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Test PSU

Hi There can someone point me in the right direction of a web site that shows how to test a ATX PSU ie what voltages etc should be coming out of what leads etc. I realize it should be under load conditons, MOBo and at least one hard drive but the rest I have no idea. So your informed help would be greatly apreciated. Kindest Regards Tony B.

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Re: Test PSU

In reply to: Test PSU

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If you have a DVM with reasonably sharp test probes

In reply to: Test PSU

[OSHA will hate you. LOL] You can probe the rear of the power connector on the mobo. The black leads are all common [ground in most peoples terms].

The main 5 volts is on pins 4 , 6, 19, and 20. The main [once] 12 volts is on pin 10 [now there is also a separate 4 pin 12 volt connector, 2 pins 12 V and 2 Gnd, it is now spec'd to be provided by a separate set of rails in the supply]. The 3.3v is on pins 1,2, and 11.

The pins run from 1 thru 10 down one side and 11 [next to 1] thru 20 down the other side. The 11 thru 20 side has 4 black wires the other row only 3 black wires. 5 volts are virtually always Red.

Minus 12 and Minus 5 volts are virtually no longer used.

Testing an ATX standalone means you have to learn how to turn the supply outputs on. Robert's link probably shows that.

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Re: Test PSU

In reply to: Test PSU

I chuckle over some stories. Why do you need to test it? Pwr supply fan runs=+12 good. Processor fan and other fans=+12 good. Hdd spins, Cdrom drive opens=+5 good. Need meter (Harbor Freight ~$5) for -5 -12 -3.3, which I have found burnt out a few times because the current rating is small.
www.duxcw.com/faq/ps/ps4.htm is a link to describe the voltages of typical ATX supply.

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What does the current rating have to

In reply to: Re: Test PSU

do with a voltage scale????? They draw virtually zero current. That's the point of a voltmeter. The old D'Arsonvals were usually 10,000 OHMs per volt. Modern digital are multimegohm.

Meter burnouts occur when one tries to measure 120 VAC when on an OHMs scale [does it every time].

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not the meter, the power supply

In reply to: What does the current rating have to

-12, -5 are rated at about 300-400ma, while other voltages are rated 5a-20a. The point being that the minus voltages can be easily burnt out. I don't think they have the same interupt as the + voltages do. Short out the +5v and the pwr supp will restart instead of burn out.
Lightening or other way excessive surges can more easily burn out -voltages, as has been my experience.

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Re: Test PSU Thanks

In reply to: Test PSU

Just a thank you to all who have contirbuted to this discussion.
Regards Tony B.

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