Need help with an SGI PSU

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Steve
Posts: 2570
Joined: Fri Sep 15, 2017 11:49 am

Need help with an SGI PSU

Post by Steve »

Hi guys n gals,

I'm currently testing an SGI Indigo2 PSU 'PEC4074'. I didn't want to just put it into a machine and hope it works so I've been bench testing it. This is a 'ground to stop' PSU which should just turn on when AC is supplied and there is some loading on the rails.
  • It doesn't turn on when turning AC on
  • Tried using my load resistors & also a HDD on the molex
  • measured pin 5 (5v standby) which should always supply 5v even when off, it was only 0.15v.
  • when turning the AC off, the 5vSB voltage slowly discharges to 0 while making an audible spiralling deceleration high pitch noise.
I'm not a PSU expert and my method of fixing PSUs is usually a shotgun approach. I'm hoping there may be someone in this forum who is good with PSUs and may look at it for me. Happy to pay for time or with my own labour if you need jobs done.

Valuable info on this PSU, non impact model:
https://forums.sgi.sh/index.php?threads ... asics.111/

Here are some photos:

PXL_20210430_180220537.jpg
PXL_20210430_180220537.jpg (345.67 KiB) Viewed 2238 times
PXL_20210430_172046543.jpg
PXL_20210430_172046543.jpg (318.39 KiB) Viewed 2238 times
PXL_20210429_192107992.jpg
PXL_20210429_192107992.jpg (397.92 KiB) Viewed 2238 times
PXL_20210429_190102023.jpg
PXL_20210429_190102023.jpg (356.97 KiB) Viewed 2238 times
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DoG
Posts: 1125
Joined: Sat Apr 07, 2018 12:26 pm

Re: Need help with an SGI PSU

Post by DoG »

Apply +5V to power good pin to make it start up?

EDIT: Sorry. I was thinking the wrong way around. It's the PSU that gives 5V on that pin when all voltages are good.
Steve
Posts: 2570
Joined: Fri Sep 15, 2017 11:49 am

Re: Need help with an SGI PSU

Post by Steve »

It's supposed to auto-start as it is a 'ground to stop' and the SB is supposed to be 5v during idle... you think I can just ignore all that and try?
User avatar
DoG
Posts: 1125
Joined: Sat Apr 07, 2018 12:26 pm

Re: Need help with an SGI PSU

Post by DoG »

Ignore my input, I just edit my first post.
Steve
Posts: 2570
Joined: Fri Sep 15, 2017 11:49 am

Re: Need help with an SGI PSU

Post by Steve »

It's ok @DoG I tried that just a moment ago, but it didn't make any difference :(
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