 Sound Sensors ................................................................................149 Engine Disables ..............................................................................150 Remote Controls ............................................................................151 Accessory Output Devices ..............................................................152 Telematic Systems ..........................................................................153 Basic Installation Tips ....................................................................154
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Section 3 - Wireless Communications: The Basics Of Installation ........................156 Transceivers ....................................................................................156 Microphone ....................................................................................158 Permanetly Installed Antennas........................................................158 Hands Free Capability And Installation Kits ..................................161 Programming ..................................................................................162 Section 4 - Navigation Basics ..............................................................................162 Types Of Navigation ......................................................................163 Mounting The Monitor ..................................................................167 Wiring ............................................................................................167 Vehicle Speed Sensor Testing And Verification................................168 Testing The System ........................................................................170 Sample Test Questions ................................................................................171
Margin Notes
GLOSSARY OF TERMS
Glossary of Terms........................................................................................176 Appendix ....................................................................................................200 Reference Materials......................................................................................206 INDEX
Index ..........................................................................................................210
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INTRODUCTION
INTRODUCTION
The objective of the MECP Study Guide is to prepare you to become a Certified Installer in your area of expertise. Put simply, this book provides you with the answers to the questions that are asked in the Basic Installer Test and the related sections of the First Class test. The Basic Installer Study Guide will also give you the information needed to study for the Advanced Electrical and Installation Knowledge & Technique portions of the First Class test. Whether you’re trying to pass the Basic Installer, First Class, or Master Installer exam, this guide will provide you with a firm foundation to build on for your Mobile Electronics Education.
INTRODUCTION Margin Notes
UNDERSTANDING THE FORMAT
For some people, sitting down and reading a study guide is not very rewarding… or informative. In fact, it can be downright frustrating. We realize that…but at the same time, we also recognize the importance for excellence in our industry. So in that vein, we have created a Study Guide that is informative and educational – and above all, easy to use! Why? Because we want to see you succeed – because your professional performance reflects positively on everyone in the industry. In addition, it also helps you and your company maintain a high level of customer satisfaction – and that can translate into repeat and referral business. Here’s how we made this book easier to use: For example, important facts or key terms are printed in bold type so they stand out on the page and are easy to locate. In addition, important notes are placed in the margins. Here’s how this book is formatted: Margin Notes with the ✍ symbol are key points taken directly from the text. They emphasize material that you’ll find in the Installer and First Class tests.
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Illustrations are included to reinforce important concepts.
■ Bold type alerts you to an important fact or key term. Many of these are included on the test, so make sure you clearly understand their meaning.
Glossary is located at the back of the book. This is essential study material for any of the test levels.
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Sample Test Questions are at the end of the section. These sample questions let you gauge your progress while preparing you for the test.
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■ Key Formulas and equations are at the back of the text. They help you understand and memorize the equations included in the test.
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WHAT IS MECP…AND WHAT DOES IT MEAN TO YOU?
Margin Notes
MECP stands for the Mobile Electronics Certified Professional Program. It was designed and developed by the Education Committee and Certification Committee of CEA – the Consumer Electronics Association, which is a non-profit organization dedicated to the Consumer Electronics industry and is a sector of the Electronic Industries Alliance (EIA). The purpose of this certification program is to foster a level of professionalism and to achieve a level of knowledge. ■
MECP is also a learning and educational tool that allows installers of all levels – through continued study and daily experience – to grow to the next level of expertise. ■
MECP is a network of schools, manufacturers, retailers, installers, and concerned industry professionals from the U.S. and Canada whose primary goal is to help make this industry educationally sound with ongoing testing and training. ■
WHY CERTIFICATION IS ESSENTIAL: CUSTOMER PERCEPTIONS
When a customer makes a commitment to upgrade their car audio, security, navigation or wireless system, they’re looking to your company to provide them with the professionalism and service that accompanies their purchase decision. Today’s customers are more demanding than ever before – they expect OEM quality on their installations. Accordingly, you need to keep pace with the latest techniques to ensure the “final product” lives up to your customer’s expectations.
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In the automotive industry, there’s a statistic – a happy, satisfied customer tells 5 friends about their positive experience; but an unhappy, dissatisfied customer tells 15 - 20 people about their negative experience. A few dissatisfied customers can quickly wipe out the good reputation of a company
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BOTTOM LINE BENEFITS
MECP certification has its benefits: ■ Demonstrates your commitment, dedication and professionalism. ■
Assures consistent quality.
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Qualifies the people who do the work.
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Demonstrates a “we care” attitude.
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Reinforces the quality of your operation.
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MAKING THE MOST OF THIS STUDY GUIDE
First and foremost – this is not a “How To” book! It is a study guide – written specifically for installers who wish to become certified professionals. Here’s how you can make the most of this information: ■ Take notes – write in the margins (that’s why they’re there). ■
Study additional sources of information to round out your knowledge.
This is not meant to be the definitive source for installation instructions; refer to the appropriate manufacturer’s publications for actual installation information. ■
If you’re taking the basic Installer test level, you need to study: ■ All of the sections on Basic and Advanced Electrical and Installation Knowledge and Technique (Study Guide 1 – Bronze level), as well as chapter 3 and the Glossary definitions. It is important that you know the basics, and have good knowledge of the technologies that you will be working with. If you are taking the First Class test, you need to study: ■ All of the sections on Basic and advanced electrical, Installation Knowledge and Technique, and Chapter 3 on Basics of Autosound, Security, Wireless & Navigation (Study Guide 1 - Bronze level) as well as the entire First Class Study Guide (Silver level) and the related Glossary definitions. It is important that you know the basics, and have a good knowledge of the technologies that you will be working with. If you are taking any of the Specialist test, you need to study: ■ All of the sections on Basic and Advanced Electrical and Installation Knowledge and Technique (Study Guide 1 – Bronze level). The information that relates to your area of specialization –Autosound, or Security. ■
If you are taking the Master Installer test, you need to know the theory behind all these technologies: ■ This is the most challenging test; accordingly, you need to study all the MECP Study Guide levels (Study Guide 1,2, & 3 – Bronze, Silver, and Gold) including the Glossary of Terms, as well as the other books referenced in the back of the Master Installer Study Guide (Study Guide 3 – Gold level).
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UNDERSTANDING THE MECP TESTS
Margin Notes
Here’s a breakdown of the different tests:
Installer Level ■
Basic Installer test – 150 questions; allotted time: 3 hours 1 Basic Electrical 2 Installation Knowledge and Technique 3 Tools and Shop Safety 4 Definitions and application of core technologies
The Basic Installer level tests basic electronics and DC knowledge and their applications to mobile electronics installations; basic knowledge pertaining to actual installations and troubleshooting; sound, music, and product; basic working knowledge and understanding of standard shop tools and safety procedures. The Basic Installer certification examination is a basic level, 150 question multiple choice and true/false examination broken down into three 50 question sections. The questions within the three sections can be further broken down into the nine categories listed below. The numbers in parentheses indicate the approximate percentage of the 50 question sections devoted to each subject matter. Electrical Section Questions 1 Ohms Law (25-30%) - These questions require the knowledge of Ohms Law formula and the math to solve a particular question. Many of these questions require computation. 2 Electronic Components (45-50%) - These questions pertain to the physical electronic components such as capacitors, resistors, etc. This also includes related topics like “farads” and “henries”. 3 Measurements & Applications (25-30%) - This classifies all questions having to do with situations where knowledge needs to be applied and/or measured in some form. This also includes the application of units and scales such as dBs, amperes, etc.. Installation Knowledge and Technique Section Questions 4 Component Application and Usage (25-30%) - These questions pertain to the actual way a component is used or applied in an installation. An example is when (or when NOT to) install a noise filter or perhaps whether an open or closed circuit is appropriate. 5 Troubleshooting and Analysis (50-55%) - These questions deal with the diagnosis of incorrect installation procedures and/or components which don’t operate properly. INTRODUCTION
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6 Installation Techniques (15-20%) - This classifies all questions which deal directly with physical installation related procedures and/or concerns. Tools and Safety Section Questions 7 Measurement and Troubleshooting (50-55%) - This classifies all questions which directly address the measurement and troubleshooting of 12volt systems. This includes both the techniques and tools. 8 Power and Hand Tools (25-30%) - This classifies all questions which deal with tools that ARE NOT considered measurement and troubleshooting tools. 9 Safety Practice and Safety Equipment (15-20%) - This classifies all questions which deal with safety and proper use of safety equipment
Specialist Level ■
Autosound Specialist test – 150 questions (50 questions/section); allotted time: 3 hours 1 Basic and Advanced Electrical 2 Autosound Section 3 General Installation Knowledge
The Autosound Specialist certification examination is a first class level, 150 question multiple choice examination broken down into three 50 question sections. The questions within the three sections can be further broken down into the eight categories listed below. The numbers in parentheses indicate the approximate percentage of the 50 question sections devoted to each subject matter. Electrical Section Questions 1 Ohms Law (20-25%) - These questions ask for and/or require the knowledge of Ohms Law formula or math to solve a particular question. Many of these questions require computation. 2 Electronic Components (45-50%) - This classifies all questions having to do with the physical electronic components such as capacitors, resistors, etc.. This also includes related topics like “farads” and “henries”. 3 Measurements & Applications (30-35%) - These questions pertain to situations where the knowledge needs to be applied and/or measured in some form. This also includes the application of units and scales such as dB’s, amperes, etc..
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Autosound Section Questions 4 Audio Theory and Analysis (40-45%) - This classifies all questions which deal with both acoustic and electronic theory and analysis with relation to sound in the mobile environment.
Margin Notes
5 Audio Components (30-35%) - These questions pertain to the physical audio components which make up a mobile audio system. This includes both passive and active electronic components as well as loudspeakers. 6 Installations and Testing (25-30%) - These questions deal directly with physical installation related procedures and/or testing of a mobile audio system. This includes subwoofer enclosure questions. General Knowledge 7 Tools (45-50%) - This classifies all questions related to Tools. This includes hand tools, power tools, measurement tools, and troubleshooting tools. 8 Safety and Installation Techniques (50-55%) - This classifies all questions which deal with safety and proper use of safety equipment. This category also classifies all questions which deal directly with physical installation related procedures and/or concerns.
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Security Specialist test – 150 questions (50 questions/section); allotted time: 3 hours: 1 Basic and Advanced Electrical 2 Security Section 3 General Installation Knowledge
The Security Specialist certification examination is a first class level, 150 question multiple choice examination broken down into three 50 question sections. The questions within the three sections can be further broken down into the eight categories listed below. The numbers in parentheses indicate the approximate percentage of the 50 question sections devoted to each subject matter. Electrical Section Questions 1 Ohms Law (15-20%) - These questions ask for and/or require the knowledge of Ohms Law formula or math to solve a particular question. Many of these questions require computation. 2 Electronic Components (50-55%) - This classifies all questions having to do with the physical electronic components such as capacitors, resistors, etc.. This also includes related topics like “farads” and “henries”. INTRODUCTION
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Margin Notes
3 Measurements & Applications (25-30%) - These questions deal with situations where the knowledge needs to be applied and/or measured in some form. This also includes the application of units and scales such as dB’s, amperes, etc.. Security Section Questions 4 Security Components (20-25%) - This classifies all questions which pertain to the physical security components which make up a 12 volt mobile security system. 5 Relays and Semiconductors (45-50%) - This classifies all relay and semiconductor questions as related to the installation of a 12 volt mobile security system. 6 Installations and Testing (35-30%) - These questions deal directly with physical installation related procedures and/or testing of a 12 volt mobile security system. General Knowledge 7 Tools (65-70%) - This classifies all questions related to Tools. This includes hand tools, power tools, measurement tools, and troubleshooting tools. 8 Safety and Installation Techniques (30-35%) - These questions deal with safety and proper use of safety equipment. This category also classifies all questions which deal directly with physical installation related procedures and/or concerns. Specialist level exams are designed to test advanced electronics knowledge and installation applications; and in-depth knowledge, understanding, application, and troubleshooting in either autosound, or security. Note: To take this exam, MECP requires notarized proof of one year’s work experience in mobile electronics.
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First Class test – 150 questions total; allotted time: 3 hours 1 Autosound 2 Basic and Advanced Electrical 3 Security
First Class level exam is designed to test advanced electronics knowledge and installation applications; and in-depth knowledge, understanding, application, and troubleshooting in autosound, wireless, security. Note: To take this exam, MECP requires notarized proof of one year’s work experience in mobile electronics.
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INTRODUCTION
The First Class certification examination is a 150 question multiple choice examination broken down into three 50 question sections. The questions within the three sections can be further broken down into the nine categories listed below. The numbers in parentheses indicate the approximate percentage of the 50 question sections devoted to each subject matter.
Margin Notes
Autosound Section Questions 1 Audio Theory and Analysis (20-25%) - This classifies all questions which deal with both acoustic and electronic theory and analysis with relation to sound in the mobile environment. 2 Audio Components (15-20%) - These questions pertain to the physical audio components which make up a mobile audio system. This includes both passive and active electronic components as well as loudspeakers. 3 Installations and Testing (55-60%) - These questions pertain directly to the physical installation related procedures and/or testing of a mobile audio system. This includes subwoofer enclosure questions. Electrical Section Questions 4 Ohms Law (15-20%) - These questions ask for and/or require the knowledge of Ohms Law formula or math to solve a particular question. Many of these questions require computation. 5 Electronic Components (40-45%) - These questions pertain to the physical electronic components such as capacitors, resistors, etc.. This also includes related topics like “farads” and “henries”. 6 Measurements & Applications (35-40%) - These questions cover situations where knowledge needs to be applied and/or measured in some form. This also includes the application of units and scales such as dB’s, amperes, etc.. Security Section Questions 7 Security Components (10-15%) - This classifies all questions which pertain to the physical security components which make up a 12 volt mobile security system. 8 Relays and Semiconductors (25-30%) - This classification includes all relay and semiconductor questions as related to the installation of a 12 volt mobile security system. 9 Installations and Testing (55-60%) - These questions deal directly with physical installation related procedures and/or testing of a 12 volt mobile security system. INTRODUCTION
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Master test – 180 questions total; allotted time: 3 hours 1 Advanced Electrical 2 Installation Knowledge and Technique 3 Advanced Autosound 4 Advanced Security 5 Troubleshooting 6 Glossary of Terms
Master Installer Level exam is the most advanced level test and is designed to test installers in advanced electrical, autosound, security and troubleshooting. In order to qualify to take the Master Installer exam, you will need a score of 70% or better on all sections of the First Class test. Note: To take this exam, MECP requires notarized proof of three year’s work experience in mobile electronics. The Master Installer certification examination is MECP’s most advanced level. This is 180 question multiple choice and true/false examination broken down into four sections. The Electrical, Autosound and Security sections are each 50 questions, and the Troubleshooting section contains 30 questions. The questions within the four sections can be further broken down into the twelve categories listed below. The numbers in parentheses indicate the approximate percentage of the question sections devoted to each subject matter. Electrical Section Questions 1 Ohms Law (20-25%) - These questions ask for and/or require the knowledge of Ohms Law formula or math to solve a particular question. Many of these questions require computation. 2 Electronic Components (35-40%) - This questions pertain to the physical electronic components such as capacitors, resistors, etc.. This also includes related topics like “farads” and “henries”. 3 Measurements & Applications (35-40%) - This classifies all questions having to do with situations where the knowledge needs to be applied and/or measured in some form. This also includes the application of units and scales such as dB’s, amperes, etc.. Security Section Questions 4 Security Components (10-15%) - These questions pertain to the physical security components which make up a 12volt mobile security system. 5 Relays and Semiconductors (30-35%) - This classifies ALL relay and semiconductor questions as related to the installation of a 12 volt mobile security system.
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6 Installations and Testing (50-55%) - This classifies all questions which deal directly with physical installation related procedures and/or testing of a 12volt mobile security system.
Margin Notes
Autosound Section Questions 7 Audio Theory and Analysis (25-30%) - These questions pertain to both acoustic and electronic theory and analysis with relation to sound in the mobile environment. 8 Audio Components (40-45%) - This classifies all questions which pertain to the physical audio components which make up a mobile audio system. This includes both passive and active electronic components as well as loudspeakers. 9 Installations and Testing (25-30%) - These questions deal directly with physical installation related procedures and/or testing of a mobile audio system. This includes subwoofer enclosure questions. Troubleshooting Section Questions 10 Audio Related Troubleshooting (30-35%) - These questions pertain to troubleshooting the AUDIO part of the system installation. 11 Security Related Troubleshooting (20-25%) - This classifies all questions which pertain to troubleshooting the security and/or convenience items in an installation. 12 General 12volt Electrical System Troubleshooting (40-45%) - This classifies all questions which deal with the vehicle troubleshooting including audio and/or security components which may be causing problems or interference with the vehicle electrical systems.
HOW THE TESTS ARE CREATED
The test questions are written and developed by: ■ A Committee of Master Installers. ■ Manufacturers’ trainers and subject matter experts. ■ Industry educators from schools and community colleges. ■ Testing and certification industry experts are used for content writing and validation of each test. The questions are designed to test your daily working knowledge of installation technologies. Hands-on applications can only be tested and proven in a school or work environment.
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Margin Notes
Most questions are multiple choice and some True/ False: ■ Multiple choice questions have four or five possible answers. Only one answer is correct in every question.
PREPARING FOR THE EXAM
Some people get “test anxiety” and while they know all of the answers, they freezeup during the test. That can be frustrating – but if you’re thoroughly prepared, the odds are on your side that rather than feeling anxious…you’ll be ready to “ace” the exam. Here are some easy steps that will help you to be fully prepared when you take your exam: ■ Read the Table of Contents to find the sections you need to focus your studies. Scan through the appropriate sections to get a “feeling” for how the information is organized. ■
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Read each section – preferably three to four times. ■ Choose a time when you’re rested and fresh to study. ■ Note important topics or areas where you are weak in the margin. ■ Re-read each section a few days later until you feel you know the information.
A week before the exam: re-read or review the chapter one more time to refresh your memory. ■ In between reading the chapters, review the Glossary so you’re familiar with the key terms and definitions. ■ Take the sample tests a few times: ■ You can take the sample test provided in the Study Guide or log on to www.ce.org and select the Tech education and Services Section. ■ The first time “tests” your knowledge of the material. ■ Subsequent reviews familiarize yourself with the type of test you’ll be taking. ■
THE DAY BEFORE THE TEST ■
Review each chapter and the sample questions.
■ Do not try to “cram” for the test the day before the test (it didn’t work in high school…it doesn’t work here, either).
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INTRODUCTION
If you have properly read this Study Guide, the information should already be in your head and the correct answers will come to you quickly during the test. ■ Last-minute cramming can confuse you and make you even more anxious about the test.
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Margin Notes
Review each area you feel you may be weak in and review your notes in the margins. ■
THE DAY OF THE TEST ■
Get plenty of rest the night before.
If you are coming straight from work, allow some extra time to relax and unwind before you start the test (at least 15 - 20 minutes). ■ During that time, “clear” your head of the day’s activities. ■
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Do not try to re-read the Study Guide at any time.
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Stay relaxed and confident that you will do well on the test.
AT THE TEST SITE
Bring the following: ■ Two sharpened #2 pencils. ■ Your acceptance letter (if needed). ■ One form of photo identification. Arrive at the test site on time or a little early: ■ Look in the lobby or front office for MECP signs or an events board that directs you to the test location. ■
Check in at the room or designated testing area. ■ Have all of your information available to give to the proctor.
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Take your test packet, sit down, relax, and wait for the proctor’s instructions. ■ Seating will be arranged every other seat, or at least an arm’s length apart. ■ Each test is different from the person sitting next to you.
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Listen carefully to the proctor’s instructions. ■ He or she will explain any last minute changes. ■ They will tell you how to fill out the scantron sheet. ■ They will also instruct you on how to hand the materials back to the proctor when you are finished.
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DO NOT MARK IN THE TEST BOOKLETS.
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Margin Notes
Any marks in the booklets cannot be permanently erased. A mark, circled answers (right or wrong), or notes, will confuse the next test applicant and could disqualify your score. ■ ■
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Do not talk during the test.
■ The appearance of cheating will immediately disqualify you from the test, so make sure you follow the proctors directions in all areas. ■
No smoking is allowed in the test room.
■ If you must leave the room, do so quietly, leaving all your test materials on the table.
If you have a question or there is a problem with your test booklet, raise your hand or wait for the proctor to come to you. ■
■ Please be courteous to others taking the test, as you would expect them to be with you. ■ Everyone wants to do well on the test and does not need unnecessary distractions.
HOW TO TAKE THE TEST
It’s common to be anxious when taking a test – most people are. That can lead to unnecessary, sloppy mistakes. Here are some tips that will help you improve your performance: ■ Make sure that you neatly write your name on the scantron sheet – as you would like it to appear on your certificate. ■
Read each questions twice before you look at the answers.
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Do not attempt to “read into” a question. ■ There are no “hidden meanings” – so don’t ask the question, “What if?”
■ Answer the question as stated – leave all preconceived notions at home…or in the install bay…on the day of the test.
Don’t skip around – answer the questions in sequence. (Can you imagine if you tried to perform an installation out of sequence? You get the idea.) ■ If you come to a question that you cannot answer, mark the question number down on your scratch paper and come back to it after you finish that section. ■ Be careful to keep your answers in numerical order – if you skip a question, make sure you skip the answer on the scantron sheet or your answers will be in the wrong place. ■
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INTRODUCTION
Marking the scantron sheet: ■ Refer to the box on the front of the sheet on how to properly mark each answer block. ■
Margin Notes
Use two or three hard strokes to darken the block. ■ Do not draw a circle, a dot, or make one soft line. ■ If the answer blocks are not marked properly, the scantron machine will score improper marks as wrong answers.
■ Once you get into the rhythm of marking the answer blocks, you’ll find that it’s easy to do correctly.
Be sure to erase all mistakes completely or the scoring machine could mark your answer as wrong. ■
AFTER THE TEST
When you are finished: ■ Follow the instructions on page one of the test booklet and take your test materials up to the proctor. ■
Leave the room quietly. ■ If you’re waiting for someone else to finish the test, wait in the lobby or somewhere away from the test room. ■ Looking in the room to see if someone has finished, or waiting in the hall outside the room, talking to other applicants, will only disturb the others still taking the test.
You will receive your test results in four or six weeks of the test date.
Congratulations and Continued Success! MECP
For testing dates and locations, call MECP: (703) 907-7689, or visit our web site at www.ce.org and select Tech education and services.
INTRODUCTION
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23
CHAPTER 1 BASIC AND ADVANCED ELECTRICAL
No matter your desires – whether professional or personal – before you can start on any project, you need a solid grasp of “the basics.” Accordingly, Chapter 1 forms the foundation of your entire MECP training. This chapter introduces some basic principles of electronics, as well as some of the more advanced formulas and laws. Both the Basic Installer level and the First Class level Electrical section of the MECP certification tests are included here. You should have a thorough understanding of each topic before moving on to the next topic. For the First Class level test you will need to study the complete First Class Study Guide available from MECP.
1
BASIC AND ADVANCED ELECTRICAL Margin Notes
It’s hard to imagine life without electricity. And while internal combustion engines power our vehicles, it’s electricity that lights the stoplamp when you put your foot on the brakes. And it’s electricity that powers the audio system. The computer may be fueling today’s technological growth, but it was electricity that started the revolution. Therefore, before you can move into more specific areas of expertise, you first need a solid foundation in electrical theory and application.
Section 1 Electrical Laws and Formulas for the Mobile Electronics Environment What do “electrical laws and formulas” have to do with you - an installer? Good question. On the surface, it may seem like a plumber studying hydrodynamic physics - sure, they both deal with the motion of fluids, but one is a little overkill. The same theory does not hold true here. Today’s installations are increasingly more complex - and the vehicles you are working on are equally sophisticated. It is no longer just about hooking up the components. Being a mobile electronics installer truly is a profession - it requires skill and training, and there’s always something new to learn. But before you can learn the “new stuff,” you need to have a solid understanding of the basic electrical theories. That way, when you encounter a particular challenge, you’ll know where to start troubleshooting. After all, you can easily figure out when you’ve used the wrong size wire gauge or have a bad connection without all that math cluttering your mind. But while handson experience is essential; understanding why a wire gauge is too small or what causes a bad ground will help you through many practical situations. A firm grasp of electronics knowledge can guide you logically to the source of almost any problem. Before getting to the mathematical relationships involved in electronics, you need to know about the two types of electrical current you will be working with in the mobile electronics environment - AC and DC. ■ “AC” stands for Alternating Current, which is current that alternates polarity between positive and negative. AC has both an amplitude component (how much) and a frequency component (how often).
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Margin Notes
“DC” stands for Direct Current, and it is current which supplies power to electronic components and is EITHER positive OR negative in polarity, but not both. DC has only an amplitude component (called potential) and a frequency of zero. ■
Alternating Current is an electronic current that periodically changes polarity (i.e., it alternates from positive to negative). ■ In an alternating current circuit, the current flow reverses its direction on each alternation. The voltage alternates from positive to negative and back again to positive.
✍
Alternating Current is
an electronic current that periodically changes polarity.
The rate of alternation (how often) is called frequency, which is measured in cycles per second, or Hertz (Hz).
■
The number of times the AC signal cycles in one second is its specific frequency. Multiple frequencies blended together is how music is sometimes classified as AC. ■
On an oscilloscope, AC looks like this:
Amplitude
+ 0
— 1 Cycle ■
Time
Figure 1. Oscilloscope., AC.
The other form of AC at work in the vehicle is the charging system. A key component of this system is the alternator. The alternator creates AC that is changed into DC by a process called rectification, which allows the battery to charge.
✍ The alternator creates AC that is changed into DC by a process called rectification.
When it comes to the audio signal, we are concerned with the “AC” that flows from the head unit through the signal processors, which is then amplified to drive the loudspeakers. That audio signal contains many varied frequencies and amplitudes which make up the tempo and pitch of individual sounds in music. ■ Alternating Current and music signals are covered in detail in the AUTOSOUND chapter of the First Class Study Guide. For now, most of our applications will focus on DC.
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Margin Notes
✍ Direct Current is defined as current that travels in one direction only.
Direct Current is defined as a current that travels in one direction only. One terminal is always positive, and the other is always negative. ■ All things that rely on the vehicle battery as their source of power operate with DC. This includes amplifiers, head units, security systems, radar detectors, car phones, and other electronic accessories. Sometimes a component, though powered by DC, may output AC. This is the case with car amplifiers. On an oscilloscope, positive DC looks like this:
+ ø ■
Figure 2. Oscilloscope., positive DC.
When analyzing electronic circuits, you’ll encounter the relationships between these four electronic properties: 1 2 3 4
Voltage Current Resistance Power
(E) (I) (R) (P)
Ohm’s Law is the electrical formula that defines the relationship of these properties to each other.
UNDERSTANDING OHM’S LAW
✍
Ohm’s
Law
describes
a specific and measurable relationship between current, voltage, resistance and power.
Ohm’s Law is one of the most basic laws of electricity. Using mathematical formulas, Ohm’s Law describes a specific and measurable relationship between current, voltage, resistance and power. Let’s look at these parameters and see how they apply to mobile electronics: The properties that you need to understand are Voltage, Current, Resistance, and Power. Power will be discussed later in this chapter.
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Margin Notes SYMBOL
PARAMETER
UNIT OF MEASURE
I
Current
Amps or Amperes
E
Voltage
Volts
R
Resistance
Ohms
P
Power
Watts
Ohm’s Law mathematically describes the interaction among these parameters. Understanding the relationship among current, voltage resistance, and power can help you figure out many different installation problems and answer many installation questions (even before the installation begins). For Example, Ohm’s Law will tell you how much power an amplifier really puts out, if the voltage supplied to an amplifier is too low, or if a higher power alternator should be considered. So lets take a look at Ohm’s law and discover how it effects our work environment. Current is the rate of electron flow through a given point, and is measured in Amperes or Amps. If you marked a point on a main road in a city and counted the cars that pass that point in a specific window of time, you could gain an understanding of the traffic flow on that road. A wider road with more lanes would allow more cars to pass in a given window of time, while a narrower road with fewer lanes would allow a smaller number of cars to pass in that window of time. This illustrates the concept of current flow in a wire or circuit. ■
Voltage is the electrical pressure that moves charged particles in a circuit, and is measured in Volts. Voltage can be considered as the force of electricity. Voltage is also sometimes called difference of potential (potential difference) and, like the force of electricity, can be thought of as electrical pressure that moves the current.
■
✍ Current is the rate of electron flow through a given point.
✍
Voltage is the electrical
pressure that moves charged particles in a circuit.
Just as the width of the road and number of lanes would effect traffic as we described with current, a vehicle’s natural ability or potential to movement would also affect traffic flow. A vehicle moving downhill could start and move much more quickly than the same vehicle moving uphill. The natural force of gravity assists that. Electrically, the natural force, (determined by potential) that moves the charged particles through the circuit is much the same concept. More electrical pressure means more potential for electronic traffic flow. What is the pressure exactly? How does it move the charged particles? Let’s start to answer these questions by first defining some terms that relate to voltage. ■
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Margin Notes
■ Charge — or electrical charge is the fundamental unit for an amount of electricity. Symbolized (Q).
Polarity — in an electrical circuit there are two different polarities: electrons posses a negative charge while protons posses a positive charge. It can also be said that an electron has a negative polarity and a proton has a positive polarity. ■
■
Potential - refers to the ability to do work.
Now with these definitions let’s discuss some actions. ■ Like charges repel - two negatively charged particles held together will repel or want to move away from one another. Likewise, two positively charged particles held together will repel or want to move away from one another. Unlike charges attract - when two unlike charges are brought close together they will attract or try to move toward each other. ■
These two reactions are proof of an electric field. Since potential is the ability of the charges to do work, it’s the difference of potential (using the natural ability to attract and repel) that allows the current to move and do work.
✍
Electrical
Resistance
describes the property that various materials possess to restrict or inhibit the flow of electricity.
2
E R
2
E R
I •R I•E P•R P I
30
P E P/R
E R
E I 2
I•R
P = Watts I = Amps
■
The basic formulas used by Ohm’s Law to find current, voltage, or resistance are as follows:
P I
P 2 I
Resistance is the opposition to current flow. To understand Resistance think of anything that limits or blocks the flow of electrical traffic. Electrical Resistance describes the property that various materials possess to restrict or inhibit the flow of electricity. Electrical resistance is measured in Ohms (Ω). Electrical resistance is relatively low in most metals and relatively high in most non-metallic substances.
■
E P
E = Volts R = Resistance
I= E R E= IxR R= E I
Figure 3. OHM’s Law.
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Margin Notes
According to Ohm’s Law: If you want to find…
and you know…
then the math is…
Current (I)
Resistance (R) and Voltage (E)
E÷R=I
Current (I)
Power (P) and Voltage (E)
P÷E=I
Current (I)
Power (P) and Resistance (R)
(Sq.Rt.) √ P ÷ R = I
Voltage (E)
Power (P) and Resistance (R)
(Sq.Rt.) √ P x R = E
Voltage (E)
Current (I) and Resistance (R)
IxR=E
Voltage (E)
Current (I) and Power (P)
P÷I=E
Resistance (R)
Current (I) and Voltage (E)
E÷I=R
Resistance (R)
Current (I) and Power (P)
P÷I =R
Resistance (R)
Voltage (E) and Power (P)
E ÷P=R
Power (P)
Current (I) and Voltage (E)
ExI=P
Power (P)
Current (I) and Resistance (R)
RxI =P
Power (P)
Resistance (R) and Voltage (E)
E ÷R=P
2
2
2
2
Let’s take a less scientific approach to understanding the relationship between current, voltage, and resistance by comparing electrical characteristics to hydraulics. Suppose you have a container of water. The pressure at the bottom of the container caused by the volume of water above it is similar to voltage. The more water, the more pressure, the more voltage, the higher the difference of potential (voltage). Container of Water
Valve On
■
Tube
Figure 4. Water Tank.
When the valve is opened, pressure forces the water through the pipe. ■ Voltage is like that “pressure” - only it is electrical pressure that is forcing charged particles through a circuit. ■ If you were to open the valve wider, more water would flow through the pipe. ■ If you were to make the valve opening smaller, less water would flow through the pipe. CHAPTER 1 BASIC AND ADVANCED ELECTRICAL
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Margin Notes
This increase and decrease in the rate of water flow is comparable to the idea of current, but remember that current is the rate of electrons that flow through a conductor. In addition, if you were to decrease the size of the pipe or bend it slightly, the rate of water flow would decrease because you would be increasing the resistance. ■ This limitation in flow volume is similar to electrical resistance, which restricts the flow of electrons. The relationship between current, voltage, and resistance is similar to the container of water - change one parameter while leaving another alone and the third has to change. It will always change according to Ohm’s law, which is the real beauty in knowing this concept. Understanding the relationship between current, voltage, and resistance can help you figure out many different installation problems. ■ Ohm’s Law will tell you things such as: ■ How much power an amplifier really puts out. ■ If the voltage supplied to an amplifier is too low. ■ If a higher output alternator should be considered. Let’s say, for example, that you’re powering up a high wattage audio system, but you choose a wire that’s too small to supply the current required by the system. The resistance in the wire will develop an unwanted voltage drop across it (E = I x R) when the amplifiers draw power. Amplifiers operating with low voltage may overheat, motorboat, or fail. An easy way to memorize Ohm’s Law is to use the Ohm’s Law Pie Chart. Simply “cover up” the letter you wish to find the value of and carry out the remaining formula.
E I R Figure 5. OHM’s Law Pie Chart.
■
Here’s another example of how useful Ohm’s Law can be in every day installations: ■ Suppose you have a resistor with a known value of 8 Ohms (R = 8), and you know the current value that flows through the resistor is 1 Amp (I = 2). What is the voltage across the resistor? Simply apply Ohm’s Law: R=8 I=2 E=IxR E=2x8 E = 16 Volts
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The following circuits show examples of how these formulas can be applied to installations. Use what you’ve learned so far about Ohm’s Law to calculate the current, resistance, and voltage.
Margin Notes
1 How much CURRENT will flow through this circuit?
■
Figure 6. Current Circuit.
2 What is the RESISTANCE of an alarm siren when 12 Volts causes 11/2 Amperes to flow?
■
Figure 7. Resistance Circuit.
3 How much VOLTAGE is supplying this circuit?
■
Figure 8. Voltage Circuit.
The answers are: 1 2 Amperes 2 8 Ohms 3 4.8 Volts
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Margin Notes
✍ Effective resistance is the “calculated” resistance that a device presents to a circuit while it is operating.
Ohm’s Law is also very practical to know when you’re trying to calculate effective resistance. ■ Effective resistance is the “calculated” resistance that a device presents to a circuit while it is operating. Knowing how to apply Ohm’s Law to determine resistance is practical because it’s fairly easy to use a VOM (Volt Ohm Meter) to measure current and voltage, but you cannot directly measure resistance in a live circuit. For example, if you have an amplifier that draws 50 Amps, with an applied voltage of 12 Volts, for full power output with both channels driven into a 4 Ohm load. How would you determine the effective resistance of the amplifier by applying Ohm’s Law? Since we know that I = 50 Amps, and E = 12 Volts, we can manipulate Ohm’s Law so that R is the isolated variable. ■
Simply divide both sides of the equation by I: E=IxR E=IxR I I R=E I
Now, insert the known values into the formula: R eff = 12V 50A R eff = 0.24 Ohms
ELECTRICAL POWER
✍ Power is the conversion of energy into work over a certain period of time.
✍ A watt represents the rate over time that the energy is
Ohm’s Law relates a fourth circuit parameter - Power. ■ Electrical POWER is the conversion of energy into work over a certain period of time, and a watt represents the rate over time that the energy is converted. It’s the result of the collective work of current, voltage, and resistance. The last parameter, “P”, allows you to determine how much a system can produce, how many amps it will draw, and therefore what gauge wire and fuse size is needed. Power determines supply and demand.
converted.
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Margin Notes
There are four basic forms of power: ■ Mechanical power, usually measured in horsepower. ■ Heat, measured in BTU’s (British Thermal Units). ■ Nuclear power, measured in Roentgens. ■ Electrical power, which is measured in Watts.
SYMBOL
P
PARAMETER
UNIT OF MEASURE
Power
Watts
✍ The law of Conservation The law of conservation of energy states that energy cannot be created or destroyed, only changed into some other form of energy. The same law is valid in audio circuits, where electrical energy is being converted into heat and sound.
of energy states that energy cannot be created or destroyed, only changed into some other form of energy.
In more advanced studies of electronics, you’ll come across the terms coulomb and joule. ■ A coulomb (pronounced koo-loam) is an electrical charge which contains 6.24 x 1018 of electrons.
✍ Coulomb is an electrical charge which contains 18
6.24 x 10
of electrons.
18
A joule (pronounced jew-el) is the energy required to move 6.24 x 10 electrons (one coulomb of charge) past a point in a circuit. ■ If one coulomb of charge moves past the point every second, the flow rate (current) is one ampere. ■
Since a watt represents the rate over time that energy (joules) is converted into work (heat, sound, light, etc.), then a watt represents the conversion of one joule per second into light, heat, sound, or some other form of work. ■
✍ Joule is the energy required 18
to move 6.24 x 10
electrons
(one coulomb of charge) past a point in a circuit.
✍ A watt represents the conversion of one joule
These definitions are not really necessary to know in every day installations; however, they help define the relationship between energy, power, and time. Getting back to Ohm’s Law, electrical power is equal to volts times amperes, or P = E x I. ■ One volt will move one amp through one ohm of resistance at a work rate of one watt. ■
per second into light, heat, sound, or some other form of work.
Resistors convert electrical energy into heat.
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Margin Notes
Remember that amperage is current flow per second, and therefore, a watt is rated in seconds. ■ Since power equals: E x I, we know from Ohm’s Law that E = I x R, P = I x R x I. This is the formula we will use to figure out the power (wattage) for most of our DC applications. ■
Here are some more ways Ohm’s Law can help you figure out different situations (in addition, see the full Ohm’s Law pie chart in the back of this book): ■ How would you find the total current (I) of an amplifier at the electrical system’s idle voltage? Simply divide the amplifier’s total root mean square (rms) wattage (P) by the vehicle’s idle voltage (E). ■ In a system with 250 Watts rms total audio output power, (125 Watts rms/channel into 4 Ohms) and an electrical system with a 12.6VDC, the equation would look like this: ■
250 = 19.84 Amps 12.6 This can appear to be complicated - but if you focus on each element in the equation, then it’s easy to understand. Here’s why it is important that you understand this equation: ■ It “tells” you what size wire to run from the battery to the amplifiers. ■ If the amplifiers are in the trunk. ■ You have a 15-foot cable run. ■ According to Figure 9, a #10 American Wire Gauge (AWG) cable is necessary to adequately power up this system. Ohm’s Law is indeed a very helpful tool to have in the bay.
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Margin Notes
30 0
12 5 15 0 20 175 0
40
30
50 60 70 80 90 10 0
50 45 40 35
20
10
1. 5
75
15
Am pe re s
100
40 0
30 25 20 15 12 10
20
■
18
16
14
12
10
8
6 4 Wire Size
2
1
1/0 2/0 3/0 4/0
Figure 9. Electrical Wire Chart.
POWER CABLE CALCULATOR Total Amperage Draw of System
Up to 4 Ft.
4 to 7 Ft.
7 to 10 Ft.
10 to 13 Ft.
13 to 16 Ft.
16 to 19 Ft.
19 to 22 Ft.
22 to 28 Ft.
0-20
14
12
12
10
10
8
8
8
20-35
12
10
8
8
6
6
6
4
35-50
10
8
8
6
4
4
4
4
50-65
8
8
6
4
4
4
4
2
65-85
6
6
4
4
2
2
2
0
85-105
6
6
4
2
2
2
2
0
105-125
4
4
4
2
0
0
0
0
125-150
2
2
2
0
0
0
0
00
The above chart shows wire gauges to be used, if no less than a .5 volt drop is accepted. If aluminum wire or tinned wire is used, the gauges should be of an even larger size to compensate. Cable gauge size calculation takes into account terminal connection resistance. ■
IASCA’s Recommended Minimum Wire Gauge Size.
Using the same example and applying it to IASCA rules - an international sanctioning body for sound-off events - you derive a much different answer. ■ The first formula is perfectly adequate for a system to operate safely. ■ In an effort to compensate for the power wasted by the amplifier, IASCA tends to overstate what is necessary for power conductors. CHAPTER 1 BASIC AND ADVANCED ELECTRICAL
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Margin Notes
IASCA uses the following formula: 250 x 2 = 500 (Watts) 500 (Watts) = 39.68 Amps 12.6(Volts) According to the IASCA wire table, this would require a #4 gauge AWG cable. For a 2 Ohm load, multiply by 2 again, as follows: 250 x 2 x 2 = 1,000 (Watts) 1,000 (Watts) = 79.37 Amps 12.6 (Volts) This would require a #2 gauge AWG cable. Whatever method you use, it is important to correctly identify the proper wire gauge to use in the installation. As a Mobile Electronics Installer, it is important for you to understand not only Ohm’s Law as a concept, but also its applications to everyday installation. Ohm’s law can figure out complex answers to installation questions by using the building blocks of current, voltage, resistance, and power. The facts don’t lie. Ohm’s Law can provide real answers to many mobile electronics questions. Now that we have covered Ohm’s Law, its time to move to more advanced formulas.
SERIES AND PARALLEL TOTAL RESISTANCE FORMULAS
One of the more important calculations you’ll make is to figure out how much of a load speakers will present to an amplifier. When designing a system, it is sometimes necessary to connect circuit components - such as speakers, inductors and capacitors - in series or parallel combinations. ■ There are occasions when combinations of multiple subwoofers in single or dual voice coil models could be optimum or be potentially damaged depending on the method of connection.
✍ Series and parallel combinations will have an effect not only on the source, which they are connected to, but on another as well.
38
■ Series and parallel combinations will have an effect not only on the source which they are connected to, but on one another as well. ■ It’s common practice to connect two loudspeakers in parallel. ■ When these “paralleled” speakers are connected to the amplifier, the combined speaker load will have a significant effect on how that amplifier performs.
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Therefore, understanding how series and parallel circuit relationships work is another useful tool, especially when you’re building crossover networks, installing multiple subwoofers, or performing system analysis.
Margin Notes
The drawing below shows resistors wired in parallel:
■
Figure 10. Resistors wired in parallel.
A series circuit is established when circuit components are connected in a string - end to end - so only one common terminal is shared between two components. Series circuits share current and divide voltage. ■ When resistors are connected in a series, the total resistance is the sum of the resistance of each component. ■ For example, when you’re trying to figure out the total resistance (Rt) of a series circuit, simply add up the numbers.
✍ A series circuit is established when circuit components are connected in a string, end to end, so that only one common terminal is shared between two components and they share the same current.
Resistance in a series circuit is additive, and the formula looks like this: Rt = R1 + R2 + R3…etc. In schematic form, it looks like this:
+ Resistor #1
#2
#3
Rt =Total Resistance Rt =R1 + R2 + R3 ■
Figure 11. Series Network.
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Margin Notes
✍ A parallel connection exists when circuit elements
Figuring parallel-total resistance formulas is a little more difficult. A parallel connection exists when circuit elements are connected so that two terminals are shared and voltage is common across the shared terminals. Parallel circuits share voltage and divide current.
are connected so that two terminals are shared and voltage is common across
When two devices (resistors, for example) are connected in parallel, the formula is as follows:
the shared terminals.
Rt = R1 x R2 R1 + R2 In schematic form, it looks like this:
Resistor #1
R1
Resistor #2
R2
+
-
■
Rt = R1 X R2 R1 + R2 Figure 12. Parallel Circuit.
Assuming that we have a 4 Ohm and an 8 Ohm resistance (similar to common speakers resistance): Rt = R1 x R2 R1 + R2 Rt = 4 x 8 4+8 Rt = 32 12 Rt = 2.67 Ohms
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Schematically, a parallel circuit with more than two resistances looks like this:
■
Margin Notes
Figure 13. Parallel Circuit with more than two resistances.
If more than two resistances are wired in parallel circuit and need to be figured into the total resistance, use the following formula: 1
R = 1 R1
1 R2
1 R3
+ …
1 RN
This formula can look complicated, but is easily accomplished with a calculator. Let’s say we are trying to solve a parallel circuit with three resistors: a 4 ohm, a 6 ohm, and an 8 ohm. Using the calculator’s 1/X function we can solve the equation in this manner. (4) (1/X) + (6) (1/X) + (8) (1/X) = (1/X) = Answer (The 1/X function takes 1 and divides it by the value of the resistor or answer. Your calculator might use the X-1 function instead, it does the same thing as 1/X.) To figure the parallel resistance of two speakers when both are the same impedance, simply divide one of the speaker’s resistances by two. ■ Remember, when devices are wired in parallel, the total resistance is always less than the resistance of the component with the smallest value. Always keep this in mind: The wiring of automobile, audio, cellular, and security systems are in parallel with the car’s battery, and they are powered by the battery. ■ Current flows through the system from the positive battery terminal to the power input of the system, through the system, through the body of the car, then it goes back to the negative terminal of the battery.
✍ Remember, when devices are wired in parallel, the total resistance is always less than the resistance of the component with the smallest value.
■ Each of these systems also has a power switch that is wired in series ultimately from the battery’s positive source to the equipment.
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Margin Notes
Series and Parallel Capacitors (to clarify the one exception to the rule) ■ Series Inductors and Resistors use the above formula for SERIES WIRING. The same SERIES FORMULA applies to PARALLEL CAPACITORS. ■ Parallel Inductors and Resistors use the above formula for PARALLEL WIRING. The same PARALLEL FORMULA applies to SERIES CAPACITORS.
KIRCHOFF’S VOLTAGE LAW
We’ve seen from some of the previous examples that single resistor circuit analysis can be figured out by using Ohm’s Law. More complicated circuit analysis, however, requires an understanding of another important electrical law Kirchoff’s Voltage Law (KVL).
✍ Kirchoff’s Voltage Law (KVL) states that the voltage
Kirchoff’s Voltage Law (KVL) states that the voltage applied to a DC series circuit must equal the sum of the voltage drops within the circuit.
applied to a DC series circuit
Vt = VR1 + VR2 + VR3.........( + Vn)
must equal the sum of the voltage drops within the circuit.
Where: Vt is the applied voltage, VR1 is the voltage drop across resistor #1, VR2 is the voltage drop across resistor #2, etc. and Vn is the remaining voltage after all of the measured drops. In other words, if you add up all the voltage drops across each individual component, the total equals the applied voltage. ■ This means that one volt dropped through wiring or connectors in a system will reduce the voltage to the equipment by one volt. This is especially true in practical applications, for example in multiple speaker or subwoofer (single and dual voice coil) installations. ■ Each speaker wired down the line to the same power cable would get a little less power to it than the one before it. Often overlooked, even in the simplest of installations, is that one bad connection or poorly crimped terminal can affect the voltage for that series section, but not for the whole system. That could explain all kinds of otherwise mysterious speaker behavior. ■
KIRCHOFF’S CURRENT LAW
Kirchoff’s Voltage Law will help you determine single loop circuits; however, solving parallel circuits which have multiple loops requires the use of Kirchoff’s Current Law (KCL):
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This law states that the total current entering a point or junction in a circuit must equal the sum of the currents leaving that point or junction. ■
Margin Notes
✍ Kirchoff’s Current Law
It = IR1 + IR2 + IR3.........( + In) Where: It is the total current, IR1 is the sum of current #1, IR2 is the sum of current #2, etc. and In is the remaining current after all of the other measured currents. Think of your power and ground connections as one big loop from and to the battery. ■ A heavy gauge ground wire is just as important, if not more so, as the power wire gauge. ■ Too small a gauge ground wire will develop a voltage drop which may also cause the amplifiers to overheat, motorboat, or fail.
states that the total current entering a point or junction in a circuit must equal the sum of the currents leaving that point or junction.
CURRENT FLOW
In the front part of this section, we covered many of the basic and advanced electrical laws you will need to know. Before we continue on to electrical components, we need to clarify current flow. There are two schools of thought on which direction current flows: 1 Conventional current flow - current flows from positive to negative in the direction voltage drops across a resistor. 2 Electron flow - current flows in the direction that electrons flow from negative to positive.
✍ According to conventional current flow, current flows from positive to negative in the direction voltage drops across a resistor.
✍ According to electron Conventional Current Flow
Electron Flow
flow, current flows in the direction that electrons flow from negative to positive.
+
+ Current
Battery
-
■
+
Resistive Load
-
+ Current
Battery
-
Resistive Load
-
Figure 14. Conventional current flow and electron flow.
Which theory is correct? Even the “experts” disagree: Scientists generally analyze circuits with the scientifically accurate, but harder to understand “electron flow” theory, which states that electrons travel from negative to positive. ■
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■ Engineers analyze circuits with “conventional current flow” theory, where current flows from higher voltage potential to lower voltage potential.
Either method - when properly applied - will result in the same answer when analyzing a circuit.
Section 2 Electrical Components With those formulas in mind, let’s look at some of the electrical components you’ll be using to improve system design and performance.
RESISTORS
✍ A resistor is an electrical component designed to have a specific resistance (or opposition) to the flow of electrons, measured in ohms.
For installers, the actual definition of a resistor is not as important as the concept behind resistance. For test purposes, however, a resistor is defined as an electrical component designed to have a specific resistance (or opposition) to the flow of electrons, measured in ohms. The concept of resistance was introduced in Section 1. It describes the property that some materials posses to restrict the flow of current. ■ Resistance is generally an undesirable characteristic in mobile electronics wiring. There are instances where an installer will use a resistor to introduce a specific resistance. ■ Resistance can be added to a signal cable to reduce the input signal voltage to an amplifier. ■ Power resistors can be used to reduce the amount of power to a speaker (essentially changing the speakers sensitivity) to connect left and right amplifier outputs into one speaker (center channel, rear mono speakers), or to change the ohm load that a passive crossover sees. ■
Resistors come in all values and power ratings: ■ The most common values are between .1 and 10 million Ohms, with power ratings of 1/8, 1/4, & 1/2 Watts for signal work, or 5, 10, 25 and up to 1,000 Watts and higher for power work. ■ A resistor’s wattage rating indicates how much electrical energy can be safely converted to heat. CAUTION: All resistors can produce heat, and you want be sure that this heat does not create a fire hazard. 44
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Remember that resistance is measured in ohms, and the color bands on the outside of a resistor indicate its value. Figure 15 shows the color band system of resistors. Use the Resistor Color Code Chart below to figure out the value of a particular resistor. When you’re using a Digital Multimeter (DMM) or analog Volt-Ohm Meter (VOM), resistance is measured on an R X (1,10, 100, 1,000) scale. Resistance values are expressed in Ohms Ω. Multiplier
Multiplier
Tolerance
2nd significant figure 1st significant figure
Tolerance
Margin Notes
Failure Rate
2nd significant figure 1st significant figure
Resistors with black body are composition. non-insulated. Resistors with colored body are composition. insulated. Wire wound Resistors have the 1st color band double width.
■
Figure 15. Color Band System (Two Significant Figures).
RESISTOR COLOR CODE
Color Black Brown Red Orange Yellow Green Blue Violet Gray White Gold Silver No Color
Significant Figures 0 1 2 3 4 5 6 7 8 9
_ _ _
Multiplier
Tolerance
Failure Rate*
1 10 100 1,000 10,000 100,000 1,000,000 10,000,000 100,000,000
±20 ±1 ±2 ±3 ±4 _ _ _ _ _
_
0.1 0.01
±5 ±10 ±20
1.0 0.1 0.01 0.001 _ _ _ _ Solderable*
_ _ _
Troubleshooting Resistors - Troubleshooting resistive problems are pretty straight forward since resistors almost always open when they go bad. An open resistor in a series circuit will stop current from flowing in the circuit. An open resistor in a parallel circuit will increase the circuit resistance and decrease the total current.
■
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✍ A potentiometer is an adjustable or variable
POTENTIOMETERS
A potentiometer is an adjustable or variable resistor. ■ It has connection points at each end of the resistive material and has a movable center contact known as a “wiper” that can be manually positioned anywhere along the body of the resistive material between the two contacts. A potentiometer is sometimes called a “pot” for short.
resistor.
Potentiometers have broad applications in this field: ■ In audio: to control volume, tone, and balance levels. ■
In security: to control sensor sensitivity.
As the wiper is adjusted, the ratio of resistance between the center contact and each end contact is changed. ■ An audio signal applied to one end point and measured at the wiper will change in level as the wiper is repositioned. ■ This is how volume and tone controls accomplish their missions, and why they are sometimes called variable voltage dividers.
SINGLE-GANG
DUAL-GANG
A 1 2
WIPER
3
1
2
B
2
1 3
3
1
SHAFT
2 B
3
A
■
Figure 16. Common Potentiometers.
Troubleshooting Potentiometers - Troubleshooting or checking a potentiometer to see if it is good takes a few steps. Because a potentiometer has a mechanical feature we can not rule out its failure and must check its operation. ■
■ Since a potentiometer has three leads, and two leads are tied to the full resistance, it can troubleshoot just like a typical resistor. The third lead is tied to the wiper arm and traverses the length of the resistor element. The wiper arm can be bent or broken and cause the resistance between it and either other lead to be intermittent, infinite, or stationary when you try to adjust the potentiometer.
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INDUCTORS
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An inductor is an example of an electronic component that possesses the property of inductance. Inductance is the property that a component possesses that opposes any change in current flow. ■ While resistance limits the flow of current in a circuit (regardless of the frequency), inductance opposes any change in the current.
■
Think of an inductor as being like a flywheel. The flywheel has inertia, and once it’s spinning at a certain RPM, it will resist any changes in RPM and continue to spin at a fixed rate.
✍ Inductance is the property that a component possesses that opposes any change in current flow.
Coils have this property of inductance. Therefore, inductors are coils of wire that resist changes in the flow of current through them. ■ High frequency signals represent rapidly changing currents. Therefore, inductors can be used to limit the strength of higher frequency signals, while still allowing lower frequencies to pass. An inductor wired in series with a subwoofer allows the low frequency audio signal to power the speaker but blocks the higher frequency signals, creating a low-pass passive crossover. ■ In this case, AC is the audio output from an amplifier. ■
Different values of inductors establish different crossover frequency values.
■
Inductor values are measured in Henries.
✍ Inductor values are
■
1,000 Millihenries = 1 Henry.
expressed in Henries.
■
Millihenries are written simply as “mH”.
Figure 17. Inductor Symbols. Top: Air-core. Middle: Ferrite-core. Bottom: Iron-core.
■
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Figure 18. Ferrite-core Inductor Construction.
■
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■
Figure 19. Inductors (coils).
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Margin Notes
Applying the series connection formulas we discussed in Section 1, when inductors are connected in series, the total inductance is the sum of the inductance of each component: Lt = L1 + L2 + L3... + Ln When inductors are connected in parallel, the formula looks like this: Lt = L1 x L2 L1 + L2
CAPACITORS
A capacitor is an electronic component that possesses the property of capacitance.
✍ Capacitance is the property of an electronic component that opposes a change in voltage across the component.
Capacitance is the property of an electronic component that opposes change in voltage across the component. ■
Capacitors are constructed by separating two or more conductors - called plates - with an insulator, called a dielectric. ■ A typical construction is two long strips of aluminum foil with plastic sheeting between the foil sheets, which is wound up to minimize its size. ■ If an AC signal is applied to its plates, the current will flow through the capacitor. What actually happens is that if an AC signal is applied to the plates, the capacitor will charge one way (hence current flows), then when the AC signal reverses direction the capacitor discharges and then charges in that direction (again current flows), this action makes it appear that AC current is flowing through the capacitor. ■ A DC voltage connected to the plates will not pass through the dielectric, and no direct current will flow. This will appear to look like an open circuit. ■
In the mobile electronics environment, capacitors have many uses: ■ They allow passage of high frequency energy (tweeter capacitors). ■ They store an electrical charge for use later. ■ They block the passage of DC (accessory noise suppression). ■ They attenuate low frequency energy (midrange capacitors).
✍ There are many types of capacitors. The three most popular are polypropylene, Mylar, and electrolytic.
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There are many types of capacitors. The three most popular are: 1 Polypropylene. 2 Mylar. 3 Electrolytic.
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Polypropylene and Mylar are known for their excellent sound quality and are used for the higher crossover frequencies. ■ Most installers agree that the difference in sound quality between polypropylene, Mylar, and electrolytic is minor in the lower frequencies.
Margin Notes
A capacitor wired in series with a tweeter and connected to an amplifier will allow the amplifier’s high frequency signal to power the tweeter, while limiting the lower frequency signals, thus creating a high-pass passive crossover. Capacitor values are expressed in Farads. Capacitance for mobile electronics applications is usually measured in Microfarads (µF). 1 million Microfarads (µF) = 1 Farad.
✍ Capacitance for mobile electronics applications is usually measured in Microfarads (µF).
■
Figure 20 ■
■
■
Figure 21.
Figure 23 ■
■
Figure 24
Figure 25
■
■
Figure 22
Figure 26
Figures 20 - 26. Various capacitors.
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Margin Notes
Regardless of type, all capacitors have a tolerance rating, which is stated as a plus or minus percentage. ■ The smaller the percentage, the more accurate the crossover frequency. Capacitors are also rated by voltage (maximum voltage applied). ■ This rating is very important to observe when constructing passive crossovers, since the amplifier output (AC voltage) may be far higher 12 volts. Many capacitors used in passive crossover networks use 50v and 100v ratings. ■ Other capacitors used for power applications might use 16v, 18v, 20v, or 24v ratings such as the input storage and filter capacitors in amplifier power supplies and “stiffening capacitors” for example.
Some capacitors are “polar” electrolytic capacitors that have a negative and a positive terminal and must be installed in the proper electrical orientation. ■ These types of capacitors are not used in crossover work, but are used in power supply circuits (such as a “stiffening capacitor”) or in noise suppression and filtering circuits on an automotive distributor, coil, or alternator. Remember! For series and parallel combinations, the formula used to find total capacitance is the opposite to that of a resistor or inductor. In series, the formula looks like this: CTOTAL
C1
C2
C3
Cn 1
CTOTAL = 1 C1 ■
+
1 C2
+
1 C3
………
1 Cn
Figure 27. Capacitor Formula.
When capacitors are connected in parallel, the total capacitance (Ct) is the sum of each component: Ct = C1 + C2 + C3... + Cn
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FUSES AND CIRCUIT BREAKERS
Margin Notes
If installed properly, a fuse can save you a lot of time and headaches. Think of a fuse as cheap insurance. ■ A fuse is simply a device that contains a wire or strip of metal which is installed in series with a power line. ■ This strip of metal is designed to melt if it receives an excessive amount of current.
✍ A fuse is simply a device that contains a wire or strip of metal which is installed in series with a power line.
Fuses are used as a safeguard against circuit or system damage. For example, if you have a customer who is a bit aggressive with the volume control of his stereo system, you can protect his tweeters from “blowing” by installing a fuse - in series with the tweeter. To determine the proper amperage of the fuse, you’ll need to know the ohm load of the tweeter as well as its continuous or nominal power rating. ■ The formula to find the amperage of the proper fuse is equal to the square root of the continuous power handling, divided by the ohm load of the tweeter. Amperage = Square root of Continuous Power/Ohm load. Sometimes you’ll run across a situation where the recommended fuse value is higher than the largest available fuse. ■ You could install fuses in a parallel combination, but that can get bulky. A circuit breaker works better in these situations, because like fuses, they are designed to blow (or open) when the current becomes excessive. ■ A circuit breaker is different from a fuse in that it usually can be reset. Circuit breakers that can be reset come as 2 types - Manual Resetting or Auto Resetting. ■
A circuit breaker is a device placed in series with a power line which, when an excess amount of current is sensed, will open the power connection, thus protecting a circuit or system. For protection at the battery, use either a fuse or a circuit breaker. The idea behind these devices is simply to open the circuit before any wires burn.
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✍ A circuit breaker is a device placed in series with a power line which, when an excess amount of current is sensed, will open the power connection, thus protecting a circuit or system.
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Margin Notes
Section 3 Basic Electrical Troubleshooting Now that you’re familiar with many of the electrical components used in mobile installations, it’s time to discuss common problems that occur when some of these components fail or are improperly installed.
VOLTAGE DROPS
✍ A bad connection or any point of resistance in the power circuit will cause a voltage drop.
In Section 1, you learned about resistance and how it opposes the flow of current. ■ When a device in a circuit has resistance, it will convert an amount of energy into heat, which results in a certain amount of power loss. ■ This loss is commonly referred to as a voltage drop. ■ A bad connection or any point of resistance in the power circuit will cause a voltage drop. A drop in voltage can manifest itself in a variety of ways: ■ Voltage drops result in poor performance, which a customer could attribute to a particular product. ■ Often, it has nothing to do with the product, but with the misapplication during an installation. Here’s an example of the multiple possibilities for voltage drops to occur: ■ When a power window is activated, a circuit is completed. ■ This circuit starts from the positive “+” battery terminal and runs through the key switch accessory terminal, the fuse block, and then through the pressed window switch and one window motor lead. ■ It then runs out the other motor lead, through the un-pressed window switch, through the chassis ground and the metal of the vehicle, and finally, through the battery ground strap to the negative terminal of the battery. In an ideal world, the load on the battery would be determined by the motor’s electrical characteristics. In the real world, the motor determines most of the load unless there is a circuit problem. ■ If a switch contact wears, or a connector corrodes, the motor may not receive the power it requires. ■ The circuit problem prevents full power from reaching the motor; some of the voltage that would normally go to the motor is lost across a weak circuit connection or contact.
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A loss can also occur if you install a window roll-up system and make wiring connections with smaller gauge wire than that of the stock wiring (See the figure below). ■
TO OTHER WINDOW
motor
M motor
BATTERY
IGNITION KEY
VEHICLE CHASSIS
■
Figure 28.
■
Figure 29.
■
Figures 28 - 31 Power Window Circuits.
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■
Figure 30.
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■
Figure 31.
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Margin Notes
VOLTAGE DROPS - SERIES CIRCUITS
In our discussion on series circuits, we mentioned that resistance in a series circuit is additive.
✍ Adding up the resistances
Adding up the resistances will give you the total resistance of the circuit.
will give you the total resis-
If the current flowing in a series circuit needs to be known (amperage), go back to Ohm’s Law, I = E/R. ■ Current remains the same anywhere it’s measured in a series circuit. ■ Add the total series resistances together and divide by the voltage. ■ To find the voltage, or voltage drop, across each resistance in the circuit, use another Ohm’s Law, E = I x R. ■ Multiply the total circuit amperage times each individual device’s resistance to obtain the voltage drop across that device.
tance of the circuit.
✍ The sum of the individual voltage drops in a series circuit must be equal to the applied voltage.
Voltage in a series circuit is distributed among the devices in that circuit, according to their resistance. The sum of the individual voltage drops in a series circuit must be equal to the applied voltage. For example, in the following diagram, with an input voltage of 6 Volts, the voltage drop across each of the lamps is 2 Volts. 2 VOLTS
V R = 10Ω
+ 6 VOLTS
-
-
+
R = 10Ω
-
+
-
V 2 VOLTS
+
R = 10Ω
V 2 VOLTS ■
Figure 32. Electrical Diagram.
In a parallel circuit, as the next diagram illustrates, the voltmeter reading has absolutely nothing to do with the value of the resistor, as the probes of the meter are theoretically connected directly across the power supply.
12v
■
54
R1 2.2kΩ
R2 1.5kΩ
vm
R3 3.6kΩ
R4 4.7kΩ
vm
Figure 33. Electrical Diagram.
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GROUND LOOPS
Margin Notes
A ground loop is probably the greatest cause of noise problems in car audio. ■ A ground loop is more than one ground path where the differences in current potential of each path create a voltage differential. ■ This can allow alternator whine to enter the system, as well as other problems. A ground loop is created by any non-zero resistances between the wiring paths used to ground or interconnect each piece of equipment. Even the frame of the vehicle itself, which is the battery ground of the car, can have varying voltage differentials caused by current flowing through different circuit paths in the frame.
✍ A ground loop is more than one ground path where the differences in current potential of each path create a voltage differential.
✍ A ground loop is created by any non-zero resistances between the wiring paths used to ground or intercon-
Chassis Dash
+
nect each piece of equipment.
-
Battery Antenna Firewall -+ RCA'S - + Head unit Amplifier
Chassis Fender
Chassis Body
■
Figure 34. Typical ground loops.
In today’s high powered audio systems, the supply current can easily be over 50 amps. Even a .01 Ohm resistance caused by a faulty crimp connection or corrosion can develop up to a .5 volt drop, which could create a source for system noise. The alternator produces pulsating DC voltage, and the battery filters out most but not all - of the ripple. Ripple is the residual AC left on the line after it has been rectified into DC. The ripple is generally variable in frequency and determined by engine speed (alternator spin). Some ripple current will always be present on the supply line and the chassis ground of the vehicle if the engine is running. The bigger the alternator output capability, generally the more ripple it will produce. ■ This can create noise in an audio system. ■ That’s why it’s extremely important to measure your ground points back to battery ground and with each other. ■
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■ Most good audio products have sufficient filtering on their +12 Volt lines, but not on the ground side. ■ Multiple ground points to the frame can allow small voltage drops to be created. Even the smallest voltage drop can carry alternator noise on it because the frequency of the AC output of an alternator is within the audible range of your sound system.
Volts
Volts
12
12
12
0
■
Volts
Time
0
Time
0
Time
Figure 35. Ripple on +12VDC.
Single point - or single area - grounding is always preferable whenever possible. ■ Though it may not be practical to have a single ground point - unless the radio, equalizer, and amplifier are in close proximity to each other - you want to avoid long high current ground wire runs. ■ This can result in enough resistance to cause a ground loop. A good ground point for the current drawing equipment - radio, equalizer, crossover, etc. - is at the firewall, and one good ground point for the high current drawing amplifiers at the trunk will work. Make sure you have referenced the two ground points back to the battery and to each other, and have no significant voltage drops (two-tenths of a volt or less). ■
Audio system wiring normally has higher resistance than the power system wiring. ■ The higher the resistance, the easier it is for the noise to enter. ■ Low quality, poorly shielded interconnect cables can easily allow noise to enter the system. ■ This is also why high voltage, low source impedance headunits units work well for noise rejection in addition to the other signal transmission advantages.
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SHORT CIRCUIT
Margin Notes
Since Kirchoff’s Voltage Law states that the voltages dropped in a series circuit must add up to the supply voltage, if a piece of equipment is short circuited, or the wiring becomes shorted out, the voltage dropped across it is reduced to 0 Volts. ■ Since the total of all voltage drops in a circuit must equal the supply voltage, more voltage must be dropped across the circuit’s wiring and connections. The current in the circuit is equal to the supply voltage divided by the total resistance. ■
✍ The current in the circuit is equal to the supply voltage divided by the total resistance.
As the resistance approaches 0 Ohms, the current in the circuit increases dramatically and often dangerously. ■ In automotive circuits, currents can easily be in excess of 200-300 Amps, resulting in melted wiring looms and electrical fires. Educated installers wire fuses at the battery to protect their circuits from the expensive, catastrophic failures short circuits can produce. ■ A short circuit will bypass any resistance (speaker, lamp) in a circuit and cause it not to operate. ■
The following diagram shows a short circuit in operation. The voltage needed to turn on the light bypasses it:
R LAMP = 8Ω SHORT CIRCUIT = 0Ω
■
Figure 36. Short Circuit Diagram.
Equate this with a power wire coming from a battery to trunk-mounted amplifiers and the wire has no fusing at the battery. ■ The fuse at the battery is NOT to protect the amplifier, but to protect the wire. ■ This power wire could either be punctured by a screw when the sill molding is put back on the vehicle, or pinched under the back seat.
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✍ The fuse at the battery is NOT to protect the amplifier, but to protect the wire.
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Using what you have learned so far, you can see that the equipment connected to the wiring will be bypassed and will not operate. ■ To avoid a short circuit and severe damage to the car, ALWAYS FUSE A POWER CABLE AT THE BATTERY AS CLOSE TO THE BATTERY AS POSSIBLE, BUT AT A MINIUM OF 10 INCHES FROM THE BATTERY TERMINAL. IASCA rules require no more than 18 inches from the battery, but for the purpose of this study we will use the MECP standard. ■
The same thing can happen to speaker leads. ■ When one is shorted to ground, the amplifiers may not work, or may give the appearance of motorboating at about half volume. ■ Most modern amplifiers have “short stopping” ability, and the amp can protect itself.
✍ An open circuit is a circuit through which no current can flow.
OPEN/CLOSED CIRCUITS
An open circuit is a circuit through which no current can flow. ■ Open circuits can be caused by something as obvious as a switch being off (or open). ■ Open circuits can be caused by something not as visible, such as a light bulb filament being burned out (open), the voice coil of a speaker being open, or even corroded terminals. ■ In any event, in a series circuit, when one device becomes open, the rest of the circuit will not work. ■ In parallel circuits, only that device which is open will not work while the circuit voltage will still be available for the remaining devices. Example of a series circuit: Certain types of Christmas tree lights in which the whole string goes out if one bulb goes out. Example of a parallel circuit: The lights in your home - if one light burns out, the others remain operational.
✍ Clipping is usually caused when a power amplifier is driven into saturation.
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CLIPPING
Clipping is distortion that’s usually caused when a power amplifier is driven into saturation. ■ Saturation occurs when an amplifier’s input exceeds its operational limit. ■ Example #1: If a 12-Volt supply powered an amplifier with a gain of 30 to 1, a signal of 1/2 Volt peak-to-peak is applied to its input.
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The output would try to produce a signal of 30 times 1/2 Volt (15 Volts) to the speakers. ■
Margin Notes
This 15-Volt signal could not be produced because the supply voltage is only 12 Volts. ■
■
The output signal would be distorted (clipped) at the top and bottom. ■ Example #2: - If the output rails of the amplifier are (+) and (-) 20 volts and the gain setting is set for a gain of 10.
As long as the input signal was lower than (+) or (-) 2 volts the output would be a non-distorted representation of the input. ■
■ Once the input went above that level, say (+) and (-) 2.5 volts (the amplifier would try to put out (+) and (-) 25 volts) the tops and bottoms above the rails would be cutoff because the max output is (+) and (-) 20 volts.
This would look like a square wave on an oscilloscope as pictured in figure below. ■
NORMAL AUDIO SIGNAL
CLIPPED AUDIO SIGNAL
■
Figure 37. Normal and clipped audio signals.
Clipping - particularly at high frequencies - will burn out a tweeter’s voice coil. ■ Distortion, or clipping, will blow a tweeter faster than too much power or too low a crossover point. While it’s true that a respectable amount of power to handle the instant demands of musical peaks and valleys is necessary for clipping-free operation, 200 Watts rms into a tweeter designed to take only 50 Watts rms will eventually damage the voice coil. ■
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✍ A filter is a component or a combination of circuit components which select or limit a signal as a function of the signal’s frequency.
✍ Digital filters are commonly used in Compact Disc players to eliminate noise caused by the sampling clock.
✍ Active filters are built with components such as operational amplifiers or transistors in circuits which require some form of external power.
✍ Passive filters provide no
Section 4 Filters Applied to mobile electronics, a filter is a component, or a combination of circuit components, which select or limit a signal as a function of the signal’s frequency. ■ In the simplest of examples, they work like a coffee filter which allows the coffee to pass through the filter, while stopping the ground coffee beans. An electrical filter allows some frequencies to pass through the circuit unchanged, while other frequencies are stopped (attenuated) by the filter. ■
Filters are used in numerous applications: 1 Digital filters are commonly used in Compact Disc players to eliminate noise caused by the sampling clock. 2 Active filters are built with components - such as operational amplifiers or transistors - in circuits which require some form of external power. ■ Active filters are used in many low level signal applications, such as tone controls and equalizers. 3 Passive filters provide no amplification and are made of resistors, capacitors, and inductors. ■ Passive filters are very effective for reducing engine noise, but the most common use for passive filters are as crossover and equalization networks.
amplification and are made of resistors, capacitors,
PASSIVE CROSSOVERS
and inductors.
Passive crossovers are used in many applications in the mobile electronics industry, especially with today’s coaxial and triaxial speaker systems. ■ A passive crossover separates the amplified audio signal into selected frequency bands. These bands of frequency are then directed to a loudspeaker that is designed for its reproduction. ■ A capacitor will send only the highs to the tweeter in a two-way (coaxial) system, or to the mid and tweeter in a three-way system. ■ This is a passive crossover in its most simple application.
✍ A passive crossover separates the amplified audio signal into selected frequency bands.
Using a passive crossover is the most efficient and least expensive way to design a speaker system in which certain frequencies are directed to a tweeter (highs) or a mid-bass driver (lows). ■ A passive crossover for a basic two-way system consists of one capacitor for the tweeter and one inductor for the woofer.
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In a passive crossover for a three-way system, one coil goes in series with the woofer; one coil and one capacitor go in series with the midrange; and one capacitor goes in series with the tweeter. ■
Margin Notes
✍ A passive crossover for a 6 dB / Octave
6 dB / Octave
HIGH L
L
+
W
AMP
sists of one capacitor for the tweeter and one inductor for
+
the woofer. M
AMP
–
–
LOW C
+
+
basic two-way system con-
–
–
6 dB / Octave C
+
+ T
AMP
–
– ■
Figure 38. A 6 dB passive crossover network.
The rate at which a passive crossover blocks or passes frequencies above or below the crossover point is expressed in dB’s per octave. ■ This is usually shown as a crossover slope (6 dB, 12 dB, or 18 dB), or a crossover order (1st order, 2nd order, or 3rd order).
✍ The rate at which a passive crossover blocks or passes frequencies above or below the crossover point is
OUTPUT
expressed in dB’s per octave.
1st-order 2nd-order 3rd-order
20
■
200
2000 FREQUENCY (Hz)
20000
Figure 39. Different crossover orders.
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✍ A bandpass filter incorpo-
BANDPASS FILTERS
A bandpass filter incorporates both high-pass and low-pass filters in order to limit and attenuate both ends of a frequency range. It will pass signals with frequencies above or below the “pass band.”
rates both high-pass and low-pass filters in order to limit and attenuate both ends of a frequency range.
Tweeter High-Pass
Midrange Low-Pass
Band-Pass
Band-Pass
High-Pass
Woofer Low-Pass ■
Figure 40. Typical crossover bands.
Section 5 Relays, Batteries and Cable
✍ A relay is an electromechanical device that uses a coil (electro) to move switch contacts (mechanical).
One of the most important electrical components is the relay. ■ A relay is an electromechanical device that uses a coil (electro) to move switch contacts (mechanical); it really is nothing more than an electromagnetically controlled switch. ■ The coil can be energized with a small amount of power while the switch contacts can be used for any number of applications, including high power circuits or reversing the polarity of a control signal. The most common applications of a relay are to provide: ■ Circuit isolation. ■ Signal inverting. ■ Increasing/decreasing current handling. ■ Logic level shifting. ■ Transfer switching.
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A relay is essentially made up of three separate sections: 1 An electromagnetic coil. 2 Movable contact(s). 3 One or more sets of stationary contact(s).
Margin Notes
Anything that can be done with a switch can be controlled by a relay. ■ The primary difference between a simple switch and a relay is that the switch contacts of a relay are controlled by magnetic force (the relay coil), while the contacts of a simple switch are controlled by manual force (your finger). Switches, like relays, come in all varieties and types. The important specifications of a switch are its: ■ Contact arrangement. ■ Current handling capability. ■ Switching characteristics. ■ Switching function. These characteristics should be considered when you’re selecting a relay for a particular task. Relays are often used in security system installations to control such things as: ■ Starter interrupts. ■ Door locking circuits. ■ Power window and sunroof circuits. ■ Flashing parking lights. ■ Power trunk/hatch releases. ■ Air horns. ■ Sirens. ■ Triggers. ■ Sensors. ■ Garage door openers. A modern security system installation usually depends on several relays to make everything work. The main elements of a relay are the coil, the spring, and the contacts. ■ These elements determine how the relay is to be rated by the manufacturer and used by the installer. ■ A typical 12-Volt Bosch relay requires a coil current of .150 Amps to energize. (Again, ohms law can be used to find the current which will change slightly based on the voltage applied to the coil. Measuring the resistance and dividing the voltage by the resistance will give you the current).
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✍ The main elements of a relay are the coil, the spring, and the contacts.
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■ The relay contacts can switch current up to their rated amperage value, but in most of the mobile electronics applications we will use 30 to 40 amp ratings. ■ The power gain of this relay is as high as 200 to 1, and is one reason relays are often found in high current automotive circuits. ■ In most circuits, a relatively weak control signal (or trigger) is used to make the relay control a higher current or voltage circuit. An alarm system’s output energizes the coil, which magnetically closes (or opens) the much heavier duty contacts, allowing the desired action to result.
Below is an illustration of the bottom of a Bosch relay (the brand we’ve chosen as an example): A schematic of a Bosch relay looks like this: 87 86
87a
85
30
SPDT ■
Figure 41. Bosch relay.
85
87
87a
86
30
SPDT ■
Figure 42. Bosch relay schematic.
The Terminals of a Bosch Type Relay are Defined as:
64
30
C
=
(Common)
87a
N/C
=
(Normally Closed)
87
N/O
=
(Normally Open)
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The relay Coil (85 and 86) This is what is powered, either by a 12-Volt trigger to 85 (or 86) with 86 (or 85) to ground, or with a negative trigger (common on alarm systems) to 85 (or 86), and 12-Volt CONSTANT to the other pin (86 or 85). ■ Usually, it doesn’t matter whether pin 85 or 86 is used for ground or 12 Volt; either way will activate the coil. ■ Whenever the relay has an INTERNAL SPIKE SUPPRESSION DIODE, 85 must always be the Negative (-) terminal and 86 must always be the Positive (+) terminal. This is so that the diode functions properly and protects the “driver” which activates the relay from the reverse voltage that’s generated when the coil field collapses. This is the case when many vehicle control computers activate relays. Most OEM relays are wired this way. If you also get in the habit of using this method it could help avoid surprise problems in future installations and aid in the diagnosis of OEM related relay problems. ■ By using either of the above methods, the coil will magnetically actuate, opening contacts 30 and 87a, while transferring the circuit path by closing 30 and 87. ■ This type of relay is known as a Single Pole Double Throw relay (SPDT).
Margin Notes
✍ Whenever the relay has an INTERNAL SPIKE SUPPRESSION DIODE, 85 must always be the Negative (-) terminal and 86 must always be the Positive (+) terminal.
30 Terminal 30 is common. One side of whatever is being controlled goes here. 30 and 87A Normally closed (NC). 30 and 87 Normally open (NO). 87a
87
30
AT REST ■
87a
87
30
ENERGIZED
Figure 43. Bosch relay schematic.
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In examining the relay in an electrical circuit, we can see that a conduction path between contacts is physically transferred when the relay is energized. ■ With the relay not energized and at rest, a circuit exists between the movable contact assembly (the common contact) and the first stationary contact assembly (the normally closed contact). ■ When the coil is energized, the pole piece moves the movable contact(s) away from the first stationary contact assembly and physically switches the movable contact(s) to the second stationary contact assembly (normally open contact). ■ This movement of the pole piece transfers the circuit path from the movable contact assembly to a second stationary contact assembly.
The following diagrams show the other types of commonly used automotive relays: 85
87
87
87 86
87
85
30 86
30
SPST
SPST 86
87b
87
87 86
87b
85
30 85
30
SPST
■
66
SPST
Figure 44. Other types of automotive relays.
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BATTERIES
Margin Notes
The vehicle battery is a chemical energy storage device and the power source to start the engine. ■ A battery has many purposes, but one common misconception is that it is the primary source of electrical power while the vehicle is being driven. ■ In reality, once the engine is running, the alternator is the primary source of electrical power while the vehicle is being driven. ■ Although batteries offer only direct current, alternating current is produced by the alternator. This AC is then rectified by diodes into direct current to recharge the battery and supply the vehicle’s circuits with the necessary power.
The following diagram shows a common automotive battery:
■
Figure 45. Automobile battery.
✍ The term rectification refers to the process of
The term rectification refers to the process of changing AC to DC current.
changing AC to DC current.
The vehicle’s battery is sometimes referred to as the electrical system’s largest capacitor. This is due to its characteristic of resisting any change in the voltage across it, and to its ability to be discharged and recharged. These characteristics enable it to smooth out transient ripple currents in a system.
✍ The vehicle’s battery is
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sometimes referred to as the electrical system’s largest capacitor.
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A car lead-acid type battery is made up of six cells. ■ In a fully charged 12-Volt battery with no load on it (open circuit), each cell has a nominal voltage output of 2.11 Volts. ■ The battery fluid is called electrolyte, which is sulfuric acid and water. ■ When a circuit is powered by the battery, a chemical reaction takes place inside the cells between its electrolyte and lead plates, and a current flow is established. ■ When the battery is recharging, the chemical reaction not only stops, but is reversed, allowing the electrical charging energy to be chemically stored within the cells for later use. ■ The output power of a battery is determined by its energy storage capacity (cold-cranking amps), and the ability of the battery to smooth ripple currents is a function of both its internal resistance and capacity. ■ As a battery ages, its ability to filter ripple current (noise) decreases, and its impedance increases. (See battery cutaway in back of book.) ■ Remember that the battery is an electro-chemical device and cannot create current instantaneously, so as current is drawn voltage will decrease. Running a “new” standard car battery until it’s dead may result in the battery’s reserve capacity being reduced by half. ■ Once an automotive lead-acid battery has been “deep-cycled,” it cannot be recharged to its original specifications. Dropping the battery’s rated voltage by 25% is what is meant by deep-cycled.
✍ A “primary” battery can store and deliver electrical energy, but cannot be recharged.
A “primary” battery can store and deliver electrical energy, but cannot be recharged. Lead-acid automobile batteries are “secondary” batteries. ■ A secondary battery can also store and deliver electrical energy, but unlike the primary battery, recharging is possible by passing a direct current through the battery in the opposite direction to that of the discharge.
CABLE QUALITY
Expert mechanical installation will be of limited value if you don’t use high-quality cable of the correct size for the electrical installation. Remember the water pipe analogy in Section 1? This is a good way to think of signal (or current) flow through speakers and power cables. ■ When a large amount of water has to go through a pipe which is too small, it will take longer for the water to go through the pipe, and the full flow of water is reduced.
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When a larger, proper sized pipe replaces the small pipe, the same volume of water flows freely, with less resistance. ■
Margin Notes
Applying this example to electricity: ■ The pipe is the power cable, which experiences increased voltage drops if it’s too small to carry the required current. ■
The water represents the current flowing. ■ If the wire is too small or too long, resistance is increased. ■ As resistance increases, the power cable will start to overheat. The heat could melt the cable and create a hazard to the system and the vehicle. ■ Also, as resistance increases, the power amplifier at the other end of this small, overworked cable suffers a significant voltage drop. This will not allow the amplifier to get the full voltage and the current it needs to operate properly, which will diminish its output and could easily cause distortion.
✍ As resistance increases, the power cable will start to overheat. The heat could melt the cable and create a hazard to the system and the vehicle.
Always remember to use the proper size (even slightly oversized) power, ground, and speaker cables. For power amplifier wiring, you will need sufficient AWG rating to handle the current load (see IASCA chart in Section 1). You will also need a high temperature, multi-strand cable. A flexible gas and oil resistant outer jacket is also desirable. Never use solid wire in the high vibration environment a vehicle creates. A common misconception is that you can skimp on the ground cable. ■ The ground cable carries as much current back to its source (the battery) as the supply cable, and should really have a gauge the same current potential of the supply cable. Using the same size gauge wire (since the ground/chassis connection is generally shorter) is a good practice to use.
✍ You will also need a high temperature, multi-strand cable. A flexible, gas and oil resistant outer jacket is also desirable. Never use solid wire in the high vibration environment a vehicle creates.
Knowing what voltage will be present at the amplifier end of the supply cable (i.e., battery voltage less voltage drop) is also important when selecting a proper gauge power cable. ■ If you know the maximum amperage the system is going to draw and the resistance per foot of cable, the voltage drop is easy to calculate. Use what you know about Ohm’s Law to figure out the following formula: E=IxR
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If you are installing a system which has a 13-Amp draw and using a AWG size #10 cable (assume that #10 cable has a resistance of .047 Ohms for a 20 ft. run), how would you find the voltage drop at the amplifier end of the cable? E (voltage)
=
I x R (amperage) (resistance)
E = 13 (Amps) x .047 (Ohms) E = .61 Volt loss Nearly two-thirds of a volt is lost between the battery and the amplifier. Think of how this could affect peak amplifier performance! When selecting speaker cables, shielded audio cables, and power cables, select ones using deoxygenated, also known as oxygen-free, copper cable. ■ Deoxygenated copper has had nearly all the oxygen removed from the copper during the manufacturing process. The result is less resistance (the speaker, amplifier input, and the amplifier itself get more power), and the wiring will not corrode and turn green as normal copper cable will over time or if the vehicle is in a damp or salty environment. There are four factors that determine the resistance of a cable: 1 The cross sectional area (i.e., the AWG size; the larger the cross-section, the lower the resistance). 2 The temperature of the conductor (higher temperature means higher resistance). 3 The “resistivity” of the material the cable is made of (copper, deoxygenated copper, aluminum). 4 The length of the conductor (more wire length equals more resistance). Although you cannot control the temperature of a cable, you can do a lot to control the other remaining factors.
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Section 6 Semiconductors TRANSISTORS
A transistor (transfer-resistor) is an electronic switch that can replace or enhance a relay. ■ A more technical description of a transistor is a solid-state device in which a large output current is controlled by small changes in the input current. Transistors have three leads: 1 Collector. 2 Base. 3 Emitter.
✍ A transistor (transferresistor) is an electronic switch that can replace or enhance a relay.
✍ Transistors have three leads: the collector, base, and emitter.
Through different connections of these leads, a transistor can do most jobs of a relay, particularly when signal inversion is desired. Transistors come in two types: 1 NPN (the NPN silicon type transistor is the one most commonly used in place of a relay). 2 PNP. Both types are made from either silicon or germanium.
Capacitor (C) M J E3055T M 839
N
B C E
Base (B)
P
(C) Capacitor
N
(B) Base
Emitter (E)
■
(E) Emitter
Figure 46. Three views of an NPN transistor.
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When used as an amplifying component, transistors heat internally as they control the current in a circuit. ■ To dissipate this heat, the transistor is mounted to a heat sink, which removes the transistor’s heat and disperses it over the area of the heat sink. ■ Always mount an amplifier in a manner in which it will dissipate heat correctly, this can prevent premature failure of the amplifier. ■ CAUTION: The metal tab of the transistor can be a collector connection and, if so, is electrically wired into the circuit. In this case, do not touch it or mount it directly to chassis metal; isolate it or insulate it first before mounting or securing it in place.
DIODES
Because of their unique isolating capabilities, diodes are being used more and more in the installation bay. ■ Diodes are perfect for isolating alarm systems from the factory electrical wiring and are also effective for battery isolation and noise elimination.
✍ A diode is a two-electrode (two-terminal) device which allows current to pass through it in one direction only.
A diode is a two-electrode (two-terminal) device which allows current to pass through it in one direction only. ■ The two leads of a diode are the anode and the cathode. ■ A diode is the simplest of all semiconductors and can be thought of as a one-way electron valve. The following diagram is of a diode with the leads marked:
(N)
CATHODE (N)
■
(P)
ANODE (P)
Figure 47. Diode diagram.
When the positive terminal of the voltage source is connected to the anode, the return circuit is connected to the cathode (making it more negative than the anode), then current is flowing from negative to positive. ■ Here, the diode is said to be forward biased. ■ On a meter, it would read a low resistance.
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A diode connected in the reverse manner will not conduct electrons, but will measure a high resistance. ■ In this case, the diode is said to be reverse biased. ■ No current will flow in a circuit which has a reverse biased diode.
Margin Notes
In the previous diagram, the positive end (anode) is shown schematically as an arrow. It’s important to memorize which is the anode and cathode because circuit diagrams (schematics) will not tell you. The following diagram shows forward biased:
(-)
(-)
(+)
NO OUTPUT
(+)
(+)
NO OUTPUT
■
(-)
Figure 48. Positive voltage applied.
Also, like transistors, pieces of “P” or “N” material are used to form the diode. ■ When a piece of N (negative) or P (positive) material is joined together, a joint called the barrier or junction is formed. ■ There is a potential (difference) in the voltages between the materials in this junction called the barrier potential. ■ In common silicon diodes, this amounts to about 0.7 Volts. ■ When a diode conducts there will be a 0.7 Volt drop across it, and less voltage will be available for the equipment. Diodes come in current handling ranges of milliamps (.001), to 1,000’s of Amps. High current diodes are used in alternators to rectify AC to DC to recharge the battery.
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✍ When a diode conducts there will be a 0.7 Volt drop across it, and less voltage will be available for the equipment.
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Unlike resistors, diodes do not have color bands that indicate their ratings. ■ The type of diode and its application are noted in the manufacturer directories. ■ The part number is printed on the diode, and the band at one end of the diode denotes the cathode (negative) end of the diode. Here’s a question you will likely come across when working with diodes: ■ In the following diagram, is the diode positioned correctly so that the light bulb will turn on when the switch is closed?
+ ■
-
v
Figure 49. Diode diagram.
The answer is yes, the diode is positioned correctly and the light will turn on. Light Emitting Diodes (LED’s) are a very special type of diode. ■ They are extremely useful as indicators (i.e., power on, function on/off, etc.). ■ LED’s are most often found in red, yellow and green, and are also available in blue. ■ In order to avoid self-destruction, a resistor is wired in series with one leg of the LED to limit the current through it.
✍ When an LED is forward biased, a voltage drop of about two volts is typical.
74
When an LED is forward biased, a voltage drop of about two volts is typical. ■ LED’s illuminate with currents of approximately 10 Milliamps and have a life of 100,000 hours or more.
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Section 7 Automotive, Electrical and Charging Systems
Margin Notes
In Section 1, we introduced the differences between alternating current and direct current. Many people assume that today’s vehicles only use DC because car batteries are DC devices. ■ The main function of the alternator is to recharge the battery and act as the primary source of electrical power while the vehicle is being driven. ■ In this section we learn that the alternator generates an alternating current internally…and outputs DC. AC is turned into DC by what is known as a rectifier bridge, which is typically built right into the alternator. A rectifier bridge is made up of diodes. At least one pair of diodes is necessary for each “phase” of AC. Alternators produce 3 phase AC so rectification to DC requires 6 diodes. Even a basic rectifier bridge in OEM alternators use a minimum of 6 diodes. Higher output and larger capacity alternators that use more than 6 diodes usually do so in groups of 6, such as 12 or 18 diodes.
✍ AC is turned into DC by what is known as a rectifier bridge.
There is a very important fact to be aware of when designing an audio system using multiple amplifiers and high amounts of power, especially with modern vehicles and sensitive electronic computer controlled subsystems: WHEN THE AMPERAGE DRAW OF A SYSTEM EXCEEDS 120% OF THE ALTERNATOR’S MAXIMUM OUTPUT, THE CHARGING SYSTEM (both the battery and alternator) WILL BEGIN TO SUSTAIN DAMAGE, particularly to the alternator’s diodes. ■
High output, high performance alternators generally use more diodes than standard alternators or higher current rated diodes (or both) and are able to handle higher capacity workloads of output. ■
✍ WHEN THE AMPERAGE DRAW OF A SYSTEM EXCEEDS 120% OF THE ALTERNATOR’S MAXIMUM OUTPUT, THE CHARGING SYSTEM (both the battery and alternator) WILL BEGIN TO SUSTAIN DAMAGE, particular-
It is always a great approach to advise the customer before any work begins that an upgraded alternator and battery may be necessary to provide reliable system performance for the audio system and power requirements in question.
■
ly to the alternator’s diodes.
Many newer vehicles have computer controlled voltage reference inputs which take voltage data off of the alternator and battery at freeway speeds and in top gear to “tweak” the output so that the car can maximize fuel economy. Many Honda and Acura vehicles operate this way. ■
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IGNITION SWITCH FUNCTIONS/POWER WIRING
The power wiring of most vehicles falls into four categories: 1 Battery. 2 Ignition. 3 Accessory. 4 Start. Battery - wire that comes directly from the battery. ■ Its first stop, after the starter, is usually the “Batt” terminal on the keyswitch. ■ This wire is electrically “hot” at all times, regardless of key position. ■ This lead is often unfused. Ignition - the position just before start, and start. ■ This lead has power to it when the engine is being cranked and also in the “run” position, which is the position the switch falls back to after vehicle has been started. ■ This is a vital wire to find when installing a security system. ■ This lead is often unfused. Accessory - usually a counterclockwise turn from the “off” position, and the “run” position. ■ It will usually power most accessories, such as radios, wipers, etc., but is wired separately from the ignition circuits. ■ This lead is often unfused. Start - used to start the engine. ■ This wire has a voltage on it only when the engine is being cranked. ■ Releasing the key from the start position puts the key into the ignition, or “run” position. ■ In the start position, ignition voltage is maintained, but all accessories are cut off because all battery power is routed to the starter. ■ This lead may be unfused.
■
Figure 50. Ignition switch diagram.
All of these wires can usually be found at the key switch and should be functionally verified with a DMM, not an incandescent type test light, so as not to damage any computers in the electrical system. 76
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Section 8 Troubleshooting Guide OVERALL
If there is no power in the entire system: ■ Check the main fuse at the battery. ■ To avoid a short circuit and severe damage to the vehicle - always fuse a power cable at the battery within six inches of the battery. If there is no power to the amplifier or amplifiers, but other components have power: ■ Check the fuses for the amplifiers first. ■ Then, check the main fuse. If there is no power to the headunit, but other components have power: ■ Check the factory fuses (at the OEM fuse panel) labled RADIO first. ■ Then, check the main fuse at the headunit in the dash. If an amplifier overheats, “motorboats” or fails: ■ Use Ohm’s Law ( E = I x R ) to determine if: ■ The gauge wire is too small. ■ The vehicle requires a higher output alternator. ■ The ground wire gauge is too small. ■ Use a DMM or a VOM to determine if: ■ A speaker may be “shorted out”. ■ The voltage to the amplifier is too low. ■ A fuse has blown. If a resistor fails: ■ Use a Volt Ohm Meter (VOM) to measure current and voltage, then use Ohm’s Law to calculate resistance. ■ Make sure you’re using the correct resistor (too low a value and it will overheat and fail). ■ When resistors are connected in series, the total resistance is the sum of the resistance of each component. ■ When devices are wired in parallel, the total resistance is always less than the resistance of the component with the smallest value. If there is a voltage drop in the system: ■ Is the voltage drop caused by a bad connection? ■ Is the wire gauge too small? ■ Look for the source of added resistance. ■ Use Kirchoff’s Voltage Law (KVL)to determine the voltage drop. ■ Remember to use effective resistance - the “calculated” resistance that a device presents to a circuit while it is operating. CHAPTER 1 BASIC AND ADVANCED ELECTRICAL
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Is there “alternator whine”?: ■ Check for a ground loop. ■ Poor crimps can cause a ground loop. ■ Check the alternator. ■ Check for audio cables which run near high current power wiring. ■ Check for passive crossovers installed near factory wiring harnesses. ■ Measure the ground point potential back to the negative battery post and with each other. ■ Single point grounding is preferred. If the input signal voltage is too high to an amplifier: ■ Add a voltage divider (resistor network) to the signal cable. If there are “burn marks” on the areas surrounding a resistor: ■ Make sure the resistor is not overheating. ■ Be sure there is adequate airflow around all resistors. If the alternator fails: ■ It may be possible that the amperage draw of the system exceeds 120% of the alternator’s maximum output. Most OEM charging systems (BOTH battery and alternator) will begin to sustain damage at that level, particularly to the alternator’s diodes. ■ If this is the case, advise the customer before any work begins that an upgraded alternator and battery may be necessary to provide reliable system performance for the audio system and power requirements in question.
SPEAKERS
If tweeters are always “blowing”: ■ Install a fuse - wired in series - with the speaker. ■ To determine the proper amperage of the fuse, you’ll need to know the ohm load of the speaker as well as its continuous or nominal power rating. ■ Check that the output is not clipping, if it is reduce volume or gain. ■ This is often a symptom of electrical (heat related) tweeter failures. If speakers are always “blowing”: ■ Check that the output is not clipping, if it is reduce volume or gain. ■ This is often a symptom of electrical (heat related)speaker failures. ■ Check that the excursion limit of the speaker is not being exceeded at high volume. ■ This is often a symptom of mechanical (excursion related)speaker failures.
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If sound quality is poor: ■ Check for a bad connection or poorly crimped terminal. ■ Check that the speakers are connected in parallel. ■ When “paralleled” speakers are connected to the amplifier, the combined speaker load will have a significant effect on how that amplifier performs. It may also cause the amplifier to run excessively hot. ■ Check to see if the LOUDNESS is switched on, if so switch to OFF. ■ Check to see if the Bass and Treble settings are boosted, if so set to FLAT.
Margin Notes
If too much power is reaching a speaker: ■ Add a power resistor to reduce the amount of power. ■ Check that the output is not clipping, if it is reduce volume or gain. If high frequencies are reaching the subwoofer: ■ Install an inductor - wired in series - to block the higher frequency signals while allowing the low frequency audio signal to power the speaker (this creates a low-pass passive crossover). If low frequencies are reaching the tweeters: ■ Install a capacitor - wired in series - to block the lower frequency signals while allowing the high frequency audio signal to power the speaker (this creates a high-pass passive crossover). This concludes our discussion of 12-Volt electrical. If you’ve read each section of this Chapter thoroughly and followed the instructions stated in the Introduction, then you should be well prepared to answer the electrical section test questions on the MECP Basic Installer exam.
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SAMPLE TEST QUESTIONS
1
What are the four different electronic properties you will encounter? A Amps, volts, ohms and joules B Power, voltage, direct current, alternating current C Resistance, voltage, ohms, inductance D Voltage, current, resistance, power E None of the above answers are correct
2
What is voltage? A The rate of electron flow through a given point B The electrical pressure that moves charged particles in a circuit C The conductivity that various materials possess D The relationship between current, resistance and power E The conversion of energy into work over a certain period of time
3
Which of the following cannot be determined by Ohm’s Law? A If a certain gauge wire is too small B If the voltage supplied to an amplifier is too low C If the system requires a more powerful amplifier D If a higher output alternator is needed E All of the above answers are correct
4 Using a VOM (Volt Ohm Meter), you can measure current and voltage, but you cannot directly measure resistance in a live circuit. A True B False 5
80
A “watt” represents the conversion of one joule per second into... A Light B Heat C Sound D Some other form of work E All of the above answers are correct
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6 What is the impact of Kirchoff’s Voltage Law if there is a poorly crimped terminal in the installation? A There is no impact B One volt dropped through a connector will reduce voltage to the equipment by one volt C One volt dropped through a connector will reduce voltage to the equipment by two volts (1:2 ratio) D One volt dropped through a connector will reduce voltage to the equipment by three volts (1:3 ratio) E There is an impact, but it is too low to measure 7
Margin Notes
Which of the following is a characteristic of a resistor? A Resists the flow of electrons B Can be added to a signal cable to reduce the input signal voltage to an amplifier C Can reduce the amount of power to a speaker D Converts electrical energy to heat E All of the above answers are correct
8 Electrolytic is known for its excellent sound quality and is used for the higher crossover frequencies. A True B False 9
How do you determine the total resistance of a circuit? A Add up all of the resistances B Multiply all of the resistances C Add the two highest resistances and divide by the lowest resistance D Divide the voltage into the current E Multiply the voltage by the current
10 What does a passive crossover for a basic two-way system consist of? A Two passive filters B One passive filter and one active filter C One capacitor for the tweeter and one inductor for the woofer D One bandpass filter E One passive filter and one relay
Answers 1 D, 2 B,
3 C,
4 A,
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5 E,
6 B,
7 E,
8 B,
9 A,
10 C
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The bottom line: Working as a Professional Installer, you have to be able to tackle the challenges that you face in your day-to-day duties. While that often requires a high degree of creativity, it also necessitates a solid foundation in the basics. This chapter focuses on some basic installation practices, including proper tool use and safety. These are best practices that every professional installer should follow. Both the Basic Installer level and the First Class level Installation Knowledge & Technique section of the MECP certification tests are included here. You should have a thorough understanding of each topic before moving on to the next topic. For the First Class level test read all of this Chapter as well as the complete First Class Study Guide available from MECP.
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Section 1 Basic Installation Practices A professional installation is not just about the quality of your work – it also includes your preparedness and professionalism. A true professional understands every aspect of the job – from the minute the vehicle arrives, until the job is done. That means caring for your customer’s vehicle – before, during and after the installation – and properly logging anything unique that occurred during the process.
VEHICLE CHECK IN
How many times has this happened to you? You finish an installation, the customer comes to pickup their vehicle…and they accuse you of denting a fender, or soiling their interior! It happens – and if it hasn’t happened to you yet…it will. But you can be prepared for the inevitable. Here are some steps you can take to guard against this type of liability: Perform a thorough “vehicle check-out” when it comes into the shop: ■ Before you begin any installation work, thoroughly inspect the customer’s vehicle. ■ Start with the exterior. ■ Inspect the trunk. ■ Inspect under the hood. ■ Inspect the interior. ■
Note any damage on the repair order. ■ Make note of any flaws in the paint, body work, scratches, tears or burns in the upholstery – anything that you could easily be blamed for later.
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Perform a complete function check of the vehicle. ■ Use your installation worksheet to document accessories that are not in working order. (See the Installer Check-out Sheet at the end of this chapter.)
Review your findings with the customer before they leave (and before you start). ■ If that’s not possible, any problem – no matter how minor – should be brought to the attention of your shop manager.
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Note: If you develop an acute eye when examining the body and finish of a vehicle, you may notice dings or scratches the customer never noticed before. That way, even if the customer doesn’t remember that the door was scratched, they cannot blame you for scratching it. 84
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Establish a Personal “Dress Code.” After you’ve inspected the vehicle, give yourself a “once-over:” ■ Be sure there are no tools in your back pockets that could gouge or rip the interior.
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If you wear jeans with brass rivets (and most have them), you should wear a jump suit or smock to prevent interior/fabrics and outside paint from being scratched. ■
■ It’s always a good idea to cover the interior with a drop cloth or blanket, and make sure your hands and clothes are free of grease and oil that could stain the interior. ■ When the installation is finished, a second inspection should be performed, starting with the function check and working back through the interior and then to the exterior.
These precautions take only a few minutes, but can save you and the shop owner from being blamed for damage that existed before the car came into the shop. Reducing unnecessary damage claims will help lower insurance costs and protect your reputation as a reliable, “topnotch” installer.
BOOKKEEPING
At most shops, when the work is done, the job is closed, invoices are filed and that’s it. But what happens if the customer comes back a year later with a question? Without accurate records, you have to “start from scratch” when determining something that could take just a couple of minutes if that information was recorded on the invoice or repair order. When the installation is complete, log the following information on the paperwork: ■ Wire codes for installing alarms. ■ Wire colors for hooking up power supply leads and power antennas. ■ Enclosure sizes for subwoofers in specific automobiles. ■ Templates that are made for special head units, antenna, and speaker installations. Taking a couple minutes at the end of an installation can save you hours of time if records are kept in well-labeled files. In addition to installation information, information on raw-materials sourcing, product sourcing, and people to contact in case of installation problems should be maintained in filing cabinets as well.
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VEHICLE DISASSEMBLY AND REASSEMBLY
It takes a lot of skill and patience to disassemble a dash or door panel and then put it back together with precision. The potential for damage during this phase of the job is enormous – and that’s why you have to follow special precautions to ensure the job is done right. ■
First and foremost – use the proper tool. ■ Always use the appropriate tools to disassemble and reassemble a vehicle. ■ A large, flat blade screwdriver to pry off door panels is not considered a proper tool. ■ Many tool companies (such as Snap-on, Mac, Klein, etc.) have a tool specifically designed for removing door panels; it’s called a “panel popper” or door clip remover. ■ This tool and many other tools from the paint and body profession apply directly to installations. A pair of pliers is not the correct tool to loosen the nut on a battery terminal, or a fender-mount antenna – an open-end wrench or an adjustable crescent wrench is the better choice. (See Section 5 of this chapter for a list and description of tools.)
✍ A pair of pliers is not the correct tool to loosen the nut on a battery terminal, or a fender-mount antenna.
When disassembling a vehicle, place each part in a labeled box or plastic bin. A magnetic bowl works well for holding metal screws and clips. ■ Never leave pieces on the floor of the shop – they will only get lost, stepped on, or broken. ■ Mark your container Left Front Door, Dash, or Rear Deck. ■ As these vehicle sections are taken apart, have the container nearby and place each part into it as it comes off the vehicle. ■
This practice will save you a lot of stress in the long run and make the job go much faster, especially during reassembly. ■ Another simple practice is to use a 6’ x 6’ square of carpet under each door and sill of the vehicle. ■ If a part happens to drop off the door or fall out of your hands, it will stop in the carpet and not bounce across the shop. ■ It will also save wear and tear on your knees.
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CABLE ROUTING/LEAD DRESS
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In Chapter 1, we emphasized the importance of good wiring habits. Proper installation of power lines, interconnect cords, and speaker cables can mean the difference between a job that lasts six months, or a job that lasts 10 years. Although this phase of installation can be tedious and time-consuming, following common sense guidelines can make it go faster, last longer, and give your install a professional appearance. Here are some simple guidelines to follow: 1 Always run power and signal leads away from each other. ■ The general rule of thumb is to run the battery power, remote turn-on lead, and ground from the head unit, equalizer, or other front-end component, down the same side of the car that the battery is on. This way most of the time you avoid having to cross the battery lead over other vehicle wiring, which can lead to inductive coupled or radiated noise.
✍ Always run power and signal leads away from each other.
2 All wiring should be run away from the car’s factory wiring due to the fact that these high-current wires can induce noise into the system. 3
Never run wiring through holes that have rough metal edges. ■ It’s easy for wiring to get pinched beneath seat tracks, clutch and brake pedals, etc. ■ Use grommets whenever wires pass through metal boundaries.
4 When choosing sources for power supply lines for equalizers, head units, and amplifiers, make certain that the power sources are noise-free and have enough current-carrying capacity for the unit each wire will be powering. 5 Terminating wiring should always be soldered, and then heat shrink tubing should be applied to cover the complete joint. ■ While each car is different, one thing they all share is a high vibration environment, which should always be considered when you’re wiring.
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✍ Terminating wiring should always be soldered then heat-shrink tubing should be applied to cover the complete joint.
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6 Pre-plan your wire routing and run the speaker wires and line--level signal leads on the opposite side of the vehicle. ■ If this can’t be done, try to keep power and signal cables as far apart from each other as possible, or a minimum of 18 inches. ■ If crossing power leads and signal leads can not be avoided, cross them at a 90º degrees or no less then a 45º degree angle. A 90º degree angle would be the optimum. ■ The speaker and shielded leads can pick up radiated noise from the battery power cable and induce that noise into the system. Routing wiring this way helps avoid alternator whine (i.e., the “siren-like” whining that appears when the rpm’s of the engine increase). ■
POWER ACCESSING
Power is not power when it comes to most installations. You have to carefully choose your source – and that can have a major impact on the functionality of your installation. Alarm installations, in particular, require that you access an assortment of power wires: ■ Remote-controlled alarm systems need a constant +12VDC lead, a switched ignition lead that stays live while the starter is being cranked, and the starter wire itself. ■ Usually the best and safest place to find all of these wires is at the ignition switch, though it is always recommended to go directly to the battery for your +12VDC connection. Here are some guidelines: 1
Remove the lower panel covering the bottom of the switch.
2 After unclipping and unwrapping some wires, access to the switch can be made. ■ On autosound systems that require constant power, never access power from the fuse block – always go directly to the battery, with appropriate fusing. ■ The fuse block is typically the noisiest spot on the vehicle to access power.
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GROUND LOOPS/GROUND PATHS
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Ground loops are probably the most frequent cause of noise problems in car audio. The procedures for eliminating ground loops can be difficult if you do not understand the theory behind what causes them. Ground loops result when all the components in an audio system do not see exactly the same ground. Differences in degrees of being grounded are called ground potential. ■ The difference in potential between all the grounds of a system is what causes a “loop,” or voltage drop, resulting in alternator whine.
✍ Differences in degrees of being grounded are called ground potential.
Wiring a vehicle properly and making absolutely sure that all components are grounded at the same spot or potential is essential. ■
Points where grounds can run into a “loop” situation include: 1 The low-level leads going from the output of a head unit to the input of a crossover or amp. (Nothing will allow noise to radiate into a system faster than inferior cable with poor shielding. Always use high quality cables.) 2 An amplifier or any other component mounted directly to the metal of the vehicle. ■ Never mount components to bare metal. Always try to use an amp rack and insulate the other components from the chassis of the vehicle. 3 Grounding several components to chassis ground through their ground lines. ■ Some preamp units get their B- connection directly from the interconnect cable – connecting the black wire to ground in this case causes an automatic ground loop. ■ Ground your preamp components to one point – usually the back of the radio – if their power supply ground is separate from signal ground. 4
The antenna input. ■ The use of antenna ground-breakers that are available on the market today is not a recommended practice, unless there is a severe grounding problem with a particular vehicle. ■ This ground is essential to the reception of AM.
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Figure 51. Ground loop.
Although there are ground-loop adapters available on the market, they are really a “Band-Aid” approach for a system that should have been wired correctly in the first place. The simplest way to avoid accessory noise problems is to never share a ground connection with the vehicle's accessory ground path, such as a fan motor or brake light ground. It is highly likely that a pop or a buzz will be heard in the system whenever the fan is turned on or the brakes are applied.
FINDING A GOOD GROUND
Finding a good ground can be tricky. ■ The best ground point in a vehicle is a place with a good physical connection to the same metal that the vehicle battery ground itself shares. Make sure that it has the same ground potential as the battery ground, however it doesn’t necessarily have to physically connect to the battery ground point. Think of the chassis and body metal of the vehicle as one extremely large gauge wire connecting the ground of the battery to other vehicle accessories. ■ Avoid choosing ground points that are secondary body or chassis components that may have the added resistance of tack welds or bolts between the main and secondary parts. A hood, trunk lid, or rear deck are primary examples of secondary body components.
Avoid choosing ground points that share connections with other vehicle accessories. This helps avoid potential noise problems from the start. ■ Be sure to scrape away the paint around the area you have chosen as your ground point and use a star washer to make a good electrical connection. ■
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Star washers are better than flat washers for grounding because: 1 Flat washers can trap contaminates between themselves and the grounding surface, which increases contact resistance.
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2 Star washers tend to bite into the grounding surface thus cleaning it and getting more surface area for lower contact resistance. ■
Always avoid using the factory headunit power and ground wiring. ■ This wiring usually has inferior gauge and often does not go directly to ground, but picks up grounds of other vehicle systems which are clustered together at one point. ■ Although many standard installation procedures of headunits call for a “factory harness adapter,” systems with signal processors, multiple amplifiers, and/or significant amounts of headunit power may be more prone to noise related problems by using factory headunit power wiring. ■ This can introduce clicks and pops in an audio system when other vehicle systems switch on and off. ■ Factory wiring also runs in harnesses past other devices in the vehicle, which can radiate or couple noise into an audio system.
PROPER WIRE GAUGES
The purpose of a wire is to conduct electric current from one location to another. Poor system wiring can induce noise and cause overall poor performance. ■ The size of the power and ground cables (Kirchoffs’ current law) used to supply battery power to an amplifier are of utmost concern. ■ Using too small a gauge cable to power an amp will limit the amount of current which an amp gets, thus limiting its performance. ■ An inadequate wire size could melt the insulation off the cable and could cause serious damage to your customer's vehicle. ■ A large gauge, multi-stranded wire – with either a fuse or circuit breaker within 10 inches of the battery – is mandatory. ■ American Wire Gauge (AWG) labeling of cable is somewhat confusing – the lower the number, the bigger the cable. For example, a #12 wire is larger and will handle more current than a #16. A #22 gauge wire is much smaller than #14.
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The chart below shows the relationship between the AWG and the diameter of the wire in inches.
AMERICAN WIRE GAUGE Current Capacity of Wire From 0 to 20 AWG
AWG 0 1 2 3 4 5 6 7 8 9 10 12 14 16 18 20
Current Capacity (Amps @ 680F) 150.90 119.60 94.80 75.20 59.60 47.30 37.50 29.70 23.60 18.70 14.80 9.33 5.87 3.69 2.31 1.46
PROPER CONNECTIONS
Terminating the end of a wire should be done as carefully as possible. ■ Most connections today are done with a crimp tool, which attaches the wire to a solderless crimp-on connector. ■ When using a crimp-tool, the seam of the metal barrel, unless it is seamless, should be in the concave part of the crimper's jaws. This makes for a secure mechanical connection. ■ For connections in the engine compartment (under the hood) of a vehicle, it’s important to solder the connection and then heat shrink the connection and terminal with a piece of shrink tubing. ■ The tubing must cover the bottom of the connector (where the wire enters to connector), as well as go all the way to the top of the connector.
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Cover as much of the connector as possible making a good weather resistant seal. ■
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When the connection is firmly attached to the firewall, it is good practice to apply noncorrosive grease to the screw head. ■ This helps reduce possible corrosion of the screw head and the terminal. ■
The only drawback to crimping is that over a period of time, oxidation can build up between the wire and the connectors. This oxidation causes a degradation in the electrical connection. In other words, it causes an increase in resistance, which will hurt the overall performance of the unit involved. Soldering is another alternative: ■ Solder should be applied so that it flows over the connection. ■ For best results, the iron should be held below the wire while applying the solder from above. ■ This allows the solder to flow from the top of the wire to the bottom more uniformly. ■ Remember to heat the connector, not the wire. ■ Two or three “balls” of solder (a cold solder joint) is not good enough because they will contain air bubbles and either break off or have little to no electrical connection value. ■ A good solder joint should be smooth, shiny, and concave. It is important to remember that solder does not go from the liquid state directly to the solid state, but has a plastic state in between. During the plastic state, a cold solder joint can occur if the joint is moved.
✍ A good solder joint should be smooth, shiny, and concave.
Avoid using wire nuts. Wire nuts were designed for a stationary, stable environment – like inside a house – not many houses are designed to accelerate, decelerate, or corner. ■ The wire nut will eventually fall off the wire leaving the exposed wiring to short to ground or to a component.
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ANTENNAS
Most automobiles use one of six types of antennas: 1 Fixed mast 2 Power 3 Collapsible mast (full length) 4 Short collapsible mast (amplified) 5 Windshield 6 Diversity Depending on the car, these antennas can be mounted through the top surface of fenders, on the sides of fenders, through the windshield A-pillar, on the surface of A--pillars, in the windshields, and along the back edges of the roof. Antenna installation varies from car to car; however, proper mounting is crucial: ■ When you’re selecting the right mounting location, refer to the guidelines supplied by the manufacturer. ■ Mounting the antenna as far away from the engine as possible will usually reduce Radio Frequency Interference (RFI). ■ If the cable under the fender is in poor shape or is corroded, the ground braid’s integrity can be compromised. ■ This will not allow the cable to reject radiated noise and will show up graphically on your AM band. ■ If the rockers under the fender are not firmly digging into metal, noise can be generated. ■ When replacing an antenna, always remove any dirt which may have accumulated where the rockers will come in contact.
✍ Most FM antennas are 31” long.
Most antennas (unless they’re electronically amplified) are approximately 31” long. This is said to be the best length for FM reception (1/2 of a quarter wavelength). Guidelines for mounting an antenna: 1 Check under the fender (front or back) for proper clearance. 2 Mark your spot with a center punch or awl. 3 Drill a pilot hole with a 1/8” bit. 4 Then use a proper size hole saw at low-to-medium speed. 5 Scrape away accumulated dirt under the fender to get the best ground possible. 6 Apply a rustproof touch-up paint to the bare metal after drilling to insure a rust free future in your installation. Some vehicle manufactures are equipping their vehicles with power amplified antennas. These antennas increase performance; however, they have power leads which must be connected to a source of power that is live when the radio is turned on. This requires a connection to the headunit’s power antenna output (some headunits share this output with the remote amplifier turn-on).
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FUSING AND CIRCUIT BREAKERS
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Installing a fuse or circuit breaker at the battery is extremely important. ■ The purpose of fusing is not to protect the component, but to protect the wire. ■ The wire has to pass through the firewall, run under the door sills, under the rear seat, and up into the trunk. The potential danger here is the sill molding screws or rear seat framing/springs puncturing the insulation of the power cable and shorting it to ground. ■ In some vehicles this is not possible because they use an under-theseat or in-trunk battery. An Audi, or BMW would be good example of this type of configuration.
✍ The purpose of fusing is to protect the wire.
There are a variety of different fuses. Figure 52 shows three popular types of fuses for automotive use.
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Figure 52. AGC, AGU and ATC fuses.
Always install a fuse in a weatherproof, rubber-type holder or a circuit breaker of proper amperage, as close to the battery as possible but no more than 10 inches from the positive battery post. What is the “proper amperage” for the fuse or circuit breaker? ■ The correct fuse or breaker must exceed total amp draw, and be able to handle the total amperage. ■ Do not use self-resetting circuit breakers. These types of circuit breakers are undesirable due to the fact that they can reset themselves until the contacts permanently fuse. (See Chapter 1 for more information on fuses and circuit breakers).
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Section 2 Noise Troubleshooting SYSTEM NOISE
Unintended noise entering a system can be an installer’s worst headache. Common sense and logical troubleshooting techniques, however, will help you through some of the most difficult problems.
✍ The first three steps involved in troubleshooting noise are to: Identify, Isolate, and Eliminate.
The first three steps involved in troubleshooting noise are to: 1 Identify 2 Isolate 3 Eliminate Identify You can identify the noise problem by making careful observations as to what kind of problem is occurring. Ask yourself some simple questions: 1 What are the symptoms? 2 What kind of noise is it? 3 Does the noise run through the whole system? 4 Does the noise go up and down with the volume control? 5 When did the noise start? 6 Does the noise rise and fall with engine speeds? 7 How long has it existed? 8 Is the noise affected by driving over bumps or dips? Isolate Once you’ve identified the problem, the next step is to isolate it to determine in what stage of the circuit the problem exists. A thorough investigation during the identification process will help you out at this point. A component failure is pretty easy to trace. A quick check of its operation and/or replacement of the component will tell you if it is indeed the problem.
✍ A word of caution is in order here. Do not make a habit of substituting parts during this stage. If the problem is a short circuit or a reverse polarity condition,
Note: A word of caution is in order here – do not make a habit of substituting parts during this stage. If the problem is a short circuit or a reverse polarity condition, it may cost you another part. Always check the electrical and mechanical environment around the component in question first, then substitute. Disconnecting and/or bypassing a component or section of the circuitry may also be necessary to isolate the problem.
it may cost you another part.
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Eliminate Once the problem has been identified and isolated, elimination will usually involve one or more of three variables:
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1 Mechanical – involves changing the locations of components and/or mechanical connections, for proximity-related problems. ■ Mechanical alterations usually involve radiated noise and Electromagnetic Interference (EMI) noise as well as other problems caused by the automotive environment. 2
Acoustical – involves phase, diffusion, interference, or loading problems. ■ This type of problem may include mechanical problems as well as require active or passive trimming of the system. (The First Class Study Guide section on Autosound will cover troubleshooting acoustical systems).
3 Electrical – deals with filtering, positive and negative DC paths, AC signal paths, grounding, and all of the variables of the automotive electrical system. ■ Troubleshooting electrical systems can be a very complicated process. It requires a basic knowledge of different types of test equipment such as an oscilloscope, LC bridge, signal generator, and distortion analyzer. A simple hand-held AM/FM radio is an excellent piece of test equipment when troubleshooting Radio Frequency (RF) problems. The most basic tool, however, when you’re troubleshooting an electrical system, is a solid understanding of the electrical components involved (see Chapter 1).
TYPES OF NOISE PROBLEMS
System noise comes in many forms: ■ Alternator whine is a whistling noise that responds in direct correlation to the RPM’s of the engine, and is usually the result of a voltage differential created by more than one ground path or a poor ground path. ■ The best way to test for alternator whine is with the audio system on and the volume turned all the way down. Then “rev” the engine. If the whine is heard, unplug the line inputs at the amp or crossover. If the whine goes away, you've more than likely got a ground loop. ■ Make sure all your grounds are assembled at one point only and that amp mounting, crossover mounting, equalizer mounting, etc., are not allowing these components to touch ground.
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✍ Alternator whine is a whistling noise that responds in direct correlation to the RPM’s of the engine, and is usually the result of a voltage differential created by more than one ground path or a poor ground path.
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✍ Cables that are too close together, or too close to stock wire looms, can pick up what is known as induced or coupled noise.
■ Cables that are too close together, or too close to stock wire looms, can pick up what is known as induced or coupled noise. ■ Proper wiring technique is essential – power and signal cables must not be run together and should be separated by at least 18 inches. ■ If you have to route power and signal cables over one another, it's best that they cross at a 90 degree angle. This practice will reduce or eliminate induced noise.
You may have a component mismatch. The home audio industry has component values that are standardized. The autosound industry, however, does not share this standard. ■ Adjust the crossover, equalizer, and amplifier input levels (full gain is not a necessity) to get the components to “mate” with each other. ■ Line isolators may be necessary. ■
If the noise persists when the line-level plugs are removed from the amp, then the noise is probably coming in on the power line (though you could have a ground loop between the amp and a bad chassis ground point, or faulty product). Try moving the location of the power cable away from such items as vehicle computers and stock wire looms. If this does not help, a noise filter can be put on the power line. Be advised, however, that an in-line passive noise filter will always drop the voltage to the amplifier and may limit its performance.
✍ If you must use a noise filter, remember that the majority of filters are most effective when placed at the noise source.
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A high amperage noise filter is a Band-Aid – not a cure – for a problem that is somewhere else in the system. ■ If you must use a noise filter, remember that the majority of filters are most effective when placed at the noise source. ■ Try to locate a noise filter close to the amp, crossover, or other device that needs filtering. ■
Radiated noise is the trickiest of all noise sources to eliminate. ■ Noise can be radiated from the vehicle's ignition system (ignition coil, spark plugs, rotor) to such vehicle components as the radio antenna, radio, and the power harnesses in the vehicle. ■ Noise can be radiated into power and signal cables by vehicle computers, fuel pumps, and key-in ignition buzzers. ■ In these cases, the only way to eliminate the noise is to bypass these systems. ■ To find the source of the noise, use a noise sniffer. ■ Make sure you find the true source of the noise because noise can sometimes come from a secondary radiator.
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The cure may be as simple as moving the secondary radiator away from the primary radiator (i.e., moving a stock wire loom a few inches from another wire loom). ■
Remember, most types of radiated noise cannot be eliminated, they can only be rerouted or redirected. ■ Popping and clicking in an audio system is usually caused by components in the system sharing a common ground path with a multitude of vehicle systems or components. ■ Brake pedals, fan motors, etc., can induce noise. ■ Identify which devices are affecting the audio system, and reground the system to a “cleaner” ground. ■ Adding a noise filter or polarized capacitor at the source of the noise will also help. ■ A good rule of thumb – avoid the constant 12-Volt power and ground wires from the stock radio. ■ The 12-Volt line usually comes from the fuse block, the noisiest point on the vehicle, and the ground is usually run to a common point with several vehicle accessories. Both are an open invitation to noise problems. ■
Substitution is the preferred method to find out how noise is entering a system. ■ If you think a noise problem is coming in on the power cable, run a new one OUTSIDE of the vehicle, away from possible noise-producing vehicle items. ■ The same can be done with line-level cables. (Remember: use high quality cables). ■ If you think the noise is coming in on the power cable, disconnect it from the vehicle’s battery and connect a shop (bench) 12-Volt power supply instead.
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✍ Remember, most types of radiated noise cannot be eliminated, they can only be rerouted or redirected.
✍ Popping and clicking in an audio system is usually caused by components in the system sharing a common ground path with a multitude of vehicle systems or components.
✍ Substitution is the preferred method to find out how noise is entering a system.
Substitution can save you the trouble of tearing the vehicle apart to find noise.
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Section 3 Battery Troubleshooting Another way noise can enter a system is if the car's battery is not fully charged. ■ A low battery will not properly filter ripple from the output of the alternator. ■ Battery problems can be caused by a number of conditions: ■ Low water in the battery. ■ Loose or corroded battery cables. ■ Slipping belts. ■ Dirt on the top of the battery. Occasionally, you’ll have a customer who doesn't drive very often, never fully charging the battery. As the battery voltage drops, equipment operation becomes unpredictable. ■ A failing car battery can cause an alarm to be triggered for no apparent reason, giving the customer the impression that the alarm is defective.
✍ When measuring current draw from the battery, never connect an ammeter in parallel with the battery.
✍ NOTE: Always wear safety glasses when working around batteries. Proper technique is discussed in Section 6 of this chapter.
When measuring current draw from the battery, never connect an ammeter in parallel with the battery. ■ When a meter is switched to the ammeter setting, it creates a direct short between the test leads. ■ Connecting these across a car battery will destroy your meter and can be extremely dangerous due to the intense heat generated in the test leads. NOTE: Always wear safety glasses when working around batteries. Proper technique is discussed in Section 6 of this chapter. Here’s how to measure current draw: ■ The circuit must be broken and the meter inserted in series. ■ Use a shunt between the circuit, then place your DMM in parallel with the shunt. Now remove the shunt. (see figure 53 below)
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Figure 53. Current measurement.
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All of the current the circuit is drawing is now passing through the leads of your meter. ■
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The following only happens if you break the circuit at either the positive or negative terminal of the battery: ■ Any current drawn by any device in the car will go through your meter. If you’re measuring 50 milliamps on the 200 milliamp scale and then open the door, the dome light will draw a couple of amps. ■ This is a 40 fold increase in current. Imagine what will happen if you try to start the car and attempt to pull 350 Amps through your meter. ■
Some cars have a delay-off dome light and some alarms will draw more current when they are first powered up. ■ If your meter does not have a high amp range, this can pose a problem. ■ If this is the case, placement of a shunt across the test leads with a wire of suitable gauge is essential. ■ After the equipment has stabilized, remove the shunt. To measure current drawn by devices installed with a power lead to the battery, simply remove the fuse and connect your meter there. ■ Start on the highest range your meter has and then work down to more sensitive ranges. To measure current draw for the entire vehicle, remove one of the cables from the battery. ■ It doesn’t matter which cable you remove (negative or positive), since the same amount of current flows in both leads. ■ It’s often easier to remove the negative cable so you don’t have to work with all the accessory leads on the positive post.
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If current drain exceeds 45 milliamps, pull the fuses out of your fuseholders at the battery. ■ Pull the radio fuse out of the fusebox, or remove a pull-out radio. ■ Make sure you’ve pulled the correct fuse by verifying that the suspect equipment is not operating. ■ When you have found which fuse, when removed, stops the current draw, you have isolated the piece of equipment. Remove any stereo equipment and bench test it to make sure you have found the problem. ■ If the current draw is in the vehicle, advise the shop manager or the customer, depending on your situation.
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If the vehicle and installed system are drawing minimal current, perform a quick inspection or test of the battery and charging system. ■ Examine the battery cables where they attach to the battery. ■ Check to see that the ground cable is not loose on the engine block, and that the connections are tight at the starter. ■ Loose or corroded cables are enough to cause a problem. ■
Flex the alternator belt. ■ If you can deflect it more than a half inch, it’s probably too loose. ■ Loose belts can cause slippage, which keeps the alternator from working at full efficiency.
HYDROMETER
✍ A hydrometer is the device used to test the chemical condition of the battery solution.
A hydrometer is the device used to test the chemical condition of the battery solution. ■ It measures the specific gravity (density) of the electrolyte (liquid) in the battery. ■ If you find one or more bad cells, while some read good, it's reasonable to assume that those cells are dead, but that the alternator is continuing to charge the other cells.
LOAD TESTING
Load testing is performed to find out what kind of effect the multi-amp system you’re installing is going to have on the vehicle's battery. A poor or weak battery may show 12 Volts on a meter but could easily fail under the load of several high current amplifiers.
✍ A poor or weak battery
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may show 12 Volts on a meter but could easily fail under the load of several high current amplifiers.
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Figure 54. Typical hookup for load test.
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If the battery is sealed (i.e., a maintenance-free battery) – meaning you cannot use the battery hydrometer – use a load tester. ■ If the battery tests okay, you may assume that the alternator is charging. ■
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If the battery fails the load test, give the alternator a quick test. ■ Measure the voltage at the battery terminal – it should be close to 13.8 Volts at all RPMs greater than idle. ■ You can use your voltmeter (see Section 4), or the meter in the load tester. ■ If the voltage does not increase when the engine is running, the alternator or voltage regulator has failed.
Section 4 Meters and Test Equipment DMMS AND VOMS
The majority of electrical measurements you’ll make during an installation – and a great deal of the troubleshooting – is accomplished with a meter. The Digital Multimeter (DMM) is a multi-purpose instrument that combines the features of an ammeter, voltmeter, and ohmmeter into one instrument. The DMM is so versatile, it’s probably the most widely used piece of test equipment in the electronics industry. DMMs read out the voltage, amperage, milliamperes, or ohms being measured on a digital readout. ■ If you exceed a range, the display will read OL (overload). It is important to be careful when measuring current in the amp positions of a DMM. Because the DMM is in series with the battery and the loads of the car, the meter normally has an internal fuse to protect itself. If the fuse has been blown by placing the DMM in the wrong setting (too low a setting when measuring high current), you might think no current is flowing. This is DANGEROUS! Besides the ease of use and interpretation a DMM offers, there is one undeniable advantage in using a DMM over the standard analog meter: In today's computerequipped vehicles, the current draw that a VOM or, in particular, a standard incandescent test light requires, can permanently damage delicate automotive computers.
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NOTE: Never probe a vehicle’s electrical system that is heavily regulated or controlled by computers with a VOM or an incandescent test light.
✍ Never probe a vehicle’s
A DMM will not emit the popping noise in the speaker that a VOM will.
electrical system that is
Here’s a word of advice: Keep the old VOM on the bench, and keep the DMM and a 1.5-Volt battery with you at the vehicle. ■ The 1.5 Volt battery can be used for checking speaker polarity and continuity.
heavily regulated or controlled by computers with a VOM or an incandescent test light.
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Figure 55. Example of a Digital Multimeter (DMM).
The Volt-Ohm Meter (VOM) is called an analog meter because a needle or pointer is read against a calibrated scale to measure the electrical parameter under investigation. ■ This measurement requires visual interpretation of the data against the meter scale, which can be a source of reading error. The analog meter has function and range scales across its display. The functions include: ■ AC volts ■ DC volts ■ Resistance ■ DC amps
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The voltage ranges from .25 to 1,000 Volts; the resistance (ohm) scales from R x 1 to R x 1K; a number of milliamp and amperage ranges; and possibly a dB range. The function and range switches are combined on some meters and are accessed through a single selector switch.
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Figure 56. Example of a Volt-Ohm Multimeter (VOM).
All meters have two leads – typically one red and one black: ■ Red is the positive lead. ■ The red lead plugs into the “+V, ohm, A” or “+” jack. ■ The red lead goes to the positive end of the measured item. ■ Black is the negative lead. ■ The black lead always plugs into the “common” or “-” jack. ■ The black lead would be attached to the negative side of the measured item. Simply set the function switch above the type of parameter to be measured and the range switch above the anticipated value being measured, without going under range. When measuring an unknown voltage or current, always select the highest range possible and work down. (This is a good practice and should be made a habit for meter safety). ■ If an analog meter goes off the scale, damage to the delicate needle movement could result if it is not internally protected. To use a VOM, set the function switch to the type of energy to be measured, then set the range switch to the amount of anticipated energy, without going under-range.
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For example, if you want to find the ignition start wire of a vehicle to facilitate the starter kill function of a security system, you would connect the meter as follows: 1 Set the range scale knob (unless the meter has auto-ranging) to the highest voltage and proper polarity that you expect to encounter. ■ Since virtually all vehicles are negative ground and deliver direct current, set the function knob at DC volts, and the ranging knob to something that would include the 12V range. 2
Connect the black (negative) lead of the meter to a good chassis ground.
3 Probe the wires coming off the ignition switch with the red (positive) lead as the starter is being cranked. ■ The wire that shows a reading on the meter – only when the key is in the “start” position – is the wire to be relay interrupted. 4 If you want to check the amperage draw of a component or security system brain you would proceed as follows: ■ Set the function knob to DC amps. Use the range selector to select the highest amperage draw you think the component could draw. ■ As a rule of thumb, check the fuse size of the component you’re testing. If the suspect component is not blowing the fuse it comes with, set your amperage scale on your VOM to a range just above the fuse rating on the component and then move down to a more accurate scale. ■
✍ Remember, amperage draw is measured with the meter in series with the device being measured.
Remember, amperage draw is measured with the meter in series with the device being measured. This means that the power wire going to the component being measured will go to one lead of the meter, and the other lead of the meter will go to the power source. The analog VOM works quite well as a speaker continuity tester. ■ Set the range scale to R x 1. ■
Connect the probes across the negative and positive terminals on the speaker. ■ A clicking or popping noise – as well as a reading on the meter‘s scale – will inform you that a speaker has continuity.
Note that when measuring ohms on an analog meter, it’s always advisable to short the positive and negative leads together and use the “ohms adjust” or “zeroing thumbwheel.” This will calibrate the pointer and adjust the ohms scale for greatest accuracy. The DMM is self-zeroing.
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Most VOMs will measure voltage – both AC and DC, amperage (usually milliamps, although some will measure up to 10 Amps on a dedicated setting), and resistance (ohms). However, a VOM cannot be used for something it’s not designed to measure. For example, you cannot measure current (amperage) with a meter that has every scale but an amperage scale. Likewise, you cannot measure ohms on a meter that does not have a resistance scale. (Remember that to measure resistance, your meter must have good batteries in it). When using a VOM on a voltage scale, its sensitivity is expressed as the ohms per volt rating. The following scale shows a resistance reading from an analog meter:
Margin Notes
✍ When using a VOM on a voltage scale, its sensitivity is expressed as the ohms per volt rating.
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Figure 57. Reading from an analog meter.
At first look, you might assume the reading is 7 Ohms. However, what range was the meter set to? If it was set to R x 1, you would be correct at saying 7 Ohms. However, what if the range scale were set to R x 100, or R x 1 K? With an analog meter, simply divide or multiply the reading you get by the position of the range switch. ■ The 7 Ohm reading on the R x 100 scale would be 700 Ohms. ■ The 7 Ohm reading on the R x 1K would be 7,000 Ohms. With an analog meter, before measuring any resistance value, be sure to zero the pointer prior to using the meter. ■ This ensures as accurate a reading as possible. ■ If the needle on the previous scale were all the way to the left, it would be exhibiting a condition known as INFINITY, where the resistance is so high that it is unmeasurable. ■ An INFINITY reading on a speaker voice coil usually indicates that the voice coil has melted or opened. ■ On the other hand, if a ZERO reading appeared on the scale, there would be so little resistance, that a voice coil with this reading would indicate a short circuit. CHAPTER 2 INSTALLATION KNOWLEDGE & TECHNIQUE
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Figure 58. Read voltage on an analog meter.
To read voltage on an analog
meter, refer to the following drawing:
The scales are used for all AC and DC voltage, and DC amperage measurements. ■ In the preceding diagram, if the range were set on the 250-Volt scale, DC voltage, we could read this directly at 25 Volts. If it were set on the 25-Volt scale, this would have to be divided by 10, or a reading of 2.5VDC. ■
With analog meters, attention must be paid to the position of the leads: ■ The red lead connects to the +, or positive input of the meter, and goes to the same polarity on what is being tested. The black lead connects to the -, or negative input of the meter, and goes to the negative polarity of whatever is being tested. ■
Figure 59. Digital readout.
DMMs have no such restrictions. If you connect the leads in the wrong direction, a minus sign appears in the display:
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Direct current is normally a steady state voltage that does not vary over time. ■ If you encounter a problem with the charging system, the VOM has the advantage of being able to easily read fluctuating voltage at the battery or
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alternator. ■ The VOM display can vary continuously, giving you a read-out in a smooth continuous manner. ■ The digital scale of the DMM does not vary continuously and cannot read the full range of voltage fluctuation. ■ Some of the newer DMMs incorporate an analog scale or bar at the bottom of the display, specifically for the purpose of reading fluctuating voltages.
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TEST LIGHTS
Today’s highly computerized vehicles have made incandescent test lights nearly obsolete. The large amount of current that an incandescent test light draws can short computer-attached logic leads to ground, destroying vehicle computers. ■ Avoiding incandescent test lights will save you time, money, and a lot of embarrassment.
✍ Avoiding incandescent test lights will save you time, money, and a lot of embarrassment.
NOISE SNIFFERS
Noise sniffers are used to “hone in” on noise-producing vehicle systems which are radiating into an audio system. They can be purchased from a number of suppliers, or can be shop made. ■ They can easily be built from an old walkman-type cassette player. ■ A noise sniffer is basically an AM radio with a wand or probe. ■ When placed in the vicinity of a suspected noise-producing component (such as the vehicle's spark plugs, ignition coil, plug wires), it will exhibit the same type of noise found in the system. ■ The closer the sniffer gets to a noise-producing component or system, the louder the noise will get. This indicates what system in the vehicle needs to be suppressed, replaced (if ignition related), or avoided.
Section 5 General Installation Tools & Equipment The mobile electronics installation bay requires a variety of different powered and non-powered tools. The following list should give you an idea of the range of tools that may be necessary: Specialty Tools:
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1 2 3 4 5 6
Door/Window crank handle spring clip removal tool Door Panel clip removal tool Hole saw bits 3/4”, 1”, 1 1/4” Unibits (sometimes called step drill bit) Special theft-resistant shaftnut removal socket Six-Point General Motors screwdriver bit
General Equipment: 1 Crimp tool – multiple gauge 2 Drill – variable-speed, reversible 3 Drill bits – high-speed, metal 1/8” to 1/2” 4 Dremel moto-tool and accessories (for plastic alterations) 5 Electrical tape (Scotch #33+) 6 Hand or Power nibbler 7 HotKnife 8 Magnet – mechanic type or other 9 Magnetic Screw drivers – Phillips #1, 2, 3; slotted #1 and 2 10 Marking set – pencils, pens, chalk, laundry type markers (indelible) 11 Mechanics Mirror 12 Metric allen wrench set 13 Pliers – channel lock, needle nose, and standard 14 Punch – 1/8” – 1/4” 15 Putty knife – 1” 16 Right and left handed metal sheers (aviation snips) 17 Sabre saw and bits-variable speed 18 Scratch awl (scribe) 19 Single hand hack saw 20 Socket wrenches – metric, 1/4” and 3/8” drive, 5mm – l4mm sock ets. S.A.E. 1/4” – 5/8” sockets 21 Soldering gun with rosin flux solder 22 Standard allen wrench set 23 Tape measure – metric and inch 24 Vacuum cleaner – portable, or wet-dry canister type 25 Volt-Ohm Meter (VOM) 26 Digital Multimeter (DMM) 27 Wire stripper – multi gauge 28 Wire ties 29 X-Acto knife, razor blades, utility knife
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30 X-Acto razor saw blades 31 Heat gun Shop Equipment for Custom Fabrication: 1 Air compressor 2 Dual trace oscilloscope 3 Extension boxes for 120V AC power 4 Fabrication components (grille cloth, carpet, glue, etc.) 5 Large glue gun 6 Large current capacity battery charger 7 Portable fluorescent lighting 8 Photographic equipment 9 Realtime analyzer (Fast Fourier Transform System) 10 Signal generator (RF and AF) 11 Shop tools: a. Drill Press b. Grinder c. Milling machine d. Router e. Sander f. Table saw g. Vises 12 Soldering stations 13 Ventilated booth – for painting and fiberglass fabrication 14 Welding torch 15 Work benches (carpeted for door panels, plain for wood working) 16 Computer for speaker enclosure design
NON-POWERED HAND TOOLS
In the category of non-powered hand tools, essentials include the following: ■ A full set of straight blade and Phillips tip screwdrivers. ■ #2 Phillips is the most common, even for screw guns. ■ A full set of S.A.E. and metric sockets, along with the appropriate ratchets, extensions, “U” joints, and handles to facilitate every conceivable angle. ■ A 10mm socket is the most commonly used socket for European and Japanese cars.
A full set of open-end wrenches, both S.A.E. and metric, as well as adjustable wrenches.
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A good pair of diagonal cutters (commonly referred to as dikes).
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A set of long-nose pliers, regular pliers, vice grips, and crimping tools.
A set of shaft sockets (although DIN-sized radios are rapidly replacing the shaft radio, shaft sockets are still invaluable). ■ Shaft sockets are like regular sockets, but have longer shafts with no internal obstacles to inhibit sliding over the shaft.
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A full set of files – both rough and finish.
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Keyhole saws, hack saws, hack saw blades, and razor knives.
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A full set of aviation metal shears (also called tin snips). ■ Be sure to get the left cutting for counterclockwise cutting, right cutting for clockwise cutting, and the straight cutting for straight cuts.
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A good pair of industrial-duty shop scissors for cutting fabrics.
A full set of metric and standard allen (hex) key wrenches, as well as a full set of torx wrenches. They are not interchangeable, so you'll need them both.
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A small level to make sure speakers are straight in doors and on rear decks.
POWERED HAND TOOLS
This category usually includes the following: Drills: ■
Cordless drills are most common.
Use drills – either cordless or cabled –which have variable speed trigger controls. ■ This allows you to control the speed at different times in the drilling procedure.
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✍ If you use a drill as a screw gun, your best choice is a cordless drill
If you use a drill as a screw gun, your best choice is a cordless drill with variable speed, reversing capability, and a clutch. ■
with variable speed, reversing capability, and a clutch.
■ One of the handiest drills is the right-angle drill, which enables you to get into areas that a regular drill cannot.
If you’re going to be drilling a 3/8” hole through double metal, the low torque and slow rpm of a cordless drill will take a lot more time; a 3/8” electric, high rpm drill will cut right through the metal. ■ Too high of a speed can burn up and destroy drill bits. ■
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When trying to turn large hole saws, advancing to a 1/2” drill, 1 hp or better, is usually necessary to provide the necessary torque. ■
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Jigsaw/Sabre Saw: ■ These saws are used for cutting metal, wood, and plastics and are available as cordless models and offer variable speed. ■
Be sure to use the proper blade for the material being cut. ■ Fine-toothed blades should be used for cutting metal and plastic; coarse blades for wood.
■ Always take safety precautions when using this type of saw, especially when cutting corrugated metal panels. ■
Eye protection is a must.
Hand Router and Power Saw: ■ These are required for woodworking, and should be operated by only knowledgeable and skilled installers or woodworkers. Soldering Iron: ■ Soldering irons can be the standard Weller 8200 soldering gun or cordless model (Ultra torch UTS 100). Be careful though – high wattage guns can damage PC boards and small connectors. ■ A 25-40 Watt pencil-type soldering iron and stand should be handy on the bench.
LARGE SHOP TOOLS
This category includes: ■ A table saw, if you’re building a lot of speaker enclosures and custom panels. ■
A drill press is desirable, but not necessary.
Some shops like to use air tools instead of, or in combination with, electric hand tools. If you’re using air tools, make sure the compressor and tank assembly are up to the capacity of the work load asked of it.
SPECIALTY TOOLS
Dremel Moto-Tool: ■ This device is about as small as an electric razor and has every conceivable attachment. ■
A Dremel tool can be used as a small electric drill or a rotary file. ■ With a saw-blade attachment, it will easily cut through ABS plastic,
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but it usually doesn’t have the power necessary to cut or grind metal. For such jobs, use an air or electric hand held grinder. Power/Hand Nibbler: ■ A hand nibbler takes small, rectangle-size pieces out of metal. ■ A disadvantage of the hand nibbler is that it is heavy and sometimes awkward to use. ■ Bosch, Makita, and other manufacturers offer a power nibbler that is much less taxing on the hands, but does leave small crescent shaped pieces of metal which can be very dangerous and should be cleaned up as soon as you are finished cutting. Signal Amplifier (Head Amp): ■ This is used to boost the voltage level of a preamp signal. ■ Commonly used when the output voltage of a headunit is too low to adequately drive an electronic crossover or amplifier. ■ It’s installed between the output of the head unit and the input of the crossover/amp. ■ The output gain is usually adjustable. EMR Detector: ■ This tool is used to find the source of low frequency tape head interference, or EMR, Electro-Magnetic Radiation. Speaker-Level Adapter/Converter: ■ This device is used to convert the speaker outputs of any head unit into line-level or preamp level leads. ■ The benefits include a much lower noise and distortion levels. ■ The preamp level can be connected to other components in the system via regular shielded leads (RCA cables).
CUTTING TECHNIQUES
Wood: Wood can be cut with a sabre saw (jig saw), a regular crosscut saw, a keyhole saw, or a table saw: ■ When using a sabre/jig saw, a rougher-toothed blade is preferable to a finer-toothed blade. ■ To smooth out roughly cut wood (speaker holes, for example), use a wood file. ■
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The best way to cut speaker holes in wood is with a hole saw.
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Make sure you have an electric drill with enough torque to handle the job, and that your hole saw blade is sharp. ■
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A router with a hole cutting attachment – if properly used – makes a perfect hole ready for rabbitting and speaker installation. It is also quicker than the other methods. ■
Metal: Metal can be cut with a hack saw, aviation shears (tin snips), or a jig/sabre saw with an appropriate fine-toothed blade. ■ For either wood or metal, a drill – with usually a 3/8” bit – can be used to drill a starter hole. This allows the sabre saw blade, or tin snips, to get started. ■ Care should always be taken not to “push” a jig saw blade as it cuts. This could cause it to heat up and burn its way through a hole instead of cutting. The saw blade could also break, injuring the user or damaging the vehicle.
An air chisel or metal nibbler should be used by only an experienced installer. ■
Upholstery: Upholstery must only be cut with a razor knife or a type of razor blade. ■ A drill can damage the fabric if it is not first cut away with a knife. ■
Carpeting can wrap around a drill, creating a hazard when it unweaves.
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Vinyl can stretch and rip apart if caught by a hot, high rpm drill bit.
Section 6 Shop Safety You’ve probably heard the popular slogan, “Safety First.” This is especially true for installers – particularly when you have three jobs waiting…and it’s four o’clock on Friday afternoon! In the real world, safety often comes last.
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✍ The Occupational Safety and Health Administration (OSHA) is the government agency that regulates onthe-job safety.
It’s important to stress, however, that the installation bay offers a variety of hazards. Electric shock, hazardous chemicals, and sharp tools are just a few. The Occupational Safety and Health Administration (OSHA) is the government agency that regulates on-the-job safety. ■ OSHA requires that all employers maintain a safe and healthy work environment. ■ The Code of Federal Regulations (CFR) lists safety and health standards, and employers face stiff fines if these standards are not followed.
While the shop owner is ultimately responsible for accidents, safety begins with the individual. Therefore, a properly maintained attitude is your most important “tool” to help promote shop efficiency and safety.
SAFETY PRACTICES
✍ Always wear safety glasses or goggles.
✍ OSHA has specific regulations for hearing protection. Listening to a sound system
The installation bay is no place for playing games or fooling around. Protect yourself from horseplay that can lead to accidents, and always wear the appropriate gear before you begin a job. You will only lose that right eye or index finger once, and after the fact is too late to start being careful. Eyes: When using power tools – such as power nibblers, routers, jig/sabre saws, radial arm saws, Dremel tools, etc. – Always wear safety glasses or goggles. ■ Some installers think wearing safety glasses makes them look “un-cool.” However, looking “cool” does little good if you’re permanently blinded by flying wood or metal chips. Ears: OSHA has specific regulations for hearing protection. Listening to a sound system
playing at 100 dBA SPL for two hours will start to cause
NOISE EXPOSURE CHART
hearing damage.
Sound Level (dBA) 80 85 90 95 100 105 110 115 120 116
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Maximum 24-Hour Exposure Occupational Nonoccupational
8 hr. 4 hr. 2 hr. 1 hr. 30 min. 15 min. 0 min.
4 hr. 2 hr. 1 hr. 30 min. 15 min. 8 min. 4 min. 2 min. 0 min.
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playing at 100 dBA SPL for two hours will start to cause hearing damage. ■ If you’re constantly exposed to high decibel sound, wear earplugs or ear protection. Respiratory: When working around sawdust or other airborne material, always wear a dust mask. Fiberglass and particle board are especially hazardous. The glue in particle board is toxic, and fiberglass can cause severe skin irritation and lung damage if it is inhaled. When working with lead based solder, it should never be heated in excess of 1000°F, at this point the solder becomes vaporized and emits hazardous vaporized lead oxide. Be sure to check the soldering iron temperature rating before soldering. Always solder in a well ventilated area.
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✍ When working around sawdust or other airborne material, always wear a dust mask.
✍ Use gloves – full or partial – to protect your fingers and
Hands: Use gloves – full or partial – to protect your fingers and skin from being torn, cut, or burned. ■ Be particularly careful when working with large power tools.
skin from being torn, cut, or burned.
✍ Never strike a match, a lighter, or anything that
SAFETY AROUND BATTERIES
creates a spark or flame
By their very nature, batteries present a number of hazards. Chemical reactions taking place inside of batteries generate flammable vapors. Therefore, never strike a match, a lighter, or anything that creates a spark or flame near a battery. Although most modern batteries are sealed, older batteries still have vent caps which need to be opened to be filled with distilled water. ■ While working around battery fluids, take extreme care not to come in contact with the main chemical ingredient, sulfuric acid. ■ Sulfuric acid is highly volatile, and will burn through clothing and skin, not to mention what can happen if it comes in contact with eyes.
near a battery.
✍ Sulfuric acid is highly volatile, and will burn through clothing and skin, not to mention what can happen if it comes in contact with eyes.
SAFE TOOL USE
Make sure you know how to properly handle any tool – powered or not – before you pick it up. ■ If improperly used, the air chisel is the most dangerous tool in the shop. ■ Just the noise generated by this tool is enough to damage hearing if protection is not used. ■ If proper precautions are not taken, a window can shatter in a door
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and the rear window seal can have its integrity diminished due to the vibrations caused by an improperly used air chisel on a rear deck. Dikes, long nose pliers, and crimp tools should have insulated handles. ■ These are insulated not only for your comfort in reducing blisters from crimping and cutting all day, but to insulate you from electrical shock, should you accidentally hit a live wire or battery terminal.
FIRE EXTINGUISHERS
The laws of most states, cities, and counties require any shop which is working on motor vehicles to have at least one fire extinguisher on the premises. Fines and/or possible jail sentences await those who refuse to comply with this law.
✍ The extinguisher best suited for a mobile electronics shop is the Halon type.
Most fire extinguishers work by removing the source of oxygen from the fire. The types of extinguishers are noted as follows: ■ Type A – for wood and paper ■ Type B – for oil and flammable liquids ■ Type C – for fires of an electrical nature ■ Halon – for all types of fires The extinguisher best suited for a mobile electronics shop is the Halon type. Always make sure that the extinguisher is serviced at the appropriate interval, according to the tag which was affixed to it during the last inspection or recharging. Should you be unfortunate enough to have to fight a fire: ■ Always point the nozzle on the extinguisher toward the base of the flames – not the burning material. ■
Only attempt to fight small, controllable fires. ■ If a fire looks as though it’s getting out of hand, always contact the fire department. ■ Never try to fight larger fires on your own. ■ Remember, what may “look” like a fire may be only the insulation melting off a wire, so don’t panic and reach for the fire extinguisher. The bills to pay for cleaning a vehicle's interior can easily eat into profits.
CLEANING THE SHOP
Keeping the shop clean is also a part of safety, to say nothing about professionalism. ■ A clean shop reassures the customers that they’ve made the right choice about your services. Follow these guidelines:
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Floors should be swept up as often as possible.
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Reels of cable should be put back on their racks. Boxes that equipment came in should be put in the owner’s car or properly recycled. ■ ■
■ When cleaning up metal chips from power nibblers, or other tools, never leave them on the floor to be swept up later. ■ These chips can find their way into customers’ tires, the interior of their cars, and the bottoms of your shoes. ■ An old magnet can easily pickup stray nibbler chips to keep them from being tracked all over the shop. ■ A heavy-duty shop vac is essential in every shop.
FIRST AID
Try as we may to operate safely, the occasional accident will happen. ■ Every phone in the shop should have the number of the nearest hospital emergency room, police department, and fire department. Every shop should have a first aid cabinet well stocked with bandages, adhesive tape, antibiotic first aid cream, eye wash, iodine, and alcohol. ■ These are available at medical supply houses and industrial supply houses. ■
The cabinet should be kept at a convenient, central location.
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It’s advisable that one or more of your crew knows basic first aid and CPR.
Finally, because installers work with a lot of rusty metal, screws, and other unsavory items, you should get a tetanus shot every seven years.
Section 7 Troubleshooting Guide OVERALL
The customer comes to you with a physical problem (scratched paint, dirty or torn interior, etc.) after the installation: ■ Review the “vehicle check-out” form with the client. ■ Show them where the damage was noted on the form prior to the installation (and that the client signed that form before work was started.)
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■ If you – or someone in your shop – did the damage, take responsibility and get it repaired.
The customer returns a year after the installation with a question and/or problem: ■ Refer to the job log (which should be kept on file). It should include: ■ Wire codes for installing alarms. ■ Wire colors for hooking up power supply leads and power antennas. ■ Enclosure sizes for subwoofers in specific automobiles. ■ Templates that are made for special head units, antenna, and speaker installations. ■ Information on raw-materials sourcing, product sourcing, and people to contact in case of installation problems.
NOISE PROBLEMS
The three keys to noise problems: 1 Identify 2 Isolate 3 Eliminate How to identify the problem: 1 What are the symptoms? 2 What kind of noise is it? 3 Does the noise run through the whole system? 4 Does the noise go up and down with the volume control? 5 When did the noise start? 6 Does the noise rise and fall with engine speeds? 7 How long has it existed? 8 Is the noise affected by driving over bumps or dips? Isolate: Once you have identified the problem, the next step is to isolate it to determine in what stage of the circuit the problem exists. Eliminate: Here are some suggestions to help you eliminate various “noise” problems: ■ Check that the power and signal leads are run away from each other. ■ Is the battery lead crossing over other vehicle wiring? ■ Is your wiring next to any factory wiring harnesses? ■ Check for passive crossovers installed near factory wiring harnesses. ■
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Is the power source noise-free?
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Does the power source have enough current-carrying capacity for the unit each wire will be powering? ■
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Are the speaker wires and line--level signal leads on the opposite side of the vehicle? ■ If this can’t be done, try to keep power and signal cables as far apart from each other as possible – or a minimum of 18 inches. ■ If you have to route power and signal cables over one another, it’s best that they cross at a 90 degree angle. ■
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Is power being accessed from the fuse block or directly from the battery? ■ The fuse block is typically the noisiest spot on the vehicle to access power. ■ Check that sill molding screws or rear seat framing/springs have not punctured the insulation of the power cable and shorted it to ground.
■ Is an amplifier or any other component mounted directly to the metal of the vehicle? ■ Always use an amp rack and insulate the other components from the chassis of the vehicle. ■
How are the preamps grounded? ■ Some preamp units get their B- connection directly from the interconnect cable – connecting the black wire to ground in this case causes an automatic ground loop. ■ Ground preamp components to one point – usually the back of the radio – if their power supply ground is separate from signal ground.
■ Do any components share a ground connection with the vehicle's accessory ground path? ■ If the autosound system shares a ground with a fan motor or brake light ground, it is likely that a pop or a buzz will be heard in the system whenever the fan is turned on or the brakes are applied. ■
Are you using the factory head unit power and ground wiring? ■ This wiring usually has inferior gauge and often does not go directly to ground, but picks up grounds of other vehicle systems which are clustered together at one point. ■ Factory wiring typically runs in harnesses past other devices in the vehicle, which can radiate or couple noise into an audio system. ■ Try moving the location of the power cable away from such items as vehicle computers and stock wire looms. ■ If this does not help, a noise filter can be put on the power line (an
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in-line passive noise filter will always drop the voltage to the amplifier and may limit its performance.) ■ If you think a noise problem is coming in on the power cable, run a new one OUTSIDE of the vehicle, away from possible noise-producing vehicle items just to check. ■
Is it radiated noise? ■ To find the source of the noise, use a noise sniffer. ■ Make sure you find the true source of the noise because noise can sometimes come from a secondary radiator. ■ The cure may be as simple as moving the secondary radiator away from the primary radiator (i.e., moving a stock wire loom a few inches from another wire loom). ■ Most types of radiated noise cannot be eliminated, they can only be rerouted or redirected.
■
Is the antenna is the source of the noise? ■ Mounting the antenna as far away from the engine as possible will usually reduce Radio Frequency Interference (RFI). ■ With the antenna – are the rockers under the fender firmly digging into metal?
■
Noise can enter a system is if the battery is not fully charged ■ A low battery will not properly filter ripple from the output of the alternator ■ Battery problems can be caused by a number of conditions; check for: Low water in the battery Loose or corroded battery cables Slipping belts Dirt on the top of the battery One dead cell with five other good cells
If there is a problem with the wiring: ■ Are wires through holes that have rough metal edges? ■
Are grommets used whenever wires pass through metal boundaries?
■
Are wires getting pinched beneath seat tracks, clutch and brake pedals, etc.?
If there is a loose connection: ■ Are terminating wires soldered and then covered with heat shrink tubing? ■ Connections in the engine bay of a vehicle should be soldered. ■ When the connection is attached to the firewall, have you applied
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noncorrosive grease to the screw head? ■ Is the solder joint smooth, shiny, and concave? (It should be). ■
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If using a crimp-tool, is it a secure mechanical connection? ■ When using a crimp-tool, the seam of the metal barrel (unless it is seamless) should be in the concave part of the crimper's jaws to ensure a secure mechanical connection. ■ Over time, oxidation can build up between the wire and the connectors (this oxidation causes a degradation in the electrical connection, causing an increase in resistance, which hurts overall performance).
In a remote-controlled alarm system installation, you do have a constant +12VDC: ■ Is the system wired to the ignition switch? ■
Is the system wired directly to the battery?
Is there “alternator whine”: ■ Here’s how to check: With the audio system on and the volume turned all the way down, “rev” the engine – if the whine is heard, unplug the line inputs at the amp or crossover; if the whine goes away, you’ve more than likely got a ground loop. ■ Make sure all grounds are assembled at one point only and that amp mounting, crossover mounting, equalizer mounting, etc., are not allowing these components to touch ground. ■
Check for a ground loop: ■ Poor crimps can cause a ground loop. ■ Check low-level leads going from the output of a headunit to the input of a crossover or amp. ■ Noise can be caused by using inferior cable with poor shielding. ■ Do you have a “good” ground? (Metal-to-metal contact).
■
Check the alternator.
Measure the ground point potential back to the negative battery post and with each other. ■ Single point grounding is preferred. ■
If a fuse is always “blowing”: ■ Be sure the fuse meets the total amp draw and is able to handle the total amperage. Remember amplifiers that run more speakers at lower impedances use more current. ■
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Use a DMM or a VOM to determine if:
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A speaker may be “shorted out.” The input voltage to the amplifier is too low. Is there an intermittent problem with the alarm being triggered for no apparent reason? ■ A failing car battery can cause an alarm to be triggered for no apparent reason, giving the customer the impression that the alarm is defective. ■ Loose or corroded cables can also cause a problem. ■ ■
In case of a fire: ■ Point the nozzle on the extinguisher toward the base of the flames – not the burning material. ■
Only attempt to fight small, controllable fires. ■ If a fire looks as though it's getting out of hand, always contact the fire department. ■ Never try to fight larger fires on your own. ■ What may “look” like a fire may be only the insulation melting off a wire – don’t panic and reach for the fire extinguisher.
Every shop should have a first aid cabinet well stocked with bandages, adhesive tape, antibiotic first aid cream, eye wash, iodine, and alcohol.
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Margin Notes SAMPLE TEST QUESTIONS
1 Which of the following is not part of the “vehicle check-out” that is performed before starting work? A Inspect the body. B Inspect the trunk. C Inspect the battery level. D Inspect under the hood. E Inspect the interior. 2 You should maintain a personal dress code to help you from being blamed for damage that existed before the car came into the shop. A True B False 3
What is the general rule of thumb regarding power and signal leads? A Always run power and signal leads next to each other. B Depending on the installation, it’s okay to cross the battery lead. C Run the wiring parallel to the car’s factory wiring for ease of routing. D Run the battery power lead down the same side as the battery. E All of the above answers are correct.
4 Ground loops are the most frequent cause of noise problems in car audio installations. A True B False 5
When should you use wire nuts in an installation? A Always. B For the power lead. C For speaker connections. D Never.
6
How do you test for “alternator whine”? A Turn the audio system on, turn volume all the way down, then “rev” the engine. B Turn the audio system off, then “rev” the engine. C Use a noise sniffer. D Use a Digital Multimeter.
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E All of the above techniques can be used to test for alternator whine. 7 Which of the following is the best diagnostic tool for use on a brand new car with a computer-controlled ignition, computerized climate control system and a trip computer? A VOM (Volt-Ohm Meter). B Test light. C DMM (Digital MultiMeter). D Hydrometer. 8 If you want to check the amperage draw of a component or security system brain, and the suspect component is not blowing the fuse it comes with, you should set your amperage scale on your VOM to a range above the fuse rating of the component. A True B False 9 According to OSHA (Occupational Safety and Health Administration), what will cause hearing damage? A Listening to a sound system playing at 90 dBA SPL for four hours. B Listening to a sound system playing at 95 dBA SPL for three hours. C Listening to a sound system playing at 100 dBA SPL for two hours. D Listening to a sound system playing at 105 dBA SPL for one hour. E Listening to a sound system playing at 110 dBA SPL for four minutes. 10 Which type of fire extinguisher is best suited for a mobile electronics shop? A Type A. B Type B. C Type C. D Halon. E All of the above are acceptable.
Answers 1 C, 2 A,
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3 D,
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5 D,
6 A,
7 C,
8 A,
9 C,
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CHAPTER 3 INTRODUCTION TO AUTOSOUND, SECURITY, WIRELESS & NAVIGATION
This chapter introduces you to the basic principles behind automotive sound, security, wireless, and navigation systems. Its purpose is to give you a better understanding of how these systems function and identify the terms associated with these technologies. The First Class level Study Guide is needed to understand these technologies fully. This chapter is meant to be an introduction only, and includes only the areas covered in the Basic Installer level exam.
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Section 1 Introduction to Audio - Autosound Basics Understanding basic acoustics will optimize your installation abilities. Accordingly, the following section will provide you with a brief overview of basic autosound principles. Ask yourself – what exactly is a “sound”? Sure, you know what “sound” sounds like – but what are the scientific properties of sound?
✍ Sound is a type of physical kinetic energy called acoustical energy.
Actually, sound is a type of physical kinetic energy called acoustical energy. ■ Acoustical energy consists of alternating waves of pressure called sound waves that travel through a physical medium such as air. In order for a sound to be heard, two conditions must be present: 1 An object needs to be vibrating (i.e., a speaker cone) 2 And there needs to be an atmosphere through which the vibrations can travel (i.e., air or water).
✍ A transducer is any device that converts one type of energy into another type of energy.
✍ An audio signal is an electrical representation of a sound wave in the form of alternating current (AC).
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In a recording studio, for example, a vibrating object – like the strings on a guitar or an artist’s voice initially produces sound waves. The sound waves may be enhanced by the reflections and vibrations of the recording environment and monitored by one or more microphones that work as transducers. ■ A transducer is any device that converts one type of energy into another type of energy. ■ The transducer coverts the acoustical energy (sound waves) into electrical energy (audio signal). ■ A microphone works the opposite of a speaker – instead of vibrating the air, the air vibrates the diaphragm, which creates electrical energy. An audio signal is an electrical representation of a sound wave in the form of alternating current (AC). [SEE SECTION 1 OF CHAPTER 1 FOR A COMPLETE DEFINITION OF AC.] ■ An audio signal is a complex combination of alternating periodic signals called sine waves. ■ The frequency of the signal refers to the number of repetitions (cycles) which are completed in one second. The more repetitions per second the higher the pitch of the sound.
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The basic sound wave is comprised of four characteristics: 1 Frequency 2 Wavelength 3 Period 4 Amplitude
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1 CYCLE 1/2 CYCLE
AMPLITUDE
PRESSURE
+
0
— TIME
PERIOD
WAVELENGTH
DISTANCE
■
Figure 60. Representation of a sound wave.
FREQUENCY
Frequency is the number of complete wave cycles that pass a particular point each second. ■ The fundamental unit used to describe frequency is “cycles per second.” ■ This measurement is more commonly referred to by the term Hertz (Hz).
✍ Frequency is the number of complete wave cycles that pass a particular point each second.
Example: A wave of 20 Hz would alternate from Point A to Point B, 20 times in one second. ■ The higher the frequency, the more of these “vibrations” are packed together in a one-second period. Frequency is directly related to the pitch of the sound we hear. 1 Hz
3 Hz
1 second
■
Figure 61. Two separate wave cycles.
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Human hearing is considered to begin at 20 Hz, which is extremely low bass; however, it can go as high as 20 kHz (or 20,000 Hz). As shown in Figure 62, audio products are designed to reproduce frequencies that the human ear is capable of hearing. SUBSONIC
SUB BASS
20
BASS
40
ULTRASONICS
LOWER MID RANGE 160
UPPER MIDRANGE
MIDRANGE
320
2500
TREBLE RANGE
5000
10000
UPPER TREBLE RANGE 20000
FREQUENCY (Hz)
■
✍ Wavelength refers to the length of distance a single cycle – or complete sound wave – travels.
✍ Wavelength = Speed of Sound Frequency
✍ When the frequency of a sound wave increases, the
Figure 62. The range of human hearing.
WAVELENGTH
Wavelength refers to the length of distance a single cycle – or complete sound wave – travels. You can determine this distance by dividing the speed of sound (1,130 ft./sec., at sea level on a standard temperature day) by the frequency: Wavelength = Speed of Sound Frequency When the frequency of a sound wave increases, the wavelength decreases. In other words, the higher the frequency, the shorter the wavelength.
wavelength decreases.
PERIOD
✍ The amount of time required for a single cycle of a sound wave is called the period of the wave.
✍ Period =
1
The amount of time required for a single cycle of a sound wave is called the period of the wave. The period is expressed in seconds per cycle and is found by using the following equation: Period =
1 Frequency
Frequency
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AMPLITUDE
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Amplitude is the measurement of how powerful the waves are in terms of pressure. Higher amplitude means higher volume in sound or higher voltage in electricity.
✍ Amplitude is the measurement of how powerful the waves are in terms of pressure.
AMPLITUDE
20
20K FREQUENCY
■
Figure 63. Example of amplitude compared to frequency.
Sound is measured in Sound Pressure Level (SPL). ■ SPL is an acoustic measurement for the ratios of sound energy and is rated using a unit called the decibel or dB SPL. The ability to create louder sound requires high amounts of power. For example, if you have a 100-Watt system at a certain volume and decide to double the power, you will only notice a minor increase in volume (typically no more than 3 dB). The decibel is a ratio and is used to compare ranges of measurements that are too wide and require too many zeros to work easily. ■ To measure SPL, set “0 dB” at the point where a person with perfect hearing is barely able to hear a tone that is in the most sensitive “vocal” range of human hearing. Sound pressure is then measured from that point near silence to 140 dB, which is the human threshold of pain (but it is not the upper limit of SPL).
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✍ SPL is an acoustic measurement for the ratios of sound energy and is rating using a unit called a decibel or dB SPL.
✍ The decibel is a ratio and is used to compare ranges of measurements that are too wide and require too many zeros to work easily.
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TYPICAL SOUND PRESSURE LEVELS OF VARIOUS SOURCES
140 130 120 110 100 90 80
Gunshot 50 HP Siren Threshold of Pain Recording Studio Monitors for: Rock Music Film Scoring Loud Classical Music Heavy Street Traffic Subway Cabin of Jet Aircraft (Cruise Configuration) Alarm Clock
70 60 50 40 30 20 10 0
Average Conversation Average Suburban Home (night) Quiet Auditorium Quiet Recording Studio Soft Whisper Extremely Quiet Recording Studio Rustling Leaves Anechoic Chamber* Threshold of Hearing (1 kHz to 4 kHz) *Note that some anechoic chambers may be very noisy; the fact that a chamber does not reflect sound internally does not mean it effectively blocks external sounds from entering. Negative SPLs, while possible, are not given since, by definition, they are below the threshold of audibility.
PHASE & POLARITY
✍ Phase is the time relationship of a sound wave to a known time reference and is measured in degrees from 0º to 360º (just like a circle).
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Phase is the time relationship of a sound wave to a known time reference and is measured in degrees from 0º to 360º (just like a circle). ■ When a loudspeaker pushes and pulls the air in front of it, it creates waves of compressed air followed by waves of stretched air. ■ This is called compression and rarefaction, and correlates with the way a sound wave or electrical wave is represented.
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As the wave moves outward from the loudspeaker, it exhibits characteristics that are important to producing sound. ■
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Figure 64. Example of rarefied and compressed air and corresponding sine wave.
Polarity, in this context, refers to the route electrons follow through the system – from the positive terminal to the negative terminal. ■ Think of it this way, if you took two wires that were connected to a speaker and then reversed them, the resulting signal would be upside down. In other words, the waveform would be the exact mirror image – so rather than the cone moving outwards, it would be moving inwards. ■ This is called a polarity reversal and it is equal to a 180° phase shift. ■ Here’s something that catches a lot of people – a lot of installers state something is “out of phase” when it is actually a polarity reversal (“out of phase” is a matter of degree, polarity defines a condition). One complete cycle of compression and rarefaction corresponds to 360º degrees. ■ If a speaker pushes and compresses the air in its very first motion and then pulls, the wave would be considered “positive polarity.”
✍ Polarity, in this context, refers to the route electrons follow through the system – from the positive terminal to the negative terminal.
✍ One complete cycle of compression and rarefaction corresponds to 360º degrees.
If it pulls the air first and then pushes, it is considered to be “negative polarity.”
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The best way to determine polarity is with a test CD and a Polarity Checker. This will not damage small speakers (like tweeters) and can be tested with the grille covers in place.
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0°
90°
180°
270°
360°
POSITIVE HALF
NEGATIVE HALF
■
Figure 65. One complete wave cycle showing positive and negative phase.
If two speakers are mounted beside each other and both push and pull at the same time, the speakers are considered to be in phase. ■ When in phase, the two (or more) speakers work together. ■ When all of the speakers do not do the same thing at the same time, the speakers are considered to be “inverted” or having inverse polarity by 180º degrees. ■ This situation occurs in unbaffled speaker installations. This tends to cause destructive interference because what one speaker is trying to produce, the other is fighting to cancel.
Destructive Interference
+ ■
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Figure 66. Destructive Interference.
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If two speakers are mounted side-by-side but one is further forward than the other (physical alignment), when the speakers are in phase, the wave from one speaker will interfere with the other to some extent. ■ The two waves are not starting from the same point, even though they are starting at the same time. ■ The sound will be out of phase anywhere from 1º to 359º degrees. ■ In Figure 67 (below), the signal is out of phase by 90º degrees. The result is a new wave that’s both reduced in amplitude (due to interference) and at a different phase than its two parents. This occurs acoustically because you can only wire a speaker polarity to be 0º or 180º degrees, depending on whether or not you reverse the two leads.
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In figure 66 (previous page), both speakers are wired identically; however, one is moved ahead or behind the other by 25% of its wavelength (90º degrees is 25%, or one-quarter, of 360º degrees). ■ If a 500 Hz tone is used, the wavelength would be 1130/500 = 2.26 feet. One-quarter of 2.26 feet is .56 feet. ■ By moving one speaker behind the other by slightly more than six inches, you would have a combined wave that is 90º degrees out of phase. ■ Move it to 1.13 feet apart and the two tones would cancel each other out (180º degrees). Since we know that the wavelength of higher frequencies is shorter than low frequencies, manufacturers will often build home speakers that have the tweeters set back slightly from the woofer so that the voice coils are aligned. This is often referred to as time alignment, and it compensates for the different sizes (lengths) of the wavelength.
✍ Time alignment compensates for the different sizes (lengths) of the wavelength.
+
=
SUM OF 2 IDENTICAL SIGNALS 90° OUT OF PHASE
SUM OF 2 IDENTICAL SIGNALS 180° OUT OF PHASE
+ ■
=
Figure 67. Sine wave example of front wave 90 and 180 degrees out of phase.
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Here’s how you can tell when a four-speaker, full-range system is out of phase (or having most commonly an inverted polarity) by just listening: 1 Balance the system left to right. 2 If the bass is strong on one channel and weak on the other, and the midrange and highs do not sound distinct, go to the amp (or head unit's internal amp) and reverse the speaker lead on one side only. 3 Listen to the system again. 4 Balance left to right to see if the distance or “muddiness” has cleared up and listen to see if the bass seems tighter. If so, the speakers could be out of phase or have an inverted polarity. Depending on you situation you could have a problem that is corrected simply by reversing polarity electrically (this is a simple fix). If the problem is phase, you could also have to change speaker position or location.
RESONANCE
All objects have a natural tendency to vibrate at certain frequencies. ■ A crystal wineglass, when tapped, will vibrate air to produce a tone somewhere between 2 kHz and 6 kHz. ■ The smaller the glass, the higher the pitch of the tone. If you were to play a tone at the same frequency that the glass produces, the glass would begin to vibrate on its own. This is known as sympathetic vibration and is caused by the natural resonance of the object. A bass drum will respond to frequencies around 30 Hz to 130 Hz. Playing a tone in this range, and at a high enough volume, will cause the bass drum to vibrate severely.
FREQUENCY RESPONSE
✍ Frequency response is the relationship between each individual frequency and its amplitude.
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Frequency response is one of the most important sonic measurements for determining quality. Frequency response is the relationship between each individual frequency and its amplitude (this includes refraction and absorption, or constructive and destructive interference). To have a flat response, a system must reproduce all frequencies in the human hearing bandwidth (20 – 20k Hz) with equal amplitude.
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A waveform that has equal amplitude from low bass to high frequency (full bandwidth) is considered to have flat response. ■ A waveform with peaks and valleys is uneven in sound and can be annoying to listen to. ■ Irregularities in the midrange areas are quite noticeable – humans are most sensitive at 1k Hz. ■ Peaks are much more noticeable than dips.
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✍ A waveform that has equal amplitude) from low bass to high frequency (full bandwidth) is considered to have flat response.
Therefore, choosing speakers that reproduce the entire audio spectrum smoothly and without voids is crucial to the performance of the system. ■ The mounting of the speakers is equally critical to ensure the smoothest possible bandwidth performance.
AMPLITUDE
AMPLITUDE
20
FREQUENCY EXCELLENT RESPONSE
■
20K
20
FREQUENCY
20K
POOR RESPONSE
Figure 68. Example of excellent and poor frequency response.
In car audio systems, three things affect the linearity or smoothness of sound: 1 The vehicle’s size and shape cause resonance at certain frequencies and cancellation of others at the seating position. 2 The materials used in the interior – such as glass, plastic and soft fabrics -- result in either reflections or absorption of the sound (they are either constructive or destructive). 3 Road noise and other ambient noise will mask sounds, primarily in the bass regions. But noise will not effect the linearity of the sound. An equalizer can help control these external factors, but only after the original acoustic causes have been identified and dealt with. ■ An equalizer should not be used as the only way to fix acoustic problems that could have been taken care of with speaker placement, crossovers, gain adjustments, etc.
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■ An equalizer should be used to compensate for personal preferences or the differences in recorded material, not an obvious hole in the midbass or a peak in the midhighs. ■ Excessive boosting of the equalizer controls can result in premature curving and can possibly damage speakers.
The human ear is very sensitive: ■ The ear is most sensitive to midrange, which is the human vocal region. ■
At low bass and high frequencies, the ear is less sensitive.
■ High frequency ability deteriorates with age (interestingly enough, women retain their high frequency perception better than men.)
✍ Fletcher-Munson curves depict the uneven frequency response of human hearing.
In order to hear flat response, you must often boost the amplitude (volume) of the bass and treble regions and reduce midrange to counteract what is known as Fletcher-Munson curves which depict the uneven frequency response of human hearing. ■ Overcoming this is most commonly achieved with the use of a graphic equalizer. However, remember that the frequency response of any sound system is affected by the environment in which it works. Figure 69 (below) shows graphs called the Fletcher-Munson Equal Loudness Contours. Using 1,000 Hz as a reference, they illustrate the relative levels that must be produced acoustically to sound equally loud.
+100
100
+80
80 60
+60
40
+40
20
+20 0 dB
Threshold of Hearing “An intensity level at which sound just becomes audible in an average person with good hearing.”
10 Hz ■
140
100 Hz
0 1000 Hz
10 KHz
Figure 69. Fletcher-Munson Equal Loudness Contours.
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OCTAVES AND HARMONICS
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An octave is a musical interval between two tones formed when the ratio between the frequencies of the tone is 2:1 (i.e., a doubling or halving of a frequency). ■ Unless it is an electronically produced pure tone, a musical note will have overtones and harmonics. ■
A musical note has octaves that double the previous octave. ■ A note at a frequency of 440 Hz has octaves at 880 Hz, 1760 Hz, 3520 Hz, etc. ■ Each octave has eight full tones above and below another given tone.
✍ An octave is a musical interval between two tones formed when the ratio between the frequencies of the tone is 2:1.
■ Octaves also relate to the vocal range of a singer or musical instrument, as in soprano, alto, tenor, basso, etc.
The fundamental frequency created by most musical instruments – with the exception of synthesizers and pipe organs – is limited to about 8 kHz. A harmonic is a weaker overtone of the original note (the fundamental frequency) and is responsible for the character of the note. When a musical note with a complex waveform has a distinct pitch (as opposed to just plain noise), that waveform can be created by combining a set of precisely related sine waves. These sine waves are called harmonics. We recognize voices on the telephone because people sound different due to the harmonic content of their voices. ■ Harmonics occur at frequencies that are multiples of the original note. ■ A note at a frequency of 440 Hz may or may not have harmonics at 880 Hz, 1320 Hz, 1760 Hz, 2200 Hz, etc., and sub-harmonics at 220 Hz, 110 Hz, 55 Hz, etc.
✍ A harmonic is a weaker overtone or undertone of the original note (the fundamental frequency) and is responsible for the character of the note.
If two instruments have exactly the same harmonic structure and strength, they will sound identical. If only one harmonic is absent or significantly altered, a difference would be discernible to those with excellent hearing. Speaker basics: ■ A basic speaker has a narrow frequency range, depending on the size of the speaker cone. ■ Large speaker cones naturally produce bass, while small cones produce higher frequencies. Since a single speaker cone cannot cover all of the frequencies in the audible spectrum, manufacturers combine a larger bass cone with a small treble driver – or tweeter – to more effectively cover the entire spectrum. The overall intention is to improve the frequency response of the system to give you a flat response and improve the sound quality.
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Special cabinet-style speakers have been designed to fill in the lower bass region, these regions are difficult for virtually any vehicle to support. ■ Subwoofer systems are intended to accurately reproduce the sub-bass region.
FUNDAMENTALS
OCTAVES
HARMONICS SUB HARMONIC
220 HZ
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440 HZ
880 HZ
1760 HZ
3520 HZ
Figure 70. Examples of octaves, harmonics and their fundamental tone.
SIGNAL TO NOISE
✍ Signal to noise (s/n) is a ratio that indicates how much audio signal there is in relation to noise, under specific conditions.
✍ A high s/n ratio is always preferable to a low s/n.
Signal to noise (s/n) is a ratio that indicates how much audio signal there is in relation to noise, under specific conditions. ■ A high s/n ratio is always preferable to a low s/n. ■ This ratio of audio output level to the level of noise is expressed in decibels (dB). ■ The s/n ratio usually begins at the noise level, whether high or low, and goes to some arbitrary nominal level. A musical note can be masked in a number of ways. Acoustically, the ambient noise that occurs in the vehicle – as well as the road, wind, and traffic – will combine to mask the quieter musical passages. This is referred to as the “noise floor,” and is concentrated mostly in the bass regions. ■ Many of today’s cars -- particularly the luxury cars -- do an excellent job of lowering the noise floor by insulating the outside noises. Electrically, the circuit noise present in electronic products will mask the very lowlevel signals that try to pass. The design of the product generally dictates how noisy it will be. ■ When parts of lower grade (more economical) are incorporated into a design, they will contribute to the thermal noise that infects the musical signal. ■ Quiet passages in the music will be covered by hiss.
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DYNAMIC RANGE OF A MUSIC RECORDING
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Dynamic range is the range of volume, in DeciBels from the softest to the loudest, produced by a source of sounds. The reference is usually a musical selection, or program signal being played. ■ A program is a structured, narrow band signal, while noise is a random, wideband signal. ■ Rock and heavy metal music have a low dynamic range since the difference between the quiet lead guitar solo of 100 dB SPL and a full crescendo of 130 dB SPL is only 30 dB. ■ Classical music can have a quiet flute solo of 60 dB SPL, followed by a crescendo of 110 dB SPL that results in a dynamic range of 50 dB.
✍ Dynamic range is the range of volume, in DeciBels from the softest to the loudest, produced by a source of sounds.
Even though the rock selection is louder overall, the classical selection has far greater dynamic range.
HEADROOM
Headroom is one of those terms that are quite common in audio jargon. But ask anyone to define headroom, and they’re at a loss. For once and for all, here is a definition: In an audio device, headroom refers to the difference in levels between the highest level in a given signal and the maximum level that the unit can handle without distortion. ■ Obviously, more headroom is desirable. ■ The music can have short peaks that are much higher in level than the average signal level. For example, a musical crescendo consumes a lot of power and can quickly push a system to its limits. ■ These short peaks are not registered by most audio level reading devices and if the musical demand is higher than the system’s ability to track it, the result is severe distortion (clipping) and probable damage.
✍ Headroom in an audio device refers to the difference in levels between the highest level in a given signal and the maximum level that the unit can handle without distortion.
Think of headroom this way: ■ Imagine you’re jumping on a trampoline in a room with a low ceiling – the consequences could be painful. ■ If you could raise the ceiling (add more “headroom”), then the chance of hitting your head on the ceiling would be lessened. In terms of a concert, the average sound level (100-110 dB SPL) is the nominal program level. ■ The difference between the highest (peak) levels and the nominal level is the headroom. ■ The classical music in the last section has more headroom than the rock concert.
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■ Classical music is usually much more demanding on a sound system than rock music just for these reasons.
90 dB Dynamic Range
Maximum Sound Level (Threshold of Pain) 120 dB SPL
30 dB SPL Ambient Noise Level 20 dB
70 dB S/N Ratio
Headroom (dB SPL) ■
120
110
100
30 90
80
70
60
50
40
30
20
10
0
Figure 71. Dynamic range and headroom.
Autosound can be studied in greater depth in the MECP First Class Study Guide.
Section 2 Introduction to Security When it comes to a security system, the system is only as good as its installation – and you have a direct impact on the quality of the installation. Accordingly, before getting to the basics, always be sure to follow these installation guidelines for security systems: ■ Use caution in determining component locations. ■ If possible, refer to the vehicle’s owner’s manual to ensure the security system is installed in harmony with the other components on the vehicle (there might be some major differences in the operating characteristics and wiring compared to previous models).
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Make sure all the connections are solid – use solder whenever possible.
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Use a multimeter to check all wires – never use an incandescent test light.
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Figure 72. Typical security system.
BASIC COMPONENTS OF A SECURITY SYSTEM
Most security systems come with a variety of components that can perform many different functions. The majority of systems you will be working with will include the following parts: ■ Control unit ■ Siren ■ Switch triggers ■ Sensors ■ Engine disable(s) ■ Remote control ■ Accessory output devices The Control Unit is the main element of all security systems. A control unit has the electronic circuitry necessary to control all the functions of the security system. It has the ability to arm and disarm, monitor triggers, and react to an intrusion. Most control units also include circuitry designed to enable/inhibit the operation of the engine. In addition, control units can include outputs designed to reflect the status of the system. These can take the form of visual (LED outputs), or Audible sometime referred to as “beepers”.
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✍ The Control Unit (sometime called the “Brain”) has the ability to arm and disarm, monitor triggers, and react to an intrusion.
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■ Since control units are the central governing element, they are often called the “brain” of the security system.
Control units chirp sirens, blink parking lights, and sound alarms in response to commands or intrusions. ■
■ More sophisticated systems include multiple trigger inputs that enable you to connect a different area of the vehicle to a different trigger input. ■ This allows the installer to divide up the vehicle into separate “zones” for the purpose of easier system management and troubleshooting. ■ Some systems with multiple trigger inputs include a method to individually monitor and verify each trigger, sometimes called “diagnostics.” ■ This aids the installer or consumer in detecting and isolating a trigger-related problem.
SIRENS
The electronic siren is the most common form of sounding device found as standard equipment in today's automotive security systems. Usually, this device is a self-contained unit consisting of three basic sections or stages: 1 The oscillator or tone generator stage 2 The amplifier stage 3 The speaker or output stage The typical electronic siren can, therefore, produce its warning sound simply by being connected to the proper power source. Electronic sirens come in all shapes and sizes, but the most common is the bell or horn shape. ■ The horn shape contributes to overall volume as well as pitch. The outer casings of some sirens are composed of metal, but the great majorities are made from various types of high temperature plastic. ■
SWITCH TRIGGERS
Switch triggers come in many different forms. The most common is the simple spring-loaded pinswitch. Others include the roller push-button type, the magnetic reed switch type, metal pressure strip type, and the mercury tilt type. Each of these types has advantages and disadvantages. There are several types of triggering devices, we will cover just a few of the most common ones:
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Spring-Loaded Pinswitch - This type of switch usually consists of a spring-loaded plastic plunger set within a cylindrical metal housing that is threaded at one end. ■
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■ Roller push-button - The roller push-button type is very similar to the spring-loaded pinswitch except that instead of using a straight linear plunger, it uses a ball or “roller” to push against an internal plunger and set of contacts. ■ This feature makes it ideal for applications where a normal springloaded pinswitch would shear off, such as uneven surfaces and sliding panels. ■ This switch is typically used to protect truck tailgates, drawers of tool boxes, hoods, and other compartments that slide open.
Magnetic Reed Switch - The magnetic reed switch (also called a magnetic proximity switch) uses magnetic force to cause a set of contacts to connect.
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This switch basically comes in two parts: a switch and a magnet. ■ The switch contains a set of magnetic “reeds” or two thin flexible slivers of metal, each with a contact at one end. ■ These reeds are enclosed inside a glass tube, insulated from each other and attached to a stationary point at one end. ■ Each reed is connected to a wire, and each wire is run outside the glass tube. ■ The whole switch assembly is typically placed inside a rectangular plastic case.
✍ Magnetic reed switches come in two basic electrical forms: Normally Open and Normally Closed.
SENSORS
Motion Sensors - A motion sensor is designed to detect motion – but what kind of motion? The main purpose behind a typical motion sensor is to detect the degree of motion a vehicle might undergo if it were being “jacked up” or if an attempt was made to “tow” the vehicle. ■ These forms of “motion” usually consist of: ■ Gentle and nearly vertical up-and-down motions (i.e., those produced by a ratcheting jack), or… ■ A gradual change in the vehicle’s angle relative to the plane on which it is parked (i.e., the change in angle that occurs when the front or back of the vehicle is lifted for towing). Shock and Impact Sensors - Shock and impact sensors are probably one of the most common sensors in use in vehicle security systems today. They are typically designed to detect the various degrees of impact that might be applied to a vehi-
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cle during a break-in attempt. Although they come in many different shapes and sizes and operate on many different principles and designs, they all fit basically into one category. ■ From the simple and primitive vibrating spring and contact type, to the more exotic piezoelectric, these sensors basically work by detecting and reacting to any shock, impact, or vibration applied to the vehicle. ■ Electromagnetic shock sensor detects vibration in the vehicle and transfers it to a processor to trigger up to two different levels of output. This sensor is usually referred to as a “two stage sensor”. These sensors can give a warning trigger for a light impact on an automobile or causes the alarm to go into full alert for a harder impact. The installer usually can set the impact level.
Figure 73. Electromagnetic Shock Sensor. ■
Some sensor designs work better than others, since some are designed to better sample and discriminate their inputs in order to avoid false alarms.
Sound Discriminators - The typical sound discriminator is designed for one single purpose – to detect and distinguish the sound of breaking glass. These sensors are commonly called “glass sensors.” Most sound discriminators consist of a microphone with frequency characteristics that are weighted in favor of the frequency that glass produces when it breaks. ■ The microphone is connected to a filter/sampling network designed to further “discriminate” and select only the “signature” sound of glass breaking. ■ The circuit feeds into a comparator which compares the level of the sound to the sensitivity threshold setting of the sensor, and then decides whether to produce a trigger or not.
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Figure 74. Sound Sensor.
SOUND SENSOR
Spatial Sensors - The category of spatial sensors includes a variety of different sensors that operate under different principles. The sensor's ultimate purpose is to protect an area of “space” either in or around the vehicle or both. ■ The basic physical principles these sensors employ fall into three categories: 1 Ultrasonic 2 Radio field disturbance 3 Infrared field disturbance Common names for these sensors include space sensors, microwave sensors, Doppler sensors, mass sensors, and radar sensors. 1 Ultrasonic Type – The first “spatial” sensor to be used in a vehicle security application was the ultrasonic sensor. This sensor usually consists of two separate sections: a sender and a receiver. Extremely high frequency or ultrasonic sound waves are emitted from the sender unit and then subsequently received by the receiver. Frequencies between 10,000 Hz and 90,000 Hz are typically called “ultrasonic” frequencies. If there is an object of sufficient mass moving within the area or “space” between the sender and the receiver, it is detected and a trigger output is produced. 2 Radio Field Disturbance Type – Radio field disturbance is by far the most common of the three types of spatial sensors. ■ These sensors operate essentially like the ultrasonic sensors in that they also send out a signal and then monitor its return. However, instead of using ultrasonic frequencies, they use even higher frequencies in the giga Hertz range, or more than 1,000,000,000 Hz (one billion Hertz). Radio frequencies in this range are also typically referred to as “microwaves.”
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Figure 75. Radar Sensor.
3 Infrared Field Type – The infrared field type is less common in vehicle security applications than the other types of spatial sensors. However, infrared sensors are used quite often in home and business security systems. Infrared sensors use light waves just beyond the visible red end of the light spectrum known as the “infrared.” Infrared radiation is well suited to the task of spatial sensing. ■ An infrared field disturbance sensor is not subject to changes in air pressure, so it will operate in a convertible or other open vehicle just like a radio field disturbance sensor.
ENGINE DISABLES
The term engine disable includes any device that either prevents a vehicle's engine from starting, or once started, prevents it from running for more than just a short period of time. First, let’s take a look at the most common types. They come in three basic forms: 1 Starter Disables 2 Ignition Disables (or diesel engine glow plug disables) 3 Fuel Delivery Disables The manner in which these three forms of engine disables function are best described by their names. ■ A starter disable works by interrupting or disabling the vehicle’s starter.
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Figure 75. Typical starter interrupt circuit.
■ An engine disable wired as an ignition disable, on the other hand, would allow the thief to operate the vehicle’s starter, but since the ignition system is disabled, the engine will fail to start.
An engine equipped with a fuel system disable would allow the starter to operate and might allow the engine to start, but since the engine’s fuel supply is effectively cut off, the engine would run for only a short time.
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REMOTE CONTROLS
Remote control security systems typically operate using technology that falls into three basic categories: 1 Radio Frequency (RF) 2 Infrared (IR) 3 Inductive or magnetic 1 Radio Frequency Transmitters - By far the most common is the radio frequency type, or simply RF. A remote control transmitter in a security system using this technology uses radio waves of a specific frequency to operate the functions of the security system.
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■ The frequencies used by most brands of RF remote security systems typically fall somewhere between 300 to 470 MHz.
This frequency band is also used by remote controls for some automatic garage door openers as well as some remote engine start devices. ■
2 Infrared - The second form of remote transmitter in use today is the infrared. Unlike the radio frequency type transmitter, the infrared must be used within line of sight of the vehicle. This is due to the fact that the infrared radiation emitted by these units travels only in one narrow straight line. 3 Inductive/Magnetic - The third form of remote transmitter is actually not a transmitter in the usual sense at all. These are typically referred to as the inductive or magnetic type. ■ Instead of “transmitting” a signal, these units use the electrical property of inductance to arm and disarm a security system. ■ This is accomplished by passing the remote within just a few inches of a special pickup usually located on one of the glass areas of the vehicle. ■ The “range” of these units is typically just a few inches.
ACCESSORY OUTPUT DEVICES
Accessory output devices incorporate circuits designed to control such things as power door locks, power windows, power trunk/hatch releases, and garage door/gate operation. These devices utilize basic building block components frequently used by installers such as relays, diodes, and timers.
✍ A relay is nothing more than a switch with contacts that are controlled by the magnetic field from an electromagnetic coil.
Relays - A relay is nothing more than a switch with contacts that are controlled by the magnetic field from an electromagnetic coil. ■ Relays – like switches – are classified by the way their contacts are arranged. ■ A relay may be designated a SPST (Single Pole Single Throw), or a SPDT (Single Pole Double Throw), or one of many other configurations. ■ Due to these various contact configurations, a relay may be used either to “make” a connection or “break” a connection, depending on how it is wired. Diodes - Another commonly used device may not be considered a “device” at all. We’re referring to the simple semiconductor component – the diode. Diodes, like relays, can help solve a vast number of installation challenges.
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A diode is nothing more than a one-way current valve. Voltage will flow through a diode in one direction only; this property can be used to allow circuits to remain isolated from each other and yet be connected to a common point as well.
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✍ A diode is nothing more than a one-way current valve.
Diodes can be used to isolate or connect circuits of either power or ground polarity, depending upon the direction in which the diode is installed. Just remember, a diode will block current flow in one direction, but allow current to flow in the opposite direction. A less accurate but more understandable explanation of this “one-way” action would be to say that when a diode is installed in a particular direction, “power” will flow in one direction, but “ground” will not flow in the same direction. In addition, the same diode will not allow “power” to flow in the opposite direction, but it will allow “ground” to flow in the opposite direction. Universal Timers - A “pulse” or universal timer can convert a momentary duration pulse from a security system or other source into a longer or shorter duration signal to perform a variety of different tasks. ■ A timer might be used to create an interface between a remote security system and the vehicle’s headlights. This would provide the driver of the vehicle with a lighted pathway for a period of time long enough to allow them to walk with a greater degree of personal security.
✍ A "pulse" or universal timer can convert a momentary duration pulse from a security system or other source into a longer or shorter duration signal to perform a variety of different tasks.
TELEMATIC SYSTEMS
Telematic systems have all of the benefits of a tracking system, but does not need a full-fledged navigation system for their operation. ■ Telematics involve the creation and development of Intelligent Transportation Systems (ITS) to track navigation, traffic volume, and safety of private and commercial vehicles on roads and highways. ■ Many commercial bus and trucking companies use these systems. A telematic system receives longitude and latitude information from GPS satellites via a GPS antenna that’s concealed in the vehicle. The system then uses an embedded cellular phone connected to a wireless network to transmit vehicle status and position information to a response center. ■ The driver can communicate with the response center by pressing a communications button. ■ Once connected to the response center, they can “see” the location of the vehicle – longitude, latitude, speed and heading.
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The response center can provide a wide array of services: ■ Dispatch roadside assistance. ■ If the driver is lost, they can provide turn-by-turn directions. ■ If the keys are locked in the car, the driver can call the response center and have the doors unlocked. ■ Some also offer a full range of concierge services, including making reservations (for airlines, hotels, restaurants, etc.) purchasing tickets or flowers, etc.
Most systems include a panic button for emergency situations ■ Thanks to the GPS capabilities, the response center can track a stolen vehicle. ■
They can dispatch help in the case of an emergency. ■ The client can keep an in-depth, confidential medical history on-file with the response center. ■ Once the panic button is pushed, the response center then “calls” the vehicle to check on the driver. ■ During a car jacking, when instructed by the police, the response center can cut off the ignition and unlock the doors, stopping the vehicle and providing access to the occupants.
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If the battery level drops or goes dead, the response center can alert the driver.
■ Some systems include airbag deployment notification – if the vehicle is in an accident in which the airbags deploy, the system automatically contacts the response center.
BASIC INSTALLATION TIPS
The first installation rule to remember is that the ultimate success of any security system is directly related to the quality of its installation. Putting this into perspective, if a pair of car speakers were wired “out of phase,” the problem could probably go unnoticed by the majority of your customers. This improperly installed system may be just an annoyance, nothing more serious. It may not even impact the reputation of your company. However, an improperly installed security system might awaken your customer and surrounding neighbors at 2:00 a.m. with false alarms. An improperly installed system may cause electrical damage to factory wiring or fail to protect the vehicle. The customer is placing a great deal of trust in you and your installation quality. If a vehicle is damaged or stolen as a result of faulty installation, the owner will feel betrayed by the installer and the shop itself. Not only will you have lost one customer, but those future referrals that a “satisfied” customer will provide. 154
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Several physical and electrical factors can affect the overall quality of an installation. A few “do’s and don’ts” for any installation include the following: 1 Never begin a job without first reading both the Owner's Manual and Installations Instructions Manual for the product.
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2 Inspect the vehicle for preexisting defects, and point them out to your customer before you begin work. 3 When troubleshooting a malfunction or problem, observe the vehicle under the ambient condition in which the malfunction occurred. 4 Whenever possible, run wires alongside factory looms and cables. This will make your work look “factory installed” and will significantly enhance the overall security and durability of the system. 5 Always run a separate dedicated main power wire directly from the vehicle's battery to the security system's main power lead. This can prevent many common sources of installation--created “failures,” such as inductive load electrical noise. 6 Avoid using a simple incandescent test light to probe a vehicle’s wiring. Incandescent test lights can damage sensitive vehicle computers, as well as passive restraint systems, such as airbags. A digital multimeter (DMM) is the safest way to test vehicle circuits. 7 Never connect power to, or operate, any system until all the wiring connections have been completed. 8 Install wires in a secure fashion so they will not be susceptible to damage from moving parts and will maintain their position over time. 9 Make sure that the proper wire gauges for the circuits and devices installed are used. 10 Test every wire connection and circuit before moving onto the next one. 11 Always confirm that the “ground” points you select for use are truly “ground.” A good ground connection will measure less than 0.1 Ohm. 12 Know what wires you are tapping into. Never tap into wires that are coming from a “black box”: This may be a sensitive computerized device, such as an engine control computer.
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13 When installing additional sirens to any security system, always connect the main (or first) siren directly to the security system’s output. Then connect any other sirens (internal, external, or backup) through a Boschstyle relay. The relay power must be supplied from a separate fused wire from the battery. This technique will ensure that the main siren will continue to function even addition sirens are shorted out or defeated. 14 Always make sure the mounting area of a device or component is safe from contamination by water or heat, as well as from intentional damage or unintentional damage by a mechanic performing routine vehicle maintenance. These simple rules are ingrained in the minds of good installers. They have learned over time that when you consider all the different consequences of the installation during each step, the job goes smoother, works better, and best of all does not come back! Security Systems can be studied in greater depth in the MECP First Class Study Guide.
Section 3 Wireless Communications: The Basics of Installation Cellular Installations There are countless ways to install a cellular telephone. Accordingly, we do not have the luxury of being able to cover each application. Therefore, we will cover the basics. As most of you already know, properly planning the installation will reduce the number of unprofitable service calls. ■ A majority of all problems that occur with cellular telephones can be traced back to installation problems.
TRANSCEIVERS
Transceiver is short for transmitter/receiver. It refers to a device that can both transmit and receive signals.
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Mounting Location The preferred location of the transceiver is in the trunk, even though most late model transceivers can be mounted in various other places (including under the front seat or under the rear seat; depending upon the type of car and manufacturer of the telephone). ■ If the transceiver is trunk-mounted, it should be securely mounted by bolting the transceiver mount bracket to a suitable surface. ■ Pay attention not to puncture the gas tank or any other device.
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■ If the transceiver is mounted under the front seat, remove the seat and bolt the mount bracket to the floor.
It’s extremely important that the transceiver be securely installed. If there is a collision, the transceiver could become a flying projectile that could cause severe injury. Once the transceiver is securely mounted, the data cable, power cable, and antenna cable should be run from their location. ■ Be careful not to pinch the data cable or the antenna cable. The antenna cable should have large radius bends to prevent the center conductor from getting kinked or pinched. ■
The power cable can be sourced at the fuse box and should include the appropriate fuse (check the install manual for the correct size). ■
Typical current draw of a 3 Watt cellular telephone is 1 - 3 Amperes during transmit, and from 0.1 - 1 Amperes during standby. ■ It’s a good idea to attach a card at the battery fuse that tells the owner to remove the fuse when jump starting the vehicle. ■ Removing this fuse prevents the handset programmable telephone from dropping its programming information due to a voltage surge, which can occur when jump starting a car. ■ Removing the battery lead fuse also protects the telephone from damage if the jumper cables are connected backwards.
✍ Typical current draw of a 3 Watt cellular telephone is 1-3 Ampers during transmit, and from 0.1-1 Amperes during standby.
The ground lead should be connected to a good chassis ground somewhere near the transceiver. The ignition lead can be hooked up to the ignition wire that does not lose power during the crank position. This provides a good source that does not allow the phone to cut off during cranking the automobile. ■ If you do not know which ignition wire to use, probe the suspect wires with a Digital Multi-Meter to see which one is hot when the key is turned on, and in the crank position.
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The data cable should be routed under the carpet, away from foot areas, to wherever the control unit is mounted. ■ Most telephones include a hands-free microphone and sometimes a separate hands-free speaker.
MICROPHONE
The hands-free microphone can be mounted almost anywhere, but there are a few precautions: ■ If the microphone is mounted in the dash, make sure that the small holes around the shell of the microphone are not blocked or plugged. ■ These holes are used for noise canceling, and the microphone will not work correctly if it is flush mounted or the holes are plugged. Since the wires inside the microphone cable are extremely small (usually 28-30 gauge), be sure that you do not pinch the cable or pull on it when routing it behind the trim. ■
■ Make sure that the microphone is located as far away as possible from the hands-free speaker. This will prevent feedback and allow the user to turn up the volume of the hands-free speaker in order to hear the other person.
PERMANENTLY INSTALLED ANTENNAS
✍ At cellular frequencies, the standard RG-58 cable that is supplied with most cellular antennas has a loss of about 3 dB over the 12-15 foot length of the cable.
The majority of installation problems are the result of improper antenna installation. ■ At cellular frequencies, the standard RG-58 cable that is supplied with most cellular antennas has a loss of about 3 dB over the 12-15 foot length of the cable. ■ Any disturbance to the cable will cause even greater losses – such as kinks in the cable or routing it next to a device that could cause static. ■ It’s extremely important to keep all bends to a minimum. ■ When bending the cable – such as the 90º degree bend that you use coming out of the headliner into the coupling box on a glass mount antenna – use large radius bends. ■ Crimped-on connectors – whether they’re TNC or mini-UHF – must be crimped on with a pair of antenna-connector crimping pliers made specifically for the type of connector that you are using (see figure 77). ■ A regular pair of pliers will smash the outer braid against the dielectric, forcing the outer braid to get close to or even touch the inside conductor.
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The distance between the outer and inner conductors determines the impedance of the cable. ■ Impedance changes in the cable affect the Voltage Standing Wave Ratio (VSWR), which in turn affects the transmission and reception of the signal. ■ A bad crimp can cause up to a 1 dB loss.
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✍ A bad crimp can cause up to a 1 dB loss.
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Figure 77. Special TNC crimping tool; a properly prepared cable.
When installing a glass-mount antenna (see figure 78), the antenna should be as close to the top of the glass as possible. ■ This ensures that the phasing coil portion of the whip (or radiator) will be as high above the roofline as possible. ■ The higher the antenna, the better the reception.
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Figure 78. Glass-mounted antenna.
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Be careful when mounting a glass-mount antenna on glass that has a defogger or FM antenna between the pieces of glass. ■ Always mount the coupling box so it is either centered between the defogger lines or above the defogger lines [grids] (see figure 79). ■ If you mount the antenna over the lines, the radio frequency (RF) energy will be radiated into them, causing a substantial loss in power. ■ If the glass has a high lead content, such as Rolls-Royce glass, it’s important to make sure that the antenna can perform correctly with this type of glass. ■ The Antenna Specialists Company is one of the companies that makes a device called the KAV-850 Capacitance Tester (see figure 80), which tests the ability of a glass-mount antenna to transmit through various types of glass.
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Figure 80. Capacitance glass tester.
Figure 79. Glass-mounted antenna properly installed between defogger grids. ■
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If you like to paint antennas to match or contrast the car's color, keep one thing in mind: ■ Depending on the paint used, this can cause up to 1 dB of loss due to dissipation of the radiation pattern caused by the metal content of the paint.
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When mounting the antenna, make sure that the whip is vertical. ■ If the whip is 30 degrees off vertical, there can be as much as 3-dB loss in the radiated signal. Mounting techniques, proper mounting locations, and the proper antenna are the most important considerations when installing a cellular telephone.
HANDS FREE CAPABILITY AND INSTALLATION KITS
A more common type of installation is not having a permanently mounted cellular phone installed in the vehicle. The more convenient hand held versions are readily available. Several manufacturers have created adapters that allow hand-held phones to operate in a hands-free manner. ■ These systems provide the benefits of a built-in car phone, with the added advantage of flexibility that’s unique to portable phones. This type of system consists of the following components: ■ Universal base unit – mounts near the driver and connects to the vehicle’s electrical system as well as to the microphone and an external antenna. ■ The base unit contains a separate speaker so the driver can clearly hear the conversation. Installation for Hands Free Kits: 1 Install the base unit – choose a location so the base unit and the phone are within easy reach of the driver and will not interfere with the operation of the vehicle. 2
Install the wiring harness: ■ This is very similar to the permanent mount cellular phone wiring. ■ Connection to an unswitched power source (constant 12 volts positive). ■ Ignition connection, (switched) power. ■ Ground connection. ■ Microphone jack, usually to the wiring harness plug. ■ Do not route any cables near ABS or other electrical harnesses sensitive to radio frequency emissions.
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3 Microphone installation is very similar to the installation of the hands free microphone in the permanent mount cellular phone. ■ Position the microphone within 1 - 2 feet to the person speaking; route the microphone wire so it is out of the way for safe operation. 4
Connect the cable from the external antenna to the base unit.
PROGRAMMING
Programming the cellular phone is critical to its operation. Each cellular phone will have its own unique programming sequence. Please refer to the individual manufactures programming instruction for guidance with this area of installation. Wireless Communications can be studied in greater depth in the MECP First Class Study Guide.
Section 4 Navigation Basics Navigation systems are the latest frontier in the world of automotive electronics. These systems are, in essence, a sophisticated navigation computer that’s installed into the vehicle. Then with the aid of the U.S. government’s Global Positioning Satellite (GPS) system, the driver is guided to his or her destination, or the vehicle can be tracked for the purpose of theft retrieval. This section will give the installer the basics of navigation type technologies and there installation. These systems can take on different configurations: ■ Stand-alone units. ■
Units that are integrated with the AM/FM/cassette/CD audio systems.
■ Units that have GPS/hybrid Wireless capabilities can provide two-way communication to a response center. ■
Units that only provide verbal navigation commands.
■
Units that provide verbal and visual navigation commands. ■ Some can be accessed via a wireless remote control.
In essence, the goal of vehicle navigation systems is to do away with conventional road maps by providing the driver with a system that plots the quickest route from Point A to Point B.
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TYPES OF NAVIGATION
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Presently, there are four basic navigation systems in the marketplace: 1 Voice activated. 2 Telepath™. 3 GPS locators. 4 Advanced Route Guidance systems. Voice Activated The first voice activated navigation systems reached the market in early 1995. ■ A voice activated system operates via a specially designed CD or DVD that contains a database of roads, highways, landmarks and thousands of points of interest (POI). ■ Each street name, highway, city and POI has been recorded on the CD. ■
The CD or DVD is loaded into a specially designed changer or player.
■ The user can activate the system via microphone mounted in the car by saying a specific word like, “Navigator.” ■ The voice activated system then asks a series of questions like: ■ Where are you starting from? ■ Where do you want to go? ■ The system then gives you verbal commands, “Where to go next.”
Telepath™ This system was developed by Delco Electronics (a division of General Motors). ■ Telepath uses the GPS signal to find its current location. ■
The user inputs their destination via a small LCD type display. ■ Destinations can be entered via address, intersection, or landmark (such as “ATM” or “GAS”).
GPS Locators GPS Locator systems utilize a “moving map” on a video screen in the vehicle to direct the driver. ■ This system utilizes a digitized map of a specific area with “hidden” longitude and latitude coordinates. ■
The system incorporates a GPS receiver. ■ The GPS receiver must receive at least three GPS satellite signals to determine the correct longitude and latitude coordinates.
■
The GPS information is then compared to the digitized map data. ■ When the current location is found on the map, that image of the map is displayed on the screen.
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These systems rely only on the GPS signal to find the location of the vehicle. ■ The U.S. government only guarantees GPS accuracy up to 300 feet, which can easily lead to errors on the map. ■ This system does not take into account vehicle speed or direction, therefore, turn-by-turn guidance is not completely accurate. This system can show the driver their destination on the digitized map, but it’s up to the driver to figure out how to get from Point A to Point B. ■
Advanced Route Guidance Systems This type of system utilizes three different input sensors to determine the present location and track the progress of the vehicle: 1 GPS antenna/receiver – uses GPS satellites to determine the current position of the vehicle. 2
Gyro sensor – determines the direction in which the vehicle turns.
3 Vehicle Speed Sensor (VSS) – determines how far and how fast the vehicle has traveled. Thanks to the gyro sensor and speed sensor, these systems more accurately display the vehicle’s position and track the vehicle’s progress – even when driving in areas where the GPS signal may be blocked Here are the basic elements of an advanced route guidance navigation system: 1 Main navigation ECU – the “brains” of the navigation system. Includes a built-in gyroscopic sensor, speed pulse sensor, Global Positioning Satellite receiver, and DVD or CD-ROM drive. It processes: ■ The incoming data from the vehicles speed sensor. ■ The speed of the vehicle. ■ The direction coming from the gyro sensor. 2
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GPS antenna – receives incoming satellite signals. ■ Antenna has a small footprint and some have a magnetic base. ■ Designed to be mounted with inside applications as well as outside of the vehicle. ■ Antenna must have a clear view to the sky to receive satellite information. ■ GPS reception can be slightly reduced when the antenna is mounted inside the vehicle.
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3 CD-ROM’s or DVD’s– contain the maps for each locale (which can be updated periodically). ■ Some companies rely on universal mapping software. ■ Other companies provide customized DVD or CD-ROM discs. ■ DVD has the ability to store entire countries. ■ On some systems, when you install the system, you have to install the correct CD for your geographic area – it’s not like changing music CDs. ■ Other systems allow you to swap CDs when you change geographic areas. ■ Use care when handling the DVD or CD-ROM. ■ When the DVD or CD-ROM is removed from the ECU, place it in the supplied jewel case. ■ Do not expose to extreme heat. 4
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Video monitors – displays directions. Some monitors include a built-in speaker. ■ Has to be mounted within view of the driver. ■ If customer is concerned about theft, some monitors are available with quick release brackets. ■ Some monitors can be used to interface and control the audio system. ■ Most monitors allow the driver to “zoom in” and “zoom out” to show more or less detail on the map. ■
5 Remote control – many systems include a wireless remote control to help operate the navigation system. Basics of Installation There are countless ways to install a navigation system. Accordingly, we do not have the luxury of being able to cover each application. Therefore, we will cover the basics. As most of you already know (and as we discussed in Chapter 2), properly planning the installation will reduce the number of unprofitable service calls. ■ Over 80% of all problems that occur with navigation systems can be traced back to installation problems. Following are the basic guidelines you should follow when installing an Advanced Route Guidance Navigation System.
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Mounting the ECU On some systems, the main navigation computer is designed to be mounted in the trunk; on others, it can be mounted in the trunk or the glovebox (depending on available space). ■ Find a suitable location for the ECU. ■ Avoid any moving parts, places where moisture can arise, or locations near extreme heat. ■ Locations such as under the front seats, or hanging from the rear package tray work the best. ■ The ECU must be mounted horizontal (less than 5°). The gyro sensor mounted inside the ECU will not work properly when the unit is mounted on its side. Mounting the Antenna The GPS antenna needs to be mounted in a location that is the most “visible” to the GPS satellites. Therefore, you need to carefully plan the location. When determining the mounting location, follow these guidelines: ■ Do not mount under any metal surface. ■ Some window tinting material has a high metal content (titanium), which can reduce the GPS antenna’s reception. ■ Some newer vehicles – like the Oldsmobile Aurora – incorporate special heat resistant glass that will cause GPS reception problems. ■ For those situations, it’s best to install the GPS antenna on the roof or the rear trunk lid. ■ Mounting the antenna under dense plastics or cardboard may inhibit reception. ■ The GPS antenna can receive the needed signals when mounted inside the vehicle, but some precautions must be taken to ensure proper performance: ■ Mount the antenna in a location in the vehicle that allows the best “line-of-site” performance. Locations such as the rear package tray or front dash work the best. ■ Secure the antenna with double sided tape or silicone. ■ This helps prevent the magnetic base from moving and scratching the paint. ■ Carefully route the antenna cable and connect it to the ECU. ■ The cable is matched to its length – do not shorten or extend. ■ Avoid making sharp bends in the cable. ■ Wind excess cable into large loops.
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MOUNTING THE MONITOR
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Like most installations, you have to plan out where you want to install the monitor. It’s needs to be convenient, yet unobtrusive – you don’t want it blocking any of the vital controls. ■ If possible, talk with the customer to hear their thoughts on where they want to mount the monitor. Try to mount the monitor so the driver can see the monitor without too much distraction. ■ If the monitor will be mounted low, angle it up for best performance. ■ Always check with the customer before drilling holes to ensure the location works for them. ■ You may want to tape the monitor in place to ensure the client likes that location and that it’s not awkward or in their outward line of sight. ■ Do not mount the monitor where it could be struck by an airbag in the event on an accident. ■
Once the installation is complete, adjust the monitor’s brightness level for best performance. ■ Most monitors have a separate brightness adjustment for day and night viewing (when you turn on the parking lights, the display dims). Most monitors come with a fixed length of cable that cannot be extended. Keep this in mind when routing the monitor cable to the ECU.
WIRING
Wiring most navigation systems is about as simple as wiring a cellular phone or a head unit. ■ Typically, there are only six wires to connect on the main harness. ■ If there are any remaining wires, they are usually used to connect the navigation system to the audio system.
SAMPLE WIRING CODES
Yellow..........................................Battery (+) Black............................................Ground Red ..............................................Ignition (+) White/Blue ..................................Illumination (+) Orange/White..............................Reverse Lights (+) Green/White................................Vehicle Speed Sense (VSS)
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In general, the basic connections for power, ground, ignition and illumination should be very straightforward. ■ The reverse light input is a necessary connection. The navigation unit must know when the vehicle is driving in reverse, so it can compensate when determining the precise location of the vehicle. ■ It can typically be found at the transmission switch, the main wire harness that runs to the tail lights or at the reverse light itself. The most difficult wire to find will be the VSS wire. ■ Some manufacturers, have a special Application Support team that helps installers locate the VSS wire. Caution: Some older vehicles may not have VSS wires. Under those circumstances, you must install a speed pulse generator onto the speedometer cable.
VEHICLE SPEED SENSOR TESTING AND VERIFICATION
Once the Vehicle Speed Sensor (VSS) has been installed, you have to test to make sure it is functioning, and then verify its accuracy. There are two types of Vehicle Speed Sensors: 1 Analog 2 Digital Analog VSS NOTE: If you’re working with an analog VSS, DO NOT hook up the analog speed pulse wire to the navigation system before undergoing the initialization process. Analog speed pulse is measured as AC voltage with reference to chassis ground. ■ Due to varying AC voltages and frequencies, the only accurate way to verify an analog speed pulse is to use an oscilloscope. ■ If you do not have access to an oscilloscope, verify that the wire does not have a positive DC voltage by using your digital multimeter. ■ Next, set your digital multimeter to AC voltage at the 30-volt range or on auto-range. ■ Connect the black lead of the multimeter to chassis ground. ■ Probe the speed pulse wire with the red lead. ■ The meter should read zero volts. ■ Start the car and drive slowly (you should have someone riding with you to read the multimeter while you drive).
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The meter should slowly begin to show an increase in voltage. ■ At slower speeds, the voltage should be approximately 2 - 5 volts AC. ■ As vehicle speed increases, AC voltage will increase. ■ Maximum AC voltage should be somewhere around 5 - 8 volts at 60 mph.
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Do not confuse this process with checking the tachometer wire. The tachometer wire increases voltage with the engine’s RPM. The speed pulse wire increases voltage with the vehicle's actual speed. After verifying the analog speed pulse wire, you must follow certain procedures to initialize the navigation system to accept an analog speed pulse prior to attaching the wire to the system. ■ Check the manufacturer’s installation instructions for the proper procedures. Digital VSS To test and verify a digital VSS, you will need a digital multimeter set to DC Volts at the 30-volt range or on auto-range. ■ Be sure to question the customer so you understand the powertrain layout of the vehicle. ■ For front-wheel drive, jack up only one of the front two wheels. ■ For rear-wheel drive, jack up only one of the rear wheels. ■ For all-wheel drive vehicles, you will need to jack up all of the drive wheels (if you cannot switch to 100% rear-wheel drive or 100% frontwheel drive). ■ For 4-wheel drive vehicles that drive only the rear wheels when in 2-wheel drive mode, jack up only one of the rear wheels. ■ For vehicles with a locking differential, you will need to jack up both (or all) of the drive wheels. ■ Be sure to block the remaining wheels to prevent the vehicle from rolling. ■
Connect the Black lead of the multimeter to chassis ground.
■
Probe the speed pulse wire with the Red lead.
■
Turn the ignition key to the “ON” position, but do not start the vehicle.
■
Read the multimeter.
It should show zero volts (off) or a voltage ranging from 5 - 12 volts (on). ■ The voltage range will differ depending upon the vehicle, however it will not fluctuate.
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■
Rotate the tire slowly.
■ The voltmeter should change state between zero volts (off) and 5 - 12 volts (on) or vice-versa within 2-3 rotations of the tire.
That is all you have to do to verify the digital speed pulse.
TESTING THE SYSTEM
Unlike your typical installation, a navigation system is not fully functional the first time you switch it on. For example, you have to allow the ECU time to get “in sync” with the GPS satellites. Follow these guidelines: ■ Park the vehicle in an area outside where the GPS antenna has good reception. ■ Make sure the vehicle is away from tall buildings or trees. ■
Turn on the unit. ■ This process takes between 10 and 30 minutes while the system receives the GPS data and finds the approximate vehicle location.
■
Once the unit “wakes up,” typically a disclaimer screen will appear.
■
Press the “ENTER” button.
■
The map screen should appear. ■ In some instances, the vehicle icon may appear on a blank map screen (no roads are illustrated) – this condition is normal.
■ Somewhere on the screen will be a GPS signal icon (it should be in the shape of a satellite). ■ Once the unit receives the GPS data, the GPS icon will change (in some instances, it will change color – from dark gray [no reception], to light blue [minimum reception], to yellow [maximum reception]).
The vehicle icon should now be visible on the map, and the monitor should show the approximate vehicle location. Don’t worry if the map position is a block or so away from your actual position – the system will correct itself as you drive. These are only basic guideline for installation. For further guidelines consult the individual GPS manufacturer. Navigation Systems can be studied in greater depth in the MECP First Class Study Guide.
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Margin Notes SAMPLE TEST QUESTIONS
1
At what frequency is the human ear most sensitive? A 25 Hz to 35 Hz. B 100 Hz to 250 Hz. C 1000 Hz to 2000 Hz. D 15000 Hz to 20000 Hz.
2
What is sympathetic vibration? A Noises made by processors. B The natural resonance of an object. C Distortion. D Ignition noise.
3
An audio signal is an electrical representation of what? A Sound Wave. B Octave. C Potentiometer. D Inductance.
4 Destructive interference refers to two speakers whose sound waves are working against each other and our out of phase by: A 45º degrees. B 90º degrees. C 180º degrees. D 270º degrees. E 360º degrees. 5
A Magnetic Reed Switch, also called a magnetic proximity switch: A Uses magnetic force to cause a set of contacts to connect. B Uses kinetic energy to open and close a set of contacts. C Has input for multiple switch triggers. D Can replace the use of a relay.
6
The most common used device to interrupt a vehicle’s starter is a: A Electronic switching capacitor. B Heavy duty diode. C Electromagnetic switch. D Pulse timer.
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7 Is an impact sensor the best device to detect breaking glass during a break in attempt? A True B False 8
A “pulse” or universal timer can be used to: A Remove unwanted EMI from you security system. B Add a pulsed output for alternating flashing parking lights. C Convert a momentary duration pulse into a longer or shorter duration signal. D Reverse the pulse from negative to positive for door triggers.
9
A glass mount antenna will transmit and receive best: A When mounted over two defogger grids. B When it is mounted over an FM antenna grid. C When mounted between or above the defogger grids. D When place at a 45º degree angle to the ground plane.
10 Extending the length of the RG 58 coax cable supplied by the manufacture (normally 12-15 feet) can result in as much as 3 dB of signal loss. A True B False 11 The small holes on the side of the hands free microphone are commonly used for: A Decoration. B Noise canceling. C The mounting clip. D Have no specific purpose. 12 Painting cellular antenna mast with car paint can typically cause up to 1 dB of loss. A True B False
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13 Which of the following materials will not attenuate the signal from a GPS antenna: A Metallic window tint. B Line defrosters. C Electrically heated windshields. D Factory pigment tinted glass. 14 The best choice of mounting position for the GPS antenna is: A Under the trunk lid. B Under the hood. C Under the headliner. D On the rear deck or dash. E On the center console. 15 The length of antenna cable on a GPS receiver is; A Unmatched. B Preset. C Random. D Uncorrelated. 16 A true VSS signal will vary in proportion with; A Engine temperature. B Engine RPM. C Ignition voltage. D Battery voltage. E Vehicle speed.
Answers 1 C, 2 B, 11 B 12 A
3 A, 13 D
4 C, 5 A, 6 C, 7 B, 14 D 15 B 16 F
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9 C,
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Glossary of Terms
GLOSSARY OF TERMS
GLOSSARY OF TERMS Margin Notes
ABC
AC (Alternating Current) – Energy that alternates back and forth at a certain frequency. The frequency is measured in hertz. In automobiles, AC is produced by the alternator and then rectified to DC. Acoustical Energy – Energy consisting of fluctuating waves of pressure called sound waves. Acoustics – A science dealing with the production, effects, and transmission of sound waves through various mediums. Active Arming – A method for arming a security system that requires some action by the driver/operator. This action could include pressing a button on a remote transmitter or entering a code on a keypad. Air Horns – A type of horn that uses compressed air instead of an electric diaphragm or voice coil to produce sound. These horns are usually driven by an electric air pump that receives its trigger from a host security system. Alarm Reset – The property of an alarm system that resets the alarm to an alarmed state after a pre-determined period of time. Alarm Re-triggering – A condition that occurs in a security system that has been triggered. Instead of sounding the siren for its designated time interval, it is retriggered and made to sound again. Alternator – A mechanically driven automotive device that generates DC power; it is the primary source of vehicle power. Alternator Whine – A siren-like whining that occurs when an engine’s RPMs increase. The noise is usually the result of a voltage differential created by more than one ground path or a poor ground path. Ambience Synthesizer – A unit that produces an artificial ambience pattern; one that is used to create the impression of the listener and/or performer being in a particular performance space. Ammeter – An instrument used for measuring the amount of current flowing in a circuit. Amperage – A unit of electrical current; the force through which the energy is pushed through a conductor. Measured in amps; Ohm’s Law symbol is I.
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GLOSSARY OF TERMS
Ampere – The unit of measurement used to determine the quantity of electricity flowing through a circuit. One ampere flows through a 1 Ohm resistance when a potential 1 Volt is applied.
Margin Notes
Amplification – An increase in signal level, amplitude, or magnitude. Amplitude – The measure of how powerful sound waves are in terms of pressure. Amplitude Modulation (AM) – A method of modulation in which the amplitude of the carrier voltage is varied in proportion to the changing frequency value of an applied (audio) voltage. (See also Frequency Modulation) Analog – An electrical signal in which the frequency and level vary continuously in direct relationship to the original acoustical sound waves. Analog may also refer to a control or circuit which continuously changes the level of a signal in a direct relationship to the control setting. Analog Switch – A hardware-oriented switch that only passes signals that are faithful analogs of transducer parameters. Anode – The electrically positive pole of an electronic device such as a semiconductor. A diode, for instance, has a positive and a negative pole; these are known as the anode and the cathode. Antenna – A mechanical device, such as a rod or wire, that picks up a received signal or radiates a transmitted signal. Arm – The term used to describe the act of causing a security system to reach a state in which it will protect the vehicle. Arming Delay – A term used to describe the elapsed time between the moment a security system is first told to arm and the moment it is actually armed. This normally applies only to systems that are passively armed, but it can apply to actively armed systems, as well. Attenuate – To lessen the amount of force, magnitude, or value of something. Audio Frequency Spectrum – The band of frequencies extending roughly from 20 Hz to 20 kHz. Audio Oscillator – A device that produces tones at specific frequencies for testing either equipment or entire systems. Audio Signal – An electrical representation of a sound wave in the form of alternating current (AC) or voltage.
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Auto Reset – The ability of a security system to automatically reset itself after being triggered.
Back-up Battery – A separate battery added to the security system as an alternate power supply to serve as a backup in case the vehicle’s main battery is disabled by a thief. Back-up batteries are typically the lead-acid gel cell type and are most effective when hidden from detection. Ballast Wire – The name given to a special resistance wire used between the ignition switch and the engine’s high voltage coil.This wire is typically composed of a carbon compound instead of normal copper. Bandpass Filter – In mobile electronics, a device which incorporates both highpass and low-pass filters in order to limit and attenuate both ends of the frequency range. Bandwidth – Refers to the “space” in the frequency response of a device through which audio signals can pass (between lower and upper frequency limits, those points where the signal level has rolled off 3 dB). Bass – The low audio frequency range, normally considered to be below 500 Hz. Bass Reflex – a vented enclosure that allows control of rear radiated sound waves. Battery – A device that stores electrical energy. A battery makes direct current through a collection of cells. Bias – An unbalanced sound level. Boomy – Usually refers to excessive bass response, or a peak in the bass response of a recording, playback, or sound reinforcement system. Bridging – Bridging combines two channels of an amplifier to turn it into a one channel amplifier. Brain – The common term used to refer to the main control unit of a security system. (See also Control Unit) Butterworth Filter – A filter with a pass-band with no ripple but usually sacrifices some steepness in attenuation.
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GLOSSARY OF TERMS
Capacitance – The property exhibited by two conductors separated by a dielectric, where an electric charge becomes stored between the conductors. (Also see Farad.)
Margin Notes
Capacitor – An electronic device that stores energy and releases it when needed. Also used to direct high-frequency energy to tweeters. Rated in Farads. Cathode – The electrically negative pole of an electronic device such as a semiconductor. CDPD (Cellular) – Cellular digital packet data. Digital data non-voice two-way communications transmitted in the cellular band. Cell – A single unit for producing DC electricity by electrochemical or biochemical action. A common vehicle battery is composed of a number of individual cells connected together. Each cell is typically rated at 2.11 volts; a common 12VDC automotive battery is composed of six separate two-volt cells. Cellular Telephone – A device consisting of a control unit, a transceiver, and an antenna that processes calls to be sent to or received from the cellular system. Channel (Cellular) – A frequency or band of frequencies assigned to a station or communications system. Also, a sub-circuit of a larger system (e.g., voice channel, control channel, paging channel). Channel (security) – The term used to describe the number of different functions possible for manipulating the buttons on a remote control transmitter. Chassis – The metal frame of the vehicle. Chebyshev Filter – A filter that has some ripple in the pass-band but has an initial attenuation slope which is steeper than a Butterworth filter. Chirp – The term used to describe the brief sounding of a security system’s siren designed to indicate the state of arm of the system. Circuit – A closed path through which current flows from a power source, through various components, and back to the power source. Circuit Breaker – An electromechanical device designed to quickly break the electrical connection should a short circuit or overload occur. A circuit breaker is similar to a fuse, except it will reset itself or can be manually reset, and will again conduct electricity.
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Clipping – Distortion that occurs when a power amplifier is overdriven. This can be seen visually on an oscilloscope, when the peaks of a waveform are flattened, or “clipped off,” at the signal’s ceiling. Closed Circuit – A continuous unbroken circuit in which current can flow without interruption. Also known as a closed loop. Closed Loop – A feedback path in a self-regulating control system. Unlike a standard open state trigger that needs to have a connection established to serve as a trigger, a closed loop trigger will act to trigger a security system when its loop (connection) is broken. Closure Wire – The name given to describe a wire found on some vehicles that, when given a certain duration input, will cause the doors to lock and the windows/sunroof to close. Code – The aspect of a security system that can be tailored by the manufacturer or the installer to personalize the particular system for a user or group of users. A remote security system that is coded will operate only with those transmitters that are coded to the same code. Coaxial Speaker – A coaxial speaker has a large cone for the low range and a smaller tweeter for the high spectrum. There is a crossover network that divides and routes the signal to the correct driver. Named for two speakers sharing a single axis. Co-Linear Antenna – An antenna that uses a phasing coil to electrically connect stacked elements in the proper phase relationship. Compliance – The measurement in liters or cubic feet of the volume of air that is equal to the compliance of a speaker’s total suspension. Cone – The most common shape for the radiating surface of a loudspeaker. Often used to refer to the part of the speaker that actually moves the air. Control Unit – The central processor for a security system. Constant Output – An output of a security system that provides a constant or continuous output to drive a device. Often used for sirens and engine interrupts. Control Unit – The central processor for a security system. (Also see Brain.) Coulomb – An amount of electrical charge which contains 6.24 x 1018 of electrons. Crossover – A device that separates the different frequency bands and redirects them to different components.
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Crossover Frequencies – The frequencies at which a passive or electronic crossover network divides the audio signals, which are then routed to the appropriate speakers.
Margin Notes
Crossover Network – A unit that divides the audio spectrum into two or more frequency bands. Current – The rate of electrical or electron flow through a conductor between objects of opposite charge. Symbol I, measured in amperes or amps. Current-fed Antenna – An antenna in which the feeder or transmission line is attached to the radiator at a current loop. This type of antenna requires a ground plane. Current Sensing – A name given to a form of alarm system trigger that relies on sensing a change in the power supply of the vehicle. More accurately called voltage sensing, this feature is found on many inexpensive alarms.
DEF Damping – The reduction of the magnitude of resonance by the use of some type of material. The damping material converts sound to energy, then disperses the energy by converting it to heat. DAT – Digital Audio Tape. DC – Direct Current. A flow of electrons that travels only in one direction. Decibel (dB) – The standard unit of measurement used to indicate the relative intensity of sound. Dedicated Fuse – A fuse designated to supply power and protection for one particular circuit only. Destructive Interference – A phenomenon that occurs when speakers are 180 degrees out of phase. For example, what one speaker is trying to produce, the other speaker is fighting to cancel. One speaker’s wave is in the positive phase (compression), while the other speaker’s wave is in the negative phase (rarefaction). Diaphragm – A thin metal or dielectric disk used as the vibrating member in loudspeakers. Also known as a cone.
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Margin Notes
Difference of Potential – The algebraic sum of voltages at two points of different electrical potential. Diode – A two-electrode (two-terminal) device that allows a voltage/signal to pass through it in one direction only. DIN – Deutscher Industrie Normen. German industrial standards that are used in many European countries. DIN size refers to the stereo size that fits most European cars. Disarm – The opposite of arm, or the term used to describe the action of placing a security system in an inactive or standby mode. Distortion – Sound that is modified or changed in some way. In a speaker, distortion is produced by several factors, many of which are related to poor construction. Voice coil rubbing (caused by being overdriven) is the most common cause of distortion. DMM – Digital Multimeter. A digital meter that gives a precise reading of voltage, current, or ohms. This type of meter “samples” the input and feeds it to a digital readout. Dolby System – A unique patented noise reduction system that electronically eliminates the irritating noise (tape hiss, circuit noise, etc.) without sacrificing the original tonal quality. Dome Light – The common term used to describe the overhead (or headliner) mounted interior courtesy light. Door Lock Solenoid – The proper name for the electric bi-directional actuator used to provide powered control of vehicle door locks. Also called a Door Lock Actuator. Doppler Sensor – Another name for a spatial type sensor, also commonly called a radar sensor. DPDT – Double Pole Double Throw. A term used to describe a relay that has two separate poles or contacts and can throw or make electrical contact with two separate stationary contacts. Dress – The arrangement of signal leads and wiring for optimum circuit operation, cosmetic appeal, and protective routing. Driver – Another term for a loudspeaker. Often used when the loudspeaker is coupled with a horn for acoustic coupling and controlled dispersion of sound.
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DSP – Digital Signal Processing (or Processor). A type of processing accomplished by a micro-computer chip specifically designed for signal manipulation, or a component using such processing. The term is often misused as a synonym for ambience synthesizer; however, DSP can do much more than sound field creation.
Margin Notes
Duty Cycle – An engineering term used to describe the actual time (or frequency) that a circuit or device operates. A pulsing alarm output that is on for seven-tenths of a second and off for three-tenths of a second would have a 70% duty cycle. Dynamic Range – The range difference between the quietest and the loudest passages of the musical selection or program signal being played.
Efficiency – The measurement of a loudspeaker’s ability to convert power to work. Formula: Efficiency = (power out/power in) x 100. Efficiency is always expressed as a percentage. Electrolyte – The name for the mixture of diluted sulfuric acid found in standard lead-acid vehicle storage batteries. Electrolytic Capacitor – A capacitor with a negative and a positive terminal that passes only alternating current. Electrolytics are available in polarized and nonpolarized configurations. Non-polarized (NP) capacitors are useful as inexpensive crossovers, blocking low frequencies from passing through to mid- or high-frequency speakers. Polarized capacitors have specific positive and negative poles. This type of capacitor is useful for storing and releasing energy. Emergency Override – A button or switch, possibly separate or hidden from the commonly used controls of a security system, that is used specifically to override or disarm a security system in the event that the primary means is unavailable or disabled. EMR Detector – A tool used to find the source of low-frequency tape head interference (electromagnetic radiation, or EMR). Engine Disable – A means, either electrical or mechanical, of preventing the vehicle’s engine from either starting or running. The most common variety of engine disable uses a simple automotive relay to inhibit either the starter or the ignition. Entry Delay – The time interval a security system waits before sounding the alarm after a vehicle’s door has been opened. ESN – A phone’s electronic serial number.
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Margin Notes
Exit Delay – The name given to the amount of time a security system waits once it’s given a command to arm. Exit delays are usually found on non-remote security systems that rely on keypads or the ignition switch to arm. This delay gives the operator time to exit the vehicle before the system arms.
Farad (F) – The basic unit of capacitance. A capacitor has a capacitance of 1F when a charge of 1 volt across the capacitor produces a current of 1 ampere through it. Named after Michael Faraday. FCC – Federal Communications Commission. The U.S. government agency that oversees and regulates electronic communications. Fidelity – A term used to describe the accuracy of recording, reproduction, or general quality of audio processing. Flashing Lights – A term used to describe the interfacing of the vehicle’s parking lights, dome light, emergency lights, etc., with a security system so that the lights flash by the system. Flat Response – An output signal in which fundamental frequencies and harmonics are in the same proportion as those of the input signal being amplified. A flat frequency response would exhibit relatively equal response to all fixed-point frequencies within a given spectrum. Fletcher-Munson Curves – A set of curves that depict the uneven frequency response of human hearing. FM – See Frequency Modulation. Free Air Resonance – The frequency at which a speaker will naturally resonate. Frequency – The term in physics that refers to a number of vibrations or cycles that occur within a given time. Frequency Counter – A device that assists in speaker parameter testing, as well as identifying the frequency of specific tones. Frequency Modulation (FM) – A method of modulation in which the frequency of the carrier voltage is varied with frequency of the modulating voltage (See also Amplitude Modulation)
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Frequency Response – A term that describes the relationship between a device’s input and output with regard to signal frequency and amplitude.
Margin Notes
Fundamental Frequency – The lowest frequency component of a harmonic series. Fuse – A device designed to provide protection for a given circuit or device by physically opening the circuit. Fuses are rated by their amperage and are designed to blow or open when the current being drawn through it exceeds its design rating. Fusible Link – Designed to perform the same task as a fuse, but resembles a wire. Fusible links are commonly used in ignition switches and other high-current circuits.
GHI Gain – Refers to the degree of signal amplification. Generator – A rotating machine that produces DC electricity. Also an electronic device used for converting DC voltage into AC of a given frequency and wave shape. Glass Sensor – A device designed to detect the sound of breaking glass or metalto-glass contact, thus triggering a security system. Also called sound sensors, glass-breaking sensors, or sound discriminators. Ground – The term given to anything that has an electrical potential of zero. Most modern vehicles are designed around a negative ground system, with the metal frame being the vehicle’s ground. Ground Loop – The term given to the condition that occurs when a voltage potential exists between two separate ground points.
Harmonic – The overtones and undertones that define the acoustic difference between two sounds with the same fundamental frequency. Harness – The universal name for a bundle or loom of wires that compose the wiring for a system. Headroom – The difference between the highest level present in an audio signal and the maximum level an audio device can handle without noticeable distortion. Hertz (Hz) – The unit of frequency within a specific period, such as alternating or pulsating current; 1 Hz = 1 cycle per second.
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Margin Notes
High Frequency – Refers to radio frequencies in the 3-30 MHz band. In audio it usually refers to frequencies in the 5-10 kHz band. High Pass Filter – A network of components which attenuate all frequencies below a predetermined frequency selected by the designer. Frequencies above cut-off are passed without any effect. Horn (Audio) – Refers to a loading device when part of a bass enclosure, or a directional device when used with a high-frequency driver or compression driver. Horn (Security) – Refers to the built-in factory horn in the vehicle. Factory horns can be of the diaphragm type, voice coil type, or air-pump driven type (air horn). All types of horns can be interfaced to a security system.
Ignition Kill – A device designed to prevent the vehicle’s ignition circuit from operating. An ignition kill device can work by either interrupting one or both of the primary wires leading to the ignition coil or by shorting out (grounding) the ignition coil’s positive primary wire. Also called Ignition Disable. Ignition Power – Refers to a source of power in the vehicle, controlled by the ignition switch, that has +12VDC on it when the ignition key is not in the run and start positions. Imaging – The width and definition of a sound stage. Instruments should appear to be coming from their correct positions, relative to recording. Impact Sensor – A sensor designated to detect various degrees of impact or vibration applied to the vehicle and then produce an output to trigger a security system. Impedance (Audio) – A measurement of the resistance to the audio current by the voice coil of the speaker. (See also Nominal Impedance) Impedance (Electrical) – The total opposition offered by a device or circuit to the flow of alternating current (AC). Inductive Coupling – Radiated noise that is transmitted through a magnetic field to surrounding lines. Inductor – An electrical component in which impedance increases as the frequency of the AC decreases. Also known as coils that are used in passive crossovers. Inductors are rated in Henries.
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Infinite Baffle – A loudspeaker baffle of infinite space that has no openings for the passage of sound from the front to the back of the speaker. Also, a sealed enclosure where the internal volume is greater than the Vas of the driver.
Margin Notes
Infrared Sensor – A type of spatial sensor that uses infrared energy to detect an object (a hand, arm, or body) entering a protected area. (See also Spatial Sensors) Input (Audio) – The high-level (speaker) or line level (RCA) signal connections that run into one component from another system component. Input (Security) – Any wire on a security system designed to accept a signal from some outside source such as the vehicle’s wiring. Door trigger, hood trigger, trunk trigger, and sensor trigger wires are all inputs. Instant Trigger – The term used to describe any trigger input on a security system that is designated to cause the system to respond instantly when triggered. Integrity – The expected durability of a component or connection.
JKL Joule – A unit of energy equal to one watt per second. Jump – To provide a temporary circuit around a component or other circuit.
Keypad – A panel usually made of metal or plastic with numbered push-buttons (like a touch-tone telephone) designed to provide access to certain types of security or cellular systems. Kirchoff’s Current Law (KCL) – A law stating that the total current entering a point or junction in a circuit must equal the sum of the current leaving that point or junction. Kirchoff’s Voltage Law (KVL) – A law stating that the voltage supplied to a DC circuit must equal the sum of the voltage drops within the circuit. kHz – Abbreviation for kilohertz, or 1000 cycles per second.
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Margin Notes
Last Door Arming – A feature found on some security systems that enables the system to suspend itself from arming until the last door of the vehicle has been secured. LCD – Liquid Crystal Display. LEDs – Light Emitting Diodes. A form of diode that sheds light. Used in may systems for indicator purposes. Loudspeaker – An electro-acoustic transducer that converts electrical audio signals at its input to audible sound waves at its output. Low Frequency – Refers to radio frequencies within the 30 -300 kHz band. In audio it usually refers to frequencies in the 40-160 Hz band. Low Pass Filter – A network of components which attenuate all frequencies above a predetermined frequency selected by the designer. Frequencies below cut-off are passed without any effect.
MNO Magnet – A device that can attract or repel pieces of iron or other magnetic material. Speaker magnets provide a stationary magnetic field so that when the coil produces magnetic energy, it is either repelled or attracted by the stationary magnet. Memory – The word most commonly used to refer to a system’s ability to retain specific information. Microprocessor – A semiconductor that can be programmed to perform a variety of tasks in many different systems. Midrange Driver – A loudspeaker specifically designed to reproduce the frequency in the middle of the audible bandwidth. Most musical energy lies in the midband. Milliamps – A unit of measurement of electrical current equal to 1/1000th of an ampere. The milliampere is the most common unit used when measuring quiescent (minor) current drain. Module – A term commonly used to describe a self-contained part or device that can perform a specific function.
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Motion Sensors – A sensor specifically designed to detect a gentle or sharp upand-down or side-to-side motion of the vehicle.
Margin Notes
Multimeter – A common term used to describe a Volt-Ohm-Meter, or VOM. A multimeter usually can measure volts, ohms, and amperes or milliamperes.
Negative Door Switches – A common type of switch found on most modern vehicles which provides the trigger for the factory interior lights, key buzzer, factory alarm, etc. Negative Lead – The lead or line connected to the negative terminal of a current, voltage, or power source. Noise Floor – The noise power generated by an audio device in the absence of any input signal. It is generally measure in decibels. Nominal Impedance – The minimum impedance a loudspeaker presents to an amplifier, directly related to the power the speaker can extract from the amplifier. Normally Closed – Refers to the electrical state in which a switch may rest. Its contacts are held together or closed so that current is allowed to flow through its contacts. Normally Open – Refers to the electrical state in which a switch may rest. Its contacts are held apart or open so that no current flows through its contacts.
Octave – A musical interval between two tones formed when the ratio between the frequencies of the tone is 2:1. Ohm – The unit of measurement for electrical resistance. Ohm’s Law – The statement of the relationship between current, voltage, and resistance. Where I = Current, E = Voltage, and R = Resistance, I=E/R, E=IR, and R=E/I. Open Circuit – A circuit containing a switch, filament, voice coil, etc., which is not intact and current cannot flow through. Oscillator – A device that produces an alternating current or pulsating current or voltage electronically. OSHA – Occupational Safety and Health Administration. The U.S. government agency that regulates workplace safety and health.
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Margin Notes
Output (Audio) – The high-level (speaker) or line-level (RCA) signals sent from one system component to another, or the high-level signal from an amplifier to the system speakers. Output (Security) – Any wire on a security system designed to produce a signal intended to be wired to some outside circuit or device. Siren wires, flashing light wires, and door locks are all outputs. Override Switch – A switch that provides a secondary means to disarm or override a security system in the event the primary means is unavailable. (See also Emergency Override)
PQR Pager – A device designed to transmit a signal to the owner of a vehicle in order to alert him or her that the alarm has been triggered. Pain Generator(s) – A name given to a type of siren that is specifically designed to produce a sound of the proper volume and pitch so as to cause physical pain to a thief’s ears. Panic – The name given to the feature of a security system that provides the ability to the operator to cause the system’s siren to sound at will. The panic feature is typically initiated either by pressing a button or buttons on the remote control transmitter by keypad command, by push button, or by toggle switch. Parallel Wiring – A circuit in which two or more devices are connected to the same source of voltage, sharing a common positive and negative point, so that each device receives the full applied voltage. Passive Arming – The ability of some security systems to arm without requiring any direct action from the operator of the vehicle. Passive arming is usually accomplished when the operator exits the vehicle in the normal fashion. (See also Last Door Arming) Passive Crossover – An electrical circuit consisting of capacitors, inductors, and resistors designed to separate an audio signal into specific speaker groups. Passive Repeater Antenna – A non-permanently installed, glass-mount antenna that is without physical connection to the cellular telephone.
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PCS (Cellular) – Personal communications system. Hand-held telephones that operate in bands of 1900 megahertz and above.
Margin Notes
Peak – An emphasis over a frequency range not greater than one octave. Period – The amount of time required for a single cycle of a sound wave. Phase – The timing of a sound wave that is measured in degrees from 0 to 360. Phase Shift – Frequency interaction in the crossover region of passive crossovers that can cause some frequencies to be delayed with respect to other frequencies. Piezo – The name usually given to piezo electric drivers. This type of driver has no voice coil or magnetic assembly. Instead, piezo electric material expands and contracts when voltage is applied. The material vibrates and either radiates sound directly or drives a diaphragm. They can be used effectively only on high frequencies. Piezo Sensors – A type of shock or impact sensor that utilizes the properties of the piezo electric effect inherent in some materials. A piezo sensor typically uses a piezo electric element to sense impacts or vibrations applied to a vehicle. Pinswitch – A simple, spring-loaded mechanical switch, used in many different vehicles, that’s designed to turn on interior lights when doors are opened. Pinswitches are also used in the installation of most security systems in the hood or trunk/hatch as a means of triggering the system if such points are opened. Point of Entry – The term used to describe the doors, hood, trunk/hatch, windows, sunroof, or any other point through which a thief can gain entry into a vehicle. Polarity – In electricity, refers to the condition of being either positive or negative. Polarity Reversal – A DPDT switch connected between a pair of DC input terminals so that the polarity of a pair of output terminals can be reversed or switched. Portable Cellular Telephone – A hand-held cellular telephone designed to operate as a self-contained unit. Portable cellular telephones are restricted to 0.6 watts. Positive Lead – The lead or line connected to the positive terminal of a current, voltage, or power source. Potentiometer – A variable resistor made with either carbon or wire wound material that attenuates a signal.
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Margin Notes
Power – The amount of energy (in joules) that a device delivers or consumes divided by the time (in seconds) that the device is operating. Power Door Locks – The feature where door locking and unlocking is performed by some mechanical means other than human power. Power door locks may be electric, vacuum, or a combination of the two. Power Line Noise – A varying AC ripple that is found riding on a DC voltage. It is recognized by a whining that varies with engine speed. Power Windows – The feature where the opening and closing of the vehicle’s windows is performed by some mechanical means other than human power. Power windows are typically operated by electric motors. Pre-amp – A circuit unit that takes a small signal and amplifies it sufficiently to be fed into the power amplifier for further amplification. A pre-amp includes all of the controls for regulating tone, volume, and channel balance. Programming Adapter – A device used for programming cellular telephones that allows the telephone to be programmed only when the device is attached. Proximity Sensor – A common term for a spatial-type sensor that can be either the radar, ultrasonic, or infrared type. (See also Spatial Sensor) Pulsed Output – An output of a security system usually used to flash parking lights or honk horns; it is pulsed or turned on and off by the security system.
Quiescent Current – A term that describes the amount of current consumed by a circuit when it is not performing any work (sometimes referred to as standby current). Qtc – Measurement of a speaker and enclosure working together as one. Qts – The measurement of the speaker as a motor, taking into consideration all mechanical and electrical losses.
Radar Sensor – A common name for a type of spatial sensor. Range (Audio) – Usually described as frequency range, this is a system’s frequency transmission limit, beyond which the frequency is attenuated below a specified tolerance. Also, the frequency band or bands within which a receiver or component is designed to operate.
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Range (Security) – The term used to quantify the maximum operating distance that can exist between a vehicle and the remote control transmitter. Range is usually expressed in feet or yards.
Margin Notes
Rarefaction – A state or region of minimum pressure in a medium traversed by compression waves (sound waves). Real-Time Analyzer (RTA) – A spectrum analyzer that measures an audio signal while it is being reproduced. Receiver – A device designed to receive a signal or command from a source such as a transmitter. Relay – An electromagnet switch that allows small, relatively low-level signals to operate higher amperage devices. Also used when polarity reversal is necessary. Remote – A common name for the remote control unit transmitter used with a remote security system. Remote Start – The feature where a security system or accessory module allows the vehicle operator to start the engine using a remote transmitter without actually being inside the vehicle. Reset – The ability of a security system to automatically stop sounding the siren and return to an armed state after being triggered, as long as no further trigger conditions are present. Resistance – The electrical term used to describe the property that various materials possess to restrict or inhibit the flow of electricity. Electrical resistance is relatively low in most metals and relatively high in most nonmetallic substances. Electrical resistance is measure in ohms. Resonance – The term used to describe the tendency of objects to vibrate at certain frequencies. This can be a useful or undesirable effect, as in planned enclosure or driver resonance, or as in unplanned enclosure resonance or wall resonance. Retriggering – See Alarm Retriggering. RF – Radio Frequency. An AC frequency that is higher than the highest audio frequency. Ripple – The deviation from a flat response in the passband.
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Margin Notes
RMS – Root Mean Square. Roll-Off – Relates to the attenuation of frequencies, above or below a given point, at a specific rate. Roof-Mount Antenna – A permanently-installed antenna located in the center of the vehicle’s roof.
STU Scanning – The popular term given to the way a thief breaks into a remote security system by quickly and sequentially transmitting all the possible security codes of a victim’s security system. Seat Sensor – A pressure-activated switch designed specifically for use in detecting any pressure applied to vehicle’s seat. Sensitivity – The rating of a loudspeaker that indicates the level of sound intensity the speaker produces (in dB) at a distance of one meter when it receives one watt of input power. Sensor – A device designed to detect or sense an intrusion or attack upon a vehicle by monitoring such things as motion, vibration, impact, sound, or the presence of a foreign mass. Sensor Bypass – The ability of a security system to automatically or manually delete or bypass the triggers from all or some of the sensors tied into the security system. Shock Sensor – A sensor that is specifically designed to detect a shock or impact applied to the vehicle. Short Circuit – The condition that occurs when a circuit path is created between the positive and negative poles of a battery, power supply, or circuit. A short circuit will bypass any resistance in a circuit and cause it not to operate. Signal-to-Noise Ratio – The s/n ratio indicates how much audio signal there is in relation to noise, or a specified noise floor. Siren – Any kind of device, mechanical or electronic, that is designed to produce a loud warning sound when triggered by a security system.
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Sound – A type of physical kinetic energy called acoustical energy. (See also Acoustical Energy)
Margin Notes
Sound Discriminator – A device designed to listen to, evaluate, and discriminate between the sounds that may be heard within the interior of a vehicle, and then trigger the security system if the sound fits within the parameters of what the sensor is designated to react to. Sound Pressure Level (SPL) – An acoustic measurement for the ratios of sound energy. Rated in decibels (SPL, dBA, SPL dBC). Sound Waves – Fluctuating waves of pressure that travel through a physical medium such as air. An acoustic wave consists of a traveling vibration of alternate compressions and rarefactions, whereby sound is transmitted through air or other media. Spatial Sensors – Devices specifically designed to detect intrusions into or around the vehicle by monitoring the space in and around the vehicle for intruders. These sensors work on a variety of different principles, including ultrasonics, radar, radio frequency, and infrared. SPDT – Single Pole Double Throw. A relay that has only one pole or contact but whose contact can throw or make electrical contact with two separate stationary contacts. This is the most commonly used relay in the mobile electronics industry. Spider – A flat, round, springy device that holds the vibrating cone of a dynamic loudspeaker. The spider is where the diaphragm meets the voice coil. SPST – Single Pole Single Throw. A relay that has only one pole or contact and can only throw or make electrical contact with one stationary contact. Staging – The accuracy with which an audio system conveys audible information about the size, shape, and acoustical characteristics of the original recording space and the placement of the artists within it. Starter Disable – Any circuit or device used alone or in conjunction with a security system that is designed to prevent the vehicle’s starter from operating. Status – The state a system is in at any given time. Subwoofer – A loudspeaker made specifically to reproduce frequencies below 125 Hz.
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Margin Notes
Switch – A switch is any form of mechanical, electronic, electromechanical, magnetic, or mercury device that either opens or closes a circuit. Switch Sensing – Refers to the inputs on a security system designed to detect a switch closure from such triggers as a door, hood, or trunk/hatch pinswitches. System Reset – See Reset and Alarm Reset.
TDMA (Cellular) – Time division multiple access. A digital communications scheme used in some switching systems. Total Harmonic Distortion (THD) – Given as a percentage, a measurement of how much a device may distort a signal. Figures below 0.1% are considered to be inaudible. Transceiver – A combination radio transmitter/receiver usually installed in a single housing and sharing some components. Transducer – Any device that converts energy from one form to another, e.g., electrical to acoustic or vice versa. Loudspeakers and microphones are two types of transducers. Transfer Function – The change in the low end of a low frequency system brought on by loading the device into the cabin of a vehicle. Transistor – An active (commonly three-terminal) solid-state device in which a larger output current is obtained by small changes in the input current. Transmitter – The name given to the hand-held remote control unit used by a vehicle operator to arm/disarm and perform accessory functions on a vehicle security system. More commonly called a remote. Transportable Cellular Phone – A three-watt mobile telephone combined with a high-capacity 12-volt battery and portable antenna. Trigger – The common name for any type of stimulus that will cause a security system to produce an alarm. A trigger could come from a pinswitch, a sensor, or a direct command from a transmitter or accessory button. Trunk Lines – The way the cellular system transfers the mobile calls to the landline network.
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Trunk Release – The ability of a system to release the latch of the trunk/hatch by remote control.
Margin Notes
Tweeter – A small loudspeaker or driver meant to reproduce high frequencies.
Ultrasonic Sensor – A form of spatial sensor that is designed to detect an intrusion into a vehicle by monitoring the space within the vehicle with ultrasonic energy. Unfused Wire – Any section of wire between the power supply and a load that does not include the protection of a fuse or circuit breaker.
VWXYZ Valet – A word used to describe the state in which a security system may be placed in which it would be prevented form arming passively and/or actively. Valet Switch – The switch designed to provide the control to place the security system into or bring the system out of the valet state. Vas – Compliance. A measurement in liters or cubic feet of the volume of air that is equal to the compliance of the speaker’s total suspension. Voice Coil – A coil of wire that takes in the electrical energy coming from the amplifier and converts it into acoustic energy or mechanical motion. Volt – The term used to refer to the property of electrical pressure through a circuit. Voltage – The electrical pressure produced to do work. Voltage Drop – The amount of energy consumed when a device has resistance in its circuit. The voltage (E) measured across a resistance (R) carrying a current (I). E=IR. (See also Volt) Voltage Sensing – A name given to a form of alarm system trigger that relies on sensing a change in the voltage of the vehicle. VOM – Volt-Ohm-Meter, sometimes called a Volt-Ohm-Millimeter. A multimeter that measures voltage, ohms, and milliamperes.
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Margin Notes
Watt – The basic practical unit of measure for electrical or acoustical power. Wattage – Electrical power. Wave – A single oscillation in matter (e.g., a sound wave). Waves move outward from a point of disturbance, propagate through a medium, and grow weaker as they travel farther. Wave motion is associated with mechanical vibration, sound, heat, light, etc. Waveform – The shape of a wave. Wavelength – The length of distance a single cycle or complete sound wave travels. Window Roll-up – The term used for the feature that causes the window(s) on a vehicle to close upon arming, or open and close as part of a convenience feature of a security system. Woofer – A large dynamic loudspeaker that is well suited for reproducing bass frequencies.
Xmax – The distance a speaker cone can travel before that magnet loses control over the voice coil.
Zero Output – The absence of output signal or output power. Zone – The specific area of the security system’s coverage, or a term used to describe a specific trigger input.
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APPENDIX Margin Notes
NOISE EXPOSURE CHART
Sound Level (dBA)
Maximum 24-Hour Exposure Occupational Nonoccupational
80 85 90 95 100 105 110 115 120 ■
8 hr. 4 hr. 2 hr. 1 hr. 30 min. 15 min. 0 min.
Figure A-1. Noise Expousure Chart.
2
E R
2
E R
I •R I•E P•R P I
200
P E
P I
P/R
E R
E I 2
IR •
P = Watts I = Amps ■
4 hr. 2 hr. 1 hr. 30 min. 15 min. 8 min. 4 min. 2 min. 0 min.
P 2 I
E P
E = Volts R = Resistance
Figure A-2. OHM’s Law.
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Margin Notes
■
Figure A-3. Electronic Symbols.
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MAGNUSON-MOSS ACT
Margin Notes
Have either of these situations happened to you? A customer wants to purchase an aftermarket accessory for his new car, but is concerned because the car dealer has told him that any accessory (i.e. car alarm, CD player, etc.) not purchased and installed by the dealer will void the car’s warranty? Or the customer has purchased an aftermarket accessory and then returns to your store because the dealer has refused to perform warranty work based on the fact that the customer purchased your product, which had nothing to do with the problem the customer is now experiencing? It is important for retailers to know their rights under the antitrust laws so they can assure their customers that any such purchase will in no way affect the warranty on their cars.
IT IS A VIOLATION OF FEDERAL ANTITRUST LAWS—
1
For a manufacturer (or its authorized representative) to condition a warranty on the purchase and use of its own parts or service.
2
For a manufacturer (or its authorized representative) to refuse to honor a warranty unless the manufacturer can show that an aftermarket accessory is the cause of a particular malfunction otherwise covered by the warranty.
KNOW YOUR RIGHTS
For more information, contact Federal Trade Commission at (202) 326-2222 or write to the Consumer Electronics Association - Mobile Electronics Division, 2500 Wilson Boulevard, Arlington, Virginia 22201-3834.
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INSTALLER CHECKOUT SHEET
Customer Name: _______________________________
Phone#: _______________
Vehicle Year: __________________________________
Tag#: _________________
Make: _________________________________
Inspected: Y____ N____
Model: _________________________________ Color: _________________________________
Date: ________________
SYSTEMS WORKING Yes No Horn Turn Signal Flashers Headlights Dashlights Cig Lighter Clock Wipers Rear Defroster Fan/Heater/AC Sun Roof Plate Lights Elec Windows Elec Door Lock Elec Seats Elec Mirrors Elec Sunroof Speedometer
____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____
WORKING Yes No
____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____
Domelight Power doorlocks Gauges Brake Lights Back-up Lights Power Antenna _____________ _____________
____ ____ ____ ____ ____ ____ ____ ____
____ ____ ____ ____ ____ ____ ____ ____
Comments on Interior: ____________________________________________________ ______________________________________________________________________ Comments on Exterior: ____________________________________________________ ______________________________________________________________________ Comments on Battery & Cables: ____________________________________________ Installer: ________________________
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APPENDIX
NOISE PROBLEM CHECKLIST Invoice #: ________________________________
Date: ____________________
Customer Name: _______________________________________________________ Car Yr/Model: __________________________________________________________ Installer Name: _________________________________________________________ Equipment Installed:_____________________________________________________ _____________________________________________________________________ _____________________________________________________________________
EQUIPMENT PERFORMANCE
Rate 1 Thru 5 (1 = Noise Free 5 = Extremely Noisy) AM Section FM Section Tape Section Compact Disc CR02 Bias Low Bias
____ ____ ____ ____ ____ ____
Balance Scan Clock AM MPX Section FM MPX Section Dolby B Section
NOISE TYPES Ignition ____ Wiper Motor ____ Horn Relay ____ Window Defogger ____ ENTRY POINTS Antenna +12VDC +12VDC Clock Lead Antenna Lead Case Radiated Internal Noise
____ ____ ____ ____ ____ ____
____ ____ ____ ____ ____ ____
Air Conditioning Electric Windows Alternator Power Windows Type Type Type Type Type Type
of of of of of of
Noise Noise Noise Noise Noise Noise
____ ____ ____ ____
Fader ____ Seek ____ Memory ____
Blinker Instrument Gauges Computer Clock Power Seats
_________________________ _________________________ _________________________ _________________________ _________________________ _________________________
COMPONENT AFFECTED Deck ____ Compact Disc ____ Crossover ____ Equalizer ____ Amplifier ____ Powered Speakers ____ SOLUTIONS Changed Ground ____ Removed Grounds ____ New 12VDC Source ____ Radiator ____
____ ____ ____ ____
In-Line Suppressor(s) ____ Braided Cable Grounds ____ Antenna Isolator ____
FM Signal ____ Alarm System ____
Grnd Loop Isolated ____ New Power Supply ____ Secondary Noise Suppressor(s) ____
COMMENTS: ____________________________________________________________ ________________________________________________________________________ Signed____________________________________________ Date: ______________
APPENDIX
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205
REFERENCE MATERIALS Margin Notes
Alternator Whine, David Navone, Navone Engineering, 4119 Coronado, Suite #4, Stockton, CA 95204; Autosound Technology 2000, (919) 570-0341. Audio Control Technical Papers 101, 102, 103, Richard Chinn, Audio Control, Lynwood, WA. Autosound Technology 2000, Tech Briefs, 2112 Westover Terrace, Burlington, NC 27215; (919) 570-0341. Basic Electricity and DC Circuits, Ralph Olivia and Charles Dale, Texas Instruments, 1979. Beat the Book with Fluke Meters, John Fluke Manufacturing Company, 1987, Everett, WA. Buchsbaum’s Complete Handbook of Practical Electrical Reference Data, Second Edition, W. Buchsbaum, Prentice Hall, 1982. Building Speaker Systems, G. McComb, Master Publishing, Inc., 1988. Cellular Installation Handbook, Revised Edition, Bishop and Associates, 22121 17th Ave., S.E., Bothell, WA 98021. Cellular Mobile Radio Telephones, S. Gibson, Prentice Hall, 1987. Cellular Telephone Installation Handbook, Michael Losee, Quantum Publishing, 1988, Mendocino, CA 95460. Handbook of Electronic Tables and Formulas, Sixth Edition, Howard W. Sams Engineering Staff, Howard W. Sams and Company, 1988. High Performance Loudspeakers, Third Edition, Martin Colloms, Pentech Press, 1985. How to Design and Build Audio Amplifiers, Second Edition, M. Horowitz, Tab Books Inc., 1980. Loudspeaker Design Cookbook, Vance Dickason; Old Colony Sound Lab, (603) 924-6371.
206
THE BASIC INSTALLER STUDY GUIDE
REFERENCE MATERIALS
Loudspeaker and Headphone Handbook, John Borwick, Butterworth and Company, 1988.
Margin Notes
Musical Acoustics, D. Hall, Wadsworth Inc., 1980. Noise Control – OSHA, Department of Industrial Relations, State of California #S680, 1986. Sound Reinforcement Handbook, Gary Davis and Ralph Jones, 1988, Hal Leonard Publishing, 7777 W. Bluemound Road, Milwaukee, WI 53213.
REFERENCE MATERIALS
THE BASIC INSTALLER STUDY GUIDE
207
Index
INDEX
INDEX ABC
Accessories ......................................................................28, 76, 84, 90, 99, 110 Accessory Output Devices......................................................................145, 152 Acid..................................................................................................68, 117, 183 Air Horns ................................................................................................63, 176 Air Pump........................................................................................................176 Alarm ..............................................33, 64-65, 72, 88, 100, 123-124, 134, 148, ............................................176, 181, 183, 189-190, 193, 196-197, 203, 205 Alarm System ..........................................................64, 123, 176, 181, 197, 205 Alternating Current..................26-27, 67, 75, 80, 130, 176-177, 183, 186, 189 Alternator Whine ....................................55, 78, 88-89, 97, 123, 125, 176, 206 Alternator ................................27, 29, 32, 50, 55-56, 67, 75, 77-78, 80, 88-89, ......................................97, 100, 102-103, 108, 122-123, 125, 176, 205-206 American Wire Gauge ..........................................................................36, 91-92 Ammeter ........................................................................................100, 103, 176 Amperage ..................................................36-37, 51, 54, 64, 69-70, 75, 78, 95, ....................................................98, 103, 105-108, 123, 126, 176, 185, 193 Ampere ....................................................................................35, 177, 184, 188 Amplifier ................29, 32, 34, 36-38, 44, 47, 49-50, 56-59, 69-70, 72, 77-81, ........ 89, 91, 94, 98, 114, 121, 123, 146, 178, 180, 189-190, 192, 197, 205 Amplitude ..........................................26-27, 131, 133, 137-140, 177, 184-185 Analog Meters ................................................................................................108 Analog Switch ................................................................................................177 Anode ................................................................................................72-73, 177 Antenna ..................................85-86, 89, 94, 98, 120, 122, 153, 157-162, 164, ............................166, 170, 172-173, 177, 179-181, 190, 194, 196, 204-205 Arm................................46, 116, 145, 152, 177, 179, 182, 184, 187, 190, 196 Audio ..........................................................26-27, 32, 35-36, 41, 46-47, 55-56, ..............59-60, 70, 75, 78-79, 89, 91, 97-99, 109, 121, 123, 125, 130, 132, ....139, 142-143, 162, 165, 167, 171, 177-178, 181, 184-190, 192-195, 206 Audio Signal............27, 46-47, 60, 79, 130, 142, 171, 177, 185, 190, 193-194 Audio System........................................................26, 32, 55-56, 75, 78, 89, 91, .................................................... 97, 99, 109, 121, 123, 125, 165, 167, 195 Autosound Systems ..........................................................................................88
210
THE BASIC INSTALLER STUDY GUIDE
INDEX
Bandpass ............................................................................................62, 81, 178 Bandpass Filter ..................................................................................62, 81, 178 Bass Reflex......................................................................................................178 Battery ..........................27-28, 36, 41, 43, 51-52, 55-58, 67-70, 72-73, 75-78, ................................86-88, 90-91, 95, 99-104, 108, 111, 117-118, 120-125, ....................................................154-157, 167, 173, 178-179, 194, 196, 204 Bookkeeping ....................................................................................................85 BOSCH ..............................................................................................63-65, 114 Bridging..........................................................................................................178
Cable ......................36-38, 42, 44, 58, 62, 68-70, 77-78, 81, 87-89, 91, 94-95, ..........98-99, 101-102, 118, 121-123, 157-159, 162, 166-168, 172-173, 205 Capacitance Glass Tester ................................................................................160 Capacitor ................................48-50, 60-61, 67, 79, 81, 99, 171, 179, 183-184 Cathode ......................................................................................72-74, 177, 179 Cell ..........................................................................................68, 122, 178-179 Cellular ....................................................................41, 153, 156-158, 161-162, ..........................................................167, 172, 179, 187, 190-192, 196, 206 Cellular System ......................................................................................179, 196 Cellular Telephone..........................................156-157, 161, 179, 190-191, 206 Channels ..................................................................................................34, 178 Chassis ........................52, 55, 69, 72, 89-90, 98, 106, 121, 157, 168-169, 179 Chirp......................................................................................................146, 179 Circuit........................................27, 29-31, 33-35, 38-45, 47-48, 51-52, 54-55, ..........57-58, 60, 62, 64-66, 68, 72-73, 77, 80-81, 91, 95-96, 100-101, 107, 120, 142, 148, 151, 155, 176-177, 179-183, 185-187, 189-190, 192, 194-197 Cleaning............................................................................................91, 118-119 Clipping ............................................................................8-59, 78-79, 143, 180 Closed Circuit ................................................................................................180 Coil ......................................38, 42, 50, 58-59, 61-66, 98, 107, 109, 152, 159, ..................................176, 178, 180, 182, 186, 188-189, 191, 195, 197-198 Co-linear Antenna ..........................................................................................180 Compliance ............................................................................................180, 197 Conductors ................................................................................37, 48, 159, 179 Connections ..............................................................43, 53, 57, 71, 90, 92, 97, ..................................................................102, 122, 125, 144, 155, 168, 187 Constant Output ............................................................................................180 Contacts ................................46, 62-66, 95, 147, 152, 154, 171, 182, 189, 195 Control Unit ..........................................................145, 158, 178-180, 193, 196 Coulomb ..................................................................................................35, 180 INDEX
THE BASIC INSTALLER STUDY GUIDE
211
Coupling................................................................................158, 160, 182, 186 Coupling Box ........................................................................................158, 160 Crimping..........................................................................93, 111, 118, 158-159 Crossover ............................................39, 44, 47, 49-50, 56, 59-62, 79, 81, 89, ........................................................ 97-98, 114, 123, 180-181, 190-191, 205 Current ................................26-36, 38-45, 47-48, 51-52, 54-58, 62-64, 67-69, ....................................71-75, 77-78, 80-81, 91-92, 100-103, 105-109, 111, ............................123, 130, 153, 157, 163-164, 176-189, 191-192, 196-197 Current Draw ........................................................................100-101, 103, 157 Current-fed Antenna ......................................................................................181 Cutting............................................................................................112-115, 118
DEF Damping ........................................................................................................181 Decibel ..........................................................................................116, 133, 181 Dedicated Fuse ..............................................................................................181 Defogger Lines................................................................................................160 Destructive Interference ........................................................136, 138, 171, 181 Diaphragm ............................................................130, 176, 181, 186, 191, 195 Difference of Potential ........................................................................29-31, 182 Digital ........................................................45, 60, 103-104, 108-110, 125-126, ............................................................155, 157, 168-170, 179, 181-183, 196 Digital Audiotape (DAT) ................................................................................181 Digital Multimeter ....................45, 103-104, 110, 125-126, 155, 168-169, 182 DIN ................................................................................................................182 Diode....................................................65, 72-74, 152-153, 171, 177, 182, 188 Direct Current..............................27-28, 48, 67-68, 75, 80, 106, 108, 178, 181 Disassembly......................................................................................................86 Dome Light....................................................................................101, 182, 184 Door Lock ..............................................................................................182, 204 Drills ..............................................................................................................112 Driver ........................................................60, 65, 110, 141, 153-154, 161-165, ..................................................167, 176, 180, 182, 186-188, 191, 193, 197 Dynamic Range ..............................................................................143-144, 183
212
THE BASIC INSTALLER STUDY GUIDE
INDEX
Effective Resistance ....................................................................................34, 77 Efficiency ......................................................................................102, 116, 183 Electrical Laws............................................................................................26, 43 Electrical Systems ............................................................................................97 Electrolyte ........................................................................................68, 102, 183 Electrolytic Capacitor ....................................................................................183 Electronic Components ....................................................................................27 Electronic Serial Number ..............................................................................183 Emergency Override ..............................................................................183, 190 EMR Detector ........................................................................................114, 183 Enclosure..................................................85, 111, 120, 178, 186-187, 192-193 Engine Disable........................................................................145, 150-151, 183
False Alarms ..........................................................................................148, 154 FARAD ............................................................................................49, 179, 184 Field Disturbance Sensor................................................................................150 Filter ............50, 55, 60, 62, 68, 81, 98-100, 121-122, 148, 178-179, 186, 188 Fire ..................................................................................44, 118-119, 124, 126 Fire Extinguishers ..........................................................................................118 First Aid ................................................................................................119, 124 Flashing Lights ..............................................................................................184 Flat Response..........................................................................138-141, 184, 193 Fletcher-Munson Curves, 140, 184 FM ....................................................................94, 97, 160, 162, 172, 184, 205 Frequency............................26-27, 47-50, 55-56, 60, 62, 79, 94, 97, 114, 122, ............................................130-133, 138-141, 148-149, 151-152, 160-161, ............................................171, 176-181, 183-186, 188, 191-193, 195-196 Frequency Counter ........................................................................................184 Frequency Response ......................................................138-141, 178, 184-185 Fundamental Frequency ........................................................................141, 185 Fuse ............................................34, 51-52, 57-58, 77-78, 88, 91, 95, 99, 101, ..........................................103, 106, 121, 123, 126, 157, 179, 181, 185, 197 Fusible Link ..................................................................................................185 Fusing ..................................................................................................57, 88, 95
INDEX
THE BASIC INSTALLER STUDY GUIDE
213
GHI
Gauges................................................................................37, 91, 155, 204-205 Glass................................138-139, 147-148, 152, 158-160, 166, 172-173, 185 Glass-Mount Antenna ....................................................................159-160, 190 Graphic Equalizer ..........................................................................................140 Ground ..........................................................26, 43, 52, 55-56, 58, 60, 65, 69, ......................................77-78, 87, 89-91, 93-95, 97-99, 102, 106, 109, 121, ..................123, 125, 153, 155, 157, 161, 167-169, 172, 176, 181, 185, 205 Ground Loop ........................................55-56, 78, 89-90, 97-98, 121, 123, 185 Ground Paths ..................................................................................................89 Ground Potential ........................................................................................89-90
Hand Nibbler ................................................................................................114 Handset ..........................................................................................................157 Harmonic ......................................................................................141, 185, 196 Head AMP ......................................................................................................114 Headroom ......................................................................................143-144, 185 Hearing Protection..........................................................................................116 Henries ....................................................................................................47, 186 Hertz................................................................................27, 131, 149, 176, 185 Horns ......................................................................................63, 176, 186, 192 Human Hearing ............................................................132-133, 138, 140, 184 Hydrometer ....................................................................................102-103, 126
IASCA ............................................................................................37-38, 58, 69 Ignition Disables ............................................................................................150 Ignition Lead ............................................................................................88, 157 Ignition Power................................................................................................186 Ignition Switch Functions ................................................................................76 Impact Sensor ................................................................................172, 186, 191 Impedance ..................................................................41, 56, 68, 159, 186, 189 Inductive Coupling ........................................................................................186 Inductor ....................................................................47, 50, 60-61, 79, 81, 186 Infinite Baffle ..................................................................................................187 Infrared Sensor ..............................................................................................187
214
THE BASIC INSTALLER STUDY GUIDE
INDEX
Installation ..........................29, 32, 38, 63, 68, 72, 81, 83-126, 130, 144, 152, ....................................154-156, 158, 161-162, 165, 167, 169-170, 191, 206 Interface ................................................................................................153, 165
JKL Joule ..................................................................................................35, 80, 187 Jump Starting ................................................................................................157
Landline ........................................................................................................196 Lead Dress ........................................................................................................87 Leads......................................................46, 58, 71-72, 85, 87-89, 94, 100-101, ....................................105-106, 108-109, 114, 120-121, 123, 125, 137, 182 Load Testing ..................................................................................................102 Loudspeaker ............................................60, 134-135, 180, 182-183, 187-189, ............................................................................194-195, 197-198, 206-207
MNO Magnet ..........................................................................110, 119, 147, 188, 198 Memory..................................................................................................188, 205 Meters....................................................................................103, 105, 108, 206 MicroFarads......................................................................................................49 Microphone ..................................................130, 148, 158, 161-163, 172, 196 Mobile Telephone ..........................................................................................196 Module ..................................................................................................188, 193 Motion Sensor........................................................................................147, 189
Negative Lead ................................................................................105-106, 189 Noise ..........................................48, 50, 55-56, 60, 68, 72, 87-91, 94, 96-100, ..........................104, 106, 109, 114, 116-117, 120-123, 125, 139, 141-144, ..................155, 158, 171-172, 176, 182, 186, 189, 192, 194, 200, 205, 207 Noise Sniffers..................................................................................................109 Nominal Impedance ..............................................................................186, 189
INDEX
THE BASIC INSTALLER STUDY GUIDE
215
Normally Closed ........................................................................64-66, 147, 189 Normally Open ..........................................................................64-66, 147, 189
Occupational Safety and Health Administration............................116, 126, 189 Octave ............................................................................61, 141, 171, 189, 191 OEM ..............................................................................................65, 75, 77-78 Ohm ..........................................................28-36, 38, 40-42, 44, 51, 54-55, 69, ..................................................77-78, 80, 105, 107, 155, 176-177, 189, 200 Ohm's Law ....................................28-36, 38, 42, 54, 69, 77, 80, 176, 189, 200 Open Circuit................................................................................48, 58, 68, 189 Oscillator ......................................................................................146, 177, 189 Oscilloscope ..........................................................27-28, 59, 97, 111, 168, 180
PQR Pager ..............................................................................................................190 Parallel Wiring..........................................................................................42, 190 Passive Crossover ..........................................44, 47, 49-50, 60-61, 79, 81, 190 Passive Repeater Antenna ..............................................................................190 Period..........................................34, 80, 93, 131-132, 150, 153, 176, 185, 191 Phase ......................................75, 86-87, 97, 134-138, 154, 171, 180-181, 191 Phase Shift..............................................................................................135, 191 Pinswitch................................................................................146-147, 191, 196 Polarized Capacitors ......................................................................................183 Portable Cellular Telephone ..........................................................................191 Positive Lead ..................................................................................105-106, 191 Potentiometer ..................................................................................46, 171, 191 Power ............................26-29, 31-32, 34-38, 41-44, 47, 49-54, 56-60, 62-64, ....................67-70, 74-81, 85, 87-89, 91, 94-95, 98-99, 101, 106, 110-111, ............113-114, 116-117, 119-122, 125, 133, 143, 146, 152-153, 155-157, 160-161, 168, 176, 178-181, 183, 186, 189, 191-192, 194, 197-198, 204-205 Power Cable ............................37, 42, 58, 69, 77, 88, 95, 98-99, 121-122, 157 Power Handling................................................................................................51 Power Line Noise ..........................................................................................192 Power Rating ..............................................................................................51, 78 Power Window ............................................................52-53, 63, 152, 192, 205
216
THE BASIC INSTALLER STUDY GUIDE
INDEX
Power Wiring ......................................................................................76, 78, 91 Programming ................................................................................157, 162, 192 Pulsed Output........................................................................................172, 192
Margin Notes
QTC ..............................................................................................................192
Radar........................................................................28, 149-150, 182, 192, 195 Radar Detectors ................................................................................................28 Radar Sensor ..................................................................................150, 182, 192 Radiated Noise..........................................................87-88, 94, 97-99, 122, 186 Radio Frequency Transmitters........................................................................151 Radio Frequency ................................94, 97, 122, 151-152, 160-161, 193, 195 Range ....................................56, 62, 101, 103-109, 126, 132-133, 138, 141, 1 ..............................43-144, 149, 152, 154, 168-169, 178, 180, 183, 191-193 Rarefaction..............................................................................134-135, 181, 193 Reassembly ......................................................................................................86 Receiver ..................................................149, 156, 163-164, 173, 192-193, 196 Reception Problems........................................................................................166 Relay......................................................................................62-66, 71, 81, 106, ..........................................................152, 156, 171, 182-183, 193, 195, 205 Remote ............................................................ 87, 94, 145, 151-153, 162, 165, ............................................................176, 179-180, 190, 193-194, 196-197 Remote Control ............................145, 151, 162, 165, 179, 190, 193, 196-197 Remote Control Transmitter ..................................................151, 179, 190, 193 Resistance ............................28-35, 37-41, 44-47, 52, 54-57, 63, 68-70, 72-73, ........77, 80-81, 90-91, 93, 105, 107, 123, 177-178, 186, 189, 193-194, 197 Resistors ....................................................35, 39-42, 44-45, 60, 74, 77-78, 190 Resonance ..............................................................138-139, 171, 181, 184, 193 Response ................................138-141, 146, 153-154, 162, 178, 184-185, 193 Retriggering ....................................................................................................193 Ripple ..............................................55-56, 67-68, 100, 122, 178-179, 192-193
INDEX
THE BASIC INSTALLER STUDY GUIDE
217
Margin Notes
STU
Safety ..................................13-16, 83, 100, 105, 113, 115-118, 126, 153, 189 Saws................................................................................................112-113, 116 Seat Sensor ....................................................................................................194 Security ..........................................................................28, 41, 46, 63, 76, 106, ....................................................126, 129-173, 176-180, 182-188, 190-198 Security System ........................................................63, 76, 106, 126, 144-146, ............................................151-156, 172, 176-180, 182-187, 190, 192-198 Semiconductors ..........................................................................................71-72 Sensitivity ..........................................................................44, 46, 107, 148, 194 Sensors ....................63, 145, 147-150, 164, 168, 185, 187, 189, 191, 194-195 Shock Sensor..........................................................................................148, 194 Short Circuit ..........................................................57-58, 77, 96, 107, 179, 194 Signal-to-Noise ..............................................................................................194 Single Pole Double Throw ..............................................................65, 152, 195 Single Pole Single Throw ......................................................................152, 195 Sirens ......................................................................................63, 146, 156, 180 Slope ........................................................................................................61, 179 Solder ........................................................................92-93, 110, 117, 122, 144 Sound ......................................35, 49, 56, 79-81, 116, 126, 129-135, 137-141, ............................................143-144, 146, 148-149, 171, 176-178, 181-183, ............................................185-188, 190-191, 193-195, 198, 200, 206-207 Sound Discriminator ..............................................................................148, 195 Sound Pressure Level ............................................................................133, 195 Sound Wave ..................130-132, 134, 149, 171, 176-178, 191, 193, 195, 198 Sources ......................................................................................87, 98, 134, 155 Spatial Sensors........................................................................149-150, 187, 195 Speaker ..........38, 41-42, 44, 47, 57-58, 60, 69-70, 77-79, 81, 85, 87-88, 104, ..................106-107, 111, 113-115, 120-121, 123, 125, 130, 135-139, 141, ..........146, 158, 161, 165, 180-182, 184, 186-190, 192, 194, 197-198, 206 Spider ............................................................................................................195 Staging............................................................................................................195 Starter Disable ........................................................................................150, 195 Starter Interrupt..............................................................................................151 Stiffening Capacitor ..........................................................................................50 Subwoofer ..........................................................................42, 47, 79, 142, 195 Sulfuric Acid ....................................................................................68, 117, 183
218
THE BASIC INSTALLER STUDY GUIDE
INDEX
Switch ........................41, 52, 58, 62-64, 71, 74, 76, 79, 88, 91, 105-107, 123, 145-147, 152, 168-171, 177-178, 183-184, 186, 189-191, 193-194, 196-197 Switch Triggers ..............................................................................145-146, 171 System Design ..................................................................................................44
Margin Notes
Telephones ....................................................................156, 158, 191-192, 206 Test Equipment ........................................................................................97, 103 Test Lights ..............................................................................................109, 155 Time Alignment..............................................................................................137 Tools..............................................................85-86, 97, 109, 111-113, 115-119 Tracking System ............................................................................................153 Transceiver..............................................................................156-157, 179, 196 Transfer Function ..........................................................................................196 Transmission Line ..........................................................................................181 Transmitter ............................................151-152, 156, 176, 179, 190, 193, 196 Trigger................................................................64-65, 112, 146, 148-149, 176, ............................................................180-181, 186-187, 189, 193, 195-198 Troubleshooting ............................................................................26, 45-46, 52, ................................................................77, 96-97, 100, 103, 119, 146, 155 Trunk Release ................................................................................................197 Tweeter ................................................48-49, 51, 59-61, 78, 81, 141, 180, 197
Ultrasonic Sensor ..................................................................................149, 197 Universal Timers ............................................................................................153
VWXYZ Vehicle ..........................................27-29, 36, 52, 55, 57, 65, 67, 69-70, 75-77, ............84-92, 94, 98-99, 101-102, 104, 106, 109, 115, 118-122, 125, 139, ............142, 144, 146-157, 161-164, 166-171, 173, 176-179, 181-198, 204 Voice Coil ..............38, 42, 58-59, 107, 176, 182, 186, 189, 191, 195, 197-198 Volt ..................................................................34-35, 37, 42, 55-56, 58-59, 65, ....................................................70, 73, 77, 80-81, 104, 107, 177, 184, 197
INDEX
THE BASIC INSTALLER STUDY GUIDE
219
Margin Notes
Voltage......................................27-34, 36, 38-40, 42-44, 46, 48, 50, 52, 54-59, ..........................63-65, 67-70, 72-78, 80-81, 89, 97-98, 100, 103, 105-109, ..........................114, 121, 123, 133, 153, 157, 159, 168-169, 173, 176-178, ............................................................181-182, 184-185, 187, 189-192, 197 Voltage Drop ................................32, 42-43, 52, 54, 56, 69-70, 74, 77, 89, 197 Volt-Ohm-Meter ....................................................................................189, 197 Volts ....................................................29, 32-35, 38, 50, 54, 57, 59, 68, 73-74, ................................................80-81, 102-106, 108, 161, 168-170, 179, 189
Watt ............................................................34-36, 80, 113, 157, 187, 194, 198 Wattage................................................................................32, 36, 44, 113, 198 Wavelength ......................................................................94, 131-132, 137, 198 Wire ..................................26, 29, 32, 34, 36-38, 43, 47, 51, 53, 56-57, 69-70, ....................76-77, 80, 85, 87-93, 95, 98-99, 101, 106, 110, 118, 120-125, ....137, 147, 155-157, 162, 168-169, 177-178, 180, 185-187, 190-191, 197 Wire Gauge ..................................................................26, 36-38, 43, 77, 91-92 Woofer..................................................................................60-61, 81, 137, 198
Xmax ..............................................................................................................198
ZONE ............................................................................................................198
220
THE BASIC INSTALLER STUDY GUIDE
INDEX
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