Blown fuses on Gigabyte GTX 980TI 6GB

[MrzPdlch]

Hey everyone,

I just went ahead and unscrewed a faulty GTX 980 TI from Gigabyte. What I found beneath the cooler was, as it seems, a common issue of that card. Two blown fuses on the bottom right corner of the card next to a MOSFET.
Now my question would be if there is any schematics of that card available to figure out which are the blown components so I can try and replace them together with the mosfet if needed.

Find some pictures of the actual GPU together with a picture of how it should look like.
I also wonder whther it might be a problem that there is some of the PCB layer gone next to the two blown fuses?

I'm only just starting my journey, so please keep that in mind if my questions were stupid

PS: I've seen the other entry about the same card, but unfortunately there are no schematics either.

[Aliencomputres]

Heloo,
Inject voltage on first fuse !

[MrzPdlch]

Heloo,
Inject voltage on first fuse !

Thank you for the reply!
Do you mean number C177?

[krsta]

The markings on the board are R17.. so they are resistors not fuses. To find what is shorted using voltage injection you would need to have a good resolution thermal camera.
You can not start injecting 12V because you dont know through what the line is shorted (example: it is shorted through core which operates at 0.9 to 1. something and you inject 12V you killed it )
If you want to inject voltage inject 0.9V and check with thermal camera.

I hope this helps a bit.

[MrzPdlch]

That makes a lot of sense, thank you for the reply!

I got myself a better camera by now and the needed tools to try my repair. I just wonder how I could figure out what value the blown transistors had. I attached some pictures of the pcb below.
another question: do I have to use a pcb sealer for the orange/copper areas?

I also assume that the Mosfet to the left is done as well (I see some solder balls sqeezed our underneath it). Any Idea where I can find a 22CA N7CC Mosfet?

[прямо]

They are probably 1206 size 0 ohm resistors.
You have to find out what is killing them before you can replace them, otherwise the same thing will happen again.

[MrzPdlch]

Thank you for your reply! I was about to find out whether the IC next to the two burnt resistors is also dead. Got me a thermal camera to see if there is anything happening on the board when I apply voltage, currently trying to figure out how I can make it visible.. any recommendations on the values for current and voltage when testing the gpu?

I also found this guy who basically only replaced one of the resistors also with a 0 Ohms resistor in order to have a fail safe option that can just burn through if anything else is failing again. https://www.youtube.com/watch?v=yD7Ud8fYGaw&t=313s

[прямо]

Which IC are you talking about? the mosfets?

You can measure their gate to source resistance to determine if they need to be replaced. Refer to the datasheet as to which pin is the gate and which pins are the source.

A good mosfet should have a gate to source resistance higher than 4 Mega ohm (some meters will even read OL/over limit)

[MrzPdlch]

Thank you for the tip! Yeah I mean the mosfet with the description 22CA N7CC (datasheet attached). But how can I apply voltage to the GPU with a desktop PSU in order to figure out if there are any more problems? Do you know whether there is a guide or something like this on this forum?
Thankful for any help or advice!

[прямо]

Btw, those blown resistors don't look like resistors to me in this photo. Maybe ferrite beads.

[speaktorob]

Btw, those blown resistors don't look like resistors to me in this photo. Maybe ferrite beads.

+1

Follow the trace in the boardview (attached, use FlexBV free to view it) for each component.

Have you taken any resistance readings, is anything coming up short?

[MrzPdlch]

Thank you two for the replies and the boardview! I was already giving up to find it since in another post about the exact same card nobody was able to share one.

speaktorob So far I can say that all D1 phases are shorted with all S2 phases from the specsheet of mosfet Q32. from G1 to G2 there is a resistance of 2.7M Ohm. in comparison, the mosfet Q29 does not have any shorts so I think that one is healthy, the Q32 is done and needs to be replaced.

Nevertheless I wonder what to do with the pads of R174 and R172 since you both are of the opinion that a ferrite bead was there before. In the video the guy soldered a 0Ohm resistior on the pads of R172.

so what are the actions?
- replace mosfet q32
- solder a 0 Ohm resistor to the R172 pads
- try the card in a test computer?

[speaktorob]

In the video the guy soldered a 0Ohm resistior on the pads of R172.

The beads are there to reduce unwanted noise from the electrical input. So 0 ohm resistors would work, but they might leave the MOSFET firing unpredictably. Maybe have a look at the datasheet for the new MOSFET you are putting in and see if it gives you the driving frequency - that's the frequency you want to isolate, e.g. have a ferrite bead with 0 ohm resistance for that frequency, but high resistance at noise frequencies.

[MrzPdlch]

Thanks for the explanation, I wasn't aware of that!

Now where to get these kinds of replacement parts? I was looking around at aliexpress and I found the Mosfet. But do you guys have a general recommendation where to buy these kinds of parts? I do have a lot of donor boards and gpus to steal from, but I would like to avoid transplanting parts with only little life left in them. Any best practices?

btw. I tested the card with in a test computer with a thermal camera attached and It was really good visible that the area around the mosfet heated up very fast. I stopped it at roughly 45 degrees to avoid additional damage or even more burnt caps/resistors.