AMD R9 270 -- dead after power supply short

[AMD_Ripper]

I have an R9. the problem is not unknown. I know clearly what happened. I was working on a home made fan I took from a server and one the PSU molex wires were exposed and grounded to the case or the 5v+12v touched and grounded. There was small spark and poof and the system shut down.

The card never turned on after that. No burns its like new.

Interestingly the power led's work, green when PCI is on and red when is off so its getting some power. However the card doesn't display anything and takes about 3 tries to power on to get the fans on, but never turns on display or detects as a slave when using multiple cards.

So no burn but no display / detect either.

My first guess was that the card is ok only the ROM got corrupt. But i'm not sure if this is even possible since I don't know video card architecture much.

I'm familiar with board level repair, did many power supplies since they're easy but not much experience with video cards and looking for a starting point.

[RJARRRPCGP]

Re: AMD R9 270 -- dead after power supply short

takes about 3 tries to power on to get the fans on, but never turns on display or detects as a slave when using multiple cards.

So no burn but no display / detect either.

Sounds like a damaged cap or SMD component...

[AMD_Ripper]

Re: AMD R9 270 -- dead after power supply short

I think it will be a mosfet. I'll update the thread with pictures and info as I figure it out but I'm looking for somewhere to start with a voltmeter. I don't want to start by de soldering parts because the R9 looks so fragile and hard to get to. Some of this stuff I'm just going to have to burn off and replace even if it was good or bad. I don't know or have anything to test capacitors in circuit. I do have a cheap cap tester that works ok on power supply type caps.

[AMD_Ripper]

Re: AMD R9 270 -- dead after power supply short

Reference Pics

[mikkhh]

Re: AMD R9 270 -- dead after power supply short

Measure the resistance from the chokes to ground.

[momaka]

Re: AMD R9 270 -- dead after power supply short

I doubt the short-circuit caused the ROM on the video card to go bad.

My best guesses about what might have happened, without more details, are as follows:
a) If PSU is from a crappy manufacturer, then the short-circuit could have cause the other output rails from the PSU to temporarily go crazy (possibly too low or too high or huge ripple/noise), thus killing a sensitive IC on the video card.
b) The video card had developed bad BGA on the GPU chio. Once that PSU shorted and the card turned off and cooled, the bad BGA made the GPU not work any more.

If it's case b) above, then a reflow is all that may be needed to bring the video card back to life.