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Sapphire RX560 4GB - SHORT
https://vlab.su/viewtopic.php?f=48&t=83263		 Страница 1 из 1
Micchaleq [ 22 ноя 2018, 19:12 ]
Заголовок сообщения:  Sapphire RX560 4GB - SHORT
Hi for everyone.

I have problem with RX560 4GB.
The problem is that I have shortcircuit and I can't find wrong component.
Firstly I check fuse (front PCB and red square) it was broken but also there are shortcircuit (green arrow). I tried apply power supply with 4Amps and 12Volts and after connected on the power supply I have about 0.007Volts and 4Amps. I dont know why volts are that small. Moreover nothing going hot.

After that I decided to lift up power section but the problem doesn't gone. Moreover I lifted up mosfet controller (RT8880C) where I have shortcircuit on enable. Futhermore I lifted up linear stabilizator where is short on the output site. On the second picture (back side of PCB) you can see area of controller and stabilizator and green arrow indicate shortcircuits.

My question is how can I check GPU before I lift it up? (it is dead or not). What can I measure and how to diagnose it in the next steps.
I can add that i have about 2 ohms on GPU (and i think that it is enough).
I suppose that GPU is ok because the production date is 1703.

Thank you for help.

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gserg [ 22 ноя 2018, 21:38 ]
Заголовок сообщения:  Re: Sapphire RX560 4GB - SHORT
I think that is the death of the mosfet in the power supply of the chip, in some of the phases to be detected is a low-power laboratory source fails, the faulty MOSFET needs to have a leak from the gate to the channel, check with a multimeter, good luck
Micchaleq [ 23 ноя 2018, 00:33 ]
Заголовок сообщения:  Re: Sapphire RX560 4GB - SHORT
gserg писал(а):
I think that is the death of the mosfet in the power supply of the chip, in some of the phases to be detected is a low-power laboratory source fails, the faulty MOSFET needs to have a leak from the gate to the channel, check with a multimeter, good luck


Thank you for answer.
I have written that I lifted up whole power section and the volts doesn't grow up. Moreover shortcircuit still present without mosfets . Hovewer I will try to do it second time. I will remove every component if i have to. I will start from those bigger.

On the other hands I have checked every mosfet (G-D, G-S, GND-G) and I had not any leak.
gserg [ 23 ноя 2018, 01:32 ]
Заголовок сообщения:  Re: Sapphire RX560 4GB - SHORT
then there are the capacitors, remove the aluminum
Micchaleq [ 23 ноя 2018, 03:39 ]
Заголовок сообщения:  Re: Sapphire RX560 4GB - SHORT
gserg писал(а):
then there are the capacitors, remove the aluminum


Yea that was it. One of aluminim capacitor was have about 50% capacity so I have replace it. However it wasn't main problem. SMD capacitor was broken. I have replace it. After that shortcircuit has gone. Unfortunetly before I had search near power section I take off GPU. Now I have to put it back and I will check if it is all or not.
Micchaleq [ 23 ноя 2018, 13:46 ]
Заголовок сообщения:  Re: Sapphire RX560 4GB - SHORT
Micchaleq писал(а):
gserg писал(а):
then there are the capacitors, remove the aluminum


Yea that was it. One of aluminim capacitor had about 50% capacity so I replaced it. However it wasn't main problem. SMD capacitor was broken. After I had replaced it shortcircuit has gone. Unfortunetly before I had search near power section I take off GPU. Now I have to put it back and I will check if it is all or not.
galkinvv [ 24 ноя 2018, 15:31 ]
Заголовок сообщения:  Re: Sapphire RX560 4GB - SHORT
No 12V leads are going directly to GPU, so even completely dead/burned GPU can't cause 12V short-circuit.
I think that highest voltage coming directly to GPU may be 5v, since DVI uses 5V-leveled I2C.
Micchaleq [ 26 ноя 2018, 20:41 ]
Заголовок сообщения:  Re: Sapphire RX560 4GB - SHORT
galkinvv писал(а):
No 12V leads are going directly to GPU, so even completely dead/burned GPU can't cause 12V short-circuit.
I think that highest voltage coming directly to GPU may be 5v, since DVI uses 5V-leveled I2C.


Thank you for answer. I haven't got much experience so every tip is very important for me. I will remember it. However I was desperate to learn and solve problem. Now the MDU1514 is broken (after I had replaced capacitor it broke).
gserg [ 28 ноя 2018, 04:36 ]
Заголовок сообщения:  Re: Sapphire RX560 4GB - SHORT
not a problem, the video core is powered by three phases, if you remove the MOSFETs from one of them , the chip will start on the other two and give a picture, it is enough to make sure that the video chip is working. It is important that other sources that do not supply the core work.
Micchaleq [ 18 дек 2018, 15:07 ]
Заголовок сообщения:  Re: Sapphire RX560 4GB - SHORT
Hello again. I have to refresh this topic because I still didn't solve problem.

Now the problem is with power on GPU and memory controller. Memory power 1,3-1,5V is present.

I think that GPU mosfets are controled by RT8880C. However on the RT8880C haven't power on enable and on VCC.
That is why my question is where I schould search. Which components are responsible for it.

On the linear stabilizator 5V and 12V are present.

EDIT:
I have checked that I have short on EN pin (RT8880C).
com77 [ 18 дек 2018, 15:38 ]
Заголовок сообщения:  Re: Sapphire RX560 4GB - SHORT
Change the PWM controller RT8880C :-):
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