820-3787 no image external/Internal

[BCN_Techs]

SMC_LID 3.4V.


I tried to connect external by HDMI and Thunderbolt nothing changes.


Usually this models get GPU hot when you turn it on. In my case it's completly cold. Only CPU is heating.

 

[2informaticos]

Why do you expect hot GPU, if doesn't get voltage?
You probably have a problem with U9600 now; reball it.
If no result, change it.
Maybe need to change U9300 too.

 

[BCN_Techs]

about 9600 it can be taken from 3332 or must be same board like smc?

u9300 already changed

 

[2informaticos]

U9600 has firmware and pick it from same model board.
I'm not sure if works from other board...

 

[BCN_Techs]

ok. changed ( reballed left same result. Changed both u9600 and U9300 for second time, but same result


Any other suggestion?

 

[2informaticos]

Bad GPU probably...

Do you get GMUX_SLP_S3_BUF_L?
Check U9600 (SYM 3 OF 3) area.

 

[BCN_Techs]

GMUX_SLP_S3_BUF_L is present 3.4V


And SYM 3 OF 3 Area cant see anything bad.


IF GPU is bad why its not powering even if bad.

 

[2informaticos]

"SYM 3 OF 3 Area cant see anything bad"
Voltage rails and reset good?
Do you get oscillation at Y9600?

 

[BCN_Techs]

DPMUX_UC_RESET_L
DPMUX_LRESET_L

both 3.3V

About Y9600 cant tell you, dont have osciloscope right now.

 

[2informaticos]

Should I suppose both power rails OK?

 

[BCN_Techs]

Yes. Both must be 3.3 tha right? If so both are ok.

 

[2informaticos]

I can only suspect bad GPU.
It has more blocks, apart of CORE.
Some of its blocks should talk with CPU, before GPU VCORE is enabled, I suppose.
Could even be a CPU issue, on the communication side with GPU...