500W ATX PSU that won't power on at all

[maverick530]

I have a 500W modular ATX power supply that all of a sudden one day did not turn on.

When I ripped it open since I saw some bulging caps, I also noticed this burn mark on the underside of the board.

It looks like a fried CR211 chip with a 152 on the chip itself. Does anyone know what this chip is and whether or not I need to buy a new one?

This is my first PSU fix, but I've been fixing LCDs for the past year. I'd love to save this PSU from the dumpster since it's a nice modular one. Any help would be greatly appreciated. Thanks!

[Khron]

Re: 500W ATX PSU that won't power on at all

That's an smd resistor, 1.5 Kohm in value. Seems connected to the gate drive transformer, and one ond of it is connected to something in the 5Vsb area...

Judging by the burn marks, it WILL need replacement, but it would be best to find the root of the problem. There's a chance that, if you replace it, that's gonna fry as well, and possibly do even more damage.

Hmmm... What're the odds the 5Vsb went over-voltage and fried this resistor on the way to the gate drive trafo?

[everell]

Re: 500W ATX PSU that won't power on at all

Looks interesting. What brand and model number. Post some pictures of the top side of the board so we can see what you have.

Good way to start is to get out that ohm meter and check the transistors in the 5vsb circuit, check the main switching transistors, and check the output diodes. If any of these large transistors/diodes are shorted, it is a great clue as to where the problem area is. Also check the fuse - it may be open. Let us know what you find.

[maverick530]

Re: 500W ATX PSU that won't power on at all

It is an ULTRA XU-ULT500P, sorry I don't have pics of the top-side yet.

[370forlife]

Re: 500W ATX PSU that won't power on at all

Wintech, really not a bad unit once recapped. Definitely try to save it.

[maverick530]

Re: 500W ATX PSU that won't power on at all

Here's a pic of the top side.