Hi guys/gals,
I'm new! Sorry to begin with such a large ask for advice & help. I'm currently trying to bring 'back to life' this PEC4074 PSU which is designed for a Silicon Graphics Indigo2 machine. These aren't standard ATX at all, also as far as things go these PSUs aren't known to have been repaired by *anyone* before, there are even people with 30+ broken units hoping to fix them one day. I honestly hope I might get some good pointers here, so thanks in advance.
Link to specifications and pin-out of the PSU 'non-impact model':
https://forums.sgi.sh/index.php?threads/indigo-2-power-supply-basics.111/Initial observations:
* Unit *should* automatically power up as soon as AC is supplied, but doesn't.
* Nothing on 'standy power' (should be 5v)
* Nothing on 5v / 12v rails
* Load resistors were used & also a molex hard drive, to try and load the psu.
What I have just finished doing:
* Re-capped the *entire* unit
* Replaced some mosfets in an area which was 'burnt' / 'darkened'
* Replaced a crumbled resistor in the same area
* Replaced the optoisolator in same area (Photos provided)
New observations after what I've done:
* Now getting 6.6v on standby voltage
* Fan visibly 'twitches' like it wants to go, before it didn't
* Tiny amount of voltage on 5/12v rails now, about half a volt
Any advice much appreciated!