FSP FX700-GLN problem

[S-10]

I have a FX700-GLN made by fsp. I plug it into my motherboard(Abit IP35 PRO), and the 3.3v light blinks, as do a USB fan when hooked to the USB ports. Nothing else. No power at all.

I checked all the caps and none seem to be leaking or bulging. Could they still be the problem, or could it be another component? I tested the PSU on another older board, and nothing, so the PSU is obviously the problem.

Thing is, about 3 weeks prior the supply was working fine. No issues. Cut to a few weeks back, I unpack it and try turning it on and I get the quoted symptoms.

Any ideas?

[370forlife]

Re: FSP FX700-GLN problem

Disconnect everything from the power supply, plug in an old disposable hard drive or two for just a light load. On the main 24pin connector, there should be a green wire, that is the PS-ON wire. Short that to any ground, and it should turn on.

If it dosen't, sounds like you have a short somewhere on the secondary. In that case you are going to have to remove the PCB from the casing and start searching for solder hairs or little solder balls that may have come loose and shorted something. If you don't find anything there, start checking the secondary schottky diodes on the secondary heatsink for shorts.

[S-10]

Re: FSP FX700-GLN problem

I'll give that a shot when I'm able to. Thanks.

If it's a short, why would it take to now to start showing symptoms? I've had it for at least 2 years with zero trouble.

[S-10]

Re: FSP FX700-GLN problem

Disconnect everything from the power supply, plug in an old disposable hard drive or two for just a light load. On the main 24pin connector, there should be a green wire, that is the PS-ON wire. Short that to any ground, and it should turn on.

Tried that. The fan doesn't come on, but I do hear some sort of, not really clicking, but some sort of noise.

What would that indicate?

[Behemot]

Re: FSP FX700-GLN problem

Poorly made transformer. Still, it does not mean it's bad, worse is if you have such an transformer e.g. in your display and have to listen to it all the time

As for the timing, if it's short or cold-solderend joint, this usually takes some time to show up. It can overheat locally or you have knocked off with it during transport etc.

Also it could actually be bad caps, FSP uses CapXons and Teapos, IIRC they often die without bulging or leaking.

[S-10]

Re: FSP FX700-GLN problem

Thinking about the short - I unplugged the PSu, smacked it on the bottom hard twice - the fan kicks on for a good 5 seconds. I plug it to my motherboard and everything seems to be working fine.

I didn't hear anything fall out, so I'm not so sure it was a piece of solder or some other problem.

Any idea what it could've been if not a piece of metal shorting it? Strange how smacking it worked.

I'll look into new caps anyway.

Thanks for the suggestion, 370.