Corsair CMPSU-400CX blowing it's fuse

[bocca]

Hi all!

I have this PSU on my desk. I used it as a reference PSU, for testing when doing servicing and all. One day there was a distinguishable soft bang inside, and although i suspected the fuse, proof came when i opened the unit.
fuse was indeed blown. Inside was glass 7A 250v fuse. As i have about a dozen laying around I trien with another one. Plugged in the PSU, took my faithful Antec PSU tester, and there it was again. Fuse blown.

I tested all the diodes, no caps are bulged (Su
scon caps are inside, excepth the big one which is either no name or SMQ labeled).

What would be the next step?

[Khron]

Re: Corsair CMPSU-400CX blowing it's fuse

Next step? Testing if the pair of APFC switching MOSFET's is shorted or not. The easiest way should be to unsolder the whole top-most heatsink (in the first two pictures).

[ben7]

Re: Corsair CMPSU-400CX blowing it's fuse

Just as Khron666 suggested, and, the bridge rectifier might be shorted too.

[tom66]

Re: Corsair CMPSU-400CX blowing it's fuse

Or the main switching MOSFETs, or standby switcher.
The SMQ cap is a Nippon Chemi-Con, or just a Chemicon capacitor. It is a decent capacitor.

[videoyves]

Re: Corsair CMPSU-400CX blowing it's fuse

Hello,

Can I re-open this post, as I have a problem with the same CMPSU-400CX PSU ?

The pictures posted by bocca are the same as mine.

Except that my PSU had burned this "TR 301", I don't know what it can be !?
The full reference can't be read. (two pictures attached)

So, I need your help...

[Per Hansson]

Re: Corsair CMPSU-400CX blowing it's fuse

It's a thermistor

[momaka]

Re: Corsair CMPSU-400CX blowing it's fuse

As Per said, it's a thermistor. Appears to be an "SCK-054". Look it up online, that's the part you need.

By the way, this PSU seems to be made by Seasonic S12II platform, IIRC. Same (or very similar) as older Antec EarthWatts EA-380, EA-430, and EA-500. Just putting these tags here in case anyone with this PSUs runs in the same issue.

Also note that these PSUs typically have less-than-stellar output caps (the old Antecs typically have OST RLS/RLX, while the PSU above as Su'scon SD). So PSU might need a recap down the road.