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The logo of the CompTIA Authorized Curriculum Program and the status of this or other training material as "Authorized" under the CompTIA Authorized Curriculum Program signifies that, in CompTIA's opinion, such training material covers the content of the CompTIA's related certification exam. CompTIA has not reviewed or approved the accuracy of the contents of this training material and specifically disclaims any warranties of merchantability or fitness for a particular purpose. CompTIA makes no guarantee concerning the success of persons using any such "Authorized" or other training material in order to prepare for any CompTIA certification exam. The contents of this training material were created for the CompTIA A+ certification exams #221 and #222 covering CompTIA certification exam objectives that were current as of August 31, 2001. How to Become CompTIA Certified: In order to become CompTIA certified, you must: This training material can help you prepare for and. pass a related CompTIA certification exam or exams. In order to achieve CompTIA certification, you must register for and pass a CompTIA certification exam or exams.
(1) Select a certification exam provider. For more information please visit http://www.comptia.org/certification/testlocations.htm. (2) Register for and schedule a time to take the CompTIA certification exam(s) at a convenient location. (3) Read and sign the Candidate Agreement, which will be presented at the time of the exam(s). The text of the Candidate Agreement can be found at www.comptia.orglcertification (4) Take and pass the CompTIA certification exam(s). For more information about CompTIA's certifications, such as their industry acceptance, benefits, or program news, please visit www.comptia.orglcertification CompTIA is a non-profit information technology (IT) trade association. CompTIA's certifications are designed by subject matter experts from across the IT industry. Each CompTIA certification is vendor-neutral, covers multiple technologies, and requires demonstration of skills and knowledge widely sought after by the IT industry. To contact CompTIA with any questions or comments: Please call + 1 630 268 1818 or email CompTIA at
[email protected] The CompTIA A+ certified professional logo is a registered trademark of CompTIA (the Computing Technology Industry Association). All rights reserved.
Copyright © 2002 CES Industries, Inc. / REV 3- I-02
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Computer Repair Program I Safety Lesson Introduction to Computer Repair Copyright © 2002 CES INDUSTRIES, INC.
All rights reserved. No part of this book may be duplicated or reproduced in any form without the specific written permission of CES InCiustries, Inc. The use of this manual and the experiments described is restricted to performance with CES Ed-Lab training eguipment and is prohibited from being used with any other training aid or electronic components or for other educational purposes. CES makes no representation that the circuits, logic, or programs described herein will not infringe on existing or future patent rights. There is, furthermore, no imf)lication in the granting of licenses to make, sell, or use any circuits, logic, or programs described herein. This does not restrict use of any materials or data sheets which may be available from other sources.
ISBN 0-86711-258-1 Printed in the United States of America
CES INDUSTRIES, INC. Educational Products Division 130 Central Avenue Farmingdale, New York 11735 Phone (631) 293-1420
CES INDUSTRIES, INC. 130 Central Avenue, Farmingdale, New York 11735
CES COMPUTER REPAIR PROGRAM Book I
Table of Contents
I. Safety Lesson Safety Lesson
1
II. Introduction to Computer Repair Lesson 1 Lesson 2 Lesson 3 Lesson 4 Lesson 5 Lesson 6 Lesson 7 Lesson 8 Lesson 9 Lesson 10 Lesson 11 Lesson 12 Lesson 13 Lesson 14
Intro to Computers The Keyboard The Monitor The Power Supply The Floppy Disk Drive The Hard Disk Drive The Motherboard The CPU/BIOS/BUS The RAM The Video Card The Multimedia System The Printer Network Systems Computer Viruses
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23 31 37
45
57 67
75 85
93 103 111 121 127
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Safety Lesson Objectives: When you have completed this lesson you will be able to: 1.
Name the three greatest dangers in working with electronic equipment.
2.
Prevent accidents by following safe work habits.
3.
Respond properly in the event of an electrical accident.
4.
Identify potential risks to equipment, when failing to use ESD (electro-static discharge) procedures.
5.
Be environmentally aware of the hazardous materials associated with computer systems, printers and other peripheral equipment.
Discussion: Most of the electronic devices we use every day, such as TV sets, hair dryers and lamps, are designed to keep you away from the dangerous voltages inside. However, accidents happen! In this lesson you will learn about the dangers of working with electronic equipment using low or high voltages, how to avoid accidents, and what to do if an accident happens. There are three main types of accidents, which you must watch out for when working with electronic equipment. 1. Electrical Shock 2. Electrical Fire 3. Injuries from power tools It is strongly recommended that the instructor and students discuss safety in the laboratory before proceeding to use any equipment.
Electrical Shock Electrical shock is what happens when an electric current flows through your body. How dangerous the shock is depends on how much current flows through your body. Depending on the strength of the shock, you may only feel a strong and unpleasant tingling CES Industries, Inc. Copyright © 2002
Safety Lesson
sensation. You might be thrown back away from the source of the current. Or you could freeze on the circuit, unable to move Or let go, stop breathing and go into ventricular fibrillation. This is a condition where your heart cannot keep its rhythm and so cannot supply your body with the blood you need to live. If you see someone who is receiving an electric shock and is unable to move, you should without touching the equipment or the person, try to shut off the power as soon as possible. Unplug the equipment or shut it off with a book or other nonmetal object. If you cannot shut off the power, then you must try to disconnect them from the equipment as quickly as possible. Do NOT use your bare hands to move someone who is in this condition. You may also get a shock. Use a dry blanket or a jacket or other piece clothing to insulate yourself from the person getting the shock. Check the person for normal pulse and breathing. If they are not breathing, then call for help immediately. See if there is a doctor or nurse, or anyone else with medical training that can help. If you can't find anyone who can help, then begin artificial respiration while someone goes for help. How to give artificial respiration is explained later in this lesson. Preventing Electric Shock
1. Do not use or even touch anything electrical while you are wet or near water. 2. Always make sure that electrical equipment is completely off before working on it. Unplug the equipment before you work on it and make sure no one can plug it in before you are finished working on it. 3. Do not operate any electrical equipment with wires hanging loose, protective covers off or safety switches defeated. 4. Insert grounded (three prong) plugs into grounded outlets. Do not use 3 wire ground adapters to make them fit into a two prong outlet. 5. Don't use any wires that are damaged or look like they may break. 6. Disconnect power cords carefully. Do not pull plugs out by the wire.
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Safety Lesson
Electrical Fires 1. Electrical fires are usually caused by short circuits or by an overload of the circuit that your are connecting the equipment to. A very large current flows, which overheats the equipment and starts the fire. Never touch any equipment that is burning or smoking. Shut the power off as quickly as possible, but never touch the equipment. 2. Never throw water or use a water filled fire extinguisher on an electrical fire. You may get a shock or even make the fire worse. Only use a fire extinguisher that has been rated for use on live electrical equipment, the NFPA (National Fire Protection Agency) designation of Class 'C' indicates that it is approved for use on live. electrical equipment. The most common fire extinguishers found in most shops or laboratories will be triclass (AB&C) or may be only 'BC' either way, if the letter 'C' is in the class designation, it is safe and proper to use. There are three types of extinguishers, which are good to use on electrical fires. They are: a. Carbon Dioxide - This is a class 'BC' extinguisher and may be used for electrical as well as flammable liquid (Gasoline type) fires. b. Dry Chemical - This type extinguisher may be a tri-c1ass or 'ABC' type or may be only a 'BC' type extinguisher, and while it will definitely handle a fire in an electronics or computer repair shop, it will destroy any equipment beyond repair that you spray with it. Therefore, is not recommended for use in electronics or computer repair type shops. c. Halon Gas - This is a class 'BC' extinguisher and may be used for electrical as well as flammable liquid (Gasoline type) fires. It will not destroy the electrical or electronic equipment that it is used on. However, halon has fallen out of favor due to the fact it is a CFC (chlorofluorocarbon) type gas, which is known to affect the ozone. layer. Tools used in electronics Most tools used in electronics are safe, if they are used properly. Screwdrivers, knives, wire cutters, and other sharp tools should be treated with respect. Do not use excessive force. If you have difficulty getting a job done with one tool, find another tool that will do the job safely. CES Industries, Inc. Copyright © 2002
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Safety Lesson
Don't throw or play with tools. Make sure a tool is in good condition before you use it. Check hammers before use to make sure the head is attached tightly to the handle. Make sure that power tools have good cords on them and that all the safety shields are properly attached. When using drills, saws, or other power tools, clamp your work down before starting. Keep your fingers away from moving parts, and always use eye protection. Don't leave power tools lying around plugged in when you are not using them. Soldering irons are especially dangerous and can give someone a serious burn. Unplug your soldering iron immediately after you are done using it and don't leave it before it cools off. Just think of what a tool that can melt metal can do to someone's skin. Minor Injuries: If someone receives a minor cut or burn, it should be washed in cold water immediately. Get medical help as soon as possible.
If a major injury occurs and someone is bleeding heavily from an arm or leg, try to slow down or control the bleeding by applying direct pressure to the injury. If possible elevate the injury to reduce or stop the flow of blood. Observe universal precautions about exposure to blood and body fluids by having rubber or latex gloves in the shop, so that you can protect yourself from diseases transmitted by blood and body fluids.
Artificial Respiration Always check for a pulse and see if the victim is breathing. If they have a pulse and they are breathing DO NOT start artificial respiration or CPR. Have someone call for professional medical assistance. Artificial Respiration Begin immediately to use artificial respiration if the victim is not breathing:
a. Turn the victim on his or her back. b. Clean the mouth, nose, and throat. If they appear clean, start artificial respiration immediately. If foreign matter is present, wipe it away quickly with a cloth or your fingers. c. Place the victim's head in the "sword-swallowing" position(Place the head as far back as possible so that the front of the neck is stretched). 4
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Safety Less.on
d. Hold the lower jaw up. (Insert your thumb between the victim's teeth at the midline - pull the lower jaw forcefully outward so the lower teeth are further forward than the upper teeth. Hold the jaw in this position as long as the victim is unconscious). e. Close the victim's nose. (Compress the nostrils between your thumb and forefinger). f.
Blow air into the victim's lungs. (Take a deep breath and cover the victim's open mouth with your open mouth, making the contact air-tight. Blow until the chest rises. If the chest does not rise when you blow, improve the position of the victim's passageway, and blow more forcefully.
g. Let air out of the victim's lungs. (After the chest rises, quickly separate lip contact with the victim, allowing him or her to exhale.) h. Repeat steps (f) and (g) at the rate of 12 to 20 times per minute. Continue rhythmically without interruption until the victim starts breathing or professional assistance arrives
Electro-Static Discharge and Damage to Electronic Equipment Electro-Static Discharge or ESD can permanently damage or destroy the electronic components that are used with all personal computers. It is possible that on a dry day, the act of walking across a carpeted floor with rubber sole shoes can produce a static charge of several thousand volts of electricity. While this electricity lacks the current or force to do any physical harm to a healthy human, the charge can be lethal to the computer. It becomes absolutely necessary to use the proper techniques to prevent damage to the computer from ESD. Following a few simple rules early in your course of study, will help prevent accidents in the future. Basic ESO (electro-static discharge) Protection Procedures
Proper Procedures for ESD protection: In order for damage to take place from ESD, the voltage and small current must pass through a component or components on the computers main board or on any of the associated circuits contained in the computer. When the electrical charge passes through a component, the voltage and current is at a high enough value, that it can actually punch a hole through the semiconductor material, thereby rendering it useless. The physical size of the internal components of an integrated circuit CES Industries, Inc. Copyright © 2002
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Safety Lesson
are becoming smaller each day I with the average size of an internal component being .8 microns in size. The ESD charge is similar to dropping a bomb on the middle of an active runway. To prevent the ESD from damaging a computer, the following procedures should always be followed. A. Always unplug the computer from the electrical supply. While some technicians will argue that keeping the computer connected to the AC (alternating current) outlet allows for a direct connection to the AC ground, more computers have been damaged by accidentally inserting or removing an expansion card or component with the power on. B. Always wear and properly use, an approved ESO Ground Strap. The ESD ground strap will protect you and the equipment from developing any electrical charges that can damage the computer. It is very important that you use a Ground Strap that is an ESD approved ground strap and not simply a piece of wire that you attach to your wrist and to ground. The approved ground strap will discharge the electrostatic charge with out connecting you directly to ground. Thus any problems that may be associated With the computer or any peripheral you may be working on, will not cause you to become part of the electrical circuit and potentially electrocute yourself in the process. C. Always use an electrostatically protected work surface or mat. This prevents the build up of static electric charges. The work surface should be ESD protected. While this may not be always possible when performing a field repair, good static protection procedures will prevent damage to a computer. D. Always touch the bare area of the computer case before beginning the repair. ESD can only occur when there isa difference of potential or a voltage difference between the technician and the computer. Touching the case equalizes this charge.
E. When removing parts and components from the computer, always place them on the anti-static surface. Whenever possible use an anti-static mat that is properly grounded to prevent damage to the component or component~, removed from a computer. If an anti-static mat is not available, be sure to use a clean area, free from any scraps of wire, aluminum foil or any other conductive material that may cause damage.
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Caution: Some tec;hnicians will use aluminum foil instead of an antistatic mat to place components on. This is a very dangerous process. Most main boards contain a battery, either lithium or nickel-cadmium, both of which can explode if they are shorted. Placing the board onto aluminum foil will short the battery terminals and may result in an explosion, possible fire or personal injury. 1. The Computer Power Supply While the output of the supply is a low voltage between 5 and 12 volts, the input voltage is directly connected to the ACline. This voltage is 120 VAC (voltsAC) at currents as high as the circuit breaker feeding the outlet. In a business environment, the current to an individual outlet may be as high as 30 amps. Once a cover is removed from the power supply, the technician may be exposed to voltages and currents that can injure or kill. Field technicians rarely, if ever, will repair a power supply on site. They will simply replace it and or repair it back in the shop. 2. The Computer Monitor The computer monitor is basically a television monitor and as such, has the same type of circuitry inside it. The Picture Tube or CRT (Cathode Ray Tube), is a fragile glass envelope, that is under a high vacuum, and if dropped, the tube can implode violently causing pieces of glass to fly in all directions. The CRT also stores an electrical charge, due to the construction of the CRT, it is possible for the tube to hold a charge for several months. This charge can be several hundred to several thousand volts. The most common monitors, 14" and 15" CRT's usually have a charge of 20 to 25 thousand volts applied to them. In addition to the CRT and its associated ability to store an electrical charge even when not turned on or plugged in, the monitor itself operates on voltages significantly higher than those found inside the average personal computer. Normal power supply voltage for a monitor is between 120 and 180 volts, with special power supply voltages of 400 to 1600 volts for deflection coils, and focus circuits. If you are not specifically trained in the service or repair of monitors and their associated dangers, do not open the back covers. 3. The Laser Printer Laser printers utilize a process similar to a photocopy process and as such, use a series of charging wires called Corona wires. These wires have high voltages applied to them during the printing process and may possess a charge as high as 5000 volts. In addition to the charging wires, the laser printer uses a CBS Industries, Inc. Copyright © 2002
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Safety Lesson
fuser roller to permanently fix the image on to the paper. These rollers operate at temperatures as high as 195 degrees Celsius. The rollers are under high pressure from springs that maintain· a constant pressure on the rollers surface and may be as high as several hundred pounds, depending upon the printer. The imaging process involves the use of laser light; this laser light utilizes the infra-red spectrum, and as such is invisible. While the output of the laser is only a few milliwatts or 1000 times less than a conventional night-light, it is still possible, especially if the light source shines directly into the eye, to cause damage to the eye. Therefore, when working on a laser printer, one should never bypass any safety interlocks associated with the safe operation of the printer, and most importantly, if you are not trained to repair the printer, you should not attempt it.
4. Dot Matrix Printers A dot matrix printer like any printer has moving parts, which pose a pinch risk to fingers, hair, ties and any other object that may get in the way of the moving print head. The print head, when printing for sustained periods of time can become very hot, and cause severe burns on contact with exposed skin. 5. Ink-Jet Printers An Ink-Jet or Bubble-Jet Printer has the same moving parts hazards as a dot matrix printer, however it does not have a print head that can become hot enough to burn skin. The major safety risk from an ink-jet printer is to the work area and the technicians clothing. The inks stain very quickly, and are normally not water-soluble, it is possible to go around with the results of your repair for weeks, after spilling the ink on your hands or cloths, not to mention the customers white carpet. 6. Phone Modems In addition to ESD precautions, the phone modem presents the technician with the distinct possibility of a nasty shock if not disconnected from the phone jack. The phone network normally operates with an operating voltage of -48 volts DC. When all the phones connected to the same line as the modem, are on the hook or hung up, this -48 volts is enough to give the technician a mild buzz, if they should happen to connect directly across the red and green phone lines. If the technician should happen to be lucky enough to be touching the phone line when it rings, the voltage on the line jumps up as high as 98 to 140 volts AC while ringing. This will cause the technician immediate discomfort, and may cause injury to himself, or others around when the tool or tools they may be holding go flying across the room. Always 8
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Safety Lesson
disconnect the modem from the phone line before performing any repair to a computer equipped with a modem.
7. Uninterruptable Power Supplies [UPS] These power supplies use batteries to produce AC output. The same type of AC current that is available at a normal household or business outlet. The voltages available at the output of a UPS are lethal. Most UPS models can produce 120 volt~ at up to 20 amps of current. In addition the voltage is present even if the power to the building or outlet is off. The batteries in a UPS will· cause a fire or severe burns if they are shorted in any way. Treat a UPS with the same respect as an outlet, even though the unit is working on a battery. Disposal procedures for batteries, cathode ray tubes and other environmentally sensitive items 1. Nickel-Cadmium batteries. These batteries while rechargeable several hundred times, do have a finite life span. When this type of battery is "dead" and can no longer be recharged, it should be recycled and not disposed of in the general waste stream. Cadmium is a dangerous heavy metal compound that can pollute ground water if not properly disposed of.
2. Lithium, Lithium-Ion batteries. While these batteries are not as dangerous to the environment as the Nickel-Cadmium battery, they should be recycled whenever possible 3. Lead-Acid, Sealed Lead-Acid or Gel Cell type batteries. All of these batteries contain lead, which must be recycled. 4. Laser Printer Toner Cartridges, these cartridges have a given life span, if they are not being recharged and reused, they should be recycled for the many parts that are contained within the cartridge. Most manufactures of printer or personal copier cartridges have some type of recycling program available to return the old used cartridge directly to the manufacturer for recycling. In general, for all disposable items, check with local ordinances regarding the availability of and requirements for recycling and the disposal of batteries, office waste, and possibly hazardous materials.
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Safety Lesson
Proper steps to safely discharge a Cathode Ray Tube (When applicable) As previously discussed, the CRT is capable of holding a significant electrical charge for long periods of time. It is necessary to discharge the CRT before performing any work on the monitor or CRT. The following procedure is a safe and correct method of discharging the CRT. 1. Turn the power to the monitor off, and remove the AC line .cord from the outlet. 2. Using a wire with a series resistor and alligator clips on both ends, clip an end to a non-painted chassis portion of the monitor. 3. Place one hand behind your back so that there is no possible way to complete a circuit while discharging the CRT. 4. Clip a small insulated screwdriver to the free end of the wire 5. Locate the "Second Anode Connection" this is the connection that contains the high voltage wire, that is normally at the top of the CRT and is usually Red. 6. While keeping your one hand behind your back, slowly insert the screwdriver under the protective rubber boot of the second anode connection. It is possible at this time that you may hear some snapping or crackling sounds, this is normal. Allow the screwdriver to remain in contact with the second anode connector for a minimum of 2 minutes to insure that the high voltage has been discharged. 7. Remove the screwdriver from under the cap. 8. Remove the second anode connector by carefully squeezing the connector together and lifting the connector slowly up and away from the CRT. 9. At this time the CRT is completely safe to handle as far as any high voltage shock is concerned. Remember that the CRT is under an extremely high vacuum pressure and a crack in the glass may result in a violent implosion of the tube.
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Assignment: Answer the following multiple-choice questions: 1.
Which type of accident happens when working with electronics equipment? a. Electrical Shock. b. Electrical Fire. c. Injuries from power tools. d. All of the above.
2.
Electrical Shock is what happens when an electric current flows through your body. a. True. b, False.
3,
Electrical fires are usually caused by short circuits or by an overload of the circuit that you are connecting the equipment to, a. True. b. False.
4.
Which one is a type of fire extinguisher used on an electrical fire? a. Carbon Dioxide. b. Dry Chemical. c. Halon Gas. d. All of the above.
5.
Artificial Respiration is used if the victim is not breathing. a. True. b. False.
6.
Electro-Static Discharge can permanently damage or destroy the electronics parts that are used with all personal computers. a, True. b. False.
7.
Which one is an ESD protection procedure? a. Always plug in the computer to the electrical supply. b, Always use an electro-statically protected work surface or mat. c. Always wear an ESD Ground Strap. d. Both band c.
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Safety Lesson
8.
12
Which is a basic ESD protection device? a. ESD approved ground strap. b. Aluminum foil. c. Both a and b. d. None of the above.
CES Industries, Inc. Copyright © 2002
Introduction to Computers
Lesson
1
Objectives: When you have completed this lesson, you will: 1.
Be able to assemble the CES 975 Computer Repair Trainer into a working computer.
2.
Use the CD-ROM Drive to access the "How Computers Work" program in Windows 98.
3.
Understand the special turning-off procedure for Windows.
Materials Needed: 1.
CES Computer Repair Trainer Model CES 975.
2.
CES Computer Repair Module Manual.
POWER SUPPLY
., Po\O/ER SUPPLY .IS CONNECTED TO EACH AND EVERY MODULE
r--
CD ROM
MONITOR
!
EXPANSION SLOTS
~
KEYBOARDlU CONNECTOR
I:
~I
MEMORY RAM MODULES
MOTHERBOARD
~
IcPul
C~frt1E(1 MEMORY
HARD DISK
FLOPPY DISK
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KEYBOARD
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Lesson 1
Introduction to Computers
Discussion: 1.
The personal computer industry has become one of the fastest growing areas of technology today. This caused an . increasing need for trained computer repair technicians in the job market. A computer repair technician must have a complete understanding of all of the hardware, programs, peripherals, and in some cases an understanding of networks and communications. This module is designed to provide the basic knowledge and understanding of the personal computer, its functions, operations, components and software. Only then can we begin to work on the skills and procedures necessary to service, repair, maintain an(j troubleshoot the personal computer of today. The main objective of each experiment in this computer repair module is to introduce you to the function of each of the major components of a personal computer. They will familiarize you with the proper operation as well as discuss the symptoms associated with a failure and teach basic troubleshooting skills. Since this is a modular program, the intention of this program is not to. actually take the computer apart and physically change the defective component, but to help you learn how to "successfully" complete the repair. This course will not get involved with the "setting up" of a personal computer. Simply put, we assume that the computer that you are working on was already built, and did work at one time. Setup procedures for advanced operation such as CMOS (Complimentary Metal Oxide Semiconductor) configuration or software configurations will not be covered in this module. Each lesson that you are about to start will begin with a discussion of the topic, followed by a specific procedure that you are to complete. A fault or trouble is inserted into the computer, followed by a discussion of the proper repair procedure associated with that fault.
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Introduction to Computers
POWER SUPPLY
J
EXPANSION SLOTS
Lesson 1
'" POVER SUPPLY IS CONNECTED TO EACH AND EVERY MODULE ~
CD ROM
MONITOR
~
KE'IBOARD~[J
CONN~ RAM MEMORY MODULES
MOTHERBOARD
§]~
-
~!~~'1
HARD DISK
FLOPPY DISK
I KEYBOARD
2.
The personal computer is a modular system, consisting of many separate components that when connected correctly function as a complete computer.
3.
Proper troubleshooting skills require the proper tools. The tools most often used by a technician in the field, consist of a good magnetic screwdriver and an anti-static wrist strap. Some professionals will cringe at the thought of using a magnetic screwdriver anywhere near a computer. They believe that damage can be done to the disk drives inside the computer. In fact, the only damage that you can cause is erasing a floppy disk if you accidentally place the screwdriver directly on top of the disk. It is possible to magnetize an area of the computer monitor and cause the· color purity to be effected if the screwdriver comes too close to the monitor. A good general rule when working with a magnetic screwdriver, is to keep it in your pocket when you are not using it to remove screws.
4.
Anti-Static Protection
Whenever you work on any electronic equipment, the possibility of damage from static electricity is great. The simple act of walking across a nylon carpet, can cause your body to develop a static charge of several thousand volts. The charge, if discharged into a component of the personal computer, will most certainly damage,if not destroy the component. To prevent this from happening, good anti-static protection should be used. The normal practice for static protection is to wear an anti-static wrist strap. This strap is conductive and will discharge any static electricity that you develop, however the strap will only work CBS Industries, Inc. Copyright © 2002
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Lesson 1
Introduction to Computers
correctly if it is connected to a proper ground. In addition, whenever working on a computer system, most technicians will keep the AC power cord connected to the AC outlet, thereby maintaining a connection to ground to aid in static protection. If your instructor is uncomfortable with keeping the AC cord plugged in while you are working on the computer, a wire with alligator clips on both ends can be attached to the frame of the computer and to the faceplate of the outlet, which will also provide static protection.
Procedure: 1.
Please locate the following components to the CES Computer Repair Module Model CES 975: A. CES Computer Repair Trainer Model CES 975
B. Power Cord for the Computer Repair Trainer C. Monitor (with power cord and cable) D. Mouse E. Keyboard
F. Printer (with printer cable) G.CO-ROM "How Computers Work" H. Stereo Headphone Jack I.
Blank 3 %" disk
2.
Connect the cable from the monitor to the video adapter that is on the right side of the CES Computer Repair Trainer.
3.
Connect the keyboard cable to the keyboard connector.
4.
Connect the mouse cable to the mouse connector.
5.
Connect the computer power cord to the power supply on the trainer.
6.
Connect the printer cable to the printer and to the computer trainer.
7.
Connect the headphones to the headphone jack, which is located near the printer cable connection.
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Introduction to Computers
8.
Plug the computer power cord, the monitor power cord, and the printer power cord into the outlet.
9.
Turn the monitor power switch to the "on" position now. Wait a few seconds until the monitor warms up and then proceed.
10.
Turn the main power switch of the CES Computer Repair Trainer to the "on" or up position now.
Lesson 1
With the "ATX" style computer, the main power switch is located on the power supply, when the mainpower is on, the user must turn the computer on by depressing a momentary switch located at the back of the trainer. With the "AT" style computer; the main power is turned on by only a large toggle switch located at the back of the trainer. The Computer is now going through the standard boot-up procedures. In about 30 seconds, you should see a blue screen. This is the normal start-up screen for Windows 98. At this time it is very important to learn the proper procedure· for turning the computer off. This is commonly referred to as the shutdown procedure.
COMPUTER SHUT-OFF INSTRUCTIONS: Since the computer repair system uses Windows as its operating system, it is very important to use the correct procedure when turning off the computer.
Failure to use the proper shut-off procedure may result in permanent damage to the computer. A.
Using your mouse, click once with the left mouse button on the start box in the lower left hand corner.
B.
Move the mouse cursor to "Shut down" and click the left mouse button once.
C.
The computer will ask, "What do you want the computer to do?" Make sure "shutdown" is selected and click on "OK". .With the "ATX" style computer, the computer will shutdown on it's own.
D.
With the "AT" style computer, the computer will tell you "It's now safe to turn off your computer".
E.
Turn the computer OFF.
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Lesson 1
Introduction to Computers
You have just properly turned off the computer. To continue the lesson, please re-start the computer now. For the balance of this lesson, you will be using the CD-ROM "How Computers Work". 11.
Before continuing with this experiment, you will notice that there is an expansion card installed in the computer that has two seven segment displays. This is called a POST Diagnostics Card. The purpose of this card is to interpret information that is sent from the BIOS (Basic Input Output System) during the startup or boot procedure. During the start up or boot procedure,a special program called the Power On Self Test or POST is automatically executed. This program will test the various major components and determine if they are present, and if they are present, are they working correctly.
12.
Each test that the POST will execute has a unique number associated with the test, this number is sent out on the expansion bus as each test is started. If you have the special hardware required to read this information, the code numbers will be displayed. When a component or device fails, the code that is displayed is the number that represents the test that has just been started. A list of these test codes can be obtained from. the manufacturer of the main board. With this information, it is possible to determine what test has failed, and therefore, a course of action in repairing the system. Each machine will have different internal code numbers representing the various steps within the POST program. You.may not always have the correct code available for the system that you are servicing and unfortunately these codes can change from motherboard to motherboard manufactured by the same company.
13.
Before continuing this experiment, note what number is displayed on the POST Card Display, NOW. The number displayed is the NORMAL or WORKING state of this individual computer, and will be displayed each and every time the computer is started and successfully completed the POST.
14.
The CD-ROM drive is located on the right side of the trainer. Open the CD-ROM tray by pressing the button on the right side of the CD-ROM drive.
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CES Industries, Inc. Copyright © 2002
Introduction to Computers
15.
Insert the CD-ROM "How Computers Work" into the drive with the label facing up. Do not touch the bottom surface of the disk.
16.
Close the CD-ROM tray by pushing the button again.
17.
Put on your stereo headphones. Plug the headphones into the jack on the right side of the trainer near the key switch.
18.
Use the mouse to double click on the icon "How Computers Work". (Left button)
19.
If a warning occurs on the screen, click on "OK".
20.
You are about to go on an overview tour ofthe computer. Move the mouse cursor to 'Tours" and click once.
21.
Now, move the mouse to "overview" and click once. This multimedia presentation should last approximately 12 minutes.
Lesson 1
Sit back and enjoy III 22.
When the final "Run a Program" section is finished, click on "Main".
23.
Now click on "Exit" to exit the program.
24.
Click on "OK" when asked "Are you sure you want to leave?"
25.
Click on "'OK" again. You have just exited the multimedia program.
Review: CPU - stands for "Central Processing Unit". It handles and controls all input and output of information. Multimedia - is the merging of video and audio, and program files to produce a presentation. Bootup - is the process of powering up a computer system. It looks for certain start-up instructions, which are stored on chips, such as the BIOS chip. Formatting a disk - it puts information on the disk so that the operating system knows where and how the files are stored.
CBS Industries, Inc. Copyright © 2002
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Lesson 1
Introduction to Computers
I/O device - stands for Input and Output devices such as: 1. 2. 3. 4. 5. 6.
Keyboard (input device) Floppy Disk Drive (input or output device) Printer (output device) Monitor (output device) CD-ROM (input or output device) Hard Disk Drive (input or output device)
Memory/Storage - the Computer has two ways to store information. 1. Memory or RAM (Random Access Memory) 2. Disk Drives (Hard or Floppy) Run a Program - the process by which the computer· loads a program into the memory, then follows the instructions contained in the program to perform a given task, such as running the multimedia disk - "How Computers Work".
Assignment: Answer the following multiple-choice questions: 1.
The CPU: a. Handles the input and output of information. b. Performs basic arithmetic (math) functions. c. Means Central Processing Unit. d. All of the above.
2.
During the boot-up process, the computer checks to see if a: a. A boot disk is available. b. Video card is installed in the computer. c. Keyboard is plugged into the keyboard connector. d. All of the above.
3.
The BIOS ROM Chip tells the operating system: a. What hard drive type is installed and how to.interact with it. b. What video card is installed. c. How much RAM memory is installed. d. All of the above.
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CES Industries, Inc. Copyright © 2002
Introduction to Computers
Lesson 1
4.
Which one is just an output device? a. Keyboard b. Disk Drive c. Printer d. Mouse
5.
Which one is just an input device? a. Disk Drive b. Keyboard c. CD-ROM d. All of the above
6.
How many ways can the computer store information? a. Two b. One c. Six d. Four
7.
What does RAM stand for? a. Random Access Memory b. Random And Memory c. Read Only Memory d. Random Write Memory
8.
Which type of storage devices does the computer use as its main storage device? a. Floppy Drive b. Hard Drive c. CD-ROM d. All of the above
9.
Formatting a disk means that the computer's operating system, puts disk information and instructions on a hard drive or floppy disk, so that the operating system knows where the information is stored, what information is stored and how much free space is available on the disk. a. True b. False
10.
Multimedia is the merging of video and audio files to produce a presentation such as the presentation that you have just seen and heard in this lesson. a. True b. False
CES Industries, Inc. Copyright © 2002
21
The Keyboard
Lesson
2
Objectives: When you have completed this lesson, you will: 1.
Understand how the keyboard works.
2.
Understand how the keyboard communicates with the system unit.
3.
Be able to locate and identify a common fault associated with the keyboard.
Materials Needed: 1.
CES Computer Repair Trainer Model CES 975.
2.
CES Computer Repair Module Manual.
Discussion: 1.
The keyboard that is used with the personal computer is nothing more than a group of switches that have been arranged into a combination of rows and columns. The keyboard is connected to the motherboard by way of a 5 conductor cables and connectors, which is connected to the keyboard input on the motherboard.
2.
The five conductor cable includes the following signals: a. Power (+5 Volts) b. Ground c. Serial Data out to the motherboard d. Keyboard signal reset e. Reset CES Industries, Inc. Copyright © 2002
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Lesson 2
The Keyboard
Inside the keyboard
3.
The keyboard utilizes a plunger attached to each of the mechanical keys that press against the contacts to form a complete electrical circuit.
4.
Inside the keyboard is a micro-controller or simply a small computer that has only one task to accomplish. The micro-controller constantly looks at each of the individual keys through a process called scanning. When a key is pressed, the microcontroller then interprets the key press into what is called the "key scan code". The scan code is a numerical representation of what key was pressed. The scan code consists of two parts for each key on the keyboard, the scan code that represents a key down, or when you pressed the key and a scan code that represents a key up, or when you released the key.
5.
This information is then converted into a serial data stream and sent to the computer system by the keyboard microcontroller. The keyboard controller on the motherboard converts the serial information coming from the keyboard. It then signals the CPU (Central Processing Unit) by way of the interrupt control system that there is keystroke information to be processed. The CPU is interrupted from the task or program that it is currently doing to service or process the interruption, in this case, the interruption is the keystroke or keystrokes you typed on the keyboard.
Equipment Setup Procedures: If your Computer Repair trainer has not been setup, ask your teacher for the equipment setup procedure sheet before beginning the following procedure.
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CES Industries, Inc. Copyright © 2002
The Keyboard
Lesson 2
Procedure: 1.
Open the CD-ROM tray.
2.
Insert the CD-ROM "How Computers Work" into the Drive.
3.
Close the CD-ROM tray.
4.
Put on your stereo headphones.
5.
Use the mouse to double click on the icon "How Computers Work".
6.
When a warning occurs on the screen, click on "OK".
7.
When the music starts and the title screen appears move the mouse cursor anywhere on the screen and click once using the left mouse button. This will help the user to quickly start the program by bypassing the title screen and make the music stop playing.
8.
You are about to go on a tour of the Keyboard. Move the mouse cursor to the picture of the Keyboard on the monitor and click once. Sit back and enjoy II!
9.
After you have listened to the description of the Keyboard, move the mouse cursor to the back of the computer and click once.
10.
Now move the cursor to the "Keyboard Port" and click once. Sit back and enjoy ,!!
11.
When the tour of the "Keyboard Port" is finished, click on "Main" to go to the main menu.
12.
Click on "Exit" to exit the program.
13.
Click on "OK" when asked "Are you sure you want to leave?"
14.
Click on "OK" again. You have just exited the multimedia program.
CES Industries, Inc. Copyright © 2002
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Lesson 2
The Keyboard
Computer Repair and Fault Insertion:
IFault Insertion I 1.
Please follow the correct procedures in turning the computer repair trainer "OFF".
COMPUTER SHUT-OFF INSTRUCTIONS: Since the computer repair system uses Windows as its operating system, it is very important to use the correct procedure when turning off the computer. Failure to use the proper shut-off procedure may result in permanent damage to the computer.
A.
Using your mouse, click once with the left mouse button on the start box in the lower left hand corner.
B.
Move the mouse cursor to "Shut down" and click the left mouse button once.
C.
The computer will ask, "What do you want the computer to do?" Make sure "shutdown" is selected and click on "OK". With the "ATX" style computer, the computer will shutdown on it's own.
D.
With the "AT" style computer, the computer will tellyou "It's now safe to turn off your computer".
E.
Turn the computer OFF.
F.
Ask your instructor for the key to the key switch located on the right side of the trainer.
G.
Insert the key and rotate the key to a horizontal position.
2.
Move fault switch to position one. This will insert a fault in the keyboard system.
3.
Turn the power to the computer repair trainer on.
I SYMPTOM I 4.
Does the computer repair trainer start normally? It should not start normally because of the fault inserted in the keyboard system.
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CES Industries, Inc. Copyright © 2002
The Keyboard
5.
Lesson 2
What symptoms did you observe? You should have observed that Windows does not start normally and that an error message has occurred on the screen. ThePOST (Power On Self Test) detected that there is a failure of a major system associated with the keyboard, and has detected the error. You should notice that the POST Card in the computer has displayed a different code other than the normal boot or start-up code.
IDIAGNOSISI 6.
Based upon these observations, there is a number of possible things that can be wrong with the computer. The keyboard may be defective. With the type of error that you have identified, the keyboard would most likely be the· problem associated with the fault observed. Keyboard failures can occur for numerous reasons, with the most common being a foreign substance like coffee, being spilled onto the keyboard. The keyboard cable may be defective. A crimp or other physical damage to the keyboard cable can also generate a keyboard error. Even though the POST has identified a keyboard error, it does not indicate whether the fault is the keyboard or its associated components. The keyboard port on the motherboard may be defective. The keyboard may be functioning 100 percent correctly, .but is unable to communicate with the keyboard controller on the main board. This type of problem may be caused by a small 1 amp fuse, located near the keyboard connector, that provides 5 volts to the keyboard via the keyboard cable. The keyboard controller may be defective. The. microcontroller in the keyboard may no longer be functional. The motherboard may be defective. When all other devices have been. tested, and you have changed the components that are easy and the least expensive to change, the only other cause for a keyboard error can be the motherboard itself.
CES Industries, Inc. Copyright © 2002
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Lesson 2
The Keyboard
I REPAIR I The keyboard is defective. Replace the keyboard, and re-test the computer to see if the problem has been solved. The keyboard cable may be defective. Even if you determine that the problem is the keyboard cable, the cable is part of the keyboard. The normal repair procedure is to replace the keyboard. The keyboard controller may be defective. It is impossible to obtain the exact microcontroller used in the defective keyboard. The repair is to replace the keyboard. The motherboard may be defective. After changing the keyboard, you have determined that the keyboard error is still present. The most iikely failure would then be, associated with the keyboard circuitry located on the motherboard. The repair procedure for the symptoms stated is to replace the defective motherboard. Repairing Procedure: 1.
Since this fault prevented the computer from starting normally, there is no need to follow a special shut-down procedure.
2.
Turn off the main power switch now.
3.
Turn fault switch to the original"No Fault" position and turn the key switch to original vertical position.
4.
Your computer is now ready to proceed with the next lesson.
Review: You should have observed that the computer was unable to start normally. The Windows startup screen never appeared. The computers internal diagnostics program known as the Power On Self Test or POST for short, detected that the computer had a defect that was detectable by the diagnostic program. The program responded with an error message that corresponded to the defect that was detected and said, "keyboard error or no keyboard present." "Press {F1} to continue".
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CES Industries, Inc. Copyright © 2002
The Keyboard
Lesson 2
Assignment: Answer the following multiple-choice questions: 1.
When pressing the letter K down on the keyboard, the plunger presses against two electrical contacts to form a circuit. a. True b. False
2.
What chip is used first by the computer to decide which key on the keyboard was pressed? a. RAM b. CMOS c. Microprocessor d. 810S
3.
The RAM does not hold the scan code until the computer is ready for it. a. True b. False
4.
The CPU chip is used in the keyboard decision-making process. a. True b. False
5.
What is the last chip used in the key decision making process? a. CMOS b. Keyboard controller c. CPU ' d. 80th A and 8
6.
How many types of keyboard ports are there?
a. One b. Two c. Three d. Four
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29
The Monitor
Lesson
3
Objectives: When you have completed this lesson, you will: 1.
Understand how the monitor works.
2.
Understand how the computer system communicates with the monitor.
3.
Be able to locate and identify a common fault associated with the monitor.
Materials Needed: 1.
CES Computer Repair Trainer Model CES 975.
2.
CES Computer Repair Module Manual.
Discussion: 1.
The monitor can be thought of as a specialized television screen. In fact, most of the circuits and components that are associated with the modern color television system, are very similar to the components that are in the computer monitor.
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Lesson 3
The Monitor
2.
The major difference between the television and the computer monitor is that the television is able to tune or select different channels and has audio circuits that allow the program audio to be heard. The computer monitor accepts the information to be displayed by way of the video card installed on the motherboard. The video signal is an analog signal that contains the color, synchronization signals and intensity signals. The monitor interprets these signals and displays the information that you see on the screen.
3.
There are many different types of monitors, and the type of monitor that you use must agree with the type of video card that you have installed on the computer. The four types of monitors that you may come across are: •
Monochrome or single color, often green or orange screen monitor.
•
CGA or Color Graphics Array monitor.
•
EGA or Enhanced Graphics Array monitor.
•
VGA or Super VGA (SVGA), video graphic array monitors. The SVGA monitor is the current and the most common type of monitor.
Equipment Setup Procedures: If your Computer Repair trainer has not been setup, ask your teacher for the equipment setup procedure sheet before beginning the procedure below.
Procedure: 1.
Open the CD-ROM tray.
2.
Insert the CD-ROM "How Computers Work" into the Drive.
3.
Close the CD-ROM tray.
4.
Put on your stereo headphones.
5.
Use the mouse to double click on the icon "How Computers Work".
6.
When a warning message occurs on the screen, click on "OK".
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CES Industries, Inc. Copyright © 2002
The Monitor
7.
When the music starts and the title screen appears, move the mouse cursor anywhere on the screen and click once using the left mouse button. This will help the user to quickly start the program by bypassing the title screen and make the music stop playing.
8.
You are about to go on a tour of the Monitor. Move the mouse cursor to the picture of the Monitor and click once.
Lesson 3
Sit back and enjoy III 9.
When the tour of the Monitor is finished, click on "Exit" to exit the program.
10.
Click on "OK" when asked "Are you sure you want to leave?"
11.
Click on "OK" again. You have just exited the multimedia program.
Computer Repair and Fault Insertion:
IFault Insertion I 1.
Please follow the correct procedures in turning the computer repair trainer "OFF".
2.
Move the fault switch on the side of the monitor to position one. This will insert a fault in the monitor sub-system.
3.
Turn the power to the computer repair trainer on.
I SYMPTOM I 4.
Does the computer repair trainer start normally? You should notice that the computer will start normally, however the information that is being displayed on the monitor appears to be scrambled, somewhat like a cable television station that you are not paying for. Depending on the type of monitor used you may see diagonal lines or a blank screen. If the screen is blank, it is because you are using a "green monitor". A green monitor blanks out when no video signal is detected. If your screen is blank, set the monitor fault switch to position 2. You will see the Windows desktop appear on the screen. While watching the screen, turn the monitor fault select CES Industries, Inc. Copyright © 2002
33
Lesson 3
The Monitor
switch to position number 1. As you rotate the switch, observe the diagonal lines on the screen before it blanks out. 5.
What symptoms did you observe? You should have observed, that the computer repair trainer did boot in the normal fashion, as indicated by the post display card on the trainer, however, it appears that the video information on the monitor is scrambled, for a few seconds and then the monitor goes blank (black).
6.
Based upon these observations, there are a number of possible things that can be wrong with the computer. •
The video card may be bad.
•
The cable to the monitor may be bad.
•
The monitor itself may be bad.
The interesting part about troubleshooting computers is that surprises happen to the best of us. What you have just experienced is what happens when the monitor you are using has a feature known as a green feature. The green feature is an energy saving feature that the manufactures have installed in accordance with recommendations from the EPA (Environmental Protection Agency) to save energy. Whenever a monitor is not in use for a few seconds, that is a loss of a video signal from the computer, the monitor turns off. What is happening with this fault is that since the video signal has been lost from the host computer, the monitor assumes that the user has turned off the computer but forgot to turn off the monitor, so it shuts off.
IDIAGNOSIS I 7.
Based upon these observations, you would diagnose the monitor problem as follows. Defective Video Card Since the computer appears to be starting normally, and at this time there is no error code displayed on the Post Card, it is possible to assume that the video card is functioning correctly. As discussed in previous experiments, the POST program will only detect a problem associated with primary hardware, and a failure that the POST diagnostic program is aware of. Since the computer did in fact boot, the chances of the video card being defective are small. However, since most repairs are accomplished by
34
CES Industries, Inc. Copyright © 2002
The Monitor
Lessoi13
"replacement", it does not hurt to try changing the video card. For this fault, the problem would remain. Defective Monitor Cable Since the monitor cable carries all the information to the monitor for video, synchronization, intensity and color, it is a possibility for the problem to be associated with the monitor cable. A quick, disconnect and reconnect of the cable, or a swap with a known working cable will verify if the cable is indeed the cause of this fault. Defective Monitor If, after swapping the cable and the video card, the problem still exists. The cause of the difficulty is in the monitor. For this you would replace the monitor, since the repair of the monitor requires more technical skill and a familiarity with television circuits.
IREPAIR I The problem associated with the computer repair trainer is a problem in the monitor circuitry itself. Since the monitor is a specialized television set, repairing the monitor requires the complete understanding of how video, color and synchronization circuits function. Most field repairs involving monitors are resolved by changing the defective monitor with a known good monitor and sending the monitor back to the manufacturer for repair. Repairing Procedure: 1.
Since this fault did not prevent the computer from starting normally, but the fault was not in the computer system itself, you can remove the fault by turning the Monitor fault switch to the original "No Fault" position,
2.
Your computer is now ready to proceed with the next lesson.
Review: The computer monitor displays information that is sent from the video card. The monitor is basically a television set that does not have any tuner or audio circuits, but can display information sent directly from a computer. The monitor that is used with the computer must be the same type of monitor that the video card is designed to operate with, otherwise severe damage may occur to the monitor.
CES Industries, Inc. Copyright © 2002
35
Lesson 3
The Monitor
The most common monitor that is available today is the super VGA monitor. This monitor has the ability to display 16.7 million colors at a resolution of 1280 X 1024 pixels. Repair of computer monitors are normally limited to those individuals that are trained in the repair of televisions since extremely hazardous voltages are present inside the monitor.
Assignment: Answer the following multiple-choice questions: 1.
The video card is not used by the computer to display images on the monitor. a. True b. False
2.
The electron gun beams bend to create the complete image, so you can see the image on the monitor. a. True b. False
3.
The term "Shadow Mask" means a metal sheet with holes in the middle to help keep the beams aligned with the phosphors. a. True b. False
4.
The beams scroll across the screen horizontally at 60 times a second. a. True b. False
5.
The term "LCD" for laptops means Liquid Crystal Display. a. True b. False
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CES Industries, Inc. Copyright © 2002
The Power Supply
Lesson
4
Objectives: When you have completed this lesson, you will: 1.
Understand how a power supply works.
2.
Understand the various connectors and their functions.
3.
Be able to locate and identify a common fault associated with the power supply.
Materials Needed: 1.
CES Computer Repair Trainer Model CES 975.
2.
CES Computer Repair Module Manual.
Discussion: 1.
The power supply is connected to the household outlet, which supplies 120 VAC (Volts Alternating Current) power to the computer. The power supply consists of: •
Circuits that change the household power into the power needed for the computer to operate.
•
A cooling fan to reduce the temperature inside the computer case.
•
A power switch to turn the computer on and off. CES Industries, Inc. Copyright © 2002
37
Lesson 4
The Power Supply
RED
POWER SWITCH
-+50CVOLTS
BLACK ] GROUND BLACK YEllOW -+12
L-.J
I
+ U'1
q,
0
0
i"l
< 0 r
.... Vl
i"l
< 0 r
.... Vl
I al
:c 0 C
;z: 0
I I +I I
....+ .... N N I
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r
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-f 0 Vl 0
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2.
The computer needs Direct Current or DC to operate and as such has the following outputs. +5, +12, -12, -5 volts DC. In addition, a special output called the power good signal is sent from the power supply to the motherboard to inform the CPU and the reset control circuits that the power supply is working and that all the necessary supply voltages are present.
3.
When the power supply is first turned on, the power good signal is held low, or set at 0 Volts, this prevents the motherboard from resetting and starting the normal boot up procedures, as the power supply voltages increase to their normal levels, the circuitry inside the power supply monitors all of the output voltages. When all voltages are at their correct level, the power good signal changes from low to high or to 5 Volts.
4.
Once the power good signal is high, the reset control logic on the mainboard will reset the CPU and start the normal boot procedure. The power supply also incorporates a logic circuit that will detect an overload or a short circuit and will immediately turn off the power. The logic circuit requires that a load be connected to the power supply at all times in order for the supply to even turn on. Therefore, it is necessary always to have something such as a disk drive or motherboard connected to the supply when testing the supply for proper operation.
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CES Industries, Inc. Copyright © 2002
The Power Supply
5.
Lesson 4
The power supply used in the personal computer is known as a switching power supply, and as such is a complicated circuit. Repairs to this type of supply are limited to the diagnosis of the problem and the replacement of the supply. Unlike all of the components in the personal computer, the voltages that are contained inside the power supply can kill you! Never attempt to open, or in any way modify the power supply unless you are a trained electronics technician familiar with the workings of switch mode supplies.
Equipment Setup Procedures: If your computer repair trainer has not been setup, ask your teacher for the equipment setup procedure sheet before beginning the procedure below.
Procedure: 1.
Open the CD-ROM tray.
2.
Insert the CD-ROM "How Computers Work" into the Drive.
3.
Close the CD-ROM tray.
4.
Put on your stereo headphones.
5.
Use the mouse to double click on the icon "How Computers Work".
6.
If a warning message occurs on the screen, click on "OK".
7.
When the music starts and the title screen appears move the mouse cursor anywhere on the screen and click once using the left mouse button. This will help the user to quickly start the program by bypassing the title screen and make the music stop playing.
8.
You are about to go on a tour of the Power Supply.
g.
Move the mouse cursor to the picture of the computer case and click once on the front of the computer.
10.
Then move the mouse cursor to the picture of the Power Supply and click once. Sit back and enjoy !l!
CBS Industries, Inc. Copyright © 2002
39
Lesson 4
The Power Supply
11.
When the tour of the Power Supply is finished, click on "Main" to go to the main menu.
12.
Then move the mouse cursor to the picture of the computer case and click once on the back of the computer.
13.
Then move the mouse cursor to the picture of the Power Supply (Back) and click once.
Sit back and enjoy!!! 14.
When the tour of the Power Supply (Back) is finished, click on "Main" to go to the main menu.
15.
Click on "Exit" to exit the program.
16.
Click on "OK" when asked "Are you sure you want to leave?"
17.
Click on "OK" again. You have just exited the multimedia program.
Computer Repair and Fault Insertion:
I Fault Insertion I 1.
Please follow the correct procedures in turning the computer repair trainer "OFF".
COMPUTER SHUT-OFF INSTRUCTIONS: Since the computer repair system uses Windows as its operating system, it is very important to use the correct procedure when turning off the computer.
Failure to use the proper shut-off procedure may result in permanent damage to the computer.
40
A.
Using your mouse, click once with the left mouse button on the start box in the lower left hand corner.
B.
Move the mouse cursor to "Shut down" and click the left mouse button once.
CES Industries, Inc. Copyright © 2002
The Power Supply
C.
The computer will ask, "What do you want the computer to do?" Make sure "shutdown" is selected and click on "OK". With the "ATX" style computer, the computer will shutdown on it's own.
D.
With the "AT" style computer, the computer will tell you "It's now safe to turn off your computer".
E.
Turn the computer OFF.
2.
Ask your instructor for the key to the key switch located on the right side of the trainer.
3.
Insert the key and rotate the key to a horizontal position.
4.
Move the fault switch on the computer repair trainer to position two. This will insert a fault in the power supply.
5.
Turn the power to the computer repair trainer on.
Lesson 4
ISYMPTOM I 6.
Does the computer repair trainer start normally? The computer did not start normally. You should notice that the computer is completely dead. There is no hard disk or floppy disk c;lctivity, the POST card is not displaying any information, and there are no beeps or error codes.
7.
What symptoms did you observe? a. You should observe that the computer did not boot at all. The monitor was dark, however the power on the indicator for the monitor was on. (Note: With some "green" monitors the power indicator light may turn orange, flashing or be off although the monitor is turned on). b. You also should have noticed that the system had no power on the indicators, the POST card was blank, however, the power indicators (+5,+12,-12,-5) were on. c. This is a common type of misleading fault, it appears to the casual user that the power supply is on, and working since the fan and some supplies are on.
CES Industries, Inc. Copyright © 2002
41
Lesson 4
The Power Supply
I DIAGNOSIS I 8.
This is an easy diagnosis, since the computer is basically "dead". There are very few components in the personal computer that can cause a totally dead machine. The most common is a defective power supply.
9.
Based upon these observations, there are several possible things that can be wrong with the computer. a. Defective Power Supply b. A Defective expansion card or slot c. Defective peripheral device connected directly to the power supply Defective Power Supply Since the power supply produces all the necessary output voltages for all devices installed in the computer, the power supply would be the first and most likely suspect. Remember the power supply can be good, but the power signal may not be set. This will cause the computer not to start, and will produce a "dead machine" Defective Expansion Card If by chance. an expansion card is defective or has a defective component on it that.causes an increased demand in current. The power supply will immediately shut down all output voltages, and this will result in a dead machine. To verify this type of problem, you would remove all the expansion cards, restart the computer and observe the system for signs of a normal boot. If the computer were to start normally, you would replace each expansion card removed, one at a time, until the computer failed to start. This would produce the defective card with the least amount of work. Defective Peripheral Device As with a defective card, a defective hard disk, floppy disk, CDROM drive, or any device connected directly to the power supply will cause the power supply to shut down. You would troubleshoot this problem the same way by removing all peripherals and restarting the computer. If it starts normally, you would replace each component, one at a time until the offending part is found.
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CES Industries, Inc. Copyright © 2002
The Power Supply
Lesson 4
IREPAIR I The repair procedure for the symptoms stated will be to replace the defective power supply. Since the power supply is a switch mode supply and is extremely complicated to repair, and the replacement cost ofa new power supply is under $50.00, it is cost effective to replace the power supply with a new one. Repair Procedure
1.
Since this fault prevented the computer from starting normally, there is no need to follow a special shut-down procedure.
2.
Turn off the main power switch.
3.
Turn fault switch to the original "No Fault" position and turn the key switch original vertical position.
4.
Your computer is now ready to proceed with the next lesson.
Review: The power supply is used to convert household current into voltages and currents that the personal computer utilizes. The supply provides 4 different output voltages and a power good signal to the computer. Inside the supply, hazardous voltages are present and no one should open the supply unless they are totally familiar with the operation.
Assignment: Answer the following multiple-choice questions: 1.
The Power Supply is a device used to convert 120 VAC to a voltage that the computer can use. a. True. J b. False.
2.
Should you open the power supply to see what the inside looks like or for any other reason? a. Yes. b. No.
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Lesson 4
The Power Supply
3.
Most AT Class Computer power supplies have another outlet for plugging in the monitor. a. True. b. False.
4.
If Windows does not start, the computer does not have to follow a special shut-down procedure. a. True. b. False.
5.
The power supply uses a logic circuit to detect: a. A short circuit. b. An overload. c. Both a and b. d. None of the above.
6.
When testing power supply voltages: a. There must be a load connected to the supply to assure a correct reading. b. There must be no load on the supply to assure a correct reading. c. The power supply switch must be in the off position. d. None of the above.
7.
Defective computer power supplies are easily repairable. a. True. b. False.
8.
Voltages contained inside the power supply can kill you. As a result the supply should never be opened by anyone other than a trained electronics technician. a. True. b. False.
9.
The power supply output voltages are both positive and negative with respect to ground. a. True. b. False.
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The Floppy Disk Drive
Lesson
5
Objectives: When you have completed this lesson, you will: 1.
Understand the component parts of a floppy disk drive.
2.
Understand how the floppy disk drive works.
3.
Be able to locate and identify a common fault with the floppy disk drive.
4.
Be able to locate and identify a common fault with the floppy drive control system.
Materials Needed: 1.
CES Computer Repair Trainer Model CES 975.
2.
CES Computer Repair Module Manual.
3.
Blank 3 %" disk. STEPPER MOTOR
POWER CONNECTOR (SUPPLIES .5'1 POYER TO DRIVE)
DATA CABLE (INPUTlOUTPUT COMMANDS FROM COMPUTER OR MUL T1-1I0 CONTROLLER)
SPINDLE MOTOR (TURNS FLOPPY DISK)
H~~~~~:JY
B.
BOTTOM VIEW
DISK SLOT
ACT~~lr:iiHT
c.
FRONT VIEW
DISK RELEASE BUTTON
FIGURE 1. 3.5" FLOPPY DISK DRIVE
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Lesson 5
The Floppy Disk Driv.e
Discussion: 1.
Before the CD-ROM, the floppy disk was the primary method of introducing new software or programs to the computer. Originally, the floppy disk was a large 8" disk that was able to hold a large amount of data for its time, 128K, however the modern floppy disk, 3%" in size, is able to hold 1.44 Meg of information.
2.
The information is stored on the floppy disk in magnetic variations, similar to the way a cassette tape stores music. The major difference between the cassette tape and the floppy disk is that the data stored on the floppy disk represents information as 1's or D's. The information is magnetic variations that are detected by the read/write head and is interpreted by the control logic on board the floppy disk drive. The music stored on the cassette tape is an analog signal that varies in frequency and amplitude. DATA CABLE (INPUTIOUTPUT COMMANDS FROM COMPUTER OR MULTI-11O CONTROLLER)
SPINDLE MOTOR (TURNS FLOPPY DISK)
WRITE PROTECT DETECTOR
DRIVE ACTIVEUGHT
46
TOP VIEW
FRONT VIEW
HI DENSITY DETECTOR
BOTTOM VIEW
DISK RElEASE
CES Industries, Inc. Copyright © 2002
The Floppy Disk Drive
3.
Lesson 5
The basic component parts of a typical 3% floppy disk drive are: a. The Disk Drive Hub This is the mechanical mount that allows the disk to be turned by the drive motor. b. The Drive Motor This motor is a servo-controlled motor, which means that a special signal is sent to the control electronics on the disk drive that monitors the speed at which the motor is turning. c. The Read-Write Head This is the most important part of the disk drive. The Read-Write head detects and produces the small magnetic signals that correspond to the information that you are reading or writing (storing) onto the surface of the disk. The read-write head is driven forward and back by a special motor called a steppermotor. d. Write Protect System A light beam is projected through a small hole cut into the plastic case of the disk. If the light is not detected, information can be stored on the disk; this is called writing to the disk. If the light is detected, the information cannot be written onto the disk. DISK PROTECTION SHUTTER ,r----
READ/Y/RITE ACCESS HOLE
DRIVE SPINDLE
A.
DENSITY DETECTION
HOLE: DISK CAPACITY NO HOLE: DISK CAPACITY
B.
= 1.44 MEG = 720 K
WRITE PROTECT SLIDE OPEN - WRITE PROTECTED CLOSED - WRITE ENABLED
Equipment Setup Procedures: If your computer repair trainer has not been setup, ask your teacher for the equipment setup procedure sheet before beginning the following procedure.
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Lesson 5
The Floppy Disk Drive
Procedure: 1.
Open the CD-ROM tray.
2.
Insert the CD-ROM "How Computers Work" into the Drive.
3.
Close the CD-ROM tray.
4.
Put on your stereo headphones.
5.
Use the mouse to double click on the icon "How Computers Work".
6.
When a warning message occurs on the screen, click on "OK".
7.
When the music starts and the title screen appears move the mouse cursor anywhere on the screen and click once using the left mouse button. This will help the user to quickly start the program by bypassing the title screen and make the music stop playing.
8.
You are about to go on a tour of the Floppy Disk Drive.
9.
Move the mouse cursor to the picture of the computer case and click once on the front of the computer.
10.
Then move the mouse cursor to the picture of the Floppy Disk Drive and click once. Sit back and enjoy!!!
11.
When the tour of the Floppy Disk Drive is finished click on "Main" to go to the main menu.
12.
Click on "Exit" to exitthe program.
13.
Click on "OK" when asked "Are you sure you want to leave?"
14.
Click on "OK" again. You have just exited the multimedia program.
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The Floppy Disk Drive
Lesson 5
Computer Repair and Fault Insertion:
I Fault Insertion I 1.
Please follow the correct procedures in turning the computer repair trainer "OFF".
COMPUTER SHUT-OFF INSTRUCTIONS: Since the computer repair system uses Windows as its operating system, it is very important to use the correct procedure when turning off the computer. Failure to use the proper shut-off procedure may result in permanent damage to the computer.
A
Using your mouse, click once with the left mouse button on the start box in the lower left hand corner.
S.
Move the mouse cursor to "Shut down" and click the left mouse button once.
C.
The computer will ask, "What do you want the computer to do?" Make sure "shutdown" is selected and click on "OK". With the "ATX" style computer, the computer will shutdown on it's own.
D.
With the "AT" style computer, the computer will tell you "It's now safe to turn off your computer".
E.
Turn the computer "OFF".
2.
Ask your instructor for the key to the key switch located on the right side of the trainer.
3.
Insert the key and rotate the key to a horizontal position.
4.
Move fault switch to position three. This will insert a fault in the floppy disk drive system.
5.
Turn the power to the computer repair trainer on.
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Lesson 5
The Floppy Disk Drive
I SYMPTOM· I 6.
Does the computer repair trainer start normally? It should be noted that the computer did start normally, and as of now, appears to be functioning correctly. This fault is what is known as a non-critical error. The computer's POST did not detect the error, nor is the error severe enough to cause the computer to halt.
7.
What symptoms did you observe? You should have observed that the computer appears normal. You will now learn about diagnostic troubleshooting. Since the computer appears to be functioning normally, you now must investigate what is wrong. The topic of this lesson is the disk drive, so you can be sure that the problem that you are looking for is associated with the disk drive system. To determine the problem, you will need a formatted floppy disk, and then proceed with the following. a. Insert the disk into the floppy disk drive. b. Open up the Icon called My Computer by double clicking on the icon. c. Double click on the floppy disk drive 3% icon. d. Wait for the computer to respond. You should have received an error message generated by the operating system that the disk in drive A is not formatted. Based upon these observations, the following may be the cause of this problem. a. Defective Diskette b. Defective Disk Drive
c. Defective Disk Drive Controller
I DIAGNOSIS I Defective Diskette The error that you just observed may be caused by a number of possibilities. The most common is that the floppy disk itself is defective or is simply not formatted. Since the operating system caused an error code to be displayed and attempted to format the floppy disk without any success, the most logical approach would
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The Floppy Disk Drive
Lesson 5
be to simply try another diskette and see if the problem is still present. Defective Disk Drive After changing the disk and trying again, unsuccessfully to format or read the disk, it is possible that the problem is associated with the floppy disk drive itself. The problem may be dirty read-write heads, which is common in areas of high dust, or it may be a drive that is out of alignment. Head cleaning can be accomplished with various head cleaning diskettes. Alignments are generally not done anymore. The cost of the equipment and the time to perform the alignment costs more than a new disk drive. Defective Drive Controller After changing the disk and the disk drive itself, the only other possibility is that the disk drive controller is defective. If the controller is an expansion card, this can easily be replaced. If the controller is part of the motherboard, the replacement can either be the changing of the motherboard, or the installation of a separate drive controller and disabling the controller on the motherboard. The problem that you observed in this case is caused by a defective floppy drive.
I REPAIR I The repair for this fault would be to replace the defective floppy disk drive. The cost of repairing the drive would far exceed the cost of a new disk drive.
Repair Procedure: 1.
Since this fault did not prevent the computer from starting normally, you must follow the special shut-down procedure.
2.
Click on "no" to answer the question do you want to format the disk now?
3.
Click on the "x" in the upper right corner of the screen to close the "My computer" window.
COMPUTER SHUT-OFF INSTRUCTIONS: Since the computer repair system uses Windows as its operating system, it is very important to use the correct procedure when turning off the computer. CES Industries, Inc. Copyright © 2002
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Lesson 5
The Floppy Disk Drive
Failure to use the proper shut-off procedure may result in permanent damage to the computer. A.
Using your mouse, click once with the left mouse button on the start box in the lower left hand corner.
D.
Move the mouse cursor to "Shut down" and click the left mouse button once.
E.
The computer will ask, "What do you want the computer to do?" Make sure "shutdown" is selected and click on "OK". With the "ATX" style computer, the computer will shutdown on it's own.
D.
With the "AT" style computer, the computer will tell you "It's now safe to turn off your computer".
E.
Turn the computer "OFF".
4.
Turn fault switch to the original "No Fault" position.
5.
Your computer is now ready to proceed.
REVIEW: Normally a problem associated with a floppy disk drive can originate from a number of causes, most of which are due to a bad disk or a improperly formatted disk. Since the disk drive was "bad", there are a few reasons that the drive itself may be unable to read the disk. The drive itself may be out of alignment, have defective read-write heads, have a defective controller or may just be dirty. The floppy disk drive is considered a disposable part, after you try the obvious, such as changing disks, and cleaning the drive, you would replace the disk drive.
INSERTING ANOTHER FAULT 1.
Move fault switch to position four. This will insert a fault in the floppy disk drive system.
2.
Turn the power to the computer repair trainer on.
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The Hoppy Disk Drive
Lesson 5
ISYMPTOM I 3.
Does the computer repair trainer start normally? It should be noted that the computer did not start normally. The POST diagnostic program detected a fatal or critical error and halted the computer.
4.
What symptoms did you observe? You should have observed that the computer did not start normally, and that the computer's internal diagnostic ROM program detected that there is a problem with the floppy disk drive system. An error message is displayed on the monitor stating the following message Floppy disk(s) fail (40). In addition to the message displayed on the monitor screen the POST Diagnostic Card is also displaying a code other than the normal code for this computer. Based upon your observations, there are a number of possible things that can be wrong with the computer. a. The disk drive is defective. b. The disk drive cable is bad. c. The drive controller is defective. d. The motherboard is bad. Defective Disk Drive Unlike the previous error, this problem caused a critical or fatal error to be generated. In order for this type of an error to occur, the problem must be detected by the POST. The post only tests for the presence of the floppy disk drive and the type of disk drive installed. The test also issues a reset drive status request, which causes the drive to look for the track 0 position. If any of the tests fail to complete, or generate any errors during the POST an error will result. Defective Drive Cable This could cause an error to be produced; however, defective cables do not normally happen by themselves. The most common "Defective Cable" is when the cable is partially connected to the device or motherboard. Always check the connectors at both ends of the device for proper connections.
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Lesson 5
The Floppy Disk Drive
Defective Drive Controller A defective drive controller will usually cause a failure and a critical error to be displayed. If the drive controller in the computer that you are repairing is a separate card, try swapping the suspected bad card with a good one, and retesting the computer. If it is part of the motherboard, you may have to change the motherboard or install a separate controller and disable the controller installed on the motherboard Defective Motherboard It is possible for the problem to be associated with a defective motherboard, specifically the DMA or Direct Memory Access channel that controls the transfer of information from the floppy disk to the memory. While this is a rare problem, it can and does happen. If after changing all the recommended components first, the motherboard would be the last resort.
I REPAIR I The fault that is inserted in this computer is related to the disk controller circuits. The disk controller interprets all operating system commands and instructs the disk drive accordingly. Since this computer has all of the peripheral controllers located on the motherboard, there are only two choices in order to repair this computer. The first is to disable the onboard controller and install an external controller in one of the expansion slots, this is the most cost effective method of repair. The second, more expensive method would be to replace the motherboard.
Repair Procedure: 1.
Since this fault prevented the computer from starting normally, there is no need to follow a special shut-down procedure.
2.
Turn off the main power switch.
3.
Turn fault switch to the original "No Fault" position and turn the key switch to the original vertical position.
4.
Your computer is now ready to proceed with the next lesson.
Review: The floppy drive is a device that is used to store data onto disks using small magnetic variations on the surface of the disk. The floppy disk is a common way to transport data to or from another 54
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The Floppy Disk Drive
Lesson 5
computer. The type of floppy disk used will determine the storage capacity of the disk, with 3~ high-density disks holding about 1.4 megabytes of data. A new type of floppy disk has been developed that stores 120 megabytes on the same type of 3~ disk, however, with the popularity of recordable compact discs holding 650700MB, they never became popular.
Assignment: Answer the following multiple-choice questions: 1.
Floppy disks are used to: a. Carry new programs. b. Save data. c. Move files from one PC to another. d. All of the above.
2.
If the write protect tab is in the open position: a. A light passes through the hole in the disk and tells the computer it is okay to write data to the disk. b. Light passes through the hole and tells the PC not to write data to the disk. c. It has no effect because floppy disks cannot be write protected. d. None of the above.
3.
Zero's and One's are the binary language of the computer. a. True b. False
4.
The most common type of floppy drive used in computers today is: a. 3.5" Disk Drive b. 5.25" Disk Drive c. Tape Drive d. 8" Disk Drive
5.
The "cookie" is: a. The working disk inside the jacket of the floppy disk. b. Coated with a thin layer of magnetic material. c. Spun inside the jacket by a motor on the disk drive. d. All of the above.
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Lesson 5
The Floppy Disk Drive
6.
The Tape Drive is another device used to store and transport data to another machine. a. True b. False
7.
The thin inner disk in a 3.5" disk is called a "cookie". a. True b. False
8.
To read the data from a disk, the read/write heads move onto the surface of the cookie. a. True b. False
9.
3.5" floppy disks can store: a. More data than a 5.25" floppy. b. Less data than a 5.25" floppy. c. The same amount of data as a 5.25" floppy. d. None of the above.
10.
The read/write head is used to transfer information to and from the floppy disk. a. True b. False
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CES Industries, Inc. Copyright © 2002
The Hard Disk Drive
lesson
6
Objectives: When you have completed this lesson, you will: 1.
Understand the component parts of a hard disk drive.
2.
Understand how the hard disk drive works.
3.
Be ablerto locc;lte and identify a common fault in the hard disk drive.
Materials Needed: 1.
CES Computer Repair Trainer Model CES 975.
2.
CES Computer Repair Module Manual. PO.....ER CONNECTOR DISK PLATTER
DRIVE. SPINDLE
R/W HEADS
HEAD POSITIONER "VOICE COIL" DRIVER [NOVES HEADS) 1/0 INTERFACE TOP VIEW
BOTTON VIE"'"
Discussion: 1.
The information is stored on the hard disk in magnetic variations; similar to the way the information is stored onto a floppy disk. The major difference between the hard or fixed disk and the floppy disk is that the disk itself is a permanent component and cannot be replaced. CES Industries, Inc. Copyright © 2002
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Lesson 6
The Hard Disk Drive
The information stored on the hard drive is a much larger quantity of data due to the fact that the hard drive has more recordingarea. This is because it has more than one recording surface, has multiple read and write heads, and has a higher recording density then that of a floppy drive. POWER CONNECTOR DISK PLATTER
DRIVE SPINDLE
. r --tl1- R/W HEADS
HEAD POSITIONER "VOICE COIL" DRIVER (MOVES HEADS)
1/0 ..
INTERFACE
TOPVIEW
2.
BOTTOM VIEW
Unlike the floppy disk when first taken out of the box, the hard drive comes from the factory completely formatted. This format is called the low level format, and like the floppy, the low level format actually defines the tracks and sectors of the disk surface. Before the hard disk is useable to the computer, additional formatting information is required. The process of low .level formatting cannot be done in the field. Special software and in some cases special hardware is required to low level format a drive. It is possible to damage a hard disk beyond repair by low level formatting the disk. Be sure whenever you think of low level formatting a disk, the drive supports the command and the software you are using is correct for the drive type.
3.
The hard disk utility from DOS called FDISK is part of the formatting procedure to make the computer able to recognize the hard disk. The FDISK utility will define the media type, and the master boot record. Once this information has been added to the disk, the DOS High Level Format, the same format program that was run in the floppy disk experiment, will be used to verify that both the low level and FDISK utility has completed its task successfully.
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The Hard Disk Drive
Lesson 6
4.
High Level Formatting erases all the information that is stored on the hard disk, however, it is a necessary step in the installation of a hard drive. Note that this utility does not actually format the disk as it does in formatting a floppy, but simply verifies that the disk surface is good. Once the disk has been verified, the Boot Sector, FAT (File Allocation Table) and Directory Structure is created, and the disk is then ready for use.
5.
The mechanical operation of the hard disk is similar to that of the floppy disk, with one major exception. The read and write heads never touch the surface of the revolving disk. The heads fly on a cushion of air, and actually float over the surface of the disk. The space between the disk and the read-write heads are smaller than the size of a human hair. The read-write heads detect the magnetic changes in the same way as the floppy disk, but never actually touch the disk. The term hard drive crash, although sometimes refers to the fact that the drive itself is not working, means the read-write head actually touched the surface of the disk. This action will destroy both the read-write head and the disk surface.
DISK PLATTER
DATA INTERFACE
POWER CONNECTOR~
'%
DRIVE SELECT JUMPERS DRIVE SPINDLE R/W HEADS
HEAD POSITIONER "VOICE COIL" DRIVER (MOVES HEADS) 1/0 INTERFACE
TOP VIEW
6.
BOTTOM VIEW
The hard drive is sensitive to shock, simply bumping a running drive can damage the disk. Caution should always be exercised whenever handling, moving or transporting a computer with a hard drive. Note that all of the modern drives will automatically park and lock the drive heads so that manually parking is no longer necessary. CES Industries, Inc. Copyright © 2002
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Lesson 6
7.
The Hard Disk Drive
The interface to the hard drive consists of a data signal, which contains all the command and data information. This data is transferred on a ribbon cable that has between 34 and 50 conductors, depending upon the drive type. Most Personal Computers utilize the IDE or Integrated Drive Electronics Interface and use a 34-pin connector. Power supply requirements are +5 and +12 Volts for most hard drives.
Equipment Setup Procedures:
If your computer repair trainer has not been setup, ask your teacher for the equipment setup procedure sheet before beginning the procedure below.
Procedure: 1.
Open the CD-ROM tray.
2.
Insert the CD-ROM "How Computers Work" into the drive.
3.
Close the CD-ROM tray.
4.
Put on your stereo headphones.
5.
Use the mouse to double click on the icon "How Computers Work".
6.
If awarning message occurs on the screen, click on "OK".
7.
When the music starts and the title screen appears move the mouse cursor anywhere on the screen and click once using the left mouse button. This will help the user to quickly start the program by bypassing the title screen and make the music stop playing.
8.
You are about to go on a tour of the Hard Disk Drive.
9.
Move the mouse cursor to the picture of the computer case and click once on the front of the computer.
10.
Then move the mouse cursor to the picture of the Hard Disk Drive and click once. Sit back and enjoy!!!
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The Hard Disk Drive
11.
When the tour of the Hard Disk Drive is finished click on "Main" to go to the main menu.
12.
Click on "Exit" to exit the program.
13.
Click on "OK" when asked "Are you sure you want to leave?"
14.
Click on "OK" again. You have just exited the multimedia program.
Lesson 6
Computer Repair and Fault Insertion:
I Fault Insertion I 1.
Please follow the correct procedures in turning the computer repair trainer "OFF".
COMPUTER SHUT-OFF INSTRUCTIONS: Since the computer repair system uses Windows as its operating system, it is very important to use the correct procedure when turning off the computer.
Failure to LIse the proper shut-off procedure may result in permanent damage to the computer.
2.
A.
Using your mouse, click once with the left mouse button on the start box in the lower left hand corner.
B.
Move the mouse cursor to "Shut down" and click the left mouse button once.
C.
The computer will ask, "What do you want the computer to do?" Make sure "shutdown" is selected and click on "OK". With the "ATX" style computer, the computer will shutdown on it's own.
D.
With the "AT" style computer, the computer will tell you "It's now safe to turn off your computer".
E.
Turn the computer "OFF".
Ask your instructor for the key to the key switch located on the right side of the trainer.
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Lesson 6
The Hard Disk Drive
3.
Insertthe key and rotate the key to a horizontal position.
4.
Move fault switch to position five. This will insert a fault in the hard disk drive system.
5.
Turn the power to the computer repair trainer on.
I SYMPTOM I 6.
Does the computer repair trainer start normally? It should not start normally because of the fault in the hard drive.
7.
What symptoms did you observe? You should have observed that Windows 98 did not start normally. The computer did not even boot. The computer displayed a "Primary master hard disk fail" message.
8.
Based upon these observations, there are a number of possible things that can be wrong with the computer. •
The hard disk may be defective.
•
The hard disk controller may be defective.
•
The hard disk may need reformatting.
•
The hard disk cable may be defective.
•
The motherboard may be defective.
I. DIAGNOSIS I The Hard Disk May Be Defective The problem that is being displayed may be associated with a defective hard disk drive. Remember from the floppy disk fault, that the fault observed now is also a critical error. For a critical error to be detected it must have failed or been detected as part of the POST diagnostic test. A simple repair would be to substitute a good hard disk and restart the computer. The Hard Disk Cable may be Defective Cables, as a general rule do not become defective by themselves, however the cable may work loose from the connectors by vibration from the drives motor or from the vibration of the cooling fan on board the power supply. This would definitely cause a critical error
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The Hard Disk Drive
Lesson 6
to be detected and will halt the computer. You should remove and reinstall the cables to insure that they are connected properly. The hard disk may need reformatting While this sounds like an easy task, the disk drive requires special software to correctly reformat the disk. In addition to the special software required, all the users data will be destroyed. You want to use the reformatting method only when you are absolutely sure that the problem is associated with the track and sector information on the surface of the disk, and then only when every effort to backup and recover the information stored on the disk has been exhausted. Remember the data is gone forever once you reformat the drive. The motherboard may be defective As with the floppy disk drive, it is possible for the DMA (Direct Memory Access) controller on the motherboard to be defective. The DMA Controller is responsible for communication between the hard disk and the memory. If the motherboard has an integrated IDE (Integrated Drive Electronics) or Enhanced IDE controller, it is possible that the problem is actually the drive controller on the motherboard. As with the floppy, you can replace the motherboard or disable the drive controller and replace it with a plug-in drive controller.
IREPAIR I The problem with the computer is that the hard disk interface on the hard disk drive is defective. This would effectively make using the hard disk impossible. Since the computer is unable to boot, the diagnostic program called the eoST detected this as a fatal error, haltep the system and displayed an error code. The proper repair for this problem is to replace the disk drive since a repair is not practical. Repair Procedure: 1.
Since this fault prevented the computer from starting normally, there is no need to follow a special shut-down procedure.
2.
Turn off the main power switch.
3.
Turn the fault switch to the original "No Fault" position and turn the key switch to the original vertical position.
4.
Your computer is now ready to proceed with the next lesson.
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Lesson 6
The Hard Disk Drive
Review: The hard disk drive is the main storage device for the personal computer. All the normal program information, the operating system and any applications that you normally use are stored here. The hard disk consists of multiple platters, which are rotated at extremely high speeds, with multiple read and write heads that actually fly over the surface of the disk platter. A disk crash can occur when these heads come in contact with the disks surface. Hard disks actually require 3 steps in the initialization procedures to make them useable. •
The low-level format
•
The FDISK utility
•
The DOS High Level Format.
Proper disk repair utility programs can help maintain the integrity of your data and preserve the life of the hard disk.
Assignment: Answer the following multiple-choice questions: 1.
Data is stored on the platters in the hard disk drive. a. True b. False
2.
To store data on the Hard Disk Drive the computer moves the read/write heads and places magnetic particles on the platters. a. True b. False
3.
Which one is a type of removable cartridge drive? a. Bernoulli b. Syquest c. All of the above
4.
An optical floppy drive is the combination of a hard drive and CD-ROM technology. a. True b. False
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The Hard Disk Drive
Lesson 6
5.
Data is stored in the hard disk on the: a. Read/write heads. b. Metal coated platters. c. Plastic CD disks. d. None of the above.
6.
The read/write heads are used to: a. Convert magnetic impulses on the platters into electrical impulses. b. Turn on an electromagnet to align magnetic particles on the surface of the disk. c. None of the above. d. Both A and B.
7.
A special file is used to tell the read/write heads where the data on a disk drive is stored. a. True b. False
8.
The data stored on a hard drive is said to be permanent data because: a. It is not lost when the power is turned off. b. It will remain on the disk until you issue a command to delete it. c. None of the above. 'd. Both A and B.
9.
Pieces of a single file may be scattered all over a hard drive's platters. a. True b. False
10.
Before a hard disk drive can be used it must first be low level formatted. a. True b. False
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The Motherboard
lesson
7
Objectives: When you have completed this lesson, you will be able to: 1.
Identify the basic components of the motherboard.
2.
Locate the basic components on the motherboard.
3.
Describe the function of the basic components on the motherboard.
Materials Needed: 1.
CES Computer Repair Trainer Model CES 975.
2.
CES Computer Repair Module Manual. '" PO'WER SUPPLY IS CONNECTED TO EACH AF>!D EVERY MODULE
POWER SUPPLY
J
EXPANSION SLOTS
r--
CD ROM
MONITOR
~
tJ~~~tfgRu MEMORY IIMODULES RAM ;1
MOTHERBOARD
[§]~
"I
CACHE RAM MEMORY
HARD DISK
FLOPPY DISK KEYBOARD
Discussion: 1.
A personal computer is a modular system, consisting of many separate components, that when connected correctly, function as a complete computer.
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Lesson 7
The Motherboard
N~xt
2.
to the power supply, the motherboard is probably the most important component of the personal computer. Without the motherboard the computer would not function. To help you understand the various components on the motherboard, we will divide the motherboard into sections, with each section pictured and described on the following pages.
3.
In this lesson, we will briefly explain each of the major components of the motherboard: A. The CPU B. The BIOS C. The RAM Memory Modules D. The CACHE Memory E. The Keyboard Connector F. The Expansion Slots ISA Bus PCI Bus AGP G. Expansion Bus Adapter Cards The Video Card The Sound Card The CES Troubleshooting Card '" Po\·/ER SUPPLVIS CONNECTED TO EACH AND EVERV MODULE
POWER SUPPLY
J
EXPANSION SLOTS .
r--
CD ROM
MONITOR
~
lJ~~~@JlRU
MEMORV IIMODULES RAM ~I
MOTHERBOARD
~~
68
CACHE RAM MEMORV
HARD DISK
FLOPPY DISK
CES Industries, Inc. Copyright © 2002
KEYBOARD
The Motherboard
Lesson 7
A. THE CPU The CPU, or Central Processing Unit, is the brain of the personal computer. This highly specialized Chip controls all of the functions of the computer. It is common to see the CPU referred to as a 486DX-4/100 or Pentium 90 or P-90. This shows the type and speed of the CPU being utilized in the computer. As a general rule, the higher the number, the faster the CPU or computer operates. For example the P-90 is a Pentium Microprocessor operating at 90 MHz. Similarly, a 486':DX-4/100 is a 80486 Microprocessor operating at 100 MHz or 100 Million Cycles (Clock Operations) per second. More recently CPU's have reached speeds of 2 Gigahertz. B. THE BIOS BIOS stands for Basic Input Output System, and is a group of specialized programs that are stored on a chip that is referred to as an EPROM or Erasable Programmable Read Only Memory. The BIOS program assists the computer in the initial startup of the computer. It allows the CPU to get and give information to other parts of your system, and sets up the organization of the computer's operating system. The BIOS is designed to work with one specific motherboard and· it tells the computer what hardware is installed on your. computer, such as floppy drives, hard drives, etc. All of this information is stored ina special battery-powered Static Memory Chip, which is called the CMOS Memory. You will learn more about the CMOS Memory in a later lesson. C. THE RAM MEMORY MODULES RAM stands for Random Access Memory. RAM memory is used for storing all of the programs that the computer processes. Computer memory is usually organized in values of megabytes or millions of bytes of information and thus several D-RAM or Dynamic RAM Chips are soldered onto either 30 or 72 pin connector circuit cards called SIMM or Single Inline Memory Modules. Groups of two or more SIMM Modules may be required in your system depending upon the type of motherboard and CPU used. Newer computers utilize a DIMM chip, meaning Dual Inline Memory Module.
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Lesson 7
The Motherboard
r------,. POIJERSUPPLY IS CONNECTED TO EACH . - - - - - - - , I AND EVERY MODULE
POWER SUPPLY
,.--
CD ROM
MONITOR
EXPANSION SLOTS
n
KEYBOARD CONNECTORL..J
:MEMORY RAM ;1 IMODULES MOTHERBOARD
II
CACHE RAM MEMORY
HARD DISK
FLOPPY DISK KEYBOARD
D. THE CACHE MEMORY
Cache memory uses a very fast version of RAM memory, called static memory, which increases the exchange of information between the CPU and the main RAM Memory. The main purpose of this type of memory is to store instructions, or parts of the program that are used by the CPU either frequently or on a repetitive basis. Modern motherboards have either 256 or 512 kilobyte cache systems. E. KEYBOARD CONNECTOR
A 5 pin DIN connector at the right rear of the motherboard provides a connection path to the keyboard. This connector supplies the keyboard with power (+5 Volts) and serial data communication to and from the motherboard.
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CES Industries, Inc. Copyright © 2002
The Motherboard
Lesson 7
F. THE EXPANSION BUS SLOTS
Expansion slots or bus connectors along the left rear of the motherboard allow for the expandability of the personal computer using Daughterboards or Adapter Card Boards. There are several standard Bus types (ISA, EISA, MCA, VLB, VESA, PCI and AGP) however only the ISA, PCI and AGP buses are used on the CES Computer Repair Trainer. The other buses will be described in another lesson. ISA The Industry Standard Architecture, or ISA Bus, is the original Personal Computer Adapter Card· Connector. The ISA Bus allows for 8 bit or 16 bit data transfer at a maximum speed of 7.59MHz. All computers that are IBM compatible are manufactured with at least four expansion connectors. PCI The Peripheral Component Interconnect, or PCI Bus, is the standard for connecting peripheral devices to the motherboard. The PCI bus allows for up to 64 bit data transfers, at speeds that are equal to the system speed. In addition, the PCI bus supports a transfer mode known as burst mode, which allows for transfer speeds approaching 500 MHz. This connection was developed by the Intel Corporation and is now used in all of the new Pentium Chip based computers. AGP Advanced Graphics Port; The need for streaming video and real-time-rendered 3-D games requires an even faster throughput than that provided by PCI. In 1996, Intel debuted the Accelerated Graphics Port (AGP), a modification of the PCI Bus designed specifically to facilitate the use of streaming video and high-performance graphics. While AGP is based on the PCI Bus, and is often referred to as the "AGP bus," it is not actually a bus system. Instead, it is a point-to-point connection. In other words, the only device connecting through AGP to the CPU and system memory is the graphics card. There are no other "stops" to make on the path. Therefore, it is not truly a bus.
G. EXPANSION BUS ADAPTER CARDS The controller electronics for peripheral (external) devices, like video monitors and audio speakers, are a necessary part of most computer systems. It has become common to see them built directly onto the motherboard. Regardless of where they are physically located, their CES Industries, Inc. Copyright © 2002
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Lesson 7
The Motherboard
functions are the same. When not on the motherboard, these functions are built onto a daughterboard or Adapter Card. The function of the cards on the CES Computer Repair Trainer, noted below, will be described in later lessons. THE VIDEO CARD The video card contains all the necessary information to run the video monitor, so that the user can see the information the computer is processing. THE SOUND CARD The sound card contains all the necessary information to run digital audio files as well as digital CD-ROM audio, so that the user can hear the information the computer is processing. THE CES TROUBLESHOOTING CARD The CES Troubleshooting Card contains all the necessary electronics to troubleshoot the computer.
Procedure: 1.
Locate the following components on the motherboard of the CES Computer Repair Trainer:
A. The CPU B. The BIOS. C. The RAM Memory Modules D. The CACHE Memory E. The Keyboard Connector F. The Expansion Slots G. The Video Card H. The Sound Card I. The CES Troubleshooting Card 2.
Read Chapter 14 in the text "How Computers Work".
Review: The motherboard contains all of the necessary logic circuits, processing circuits, memory, cache, ROM and peripheral connectors necessary for the basis of the personal computer. Without a properly functioning motherboard, you do not have a working computer. All personal computers that are designed around the IBM PC, have basically the same structure in common. All PC's will have a CPU utilizing 72
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The Motherboard
Lesson 7
a member of the 80x86 processor family (286,386,486,586 or Pentium) all will have some number of ISA compatible slots, and many will have either a Local Bus or a PCI interface slot for connecting outside devices to the computer. Regardless of what type of computer you are using, all of the operations performed by the computer will be carried out on the motherboard or main board. When troubleshooting a computer, it is necessary to reduce the computer to the few external cards that are absolutely necessary to have a functioning machine. Then and only then will you be able to diagnose problems associated with the motherboard.
Assignment: Answer the following multiple-choice questions: 1.
The CPU stands for: a. Central Processing Unit. b. Computer Processor Unit. c. Calculating Processing Unit. d. Core Processing Unit.
2.
The cache ram memory is used to: a. Decrease the speed of the CPU. b. Increase the speed that information passed between the CPU and RAM. c. Predict what instructions the CPU wants next. d. Store seldom used instructions for later use.
3.
The Power Supply performs all the following functions EXCEPT: a. Cools the computer. b. Supplies the DC power needed for the computer to operate. c. Supplies the AC power needed for the computer to operate. d. Supplies a good power signal for the motherboard.
4.
The Expansion Slots: a. Store the basic input and output programs needed to run the Computer. b. Connect the CPU to the power supply. c. Connect the motherboard to external or peripheral devices. d. Connect the RAM memory to the CPU.
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Lesson 7
5.
The Motherboard
The BIOS ROM: a. Stores the users program for the computer to execute. b. Stores the basic start up programs needed to run the computer as well as programs for defining the hardware. c. Stores the frequently used instructions for faster operation. d. Assists in the connection to the keyboard.
The following 5 questions require that you look directly at the computer repair trainer.
6.
The Floppy Disk Drive and Hard Drive are connected to the computer by: a. A cable to the Keyboard Connector. b. Connecting it directly to the Motherboard. c. Connecting it to the Video Card. d. Connecting it to the CPU.
7.
The Motherboard being used in the Computer Repair Trainer uses the following types of expansion bus: a. ISA & MCA. b. ISA&VLB. c. ISA & PCI. d. ISA & EISA.
8.
The Power Supply cable connecting to the Floppy Disk Drive uses: a. 2 wires. b. 4 wires. c. 6 wires. d. 8 wires.
9.
The Monitor is connected to: a. The Power Supply. b. The Sound Card. c. The Motherboard. d. The Video Adapter Card.
10.
The ISA Bus transfers 8 bit and/or 16 bit data at a rate of: a. 33 MHz. b. 66 MHz. c. 7.59 MHz. d. 500 MHz.
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CES Industries, Inc. Copyright © 2002
The CPU/BIOS/BUS
Lesson
8
Objectives: When you have completed this lesson, you will: 1.
Be able to identify the function ofthe CPU (Central Processing Unit).
2.
Understand how the ROM BIOS (Read Only Memory Basic Input Output System) works and why it is necessary.
3.
Be able to identify and understand the various types of busses or connections associated with the computer system.
4.
Be able to utilize a ROM Diagnostic Card to locate a fault on the motherboard.
Materials Needed: 1.
CES Computer Repair Trainer Model CES 975.
2.
CES Computer Repair Module Manual. t
PO'w'ER SUPPLY IS CONNECTED TO EACH ANO EVERY MODULE
POWER SUPPLY
!
EXPANSION SLOTS
r--
CD ROM
MONITOR
~
tJ~~~t'f8RU
MEMORY IIMODULES RAM ~I
MOTHERBOARD
E§]~
CACHE RAM MEMORY
HARD DISK
FLOPPY DISK KEYBOARD
CES Industries, Inc. Copyright © 2002
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Lesson 8
The CPU/BIOS/BUS
Discussion: The CPU
The CPU or Central Processing Unit is the brain of the personal computer. This highly specialized integrated circuit controls all of the functions of the computer. The CPU of modern personal computers will normally be a 32-bit processor, which allows information to be processed in groups of 32 or 64-bits or binary digits. It is common to see the CPU specified as a 486-DX-4/100 or Pentium or P-90 this identifies the speed and type of the CPU being utilized in the computer. As a general rule, the higher the number the faster the CPU or microprocessor operates. For example, the 486-DX-4/100 is an 80486 Microprocessor operating at 100 MHz (Megahertz) or 100 Million Cycles (Clock Operations) per second. The CPU may contain many millions of transistors, and is able to perform mathematical calculations, evaluate logical instruction and control program flow. The 80386 CPU had 6 internal sections which are the Arithmetic Logic Unit, Program Counter, Internal Registers, Control Logi.c, Instruction Decoder and bus interface logic. The Pentium processor adds additional internal circuits, such as two arithmetic logic units, two internal caches one for data and one for instructions, and a specialized floating point unit for decimal math. The BIOS
This is an IC (Integrated CirCUit) chip called an EPROM (Erasable Programmable Read Only Memory), which contains the instructions or program, that allows the motherboard and CPU to function as a system. The name BIOS stands for Basic Input Output System. The program contains a specialized program called a setup or configuration program, which defines all of the hardware that you have installed on the computer. The BIOS stores the information in a memory called the CMOS memory (Complimentary Metal Oxide Semiconductor). The BIOS contains all the startup instructions, that when executed, transform the microprocessor, RAM (Random Access Memory) and ROM (Read Only Memory) into a fully functional computer. The BIOS isa Read Only Memory that contains a program known as the bootstrap program, which is started each and every time the computer is reset. In addition to the bootstrap program, all of the
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The CPUIBIOS/BUS
Lesson 8
necessary hardware interrupts are defined and properly configured when this program starts. All of the low level communication between the disk drives, hard drives, video card, keyboard, printer and other standard peripheral devices are controlled through program instructions known as interrupts. For example when you want to write a character on the monitor screen, a call to the video interrupt is sent by the software, processed by the BIOS and displayed on the screen. Without the BIOS, even the fastest microprocessor would be brain dead and would not function.
The BUS ISA (Industry Standard Architecture): This is the original Personal Computer connector. This bus allows for 8 or 16 bit data transfer at a maximum speed of 7.59MHz. All computers that are IBM (International Business Machines) compatible are manufactured with at least 4 of this types of connectors. EISA (Enhanced Industry Standard Architecture): This is an enhancement of the original ISA connector and will allow data to move in 32 bit transfers. This is sometimes known as a bus mastering architecture. VLB (VESA Local Bus): This bus may sometimes be known as the VESA or Video Electronics Standards Association bus. This is an extension slot that is added to the IS,Aconnector to allow for 32 bit data transfer at speeds up to 33 MHz. This bus is commonly used with later model 386 boards and with most of the 486 computers. This is a master-slave bus, with connections providing full 32 bit transfers under direct control of the microprocessor and direct memory access controllers. This bus is also disappearing from the personal computer market. PCI (Peripheral Component Interconnect): This is the latest standard for connecting outside devices to the mother board. This bus allows for up to 64 bit data transfers and speeds that are equal to the system speed. In addition, the PCI bus supports a transfer known as burst mode, which allows for transfer speeds approaching 500 MHz. This connection was developed by Intel Corporation and is used in all Pentium based computers. CES Industries, Inc. Copyright © 2002
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Lesson 8
The CPUIBIOSIBUS
Procedure: 1.
Open the CD-ROM tray.
2.
Insert the CD-ROM "How Computers Work" into the Drive.
3.
Close the CD-ROM tray.
4.
Put on your stereo headphones.
5.
Use the mouse to double click on the icon "How Computers Work".
6.
If a warning message occurs on the screen, click on "OK".
7.
When the music starts and the title screen appears move the mouse cursor anywhere on the screen and click once using the left mouse button. This will help the user to quickly start the program by bypassing the title screen and make the music stop playing.
8.
You are about to go on a tour of the CPU/BIOS/BUS.
9.
Move the mouse cursor to the picture of the computer case and click once on the front of the computer.
1O.
Then move the mouse cursor to the picture of the CPU and click once. Sit back and enjoy III
11.
Then move the mouse cursor to the picture of the BIOS and click once. Sit back and enjoy II!
12.
Then move the mouse cursor to the picture of the BUS and click once. Sit back and enjoy III
13.
When the tour of the CPU, BIOS, and BUS is finished click on "Main" to go to the main menu.
14.
Click on "Exit" to exit the program.
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CES Industries, Inc. Copyright © 2002
The CPUIl3IOS/BUS
15.
Click on "OK" when asked "Are you sure you want to leave?"
16.
Click on "OK" again. You have just exited the multimedia program.
Lesson 8
Computer Repair and Fault Insertion: Fault Insertion 1.
I
Please follow the correct procedures in turning the computer repair trainer "OFF".
COMPUTER SHUT-OFF INSTRUCTIONS: Since the computer repair system uses Windows as its operating system, it is very important to use the correct procedure when turning off the computer.
Failure to use the proper shut-off procedure may result in permanent damage to the computer. A.
Using your mouse, click once with the left mouse button on the start box in the lower left hand corner.
B.
Move the mouse cursor to "Shut down" and click the left mouse button once.
C.
The computer will ask, "What do you want the computer to do?" Make sure "shutdown" is selected and click on "OK". With the "ATX" style computer, the computer will shutdown on it's own.
D.
With the "AT" style computer, the computer will tell you "It's now safe to turn off your computer".
E.
Turn the computer "OFF".
2.
Ask your instructor for the key to the key switch located on the right side of the trainer.
3.
Insert the key and rotate the key to a horizontal position.
4.
Move fault switch to position six. This will insert a fault in the CPU-BIOS.
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Lesson 8
The CPUIBIOSIBUS
I SYMPTOM I 5.
Turn the power to the computer repair trainer on.
6.
Does the computer repair trainer start normally? You should have observed that the computer did not start normally, and that the computer's on board diagnostic tests detected that there is a problem. The diagnostic program contained in the BIOS detected that there is in fact a major problem with the computer, however it is unable to initialize the video system, so what you observe is a dead computer.
7.
What symptoms did you observe? You should have observed that a blank error message appears on the CES Diagnostic Card and the monitor has no display and the power indicator on the monitor is off, although the monitor is switched on.
I DIAGNOSIS I 8.
There are only a few possibilities that can cause a "dead machine" with the most likely being a problem associated with the power supply, however the following may also cause a "dead machine": a. Defective CPU b. Defective BIOS-ROM c. Defective RAM d. Defective Peripheral Component Defective CPU While this is extremely rare, it is possible to have the main CPU become damaged or defective. Most CPU failures are the result of a CPU cooling fan failure. The high-speed chips of today require fans to constantly cool them down. When a CPU overheats, it can literally self-destruct. If this is the case, you will most certainly end up with a not working computer. Defective BIOS ROM Again, the BIOS ROM is not a top winner as most likely sources of trouble. The BIOS ROM does not have any output or input duties of any kind, therefore it is not responsible for any high current load
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The CPUIBIOSIBUS
Lesson 8
switching. If the BIOS is bad, it is most likely a failure of a part of the program. This can cause a "dead machine". Defective RAM This will cause a "dead machine", however for most systems, the RAM check at the beginning of the boot process should detect the defective component. The only time that a defective RAM chip will generate a "dead machine" is when the problem occurs in the first 64K of memory. This is critical system memory, and if the POST cannot verify that this memory is good, the computer will freeze. A POST code will be displayed and the machine will not work. Defective Peripheral Component It is possible for a peripheral card to be defective and cause the computer not to start. As with any repair,you should first remove all of the peripheral cards not required for operation, then restart the computer and verify the operation.
I REPAIR I Although the computer appears to be dead (no boot-up), the fan is running and the diagnostic card LED's are ON. The machine has performed a diagnostic program and the POST card indicates a blank number. You will notice that the display has stopped changing and has locked on a number; the number for this trainer is blank. This indicates that a motherboard logic circuit has failed, and that the computer has processed all of the necessary code within the diagnostic program up to this point. Repairing the motherboard is not an option. The availability of replacement components does not exist. Normal troubleshooting skills require that you remove all of the unnecessary installed cards, and try again. If the problem persists, you then try changing or swapping the RAM memory with memory that you know is good and try to start the computer again. If the same error code persists, simply replace the main board. Repair Procedure: 1.
Sin.ce this fault prevented the computer from starting normally, there is no need to follow a special shut-down procedure.
2.
Turn off the main power switch.
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Lesson 8
The CPUIBIOSIBUS
3.
Turn the fault switch to the original"No Fault" position and turn the key switch to the original vertical position.
4.
Your computer is now ready to proceed with the next lesson.
Review: The CPU is the main brain of the computer. Without a properly functioning CPU you do not have a computer, however, the BIOS is just as important as the CPU since without a BIOS, the CPU may be working, but the computer will be brain dead. The expansion cards connect to the computer through a connection to the BUS. The type of Bus used in the computer will determine how fast and how much information can be moved in and out of the computer, the CPU, and the system.
Assignment: Answer the following multiple-choice questions: 1.
The CPU is the: a. Brain of the computer. b. Central processing unit. c. Complex microprocessor. d. All of the above.
2.
A 486 CPU is made up of: a. Six main components. b. Hundreds of thousands of transistors. c. A prefetch unit. d. All of the above.
3.
A 486DX has a built in math coprocessor. a. True b. False
4.
The ROM BIOS is the read only memory basic input/output system. a. True b. False
5.
The computer bus allows each of the computer's components to communicate with each other. a. True b. False
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The CPUlBIOS/BUS
6.
The Bus is the electronics path that the computer uses to communicate between cards, the CPU, and the outside world. a. True b. False
7.
An a. b. c. d.
8.
The main difference between a 386DX and a 486DX processor is that the 486DX has added 2 cache units and a numeric processor. a. True b. False
9.
The first generation of IBM personal computers used an 8-bit bus. a. True b. False
10.
The EISA bus is a 32-bit bus. a. True b. False
Lesson 8
ISA bus for an "AT" class computer is a (an): 8-bit bus. 16-bit bus. 32-bit bus. None of the above.
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83
The RAM
Lesson
9
Objectives: When you have completed this lesson, you will: 1.
Be able to locate the system RAM (Random Access Memory).
2.
Understand how RAM functions.
3.
Be able to utilize the ROM (Read Only Memory) diagnostic card to locate a defective RAM module.
Mater1als Needed: 1.
CES Computer Repair Trainer Model CES 975.
2.
CES Computer Repair Module Manual. !If POWER SUPPLY IS CONNECTED TO EACH AND EVERY MODULE
POWER SUPPLY
r--
CD ROM
MONITOR
J
~
EXPANSION SLOTS
KEYBOARD~U
CONNECTOR
RAM MEMORV
~ODULES ~
~
MOTHERBOARD
1810s1
Icpul
CACHEtl RAM MEMORV
HARD DISK
FlOPPV DISK
CBS Industries, Inc. Copyright © 2002
KEYBOARD
85
Lesson 9
The RAM
Discussion: The RAM This memory is called Random Access Memory, or D-RAM for Dynamic RAM. It is the memory that is used for all of the user programs that the computer processes. This memory is usually organized in values of 1 megabyte or 1 Million bytes of information, and depending upon the type of motherboard and CPU used, it may have either 72 or 168 pins. The memory can be thought of as individual slots in a post office, where each slot may hold one letter. Since the computer that you will most likely be using is a 32-bit or even 64-bit machine, there are 32 individual post. office boxes. for each and every bit of data that you wish to store. Since finding the information that you placed in the memory is very important, each memory location has an address, the same as the address in a post office. When you want to read information from a given location, the address information is.sent out to the memory. The memory then decodes the address information and returns with the information that is stored at that address. Just as it would take time to find a letter addressed to you at the post office, the RAM takes time to decode the address information, retrieve the data and finally send it on its way to the device that requested the information, normally the CPU. The time that it takes to do this is called the access time. Access times are. expressed in nano seconds or billionths of a second. The memory the computer uses is dynamic; this means that the information is stored in the memory chip, utilizing electronic devices known as capacitors. A capacitor is able to store an electrical charge with no voltage or current applied for a given period of time. However, the capacitor will slowly discharge until there is no longer a charge available. If the charge that holds your data dissipates, the data is lost forever and the cqmputer will crash, Therefore, dynamic RAM must be refreshed, or have the information rewritten periodically, to prevent the loss of information. Regardless of the type of memory, whether it is static or dynamic, all RAM if volatile, meaning that, if the power fails the data is lost. RAM is unable to maintain the information stored in each of the cells, if power is not constantly applied.
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The RAM
Lesson 9
The Cache .Memory
Cache memory is a fast version of RAM that is used to accelerate the transfer of information between the CPU and the main RAM. This memory utilizes chips that are called static memory. Static memory has extremely fast access times. The main purpose of this memory is to store instructions or parts of the program that are used frequently. Most modern motherboards have either 256K (Kilobytes) or 512K cache systems. Equipment Setup Procedures: If your computer repair trainer has not been setup, ask your teacher for the equipment setup procedure sheet before beginning the procedure below.
Procedure: 1.
Open the CD-ROM tray.
2.
Insert the CD-ROM "How Computers Work" into the Drive.
3.
Close the CD-ROM tray.
4.
Put on your stereo headphones.
5.
Use the mouse to double click on the icon "How Computers Work".
6.
If a warning message occurs on the screen, click on "OK".
7.
When the music starts and the title screen appears move the mouse cursor anywhere on the screen and click once using the left mouse button. This will help the user to quickly start the program by bypassing the title screen and make the music stop playing.
8.
You are about to go on a tour of the RAM.
9.
Move the mouse cursor to the picture of the computer case and click once on the front of the computer.
10.
Then move the mouse cursor to the picture of the RAM and click once. Sit back and enjoy !II
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Lesson 9
The RAM
11.
When the tour of the RAM is finished click on "Main" togo to the main menu.
12.
Click on "Exit" to exit the program.
13.
Click on "OK" when asked "Are you sure you want to leave?"
14.
Click on "OK" again. You have just exited the multimedia program.
Computer Repair and Fault Insertion:
IFault Insertion I 1.
Please follow· the correct procedures in turning the computer repair trainer "OFF".
COMPUTER SHUT-OFF INSTRUCTIONS: Since the computer repair system uses Windows as its operating system, it is very important to use the correct procedure when turning off the computer.
Failure to use the proper shut-off procedure may result in permanent damage to. the computer.
A.
Using your mouse, click once with the left mouse button on the start box in the lower left hand corner.
B.
Move the mouse cursor to "Shut down" and click the left mouse button once.
C.
The computer will ask, "What do you want the computer to do?" Make sure "shutdown" is selected and click on "OK". With the "ATX" style computer, the computer will shutdown on it's own.
D.
With the "AT" style computer, the computer will tell you "It's now safe to turn off your computer".
E.
Turn the computer "OFF".
2.
Ask your instructor for the key to the key switch located on the right side of the trainer.
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CES Industries, Inc. Copyright © 2002
The RAM
3.
Insert the key and rotate the key to a horizontal position.
4.
Move the fault switch to position seven. Th,is will insert a fault in the RAM.
Lesson 9
ISYMPTOM I 5.
Turn the power to the computer repair trainer on.
6.
Does the computer repair trainer start normally? You should have observed that the computer did not start normally, and that the computer's on board diagnostic tests were able to detect that there is a problem. The diagnostics program contained in the BIOS (Basic Input Output System) detected that there is in fact a major problem with the computer, however it is unable to initialize the video system, so what you observe is a dead computer.
IDIAGNOSIS I 7.
What symptoms did you observe? The only observable symptom is that of a dead computer, however utilizing the CES Troubleshooting POST (Power On Self Test) card you will notice that an error code is displayed. This is not really an error code but a diagnostic test code that indicates what part of the power on the self-test failed. If you look up the code in the diagnostic manual you will notice that the fault is related to the memory subsystem and indicates that you have a defective RAM module. The problem that you observed can be caused by the following defective components: a. Defective SIMM (Single Inline Memory Module) or DIMM (Dual Inline Memory Module) chip b. Defective Cache Memory c. Defective Motherboard Defective SIMM (Single Inline Memory Module) or DIMM (Dual Inline Memory Module) memory chip A defective memory module will definitely result in a dead machine. The most likely cause of a defective module is that one memory location or address is defective and not the entire module. CES Industries, Inc. Copyright © 2002
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Unfortunately, the POST will detect any errors and cause a critical error to be displayed or to halt the computer. The BIOS requires that the first 64K of memory be active and available before ' initializing the video system. A quick test would be to rearrange the memory chips if you have more than one, to see if the computer. will start. This is not always possible on computers that use a 72 Pin SIMM since these computers usually only have one module. Defective Cache Memory A defective cache memory chip will cause a dead machine the same way as a defective ram module will. With older motherboards, the cache memory is field replaceable, assuming that you have the part and are able to locate which cache ram is defective. A good diagnostic card such as the CES POST card will help pin-point what cache ram is not functional. Simply remove and replace the chip and restart the computer to see if the problem has been solved. However, most new computers, those of Pentium II class and higher, the cache memory is considered to be "On Die" which means that the cache is actually part of the microprocessor. Therefore, while the diagnosis process is the same, the repair process would be to replace the CPU. Keeping in mind that if the cache memory is defective on the CPU, the CPU itself will most likely not function at all and the computer would present as a dead box and not one with a cache memory failure. Defective Motherboard On rare occasion, the problem may be associated with the "glue logic". Glue Logic refers to the support chips that control various circuits on the main board. This may cause a memory problem, a CPU fault or other various problems that can and often do mislead even the most experienced technician. If the problem is associated with the motherboard or one of the support components, the only solution is to replace the motherboard. 8.
Based upon these observations, what do you think is wrong with the computer? The error that you have observed usually indicates that a· RAM module has a defective chip or chips on the module.
I REPAIR I The repair for a defective RAM module is to replace the entire module. The problem with this is that the cost of the module may be high. Most well stocked computer repair centers will have a 90
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memory tester or a SIMM Checker which will confirm without question, that the memory is in fact bad. Simply swapping the module With a known working part will often confirm your diagnosis. With the proper tools, it is possible to perform chip level repair of a module. That is to actually remove the defective component and replace it. This is not done with field level repairs. Repair Procedure: 1.
Since this fault prevented the computer from starting normally, there is no need to follow a special shut-down procedure.
2.
Turn off the main power switch.
3.
Turn the fault switch to the original "No Fault" position and turn the key switch to the original vertical position.
4.
Your computer is now ready to proceed with the next lesson.
Review: The RAM is responsible for storing all of the information that your computer is processing. It stores the application program, important information about the system, the operating system and all of the necessary information that makes your computer function. The memory is arranged in values of megabytes and may have either 3D, 72 or 168 pins depending upon the type of memory module being installed. For example, on some Pentium based computers it is always necessary to install two modules of the same size in order for the computer to function properly.
Assignment: Answer the following multiple-choice questions: 1.
The RAM is the area where the currently running program is stored. a. True b. False
2.
Information is stored in RAM by using electrical devices called capacitors. a. True b. False
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3.
Since RAM uses electricity, memory is volatile and it is important to save your work often. a. True b. False
4.
The letters RAM stand for: a. Readily available memory. b. Random access memory. c. Read all memory. d. All of the above.
5.
If the computer is turned off, all of the information in RAM is lost. a. True b. False
6.
A SIMM is a: a. Simple integrated memory module. b. Single in-line memory module. c. Second important memory maker. d. None of the above.
7.
A series of "zero's", and "one's", are stored in RAM by selectively charging or discharging a series of capacitors. a. True b. False
8.
Because capacitors discharge over time, it is necessary to send electrical signals to the RAM chips to refresh the memory. a. True b. False
9.
Because capacitors store electricity, RAM is not lost if the computer is turned off for a short period of time. a. True b. False
10.
DIMMs are easily replaced when up-grading computer memory. a. True b. False
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The Video Card
Lesson
10
Objectives: When you have completed this lesson, you will: 1.
Understand how the video card works.
2.
Understand how the video card communicates with the computer system and the monitor.
3.
Be able to locate and identify a common fault associated with the video card.
Materials Needed: 1.
CES Computer Repair Trainer Model CES 975.
2.
CES Computer Repair Module Manual.
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Discussion: 1.
The video interface card is responsible for translating the computer information of binary digital data into visual information for the user.
2.
Each video card, regardless of type, has certain common characteristics. All video cards contain memory, a BIOS Extension ROM, a video output connector and a microcontroller. Each of the common characteristics is defined below.
S 3 ACCE LLE RAT 0 R ------..
FEATURE CONNECTOR
MICROCONTROLLER VIDEO MEMORY CLOCK VIDEO OUTPUT MONITOR CONNECTOR ---£:::>o/iA
BIOS ROM PCI BUS CONNECTOR
Video Memory Random Access Memory that is used to store the information to be displayed on the monitor. Depending upon the type of display, the amount of memory will be different from computer to computer, with the minimum amount being 16K to over 4 Meg. BIOS Extension ROM (Basic Input Output System & Read Only Memory) This read only memory contains the software necessary to change the information stored in the video memory to information that can be displayed on the monitor screen. This ROM also contains the signature information that identifies the type of video card that is installed in the computer. Video Output Connector A 9 or 15-Pin connector that supplies the necessary signals to drive the monitor. 94
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Microcontroller The control logic that is responsible for the complete independent operation of the video card. The- computer (CPU) only sends the information to be displayed to the video card, it is the job of the microcontroller to translate the information and send it to the monitor in a form that can be interpreted and displayed by the monitor. Digital to Analog Converter or DAC (Optional) This component is present only on video cards that utilize the video graphics array or VGA standard. The signal that is sent to the monitor is an analog or voltage variable signal that represents the data that is to be displayed. This is the most common type of monitor and video system in use by personal computers today. 3.
Video Display Standards both past and present. As a computer repair technician, it is necessary to know about previous types of video subsystems however, all of the systems that are listed mayor may not be in wide spread use. MDA (Monochrome Data Adapter) This is the original IBM video system capable of displaying only text in one color. Normally connected to a green screen monitor, this system was utilized with very early versions of the computer. The video card contained only 16K of memory, and provided digital TIL (Transistor Transistor Logic) level signals to the monitor. This card provided 80 character columns and 24 row displays with no graphics ability. HMGA (Hercules Monochrome Graphics Adapter) This was the first video adapter to be able to display graphics on a monitor. The HMGAadapter was able to display 16 shades of gray scale on a monochrome monitor. This card contained 32K of memory and provided digital (TIL) level signals to the monitor. This card provided 80 character columns and 24 row displays with only monochrome (shades of gray) graphics ability. CGA (Color Graphics Adapter) This was the first video adapter to provide color graphics capability. Limited to 16 simultaneous colors at a maximum resolution of 320X200 pixels (Pixel = Picture Element or one dot of light on the monitor screen.) This video card had 64K of memory, and utilized digital signal output to the monitor.
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EGA (Enhanced Graphics Adapter) This video adapter increased the resolution or number of pixels that could be displayed to 640X350, but limited the color display to 16 simultaneous colors. The EGA standard was the first graphic& adapter to switch from the digital format to the analog format for displaying information on the screen. VGA (Video Graphics Array) This is the true modern standard for video display. This is an all analog video system that is able to at a minimum, display 640X480 pixels with 256 simultaneous colors. This standard also has additional sub-standards which change the maximum resolution and colors displayed. These video cards normally contain between 256K and 512K of memory. A.
SVGA Super VGA, able to display 1024X768 pixels at up to 16.7 million colors. These video cards often contain 1 Meg or more of memory.
B.
XGAorPGA Extended or Professional Graphics Adapter. This is also a VGA standard with resolutions of 1280X1024 pixels at 16,7 million colors. These video cards often contain 1 to 4 Meg of special memory called V-RAM or Video-RAM.
C.
S3 or Accelerator This is a special version of the VGA card in that, the micro:controller is optimized for use with the Microsoft Windows operating system. These cards process the video information at an increased speed over standard video c~rd& and have become more common in desktop systems .since Windows popularity has grown.
Equipment Setup Procedures: If your computer repair trainer has not been setup, ask your. teacher for the equipment setup procedure sheet before beginning the following procedure.
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Procedure: 1.
Open the CD-ROM tray.
2.
Insert the CD-ROM "How Computers Work" into the Drive.
3.
Close the CD-ROM tray.
4.
Put on your stereo headphones.
5.
Use the mouse to double click on the icon "How Computers Work".
6.
If a warning message occurs on the screen, click on "OK".
7.
When the music starts and the title screen appears move the mouse cursor anywhere on the screen and click once using the left mouse button. This will help the user to quickly start the program by bypassing the title screen and make the music stop playing.
8.
You are about to go on a tour of the Video Card.
9.
Move the mouse cursor to the picture of the computer case and click once on the front of the computer.
10.
Then move the mouse cursor to the picture of the Video Card and click once. Sit back and enjoy III
11.
When the tour of the video card is finished click on "Main" to go to the main menu.
12.
Click on "Exit" to exit the program.
13.
Click on "OK" when asked "Are you sure you want to leave?"
14.
Click on "OK" again. You have just exited the multimedia program.
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Computer Repair and Fault Insertion: Fault Insertion 1.
I
Please follow the correct procedures in turning the computer repair trainer "OFF".
COMPUTER SHUT-OFF INSTRUCTIONS: Since the computer repair system uses Windows 98 as its operating system, it is very important to use the correct procedure when turning off the computer. Failure to use the proper shut-off procedure may result in permanent damage to the computer.
A.
Using your mouse, click once with the left mouse button on the start box in the lower left hand corner.
B.
Move the mouse cursor to "Shut down" and click the left mouse button once.
C.
The computer will ask, "What do you want the computer.to do?" Make sure "shutdown" is selected and click on "OK".. With the "ATX" style computer, the computer will shutdown on it's own.
D.
With the "AT" style computer, the computer will tell you "It's now safe to turn off your computer".
E.
Turn the computer OFF.
2.
Ask your instructor for the key to the key switch located on the right side of the trainer.
3.
Insert the key and rotate the key to a horizontal position.
4.
Move the fault switch to position eight. This will insert a fault in the video card.
5.
Turn the power to the computer repair trainer on.
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I SYMPTOM I 6.
Does the computer repair trainer start normally? You should have observed that the computer did notstart normally. There was no display on the monitor and the computer presented itself as a dead machine.
7.
What symptoms did you observe? The only observable symptom i~ that ofa. dead computer. The BIOS on the computer's motherboard will run a diagnostic test of each of the installed components. If any of these components should fail an Error Code or POST Event Code will be displayed on the Diagnostic POST Card. Depending upon where in the POST, the error occurs, and the type of BIOS ROM the computer has in use, it is possible that an event code will not be displayed. If your computer returned an event or error. code, .Iook up this code number in the accompanying Diagnostic POST Card Manual, and you will observe that the problem is related to the video card.
I DIAGNOSIS ·1
8.
Based upon these observations, what do you think is wrong with the computer? The error that you observed is normally associated with a defective video card,and the repair of such faults is to simply to replace the video card with a good card and try to start the computer again. If the video card is at fault, the computer should then start normally.
9.
The following components may be responsible for the "dead computer". a. Defective Motherboard b. Defective Video Card Defective Motherboard As shown in previous experiments, the motherboard can often cause a "Dead Computer". The only way to diagnose whether the motherboard is responsible, is ei~her by changing the motherboard or by further detective work. As discussed earlier, the POST Program has executed, and detected an error. The problem is that the monitor is not displaying the information that the POST has discovered. Using the POST Card, you should notice that there is CES Industries, Inc. Copyright © 2002
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a code displayed. The code that is displayed is a Video Card Failure, not a motherboard failure. Defective Video Card Depending upon what part of the video card has failed, the POST Program will usually detect that the video card is not working correctly. The POST checks to see if the video card is installed, if it is operating correctly, and if so, what video modes the card supports. If the POST does not receive this information, an error code will be produced. As shown on the display with this error, the problem is with the video card, and not with any other component on the computer. IREPAIRI The repair of the video card is like all other peripheral cards, the technician is limited to the replacement of the defective card. Most of the components on the video board are surface mount devices, which require that special tools be present to remove them from the board. Even if you have the tools required to remove the components, and have the technical expertise to .correctly use the. tool to remove the components, it is almost impossible to find the replacement parts to complete the repair. Repair Procedure: 1.
Since this fault prevented Windows from starting normally, there is no need to follow a special shut-down procedure.
2.
Turn off the main power switch.
3.
Turn the fault switch to the original "No Fault" position and turn the key switch to the original vertical position.
4.
Your computer is now ready to proceed with the next lesson.
Review: The video card is responsible for translating the information from the computer into displayable characters, graphics, colors and patterns on to the video monitor. The video card and the monitor must have the same type of signal requirements, for example, a VGA card can only drive a VGA monitor.
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Most video cards used today. are the VGA type with resolutions greater than 640 X 480 and support millions of simultaneous colors displayed on the screen. Most super VGA cards use an S3 accelerator that is optimized for displaying . information in the Microsoft Windows Environment.
Assignment: Answer the following multiple-choice questions:
1.
Some video cards come with accelerator chips. a. True b. False
2.
The video card takes data from the computer and converts them so the monitor can display them. This is done through a chip called "OAC" or a Digital to Analog Converter Chip. a. True b. False
3.
In some computers the video card is part of the motherboard. a. True b. False
4.
CGA and EGA video cards use a: a. 9 pin 0 connector b. 15 pin 0 connector c. 25 pin 0 connector d. None of the above.
5.
VGA monitors are connected to the computer with a 15 pin "0" connector. a. True b. False
6.
The video card transfers data from the RAM: a. To the ROM BIOS. b. To the CPU. c. To the monitor. d. None of the above.
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7.
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In order to translate dat~ to useful information for the monitor, the video card uses: a. A DAC (Digital to Analog Converter) b. An A to D converter c. AP.C. ROM d. None of the above.
CES Industries, Inc. Copyright © 2002
The Multimedia System
Lesson
11
Objectives: When you have completed this lesson, you will: 1.
Understand how a CD-ROM (Compact Disk-Read Only Memory) works.
2.
Understand how a CD-ROM differs from a floppy or hard disk drive.
3.
Understand how a sound card works.
4.
Understand how the system functions With the operating system.
5.
Be able to locate and identify a common fault associated with the multimedia system.
Materials Needed: 1.
CES Computer Repair Trainer Model CES 975.
2.
CES Computer Repair Module Manual.
The CD-ROM Drive
The Sound Card
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Discussion: 1.
The CD-ROM or Compact Disk-Read Only Memory is a mass storage device that unlike a floppy or hard disk, stores its information utilizing an optical system. The information is recorded onto the CD-ROM disk by using a laser beam to actually burn microscopic "pits and flats (lands)" on the surface of the disk. The construction of the disk is such that when laser lights strikes the surface of the disk areas that have not been changed into a pit but remain a flat (land) the laser light reflects back to a detector. Areas that have been changed into a pit, scatter the light and therefore do not reflect any light back to the detector. This reflection or non-reflection becomes the 0 or1 that represents the data stored on the disk. The advantage to an optical system is that there is no physical contact with the disk and no magnetic pulses to become damaged or diminished. In theory a Compact Disk with proper handling can last forever.
The CD-ROM Drive
2.
The CD-ROM drive is similar to its magnetic counterpart in that the physical size of the drive is the same as a 5%" floppy disk drive and will fit into any computer that can have a 51'4" floppy drive installed. The internal construction of the drive is similar in that there is a motor to spin the CD, control electronics that translate the optical information to digital information and a read head to read the information on the CD. The read head in the CD-ROM drive is an infra-red laser that is very low power to avoid damaging the CD. The laser is focused into a very tight beam of light that shines through a lens at the disk surface (the underside of the CD). The reflected pattern of laser light passes through a lens back to the photo or light detector to determine if the data is a flat (land) (0) or a pit (1).
3.
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The CD ROM, unlike the floppy disk, spins the CD at different speeds, depending upon where the read head (laser) is positioned. Speed increases as the read head moves toward the outer edge of CES Industries, Inc. Copyright © 2002
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the CD. The speed that the disk rotates is also determined by the head position and the type of CD drive that you are using. The faster the CD drive spins the disk, the greater is the data transfer rate. It is common to hear CD-ROM drives expressed in rotational speed, such as double speed, triple speed, quad speed, hex speed, 8 speed and 16 speed drive. This indicates that a double speed transfers twice the information in the same time as a single speed and so on. Modern CD-ROM drives turn at up to 50 times that of a single speed. This is commonly referred to as 50X. 4.
The CD ROM disk information is stored as a large file of information, as such the disk operating system can not understand the information that is on the disk. The CD-ROM does not use the same file system as a floppy or hard disk an as such is not compatible in native form with the computer. The disk becomes useable through the use of software called device drivers. The device driver performs the translation from CDROM format to MS-DOS (Microsoft-Disk Operating System) format. Note that even though Windows 98 uses the file MSCDEX, Microsoft Compact Disk Extensions is not loaded in the autoexec.bat file. The operating system kernel has the MSCDEX code built in. The Compact Disk is available in several formats, 66 minutes or 74 minutes of data. The capacities of the disks are 550 megabytes or 650 megabytes respectively. And a recently released 80 minute disk that holds 700 megabytes of data.
Equipment Setup Procedures: If your Computer Repair trainer has not been setup, ask your teacher for the equipment setup procedure sheet before beginning the following procedure.
Procedure: 1.
Open the CD-ROM tray.
2.
Insert the CD-ROM "How Computers Work" into the Drive.
3.
Close the CD-ROM tray.
4.
Put on your stereo headphones. CES Industries, Inc. Copyright © 2002
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5.
Use the mouse to double click on the icon "How Computers Work".
6.
If a warning message occurs on the screen, click on "OK".
7.
When the music starts and the title screen appears move the mouse cursor anywhere on the screen and click once using the left mouse button. This will help the user to quickly start the program by bypassing the title screen and make the music stop playing.
8.
You are about to go on a tour of the Multimedia System.
9.
Move the mouse cursor to the picture of the computer case and click once on the front of the computer.
1O.
Then move the mouse cursor to the picture of the CD-ROM Drive and click once. Sit back and enjoy !!!
11.
Then move the mouse cursor to the picture of the Sound Card and click once. Sit back and enjoy !!!
12.
When the tour of the Multimedia System is finished click on "Main" to go to the main menu.
13.
Click on "Exit" to exit the program.
14.
Click on "OK" when asked "Are you sure you want to leave?"
15.
Click on "OK" again. You have just exited the multimedia program.
Multimedia Repair Discussion The multimedia system is an area of computer repair that can be frustrating. Locating and repairing faults associated with the multimedia system is difficult due to the large variety of components, and lack of formally defined standards for the type of multimedia system. Often problems associated with multimedia systems occur on the initial installation and not with a working system.
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I DIAGNOSIS I Problems associated with A multi-media system could be caused by the following: a. Defective CD-ROM Drive. b. Defective CD-ROM Controller. c. Defective or not installed CD-ROM Driver. d. Defective or not installed Sound Card. Defective CD-ROM Drive Defective CD-ROM drives can be diagnosed by utilizing a known working CD-ROM. Error messages displayed are similar to normal DOS error messages, such as drive not ready or error reading drive. Testing a CD-ROM drive should include a general internal cleaning using a CD-ROM cleaning kit. Dirt that has built up on the laser or the internal optics will cause read errors that often simulate defective drives. Note that cleaning a CD-ROM should be done with a cleaning kit and not by opening the drive. A complete cleaning with laser power adjustments and optic alignment requires specialized tools and therefore is never recommended to be done in the field. Defective CD-ROM Controller A defective CD-ROM controller could also produce similar symptoms indicating a defective CD-ROM drive. In the case of the computer repair trainer, and most of the computers that utilize the PCI (Peripheral Component Interconnect) bus, the CD-ROM is normally connected directly to the motherboards on board controller for the hard disk or IDE (Integrated Drive Electronics) Interface. This being the case, the POST would detect a problem associated with the controller and report it during the boot. In fact, in most cases the computer will not start and would generate an error. Defective or not installed CD-ROM Driver This error can also cause the CD-ROM not to function. The CDROM Driver is a software program that acts as the interface between the computer hardware, the operating system and the CDROM. If the driver is not functional or is not installed, the CD-ROM will not operate correctly. This type of error is usually detected by the operating system in terms of an error that will state that the drive you selected is an invalid drive specification.
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Reinstallation of the driver software will normally fix this type of an error condition. Windows 98 users should note that the driver is installed during initial installation and is defined in the registry file. If this file is corrupted or if the driver is corrupted, a complete system crash may occur. This may result in having to completely reinstall the Windows operating system. Defective or not installed Sound Card Sound cards under normal situations do not usually fail. During the initial installation of the sound card, however, the usual problems of addresses, interrupts, DMA (Direct Memory Access) channels and conflicts do apply. Most of the sound cards that are available on the market today are utilizing the Plug and Play standard. This normally indicates that you simply install the card and run the configuration software, and the card will be initialized and work correctly. In reality the Plug and Play standard sometimes can be called the Plug and Pray standard since it does not always work correctly in each and every situation. In addition to problems associated with the installation and software, games will sometimes not detect a sound card if the installation is different from the original manufacturers configuration. If a sound card is not functioning, check the installation using the diagnostics included with the card. If the card functions normally, the problem may be associated with the installed drivers or the configuration of the card.
IREPAIR I The repair of a CD-ROM drive is not always a physical repair. Unlike a floppy disk or a hard disk, the CD-ROM uses laser light to read the surface of the disk. Where a CD-ROM can hold multimegabytes of information, it is possible for the disk to become useless by a single fingerprint or scratch on the surface of the disk. Whenever an error is displayed on a CD-ROM Drive, always change disks and try the operation again. If an error code is still displayed, use a laser-cleaning disk to clean the objective lenses inside the drive, then try to read the disk again. If after trying both a new disk and a cleaning, the error code still persists, you would then proceed with additional diagnostics to determine what is the problem. Unlike other devices in the personal computer that are simply replaced when bad, there are special software drivers associated with the CD-ROM that should be reloaded, and reconfigured before 108
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you replace the drive. Since most problems with CD-ROM's are associated with the disk or the software driver, it is common to be able to repair the CD-ROM problem without ever changing the drive.
Review: The CD-ROM is a device that is used for storing far more information than is possible on a floppy disk. The data is recorded using a laser beam, and is read back by the reflections caused by the original pits and flats on the surface of the disk. The information on the disk is read by a laser and as such, the surface of the CD-ROM disk never comes in direct contact with the read or writes head. Unlike a floppy disk or a hard disk the speed of the CD-ROM changes as the laser tracks across the surface of the disk, with the disk spinning faster at the outermost edge and slower at the innermost track. The Sound Card often acts as a CD-ROM interface allowing the connection of the CD-ROM to the computer and reproduces the digital audio information into sound that we can hear.
Assignment: Answer the following multiple-choice questions: 1.
A CD-ROM reads data using: a. A magnet and a coil. b. A magnetized resistor. c. A narrow beam of laser-light. d: None of the above.
2.
The surface of a compact disk contains: a. A Positive charged magnetic surface. b. A Negative charged magnetic surface. c. Pits and Lands. d. None of the above.
3.
A narrow beam of laser-light is created in the CD ROM by a: a. ROM BIOS. b. Zener Diode. c. Germanium Diode. d. Laser Diode. CES Industries, Inc. Copyright © 2002
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4.
The laser beam is reflected back from the surface of the disk when the beam strikes: a. A land on the disk. b. The smooth plastic coating of the disk. c. A pit on the disk. d. None of the above.
5.
The reflected laser beam creates the binary code (0,1) when the beam strikes against the: a. Disk surface. b. Light sensing diode. c. Prism. d. None of the above.
6.
All a. b. c. d.
7.
The sound card translates a series of numbers into analog signals that produce the sound we hear. a. True. b. False.
8.
The DSP chip on the sound card is the: a. Direct sound proportion maker. b. Digital sound player. c. Digital signal processor. d. All of the above.
9.
A compact disk stores much more information than a conventional magnetic disk. a. True. b. False.
10.
A compact disk can be erased and re-used many times. a. True. b. False.
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Multimedia Systems include the computer, the monitor, and the: Printer and modem. Scanner. CD ROM and sound card. None of the above.
CES Industries, Inc. Copyright © 2002
The Printer
Lesson
12
Objectives: When you have completed this lesson, you will: 1.
Understand the different types of printers.
2.
Understand how a printer works.
3.
Understand how the computer communicates with the printer.
4.
Be able to locate and identify a common fault associated with the printer.
Materials Needed: 1.
CES Computer Repair Trainer Model CES 975.
2.
CES Computer Repair Module Manual.
A Laser Printer
Discussion: 1.
All printers regardless of the type have one thing in common. They take the information that is displayed on the monitor and convert it into a hard copy on paper. The printer accepts information in either a parallel format or a serial format and processes the information accordingly. The most commonly used printer interface is called the parallel or centronics interface.
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2.
The Printer
The most common\'j used printer is catted a \ine printer. A tine printer prints one line of information at a time, usually by each individual character at a time.
A Laser Printer
There are page printers, which are commonly referred to as laser printers. This type of printer accepts one full page of information into the internal memory and then prints the entire page atone time. A Page printer requires that there be enough memory installed in the printer to be able to print the entire page. Graphics information requires that a larger amount of memory be installed into the printer. There must be one memory location for each dot of information that is to be printed.
3.
There are three popular types of printers available today: the dot matrix printer, the ink-jet or bubble jet printer and the laser printer. Two specialty printers for high-end color printing are also available, but cost many thousands of dollars. They are the thermal color transfer printer and the dye sublimation printer.
4.
The Dot Matrix Printer This printer places characters onto the paper by using a print head that contains as many as 24 individual wires or pins. These pins are fired by a signal from the printer controller. When the pin is fired it extends out of the print head, striking an inkfilled ribbon and causing a dot to appear on the page. By arranging the dots in a pattern or matrix, it is possible to create all of the alphanumeric characters as well as print graphics. This is the lowest cost printer, but suffers from two common problems, they are noisy and the print quality is poor.
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The Ink-Jet or Bubble Jet Printer This printer also prints characters on the page using a series of dots, however the dots are formed by using liquid ink. The ink-jet printer will shoot a controlled drop of ink for each dot that is to be printed. Unlike a dot matrix printer that has a maximum of 24 pins, an ink-jet printer has as many a 75 individual nozzles in a quarter of an inch. This equals 300 dots per inch or DPI. There are some printers that have 150 dots in the same quarter of an inch, which represents 600 dots of information per inch. The inkjet printers produce letter or near typeset quality in text mode and can produce stunning graphic outputs. Many inkjet printers have a separate color head, with yellow, magenta, and cyan colors. This allows the printer to produce full color graphics with very good color reproduction. The only disadvantage to an ink-jet printer is that the printing process is a wet process and will cause wrinkling in the paper if special paper is not used.
6.
Laser Printer A laser printer uses technology similar to a copy machine. Laser light strikes a charged, light sensitive drum to create what is known as a latent image. This image is at this point not visible, but is an exact reproduction of what you are trying to print. The latent image is then developed by passing over toner particles that have an opposite electrical charge as the latent image. The toner then sticks or is attracted to all of the areas that are to be printed. The image is now fully visible on the surface of the light sensitive drum. The paper now comes in close proximity to this drum, and an electrical charge is applied to the paper, that is again opposite to the charge on the latent image. The image is then transferred to the paper, but is held in place only by a static electrical charge, the image at this point is not permanent. The final step in printing is to press the paper through heated rollers that cause the toner to fuse or become permanent with the paper. The laser printer is able to print at 300 or 600 dots per inch and produces a letter quality, typeset output without the wet process problems associated with ink-jet printers.
7.
Regardless of the type of printer, it is absolutely critical that you install the correct software to operate the printer. This software is known as a printer driver, and acts as an interpreter to change the information displayed on the monitor, to commands that the printer is able to understand. If the correct driver has not been installed,
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the printer will either not print at all, or if it does print it will print sheets of garbage with unrecognizable characters as its output. 8.
Most modern printers require special bi-directional cables that allow the printer and computer to communicate with each other, using commands and information that is more than simply error or paper out information. It is necessary that you have a bi-directional cable of the proper type if your printer so requires it. This printer cable is called either by it's descriptive name, a bi-directional cable or by the industry standard name of IEEE-1294. In older computers, it is possible that the parallel printer interface card may have to be changed to accept a bi-directional connection. If the card supports this feature at all. You will know immediately if the computer requires a card change when no matter what you do to configure one of these type printers the same error is constantly displayed.
Equipment Setup Procedures: If your computer repair trainer has not been setup, ask your teacher for the equipment setup procedure sheet before beginning the following procedure.
Procedure: 1.
Open the CD-ROM tray.
2.
Insert the CD-ROM "How Computers Work" into the Drive.
3.
Close the CD-ROM tray.
4.
Put on your stereo headphones.
5.
Use the mouse to double click on the icon "How Computers Work".
6.
If a warning message occurs on the screen, click on "OK".
7.
When the music starts and the title screen appears move the mouse cursor anywhere on the screen and click once using the left mouse button. This will help the user to quickly start the program by bypassing the title screen and make the music stop playing.
8.
You are about to go on a tour of the printer. Move the mouse cursor to the picture of the printer and click once. Sit back and enjoy !!!
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9.
When the tour of the printer is finished click on "Exit" to exit the program.
10.
Click on "OK" when asked "Are you Sure you want to leave?"
11.
Click on "OK" again.
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You have just exited the multimedia program.
Computer Repair and Fault Insertion:
I Fault Insertion I 1.
Please follow the correct procedures in turning the computer repair trainer "OFF".
COMPUTER SHUT-OFF INSTRUCTIONS: Since the computer repair system uses Windows 98 as its operating system, it is very important to use the correct procedure when turning off the computer.
Failure to use the proper shut-off procedure may result in permanent damage to the computer. A.
Using your mouse, click once with the left mouse button on the start box in the lower left hand corner.
B.
Move the mouse cursor to "Shut down" and click the left mouse button once.
C.
The computer will ask, "What do you want the computer to do?" Make sure "shutdown" is selected and click on "OK". With the "ATX" style computer, the computer will shutdown on it's own.
D.
With the "AT" style computer, the computer will tell you "It's now safe to turn off your computer".
E.
Turn the computer "OFF".
2.
Ask your instructor for the key to the key switch located on the right side of the trainer.
3.
Insert the key and rotate the key to a horizontal position.
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Move fault switch to position ten. This will insert a fault into the Printer system.
5.
Turn the power to the computer repair trainer on.
6.
Make sure that the printer power is turned on.
ISYMPTOM I 7.
Does the computer repair trainer start normally? The computer should have started normally.
8.
What symptoms did you observe? Since the problem has been installed in a peripheral device, the power on diagnostics of the computer will not detect this fault. The only way that this fault will become visible is when you try to access the printer. To test this fault, follow this procedure. a. b. c. d. e. f. g. h.
Click on the "Start" button. Slide the cursor up and select "Programs". Select "Accessories". Slide the cursor to the program called "Notepad". Click on the "Notepad" program. Type a few lines of text on the screen. Select the "File" menu item. Slide the cursor down to the "Print" option.
The computer should have returned an error regarding the status of the printer, and that it is unable to print your document.
I DIAGNOSIS I Based on your observations, the following are possible causes for the printer error that you are experiencing. a. Defective Printer Cable b. Defective Printer Interface c. Defective Printer Defective Printer Cable
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between them. The most obvious being that the cable is simply not connected to either the printer or the computer, or the cable is not making solid contact on either the printer or the computer side. In some cases the problems may be associated with the type of cable used. For most of the newer ink-jet and laser type printers a bidirectional cable is required for proper operation of the printer. If the cable is not bi-directional errors ranging from installation problems to being unable to print are possible. Defective Printer Interface The printer interface or printer port allows communication between the printer and the computer. If the interface is defective, the ability to print will be effected. On the computer repair trainer, the printer interface is directly on the motherboard, this would leave you only two choices. Defective Printer It is possible for the problem to be with the printer itself, and not a problem associated with the computer or cables. The printer, like the CD-ROM, also requires that special drivers be installed to allow the printer to function normally. The first step in troubleshooting a printer problem is always to verify that the proper drivers are loaded and that they are functional. Whenever possible, try printing a selftest from the printer, this will confirm that the printer is actually able to produce an output. If the printer will print a self-test correctly, the problem is with the computer or the associated interface, this includes the software drivers for that specific printer.
IREPAIR I The problem that you have observed is a common problem with a printer, that is the interface or connection to the printer is not working. It occurs after someone connects a printer to a live computer. The parallel port interface is damaged, and now the printer is no longer able to receive data from the computer. The parallel port can be damaged by connecting a printer or other device to it when the power is on. Repair Procedure:
1.
Since this fault did not prevent the computer from starting normally, you must follow the special shut-down procedure.
2.
After the computer has displayed "You may now turn off your computer", turn off the main power switch.
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3.
Turn the fault switch to the original "No Fault" position and turn the key switch to the original vertical position.
4.
Your computer is now ready to proceed with the next lesson.
Review: There are many different types of printers that can be used with a computer. Each printer has its unique type of interface, and software requirement. For the printer to operate properly, the correct drivers must be installed before the printer is used. The parallel interface can be damaged by connecting or disconnecting any device while the power is on. Certain printers require the use of a bi-directional cable to allow communication both to and from the printer.
Assignment: Answer the following multiple-choice questions: 1.
In a. b. c. d.
2.
Paper is pulled into a laser printer between 2 electrically charged rollers that give the paper a static charge to attract: a. Ink from a cartridge. b. Toner. c. The dot matrix. d. None of the above.
3.
Toner is fused to the paper by: a. Exposing it to light. b. Heat. c. A hot-air gun. d. None of the above.
4.
The size of outline fonts is controlled by: a. The monitor. b. The printer buffer. c. Software. d. None of the above.
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a laser printer, the laser beam sprays an image across: The paper. The print cylinder or drum. The toner. All of the above.
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5.
Three major types of printers are the laser, ink-jet, and the dot matrix printer. a. True b. False
6.
Laser printers heat a tiny bubble of ink until it bursts, shooting the ink onto the paper. a. True b. False
7.
The ink-jet printer uses a fusing system to dry the ink on the paper. a. True b. False
8.
A Wax Thermal Printer melts ink and wax onto the paper to produce the color images. a. True b. False
9.
A Dot Matrix uses a series of pins that strike a ribbon coated with ink to transfer dots to the paper. a. True b. False
10.
The size and shape of Post Script and Outline fonts is controlled by: a. ROM. b. BIOS. c. Software. d. All of the above.
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The Network Systems
Lesson
13
Objectives: When you have completed this lesson, you will: 1.
Understand the basic components of a network.
2.
Be able to locate and identify a network interface card.
3.
Be able to describe the difference between a client and a server computer.
Materials Needed: 1.
CES Computer Repair Trainer Model CES 975.
2.
CES Computer Repair Module Manual.
Discussion: 1.
Computer networks are fast becoming the most extensive growth area for personal computer technicians. Most businesses have some type of network installed at their site. Managing, administrating and operating networks can be a challenge at best.
2.
A network can be thought of as a group of individual computers that are connected together in some fashion to communicate with each other to share information, files and programs. The most common use of a network is the Internet, where millions of computers are connected world wide to share multi megabytes of information daily.
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3.
The Network Systems
In order for a network to function, it is necessary to have three items installed, properly configured and above all maintained. The first is the network interface card. The network interface card is an adapter card, like a video or sound card, that is inserted into the computers expansion slot. Once installed, the card must be configured to an address, interrupt and DMA (Direct Memory Access) channel that is not in use by any other piece of hardware. After the card is configured and the network software or network operating system has been installed, the network card receives the information from the computer, by way of the network operating system, that is to be sent out over the network. Before it can broadcast over the network, the data must be converted from the parallel data transported over the computers data bus into serial data that is compatible with the type of network in use. The most important item when setting up the network interface card, is that the network will not function at all, unless all the cards on the network are the same type. For example, all the cards must be Ethernet, Token-ring, or Arc-net, otherwise they cannot communicate with each other. It is possible to have mixed environments on a network, but special hardware and software is required, and this will not be discussed here.
4.
The network operating system. Once the network card is installed, it is necessary to configure the operating system. The operating system is actually the software that runs the network. The workstation that someone uses to access files or programs is called the client. The computer that stores all of the files and programs and retrieves them on demand is called the server. Most networks utilize a client/server type arrangement. There are other types of network operating systems, where each workstation is able to share files and resources with each other. This type of network is called Peer to Peer. A Peer to Peer network is normally utilized where file security is not a major concern, such as in a small office, where everyone shares all files.
5.
The final step in building the network is the cabling. Installing and properly connecting the cable is a big part in the overall reliability of the network. Once the type of cable has been decided, installation and final testing is performed.
6.
All networks have a few basic parts in addition to the hardware and software requirements. The first is the file server or server. This computer has all of the master files, network control software, and any applications that are to be shared over the network.
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The Workstation or client computer is connected to the network, and uses the information that is provided by the server. Regardless of the type of network, all networks can share only logical resources or files and information. No network can share memory, processors or any physical device with the exception of a CD-ROM, printer or disk drive.
Procedure: 1.
Open the CD-ROM tray.
2.
Insert the CD-ROM "How Computers Work" into the Drive.
3.
Close the CD-ROM tray.
4.
Put on your stereo headphones.
5.
Use the mouse to double click on the icon "How Computers Work".
6.
If a warning message occurs on the screen, click on "OK".
7.
When the music starts and the title screen appears move the mouse cursor anywhere on the screen and click once using the left mouse button. This will help the user to quickly start the program by bypassing the title screen and make the music stop playing.
8.
You are about to go on a tour of the Network Interface Card.
9.
Move the mouse cursor to the picture of the computer case and click once on the front of the computer.
10.
Then move the mouse cursor to the picture of the Network Card and click once. Sit back and enjoy I!!
11.
When the tour of the Network Card is finished click on "Main" to go to the main menu.
12.
Click on "Exit" to exit the program.
13.
Click on "OK" when asked "Are you sure you want to leave?"
14.
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Review: Computer networks are utilized whenever you want to share resources such as files and printers. Each computer becomes a workstation or client on the network. Depending upon the access rights that are granted to the client, it is able to access the files and resources requested. All networks are connected with some type of cable, to one or more central file servers. A network can be a local area network or LAN, in which all the computers connected are located in the same building. A network can be a Wide Area Network or WAN, where the computers may be located many hundreds of miles away from each other. The Internet is an example of a very wide area network.
Assignments: Answer the following multiple-choice questions: 1.
The network interface card: a. Allows the computer to communicate with the monitor. b. Allows the computer to communicate with other computers. c. Allows the computer to communicate with the keyboard. d. None of the above
2.
The Main Computer that stores all the files and program information to be shared over the network is called: a. Peer to Peer b. The workstation c. The fileserver d. The master computer
3.
When two or more computers are connected in the same location, the network is called a: a. WAN b. LON c. LAN d. None of the above
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4.
When two or more computers are connected across a great distance the network is called a: a. WAN b. LON c. LAN d. None of the above
5.
When two or more computers are installed in one location, and each computer has access to all files equally the system is called: a. Peer to Peer Network b. Client Server Network
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Computer Viruses
Lesson
14
Information Sheet Objectives: When you have completed this lesson, you will be able to: 1.
Identify what a computer virus is.
2.
Identify the symptoms of viral infection.
3.
Immunize your system from viruses.
4.
Remove an existing virus from a computer.
Materials Needed: 1. CES Computer Repair Module Manual.
Discussion: 1.
As with all personal computers and software associated with the computer, the computer virus is quickly becoming a major source of problems for the computer owner. Virus programs can range from an amazing annoyance, to a major loss of vital computer information. This section on viruses is intended to help you understand what a virus is and some ways to prevent them from infecting your machine.
2.
A virus is a specialized type of computer program, often written by someone for a 'why not' reason. Some viruses will do nothing more than draw a picture of an ambulance on the screen, sound a siren and animate the ambulance across the screen. Other viruses such as the Monkey virus will completely destroy the hard disk drive and all of the contents on the drive.
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3.
Most virus programs are extremely small, well written pieces of software code, that often occupy less then 512 bytes of memory and disk space. The viral code will often be placed on floppy disks, in the boot sector of the disk. This viral code will infect the host computer as soon· as the infected floppy disk is read. Often the virus will be transferred to the host computer, where it will immediately begin its dirty work. Some viruses will simply transfer and infect the host, and then wait for a specific date and time to activate. This is called a time bomb virus.
4.
When a computer is infected with a virus, depending upon the virus code, each and every disk that is inserted in the computer will also become infected with the virus. As the virus replicates, each and every computer that the disk is inserted in will become infected with that virus.
5.
TYPES OF VIRUSES There are a few types of commonly seen viruses that will cause all types of problems with computers. The most common type of virus is the Boot Sector Infector. This virus makes its home on the boot sector of the infected disk; the program code is therefor loaded each time the computer is turned on. Often this type of virus will relocate parts of the DOS (Disk Operating System) directory structure to make room for the viral code.
6.
Trojan Horse This type of virus looks like a normal computer program to the casual user. It may be a game, a business program or any other type of program, but when run, the viral part of the program takes over and destroys files and directories.
7.
Virus Detection With computer repair it becomes necessary to determine whether the problems lies with the hardware or the software, and if the problem is viral in nature. For example, the computer reports that there are unreadable sectors on the hard disk. When repairing this problem, you have to determine whether the problem is a hard disk that is about to die, or whether the problem is a virus, slowly destroying the hard disk. The most common symptom of a virus is that things start to happen for no apparent reason, often after a new program or disk has been loaded. Confirmation of a virus requires that special software be used to detect and remove known viruses.
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8.
Stealth Viruses There are new strains of viral code that try to mask their presence by confusing the virus scanner software. These viruses, called stealth viruses, will change their code and data segments to confuse the detection process. This type of virus can be very difficult to detect and remove.
9.
Removing a virus Software companies such as McAfee and Associates, Norton Utilities, Microsoft and others, all produce some type of anti-virus software. Each program is able to locate and remove most types of viruses, however no. program can detect all the different types of viruses that are around, much less work on every type of virus effectively. They are however, a good defense if they are kept up to date. Anti-viral software is only as good as the version that you are running. If the software is more than 30 days old, the chance of finding a new virus is almost nil. Most virus programs will have provisions for either a subscription service or a download service, to keep the virus signatures current. In some extreme cases, it may become necessary to completely reformat a hard disk to remove avirus and reload all of the originally installed software.
10.
Preventing Disaster It .is important that part of the repair procedure for any computer involves practicing safe repair procedures. You should always make backup copies of all of your diagnostic software, and never use the original disks on any computer. Whenever using your diagnostic software on a computer with a suspected virus, never re-use the diagnostic disk. Reformat it and recopy the diagnostic software on to the disk for use on another computer. A good technician treats all computers equally, that is, they are all infected. This will prevent cross contamination. Regular virus scans on a computer is a necessity, as is a good virus shield program. This is especially true if the computer is using any online or Internet service access. Full and daily backups of the hard disk will also help prevent the total devastation of a hard disk and its data, if a virus or other disaster should strike.
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Assignment: Answer the following multiple-choice questions: 1.
It is important to always have the latest virus signatures when using an on-line service, installing a new program or using information from a data disk. a. True b. False
2.
When you discover a virus on a machine, should you insert a disk in the disk drive and copy a file to the disk from that machine? a. Yes b. No
3.
After a virus has been detected, you should try to detect and clean the virus before further damage is done to the machine. a. True b. False
4.
It is important to back up the information on your machine as often as possible, to assure that your data and programs are safe before disaster strikes. a. True b. False
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