Corsair HX650 no power (possible fix ?)
Good day folks. I've got a pretty tempting project on my hands here: someone gave me a Corsair HX650 semi-modular PSU to have a look and said I could keep it if I can't figure it out...how could I say no to that ? 
The game was on !
So: the thing doesn't turn on despite 5vSB being present on the purple wire - one of the worst case scenarios and the most difficult situations to diagnose....
Took the board out (which took way longer than necessary) and started measuring stuff...no shorts in any of the main semis, obviously, since the fuse is OK and has standby. No obvious signs of capacitor failure either.
I slowly began tracking the problem down to the only major component that could pe causing this sort of behaviour: the UCC28515 IC located on a small riser in the very corner of the supply, tucked away behind the PFC coil....ok, now what ? I browser around a bit and found THIS where they actually managed to fix one. It's a different corsair PSU, but it's almost identical nonetheless. I'm hoping there are some native russian speakers around here who can translate that better than google can, but it was enough for me to sort-of get the gist. Apparently I was right on the UCC IC being the cause: it's not receiving VCC due to a small SMD transistor gone bad, apparently Q306 from what I can make out. I don't have the PSU in front of me right now, so I'm having a hard time following where this transistor is located, esp since they weren't clever enough to actually mention the damn part number :| I THINK it's near the pins where the daughter-board plugs into the main PCB.
Will do some more testing tmmoz and post back. Just wanted to open the thread in case someone had a similar experience or at least one that comes close and can provide some feedback. Cheers....no need for pictures since the russian forum has all you may need
The game was on !So: the thing doesn't turn on despite 5vSB being present on the purple wire - one of the worst case scenarios and the most difficult situations to diagnose....
Took the board out (which took way longer than necessary) and started measuring stuff...no shorts in any of the main semis, obviously, since the fuse is OK and has standby. No obvious signs of capacitor failure either.
I slowly began tracking the problem down to the only major component that could pe causing this sort of behaviour: the UCC28515 IC located on a small riser in the very corner of the supply, tucked away behind the PFC coil....ok, now what ? I browser around a bit and found THIS where they actually managed to fix one. It's a different corsair PSU, but it's almost identical nonetheless. I'm hoping there are some native russian speakers around here who can translate that better than google can, but it was enough for me to sort-of get the gist. Apparently I was right on the UCC IC being the cause: it's not receiving VCC due to a small SMD transistor gone bad, apparently Q306 from what I can make out. I don't have the PSU in front of me right now, so I'm having a hard time following where this transistor is located, esp since they weren't clever enough to actually mention the damn part number :| I THINK it's near the pins where the daughter-board plugs into the main PCB.
Will do some more testing tmmoz and post back. Just wanted to open the thread in case someone had a similar experience or at least one that comes close and can provide some feedback. Cheers....no need for pictures since the russian forum has all you may need
Comment