820-3330 chime boot to black screen.

[Mac Repairs]

This board no liquid damaged.
Boot & chime to black screen. no backlight no video.

Tried with known working screen, no luck.

PPVCORE_GPU 0V. P1V5_GPU_S0 0V.
Appreciate your advice.

 

[2informaticos]

No reason to check another screen, if no GPU voltages present.
Try to resolder U8900 with leaded solder.

You can consider disabling GPU, if result to be faulty.

 

[Mac Repairs]

Hi thank you for advice.
Resolder U8900 still no video . issue is GPUVCORE_EN on on pin 38 not present.

 

[2informaticos]

Check GPU power sequence at page 92.