A1278 820-3115-B no chime

[hgoncalves]

Hello,

I have an A1278 820-3115-B, with no liquid damages, that has no chime. It powers on, but doesn't do anything. Just shows a black screen. Connected to the power supply, it consumes about 750mA.

Can anyone help?

 

[2informaticos]

The chime is not a relevant test.
Did you test USB activity?
Do you get voltage on all coils, including VCORE?

 

[hgoncalves]

Hello 2informaticos,
I have no activity in USB.
L9701 has 0V; L3895 has 2.5V on both pins; L7760 has 1.75V on both pins; L7520 has 0.9V on both pins. L7510 has 0.5V on pin 1 and 0.9V on pin2; L7550 has 0V on both pins.

 

[2informaticos]

Do you get 0.9V on VCORE from the beginning, or you note a drop from 1.15V?

BTW, measure coil voltages on the output pin only...

 

[hgoncalves]

On both coils i have 0.9V from the begining

 

[2informaticos]

Then board doesn't boot.
PLT_RESET_L goes high?
Try known good BIOS file.

 

[hgoncalves]

Yes, PLT_RESET_L is 3.3V