820-3332 GPUVCORE_EN missing

[macfix]

Hello everybody

I m working on liquid damaged 820-3332 , board is turning on, chime, usb mouse light is ok but no picture LCD. When checked voltage and heat GPU is cold and no GPU voltages, measured U8900 voltages and no GPUVCORE_EN. Its come from U9100 reballed and replaced also U9100 but nothing change . What can i do next step?

 

[dukefawks]

The next step should have been the first step, resolder U8900.

 

[macfix]

Thank you dukefawks but resolder and replaced U8900 same issue

 

[dukefawks]

GPUVCORE_EN only comes high when GPU recognized. It also does not stay high when all power good signals don't come on in time. Could be anything around the GPU area, corrosion under it. Maybe even a dead GPU too.