[SOLVED]820-3787 MacBook Pro 15 no GPU core

[Salvatore951]

820-3787 MacBook Pro 15 no liquid damage, PPVCORE_GPU is about 60mv, I replaced u9300 but no changes.

Macbook boots os fine, keyboard backlight turns and I can hear OS sound, but there is no backlight and no video.

GPUVCORE_EN is 3.25v
GPUVCORE_PGOOD is 3.2v

 

[Salvatore951]

customer send me this picture that show initial problem, now I revived it it has no video.

 

[aprendiz]

Unplug display and try external only, also try another display assembly...

 

[Salvatore951]

obviously I already tried woking display but no changes. There is no ppvcore_GPU, I can't get video without vcore. Could you help me to diagnose Gpu vcore problem?

 

[dukefawks]

There will be no ppvcore_GPU while booted in OSX as it will be running on Intel GFX. Is ppvcore_GPU present when it is just powered on without being booted?

 

[Salvatore951]

I fixed by replacing lcd and clearing pads under u9300, probably Chinese refurbished lcd screen is not good quality as original one and caused artifacts or no signal.