Need help to repair low voltage from gray Power Good wire on Antec Earthwatts 500W Power Supply

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ZhouYu

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Hello World!

My computer powers on without POST. Fans and other devices are all on but there is no BIOS. I need some guidance on how to repair an Antec Earthwatts 500W power supply on my own.

Layout of the PSU can be found at http://www.hardwaresecrets.com/article/Antec-EarthWatts-500-W-Power-Supply-Review/526/

What has been done :
1. Tested with another Power Supply - computer powers on and OS boots up.

2. Jump started the PSU through the green wire and measured the voltage. 3.3v, 5v (red + purple), 12v, -12v are all within their respective tolerable range. Gray "Power Good" wire shows a reading of 0.06v which is far from the expected 5v or somewhere between 2.5v-5v.

3. Replaced all bloated capacitors.

4. Tested (by unsoldering 1 leg) the only diode I could see and it is good.

5. Couldn't see other burned/damaged components.

Are there anything else I should be checking without taking apart every component to see if they're damaged?

I've also read http://www.tomshardware.com/answers/id-1790542/repair-psu-dead-rail.html that there could be some diodes on the heatsinks, but I don't see any in the photos above. And I'm thinking that apart from being 5v, it is not related to the 5v red wires, so it shouldn't be the diodes.

Thanks in advance.
 
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ZhouYu

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Oct 28, 2014
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Thanks Novuake and DelroyMonjo.

Yes I fully understand the risks. Well, I've sent my previous PSU for repairs before, and it exploded after I got it back. I was lucky back then that it did not kill other parts in my computer, and understand that I might not be so lucky this time.

I've searched Google several times a day the last few days, no luck in identifying the potential faulty part.
 
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antec support

antec support

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Hi,
Is that a new system you run first time with that old PSU? Normally, if it would be the PG Signal, the PC would power on for 1-2 seconds, but then power down. You describe it like the fans keep running, just no BIOS. This sounds more like MB or CPU are broken. You can check another PSU, if that is ok, then it is the PSU. But if it is a new system, it can also be that the PG Signal is ok, just not compatible with the system. This is about timing and sequencing of various voltages as a PG signal.
 
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ZhouYu

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I didn't expect to have Antec Support here :)

It's my old system and I've been using this power supply on this computer for 4 years (but I don't think it should go yet, since most of the computers in my office are much older, runs 24x7 and none of the PSU died). PC powers on, fans on, hard disks on, everything on and stays on. Only no BIOS Power On Self Test (POST).

Yes I've already tested with another PSU and computer boots up and works perfectly fine.

I'm also guessing that the problem probably does not lie with the Power Good circuit but probably there is indeed some problem with my PSU. Couldn't explain why the rest of the voltages appear stable though.

Thanks
 
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antec support

antec support

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It can be a blown diode or cap, but it can also be other things which have changed the phasing and interval of the PSUs PG Signal due to component aging. If you have already (correctly) replaced all blown/bloated caps & diodes, there is nothing you can do. We cannot handout the circuit schema as such. Sorry.
 
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ZhouYu

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Oct 28, 2014
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Thanks Antec Support. Don't think I can understand the circuit schema anyway :)

You've been a great help. I guess it's due to aging component unless it has something to do with those attached to the heat sink that I did not remove. One thing I recalled is that back then, I could hot-plug a SATA hard disk. Recently it will reboot my computer if I do that. No reboots with the other PSU.

I'm still curious how those PSU in HP and Dell desktops lasted beyond 8 years. Mine generally lasts 2-3 years, so this Antec model lasting 4.5 years is considered good, but it's also the most expensive I had :)
 
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