Hi everyone,
I bought a GIGABYTE NVidia GeForce GTX 1060 OC 6GB from ebay which was declared to be "working", unfortunately it is not.
A quick check gave me the result: defective Mosfet and burned fuse.




I already swapped both and the card started again, but after around 10 minutes under load both components are defective again.

The defective Mosfet is a AON6414A.
Any further suggestions what I could check?

Thanks in advance!

Probably driver is damaged aswell.
You will have to replace it (it's in the same position as mosfet but on backplate)

Probably symbol will be A4U or A4K and it is NCP81161

Thanks!

I think i found the drivers.
The label says "AZK".
It should be a NCP5901B then or am I wrong?



There are four of them mounted on the back.

Is there a way to check if it is defective?

yes, you be right

Check PWM following the schematic below
https://www.onsemi.com/pdf/datasheet/ncp5901b-d.pdf

Each driver is responsible for each phase of GPU power.
Check the driver that is on the site of damaged mosfet

Since I am still a noob in this.
Am I correct that I first have to desolder the defective MOSFET and swap the fuse to measure the PWM Signal?
Since currently there is still the short circuit due to the defective MOSFET.

Sorry for the (maybe) stupid question.

thrinrot
The driver changes with the mosfet. You can call with a multimeter. The driver has pins to control the gates of the upper and lower arm mosfets.
Check RC circuit for driver power supply.

There have some chance that driver have survived, but usually driver changes together with mosfets. Desolder mosfets for that phase and check with scope.

Can you please make voltage measurements on the U504?

First: thanks to all for your advices, unfortunately I did not find time to check it because of wedding preparations.

@JooereX: do you have an approximate position of U504 for me? I have no schematics for this board, what makes it hard to find it. Edit: Found it

Think I'll do my next repair session on sunday. Ill reply back afterwards what I found out.

Thanks so far to everyone of you! I'm still new to this forum but I already like it.

@JooereX
I made the measurements. The component markings read 702 H3. Do not know what this 6pin IC is, could not find a datasheet.
Voltages are shown upon the picture:




@others

I found which driver belongs to the defective MOSFET and tried to do measurements on the solder pads of the corresponding MOSFETS, but my oscilloscope simply shows nothing.
Unfortunately my scope does not show anything for the other MOSFETS too.

Tried to measure between Gate and Source for the higher MOSFETS and also Gate and GND.

Since I am a noob in this and it cant be that all MOSFETS are defective: What am I doing wrong?

it's double n-mosfet 2n7002dw. but it's not element U504, it's element Q30.
u504 right side from text "u504" (about picture), it have 5 pins.

Now i measured the correct IC ... thanks for the advice:

After swapping the driver and mosfet together the card is working fine again. Had to wait for driver delivery for testing.

Thank you all!