820-00840

[iFix]

Hi, repair people

I have this A1708 MB that had no power. There were shorted caps C6425 and C6405, both CD type C controllers, and a P13USB32 chip(not on schematics or BW). After all that I plugged in and got 20v, it stays around 0.046 and then goes to 0.056. All Ics are taken from another board for parts. One Type C is from 820-00928 board but the same controller.

PM_EN_P1V8S0 was missing so I replaced U7852, and no change. On U7852 I only have PP3V3_S5 and it's going up and down from 0.4v to 3v.

PM_SLP_S3_L is 0v

PP3V3_S5 Diode mode is 0.330

Thanks

 

[2informaticos]

"On U7852 I only have PP3V3_S5 and it's going up and down from 0.4v to 3v
-------
PM_SLP_S3_L is 0v"
Why did you touch U7852 then?

You must get steady 3V3_S5 first.
Check diode mode to ground on all big coils.
Test SMC bypass mode.

 

[iFix]

U7852 contacts were looking funny, and with a new one, I got the same readings. The big coils all have good value, except for L7900 pin 2 PPVCCPCH_S5G is 0 reading diode mode. That leads to GPU. When I inject 0.5v the GPU heats up on the thermal camera. Also L8060 pin 2 takes voltage when injected and heats up the same place on the GPU. When all in place could soldered back it's heating up as you can see on the attachment and C6465 heats up but measurement on it and that line are fine diode mode 340. Gpu gone?

PP3V3_S5 diode mode is fine, just voltage spikes as said before

 

[2informaticos]

"Your GPU" is the PCH in fact; PPVCCPCH_S5G!!!

In such case, the board is trash; not worth to change the CPU.

 

[iFix]

Yes PCH, not gpu. I was working on another board and thought I wrote PCH, not GPU, no harm done, and my GPU is not mine, it's the client's. I understand the difference between a GPU, PCH, and CPU if you're worried about that

Thanks, 2informaticos for the help as always