Computer Processor ATX Power Supply Test

Hello

I have not worked with PC power supplies so much, but perhaps I can give you some hints.

Somewhere there is an power supply switch input. I think you must connect it to GND but not sure. Test how the power switch works.

You must have a dummy load for the 5V out, i.e 10 ohms for 0.5A load. The value is not critical, but it must bee.

On the connectors, there is a Power-Good input, the orange coloured wire to pin 1 on the power connector. It is a diagnostic pin, but I don't know what voltage it must have, perhaps 5V.

Put a 60 to 100W filament lamp in serial with the main power. It will protect you from surprising when you test it. If it is OK, the bulb will only glow, but if there is a short circuit, it will light up.

If it looks OK, you can measure the output voltages. Red = 5V, yellow = +12V, blue = -12V and white -5V. Black is GND.

I know there are several types of power supplies, they can differ.

Anders

I think, the term "power good" is good information let me search around this point. Finaly I will contact you.

Thanks

Vastech sells an ATX power supply tester for about 12 USD; all you do is turn-on the power supply plug in the 20-pin power supply connector to the minitester and check it's LED lights for each output

Use a paperclip to short together pins 14 (the only green wire) and 15 (GND - any other black wire will work as well, but this is the easiest). This will cause the power supply to start up even without a load attached. I wouldn't run it for very long in this fashion though, as they are meant to run under load.

Have you practicaly tested an ATX type PC-power supply by shorting terminal 15 and 14? becuse a book about PC power supply does not recommend to make no-load test of any switch mode power supply system. Logically you may arrenge some extra fan or you may connect any disk drive. As per that book, if you test without load you will burn the suppy unit. This is just to know your exprience

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As per that book, if you test without load you will burn the suppy unit. This is just to know your exprience

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It a valid point of coursw. But you forgot "Cooling Fan" which will be the sufficient load for 300W+ PSU.

I have been working for long time on Switch-Mode Power Circuit design & Service.

So much load will do.

As a matter of fact, I have been successfully testing ATX power supplies this way for the past 12 years. NEVER have I burned one up. It is the quickest and easiest way to get the supply going, AND directly answers the OP's question of powering it without a load. That being said, however, I also stated I would not run it for very long since they are made to be run with an attached load.

Further to "laxman12786" when PSU starts expect :

1.) PSU's fan starts. It means +12V are ok [All the Orange wires are +12V]

Normally this test is sufficient to confirm that PSU is OK

To make 100% sure you may carry on following additional tests:

2.) All black Wires [Gnd] take it common point for all measurements for your multimeter

3.) All red are +5V

4.) All Yellow wires are are +12V [your fan also is running on it]

4.) Orange are +3.3v [cpu supply]

5.) Blue -12V

If all these are OK you may consider it OK

Note:

Altough the Over-voltage protectors worked to protect your PC [You may be lucky I hope] but the devices are not as fast as the ICs & transistors burn fast. [I squared x t]of

Over-voltage protectors is more than ICs & transistors. Inspite of the blown-fuse & burnt-varistor, some components may also had been sissled.

Haajee

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ATX Power Supply

(at the motherboard) Female

(at the cable) Male

20 PIN MOLEX 39-29-9202 at the motherboard

20 PIN MOLEX 39-01-2200 at the cable

Note: by Haajee

New PSU connectors are 24 pin [4pins detachable for older Motherboards] and pin # shown below may be different

BUT colour CODES are valid

Pin Name Color Description

1 3.3V Orange +3.3 VDC

2 3.3V Orange +3.3 VDC

3 COM Black Ground

4 5V Red +5 VDC

5 COM Black Ground

6 5V Red +5 VDC

7 COM Black Ground

8 PWR_OK Gray Power Ok (+5V & +3.3V is ok)

9 5VSB Purple +5 VDC Standby Voltage (max 10mA)

10 12V Yellow +12 VDC

11 3.3V Orange +3.3 VDC

12 -12V Blue -12 VDC

13 COM Black Ground

14 /PS_ON Green Power Supply On (active low)

15 COM Black Ground

16 COM Black Ground

17 COM Black Ground

18 -5V White -5 VDC

19 5V Red +5 VDC

20 5V Red +5 VDC

18 AWG is recommended for all wires except pin 11, which should be 22 AWG

For 300W configurations 16 AWG is recommended.

Contributor:

Joakim Ögren <http://www.hwb.acc.umu.se/menu_Comment.html> 1996-1998

Source:ATX Spec v2.03 <http://www.formfactors.org/developer/specs/atx/atx2_03p1.pdf> at Platform Development Support <http://www.formfactors.org/>

Copyright © The Hardware Book Team <http://www.blackdown.org/~hwb/hwb.html> 1996-2004.

May be copied and redistributed, partially or in whole, as appropriate.

Document last modified: 2002-01-13

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I know where you are coming from, but what, even after testing, it blows up your motherboard, hard disk, keyboard and mouse???

It is better to buy a new, heavily rated PS (USD 60 is enough usually, but more would be better, I paid over USD100 recently for an all singing, all dancing model) that runs nice and quiet......Don't take risks with your data.