820-00928-04

[iFix]

Hi guys.

I have this board that was liquid damaged and someone just cleaned it and left me small traces to follow for repair. When i got it was overheating U8295 which i replaced just to see but the same issue again. I measured all contact and it came to be a full short on pin 5 and 6 on U8295. Followed the line couldn't find the short but i injected voltage and the short was removed and now diode mode reading in the line is 0.112 tested with 2 different meters. With injected voltage now doesn't show any short but with external power supply shows 0.081amps pull. Any suggestions please?

Thanks

 

[2informaticos]

Which voltages do you get on the board?
5V, or 20V on USB-C meter?

 

[iFix]

20v

 

[2informaticos]

And nothing else?
Please, post some voltages/signals from power on sequence...

 

[iFix]

I'll update tomorrow probably was very busy today. Thank you

 

[iFix]

PPBUS_G3H - 12.6v
PPBUS_HS_CPU - 12.6v
PPBUS_HS_GPU - 12.6v
PPBUS_HS_OTH5V - 12.6v
PPBUS_HS_OTH3V3 - 12.6v
PPBUS_S4_HS_TPAD - 12.6v


PP3V3_G3H - 3.4v
PP3V0_G3H - 3.1v
PPVCC_S0_CPU - 0v
PPVCCIO_S0_CPU - 0v
Just stuck at 20v on usb-c meter

 

[2informaticos]

Please, do NOT waste time checking voltages in the same power rail.
Do you really think the voltage will change after miliohm resistors???

Do you get 3V3_S5/SUS?

 

[iFix]

Hi. Getting back to this old issue. Found a short on L2950 goes on the pin 2 side. I injected 0.9volts it's overheating the U2800... next step?

 

[iFix]

Also i'm getting 20v on all ports when plugged in with the usb tester.

 

[2informaticos]

Which is the exact vale of that short (ohm scale)?
Did you compare with good board?
If really low, then you need to remove U2800.

 

[iFix]

Yes after removing the U2800 short is gone. If i get from another board will it work please?

Thanks

 

[2informaticos]

There is a separate TBT ROM chip, not sure if U2800 has internal firmware board dependant.