XFX Radeon 7770 Possible Short

[leotron]

Hello there this is my 2nd post in this great community, always reading and learning something new.

I'm going straight to the point, I have this graphics card XFX Radeon HD 1ghz Edition which I was using with a faulty PSU (CoolerMaster 450w), I said faulty because the PSU was old and showing some symptoms, like the power wasn't enough for this card, so to in order to use it I decided to underclock it and it keep functioning. One day suddenly the PC reboot and the card is not displaying any signal or it's detected by Windows or Linux. When I plug this card in the PC the fan spin at full speed for a few secs and then it lower the speed at normal, I read in another website that this is a signal that it's shorted.

Going back to the card I'm going to describe what I found, primarly the 4 mosfets in the right side of the first image, I retired them I check with a multimeter and they are OK (not shorted), the PCB is the problem since the place where is soldered it's shorted. And a few other caps near that are shorted too but this maybe be something normal since some of them acts like a filter.

I suspect of the PWM , it's a APW7098 and I need some knowledge of yours to give me a clue where to start.

Also I found this other thread which discussed a similar problem, found it very helpful https://www.badcaps.net/forum/showthread.php?t=35004

In the attached images I marked with green the components that aren't shorted, and with red those who are. Some of them I desoldered to check if they were faulty.

Best regards.

[piernov]

Re: XFX Radeon 7770 Possible Short

What is the exact resistance to ground measurement on GPU VCore?

[leotron]

Re: XFX Radeon 7770 Possible Short

I'm sorry but I double check the resistances in the mosfets pins around the crossfire section and it give me another resistance. I'm gonna attach the corrections. Also I check resistance from GND to the 3 coils nears the mosfet and GND to the 12v pins molex.

What is the exact resistance to ground measurement on GPU VCore?

Thanks for answering, I'm sorry to ask you this but how do I find the VCore pin? I found an image of another GPU on the internet.

https://i.imgur.com/FpXZPxT.jpg

Thanks for your time, I'm gonna give an opportunity to this card before I sold for scrap.

[piernov]

Re: XFX Radeon 7770 Possible Short

GPU VCore is the section you were working on.
Resistance can be measured between inductors pins and ground (large black squares, I don't see marking on those 2 unlike the other ones) or across the capacitors leads (the silver/blue capacitors) that you previously removed.

EDIT: sorry answered without looking at the picture. There doesn't seem to be any short to ground on this board. What is the voltage on GPU VCore when it's running?