Question What are the most common parts that go bad in ATX power supplies?


Jul 5, 2017
I have a number of ATX supplies that are dead. I want to try to repair them, instead of spending more loot on replacements. What I'd like to know is , what are the most common parts that you need to repair ATX power supplies? I know, a lot of electrolytic capacitors. But what kind of diodes (voltge/amperage/device number), rectifier bridges (the same), power FET's (device numbers) and other common parts should I be stocking? I don't want to make the 25 mile drive to the parts store to find those parts. Thanks for any help you can provide!
First you need to determine if a particular PSU is worth spending time, money and effort on. If it lacks typical protection circuitry then it's likely a waste of time to bother. Conversely, most quality PSU's that have a full range of protective circuitry aren't as prone to fail in the first place and if or when they do, they're covered by a longer warranty that cheaper models don't have, in many cases. Things to consider:
  • Does it meet ATX and EPS 80 plus specifications?
  • Is there a thorough evaluation, by a reputable review site, of the model to begin with?
Does it have:
  • Continuous output rated temperature > 40C.
  • OCP: Over current protection.
  • OVP: Over voltage protection (and under volt protection).
  • OPP: Over power protection.
  • SCP: Short circuit protection.
  • OTP: Over temperature protection.
There's more to consider than this, but the point is, a power supply with such protection and quality that finally fails, will, for the most part, have already served its usefull life and be ready for replacement and not repair. You may find it rather rare to find a worthy subject to repair in the first place. I realize this doesn't answer your specific question. I just felt it important that you approach the subject from an informed point of view and you should 'cherry pick' what you spend your time and money fixing. Many PSU's are destined for the trash bin from the day they were made.

PSU's 101
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Reactions: darknightbacca1
Jan 23, 2020
In my experience its nearly always a dried up old capacitor, one or both of the large ones. They are usually easy to spot because the top goes domed instead of remaining flat, same with tv's that get stuck in standby.

Capacitors in cheaper items usually have approximately a 2 year-ish life expectancy, reduced when used for longer than usual per day.

Of course other parts can blow or die, check the boards for burn marks, check the rectangle quick discharge capacitors for side swelling.

It goes withoug saying do all this with the power off and items discharged and/or earthed. Be Safe.