820-01814 liquid damage - Powers on with no display

[nik1981]

Liquid damage around J5100 and some on the LCD connector on the screen end.

Removed J8500 ribbon as that was burnt at the screen end. Replaced the ribbon.
( PP5V_S0SW_LCD pin was burnt at screen end ) No short on this line.

Cleaned area around J5100, connected board to a good lcd to test.

Board powers on (PPBUS_HS_CPU 12v), fans spin, no chime, no caps led, does have power and activity on USB. No display, no backlight.

PP3V3_S0SW_LCD 0v
DFR_LID_OPEN_L 0v

I'm a little stuck now

 

[2informaticos]

Check diode mode to ground at J8500's pins 1 & 3.
Do you get external video?

 

[nik1981]

Delayed response to your reply 2informaticos, sorry.

Pin 1 & 3 are both .401v in diode mode. This seems normal as far as I can tell.

 

[nik1981]

There is no external display. The board seems to power on with fans spinning at a normal speed for 10 seconds and then the fans burst to 100% for 2 seconds before restarting the cycle.

The J8500 reading from S-UEM2 shows pins 31, 33, 37, 38, 39, 40 all slightly high. I've attached a photo

 

[2informaticos]

If no external video, most likely bad GPU.

Do you get USB activity for sure?
No jus USB power...