820-01521 Intermittent backlight.

[ronaldo]

Hi, everybody.
I need some, please.
This Mac had liquid damaged on the Audio board and its cable.
I've replaced both of than and Mac started to turn on.
But it sometimes will have a backlight for a second when turned on and then goes off.
PPVOUT_S0_LCDBKLT_F - 43.45V
Even when the backlight is off, the voltage is 43.45V.
When it boots to the system with the backlight ON, if I close and open the lid, the backlight stays off.

SMC_LID_RIGHT - 0V / D - 0.612
SMC_LID_LEFT - 1.8V / D - 0.567

R4801 - Side PP1V8_SLPS2R 1.8V - Side LID_OPEN_RIGHT 0V
I've replaced R4801 and U4802 and still same issue.

Thanks for the help.

 

[2informaticos]

Right lid sensor corroded; is placed on the speaker cable.

Remove R4805 and check if machine works correctly.

 

[ronaldo]

R4805 was removed, and then I started to get 1.8V on pin 2.
So I decided to replace U4850, and voila, 1.8V was achieved.
Even then, the screen is not going to sleep. I replaced the right speaker and now everything is working fine.

Thank you.