Make A Floating Ground 12 V Server Power Supply - MakeNotes - de

 

3/24/2021

Make a floating ground 12 V server power supply – MakeNotes.de



MakeNotes.de (https://makenotes.de/) (https://makenotes.de/) MENU

  

Make a floating ground 12 V server power supply Posted on 30.04.2020 by cf (https://makenotes.de/author/cf/)

This article describes how to make a power supply with a so called oating  Diese Website verwendet Cookies, um die Nutzbarkeit der Seite zu verbessern. Indem Sie diese Website weiter  nutzen, stimme stimmen n Sie der Verwendung von Cookies zu. (This website uses cookies to improve the user experience. By ground (https://en.wikipedia.org/wiki/Floating_ground) from a regular server using this website, you agree to the use of cookies.) power supply. This is needed for example when connection multiple DC power Ok

Dat Datens enschu chutze tzerk rklär lärung ung (Priv (Privacy acy po polic licy) y) (ht (https tps:// ://mak makeno enotes tes.de .de/da /date tenschutzerklarung/) nschutzerklarung/)

sources in series to reach r each a higher voltage. To understand why this is necessary, https://makenotes.de/2020/04/make-a-floating-ground-12-v-server-power-supply/

1/10

 

3/24/2021

Make a floating ground 12 V server power supply – MakeNotes.de

please check out my other article about making a oating ground power supply  (https://makenotes.de/2020/05/make-a-24-v-po (https://makenotes.de/2020/05/mak e-a-24-v-power wer-supply-from-two-12-supply-from-two-12-vvsupplies/).

Mains voltage is dangerous and can be lethal! Always make sure to unplug  the  the device when working on it! Even when disconnected, the capacitor(s) of a DC power supply can store a high voltage/current for a signicant amount of time. Always make sure to isolate or discharge these components rst! If you’re unsure or feel uncomfortable working on such devices — don’t do it!

Before connecting any power power supplies in series, all added  power  power supplies need  to  to have a “oating ground”. This means, there is still a  voltage of 12 V between between GND and +12V (or whatever whatever the voltage may  be), but the GND output isn’t connected to the case/PE anymore. Only the rst supply’s GND may be tied to earth/PE.

Server power supplies (and many other power supplies), in most cases, use one or more of their metal PCB standoffs, to connect to the casing and therefore the PE conductor. This is done by simply putting a exposed GND pad where the standoff later touches the PCB. This connection needs to be undone. Diese Website verwendet Cookies, um die Nutzbarkeit der Seite zu verbessern. Indem Sie diese Website weiter  nutzen, stimme stimmen n Sie der Verwendung von Cookies zu. (This website uses cookies to improve the user experience. By Finding the connections using this website, you agree to the use of cookies.) Ok

Datensch Datenschutze utzerklä rklärung rung (Privacy (Privacy policy) policy) (htt (https:/ ps://mak /makenot enotes.d es.de/da e/datens tenschut chutzerk zerklaru larung/) ng/)

https://makenotes.de/2020/04/make-a-floating-ground-12-v-server-power-supply/

2/10

 

3/24/2021

Make a floating ground 12 V server power supply – MakeNotes.de

(https://makenotes.de/wpcontent/uploads/2020/04/IMG_20200430_105519.jpg) This is where the PCB is screwed down to the case. Don’t isolate them all!

The best way to do d o this properly, is to remove r emove the whole PCB of the power supply, disconnect it from the case, turn it around and measure between the pads (if any) at the screw holes. You may nd, that all, only some or only one is connected to the GND plane of the PCB. Don’t just trust what others say, measure it yourself! Also note, that there is a difference between the DC GND and the AC “GND”/PE. The AC PE connector should always be connected to the Diese Website verwendet Cookies, um die Nutzbarkeit der Seite zu verbessern. Indem Sie diese Website weiter  nutzen, stimme stimmen der Verwendung von Cookies zu. (This website uses cookies to improve the user experience. By primary (ACn Sie input) sideusing of the power supply PCB (and therefore the case). Only  this website, you agree to the use of cookies.) the secondary (DC output) side needs to be isolated. There is usually a air gap Ok

Datensch Datenschutze utzerklä rklärung rung (Privacy (Privacy policy) policy) (htt (https:/ ps://mak /makenot enotes.d es.de/da e/datens tenschut chutzerk zerklaru larung/) ng/)

on the PCB where primary and secondary sides meet. https://makenotes.de/2020/04/make-a-floating-ground-12-v-server-power-supply/

3/10

 

3/24/2021

Make a floating ground 12 V server power supply – MakeNotes.de

So basically every screw hole pad, that is connected to (DC) GND (see picture below on the right side) needs to be isolated. If you don’t understand why, please check out the drawings in my other article (https://makenotes.de/2020/04/make-a-oating-ground-12-v-server (https://makenotes.de/2020/04/mak e-a-oating-ground-12-v-server-power -power-supply/).

(https://makenotes.de/wpcontent/uploads/2020/04/IMG_20200430_105221.jpg) Backside of the power supply’s PCB.

Only isolate screws that actually need  to  to be isolated! Don’t just replace all stand-offs with nylon spacers/washers and nylon screws! The connection to PE on the primary side of the PCB is actually needed for ltering purposes! Always reconnect the green/yellow PE conductor near the IEC connector! The case Diese Website verwendet Cookies, um die Nutzbarkeit der Seite zu verbessern. Indem Sie diese Website weiter 

needs to be connected to PE, for its protective function to work. Also there may  nutzen, stimme stimmen n Sie der Verwendung von Cookies zu. (This website uses cookies to improve the user experience. By using this website, you agree to the use of cookies.)

be some holes already isolated from the rest of the circuitry (even if they have a Ok Datensch Datenschutze utzerklä rklärung rung (Privacy (Privacy policy) policy) (htt (https:/ ps://mak /makenot enotes.d es.de/da e/datens tenschut chutzerk zerklaru larung/) ng/) copper pad around them). https://makenotes.de/2020/04/make-a-floating-ground-12-v-server-power-supply/

4/10

 

3/24/2021

Make a floating ground 12 V server power supply – MakeNotes.de

(https://makenotes.de/wpcontent/uploads/2020/04/IMG_20200430_105245.jpg) This hole already *looks* like not connected to GND or PE. But always measure and check to make sure! In this case it indeed wasn’t connected, but there could have been connections on the upper side of the PCB.

In this example (see pictures), only one stand-off needed to be isolated, because the two on the left are only connected to PE and “AC GND” (primary  (primar y  side) anyway and the one on the bottom right wasn’t connected to anything at all (except (except the case, when put together again). The one on the top right is Diese Website verwendet Cookies, umpad die Nutzbarkeit Seite zu verbessern. Indem Sie diese Website weiter  connected to DC GND (large on theder right) and will be connected to Case/PE nutzen, stimme stimmen n Sie der Verwendung von Cookies zu. (This website uses cookies to improve the user experience. By

after reassembly — therefore one needed to be isolated! using thisthis website, you really agree to the use of cookies.) Ok

Datensch Datenschutze utzerklä rklärung rung (Privacy (Privacy policy) policy) (htt (https:/ ps://mak /makenot enotes.d es.de/da e/datens tenschut chutzerk zerklaru larung/) ng/)

https://makenotes.de/2020/04/make-a-floating-ground-12-v-server-power-supply/

5/10

 

3/24/2021

Make a floating ground 12 V server power supply – MakeNotes.de

Isolating the connection

(https://makenotes.de/wpcontent/uploads/2020/04/IMG_20200430_105551.jpg) To allow a nylon/plastic spacer/washer to t b between etween PCB and stand-off, a little bit of the metal needs to be taken off with a metal le. Make sure to clean out the case carefully after.

There are multiple ways to isolate the PCB from the metal stand-off:

Diese Website verwendet Cookies, um die Nutzbarkeit der Seite zu verbessern. Indem Sie diese Website weiter  nutzen, stimme stimmen n Sie der Verwendung von Cookies zu. (This website uses cookies to improve the user experience. By using this website, you agree to the use of cookies.) Ok

Datensch Datenschutze utzerklä rklärung rung (Privacy (Privacy policy) policy) (htt (https:/ ps://mak /makenot enotes.d es.de/da e/datens tenschut chutzerk zerklaru larung/) ng/)

https://makenotes.de/2020/04/make-a-floating-ground-12-v-server-power-supply/

6/10

 

3/24/2021

Make a floating ground 12 V server power supply – MakeNotes.de

(https://makenotes.de/wpcontent/uploads/2020/04/IMG_20200430_115513.jpg) Nylon washer between case stand-off and bottom part of the PCB.

Drill out the whole stand-off and use (a bigger) nylon stand-off and screw. Clean out the metal chippings after drilling! File down the metal part and use a nylon washer and a nylon screw. Clean the metal dust carefully after after,, since it’s conductive! Use a shoulder or insulation washer(s) to isolate the hole from the metal screw.. These washers are specially made for this. This is the cleanest way  screw Diese Website verwendet Cookies, um die Nutzbarkeit der Seite zu verbessern. Indem Sie diese Website weiter 

in my personal opinion. But you need some that t correctly. Use two nylon washers (top/bottom of PCB) and a metal screw, but only, if 

nutzen, stimme stimmen n Sie der Verwendung von Cookies zu. (This website uses cookies to improve the user experience. By using this website, you agree to the use of cookies.) Ok

Datensch Datenschutze utzerklä rklärung rung (Privacy (Privacy policy) policy) (htt (https:/ ps://mak /makenot enotes.d es.de/da e/datens tenschut chutzerk zerklaru larung/) ng/)

the insides of the hole hol e on the PCB aren’t conductive and there’s there’s a little https://makenotes.de/2020/04/make-a-floating-ground-12-v-server-power-supply/

7/10

 

3/24/2021

Make a floating ground 12 V server power supply – MakeNotes.de

space between the pad on the surface at the edge of the hole itself. Be careful with this one and inspect the hole with a continuity tester to make sure, the screw won’t touch any conductive parts. If unsure, use a nylon screw.

(https://makenotes.de/wpcontent/uploads/2020/04/IMG_20200430_120446.jpg) Nylon washer between screw and top side PCB (use a nylon screw for this, if unsure!). The resistor and bridge soldered to the contact pads, are explained in my other article (https://makenotes.de/2020/04/turning-on-a-hp-dps-750rb-server-power-supply/). Diese Website verwendet Cookies, um die Nutzbarkeit der Seite zu verbessern. Indem Sie diese Website weiter  nutzen, stimme stimmen n Sie der Verwendung von Cookies zu. (This website uses cookies to improve the user experience. By using this website, you agree to the use of cookies.)

Testing the device Ok

Datensch Datenschutze utzerklä rklärung rung (Privacy (Privacy policy) policy) (htt (https:/ ps://mak /makenot enotes.d es.de/da e/datens tenschut chutzerk zerklaru larung/) ng/)

https://makenotes.de/2020/04/make-a-floating-ground-12-v-server-power-supply/

8/10

 

3/24/2021

Make a floating ground 12 V server power supply – MakeNotes.de

After carefully putting everything back together again (make sure to put back the black insulation foil and other insulation tape, like it was before) the following measurements should be made: Continuity between center PE pin on the IEC connector and the case  No continuity between the case and the GND (DC negative) pin.  Innite resistance between GND and PE (not even Megaohms!).

Turned on: 12 V (or a little bit more) voltage between GND and +12V. Turned on: 0 V voltage between case and +12V.

(https://makenotes.de/wpcontent/uploads/2020/04/IMG_20200430_105358.jpg)



Electronics (https://makenotes.de/category/electronics/), RC (https://makenotes.de/category/electronics/), Diese Website verwendet Cookies, um die Nutzbarkeit der Seite zu verbessern. Indem Sie diese Website weiter 

nutzen, stimme stimmen n Sie der Verwendung von Cookies zu. (This website uses cookies to improve the user experience. By (https://makenotes.de/category/rc/) using this website, you website, you agree to the use of cookies.)  english (https://makenotes.de/tag/english/) (https://makenotes.de/tag/english/) Ok

Da Date tens nsch chut utze zerk rklä läru rung ng (P (Pri riva vacy cy poli policy cy)) (ht (http tps: s:// //m makenotes.de/datenschutzerklarung/)

https://makenotes.de/2020/04/make-a-floating-ground-12-v-server-power-supply/

9/10

 

3/24/2021

Make a floating ground 12 V server power supply – MakeNotes.de

1 Reply to “Make a floating ground 12 V server power supply”

Pingback: Make a 24 V power supply from two 12 V supplies – MakeNotes.de (https://makenotes.de/2020/05/make-a-24-v-po (https://makenotes.de/2020/05/mak e-a-24-v-power wer-supply-from-two-12-supply-from-two-12-vvsupplies/)

Proudly powered by WordPress (https://wordpress.org/)

Diese Website verwendet Cookies, um die Nutzbarkeit der Seite zu verbessern. Indem Sie diese Website weiter  nutzen, stimme stimmen n Sie der Verwendung von Cookies zu. (This website uses cookies to improve the user experience. By using this website, you agree to the use of cookies.) Ok

Datensch Datenschutze utzerklä rklärung rung (Privacy (Privacy policy) policy) (htt (https:/ ps://mak /makenot enotes.d es.de/da e/datens tenschut chutzerk zerklaru larung/) ng/)

https://makenotes.de/2020/04/make-a-floating-ground-12-v-server-power-supply/

10/10