Dark Power Pro P7 750w

[Bungz]

Hello

I have a rather sick Be Quiet Dark Power PSU I stripped out of a machine a few months back.

Previously this has worked perfectly so I am not sure what has happened.

The 5V rail seems to have taken a dump. On boot, using a MM I can see the rail holds 5v fine for about 10 seconds then I get a audible whine (amplified with HD activity) and the rail goes all over the shop from 4.4-5v till the system restarts.

So as I am not much of a fixer beyond cap replacement could anyone give me a pointer?

Visually all looks reasonable.

Thanks!

[stj]

Re: Dark Power Pro P7 750w

could be a lot of things.
bad rectifier,
bad optoisolator,
bad reference (xx431 type device)

[Bungz]

Re: Dark Power Pro P7 750w

I am thinking that due to its symptoms should I identify those parts it would be possible to remove and replace / test them.

When I get time I will strip it down a little and remove all the rectifiers to get the heatsink out the way to see what is what.

[stj]

Re: Dark Power Pro P7 750w

given it takes a while, the faulty part may be heating up
so start with the rectifier(s)

[Bungz]

Re: Dark Power Pro P7 750w

That was my thinking, will try and get it in bits this weekend and update with pictures

[Stefan Payne]

Re: Dark Power Pro P7 750w

gotta love those huge capacitors on the modular PCB...

Anyway:
Have you checket +5VSB?

[momaka]

Re: Dark Power Pro P7 750w

Could also be a bad solder joint. Anything that looks dull or suspicious should be resoldered.

[Behemot]

Re: Dark Power Pro P7 750w

Isn't the input cap bulging? It looks like it, and it's crapxon, that's what they do.