Solved PC Power Supply output Voltages

November 21, 2012 at 10:55:58
Specs: Windows XP
I have a PC power supply taken out of my older desktop. Also have floppy drive and Hard drive taken out as well (for bench testing) when I turn power supply ON (wired to Floppy and hard drive) it comes ON and runs a few seconds and then turns itself OFF. I can't figure out what is wrong with it. Could someone help me here. I greatly appreciate it.

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#1
November 21, 2012 at 12:38:40
Many PSUs will power down like this if they don't have a minimal load applied. You really need to test with it plugged in to a motherboard, or else use resistors to provide the appropriate load. The behaviour you describe may well be by design if it works (worked) when used with a motherboard.

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#2
November 21, 2012 at 16:07:09
If the power supply came out of an older PC and you intend to use it in a newer one you need to know that in the past, the 5V rail was used more than it currently is. So, even if the rated wattage appears to be what you need, the 12V rail may be under powered.

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#3
November 21, 2012 at 21:41:45
✔ Best Answer
Thank you very much for the reply. I opened up the cover for the power supply, there was a lot of dust built up inside, used compressed air to clean as much as I could. Put it back together and teted again and it worked(guess it was Luck)
I wanted to thank you again for your time. Have a great Thanksgiving day.

Best regards,

Ben


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Related Solutions

#4
November 22, 2012 at 09:01:37
You must be very careful when opening a power supply. There are charged capacitors inside that can harm you. No need to open the case to blow it out. In the future just blow out from both ends.

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#5
November 24, 2012 at 01:52:03
Thank you OtheHill, I will keep that in mind.

Regards.

Ben


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