820-3437 turns on and chimes but no green light

[[email protected]]

820-3437 board which it turns on for a few seconds turns of and again turns on and stays on but there are two issues
1: even thou there is no green light on the charger the board stays on after second time.
2; second time that it turns on and stays on the screen lights up for a second and after that the voltage drops gradually from 31v to 8.6v.

 

[JohnB8812]

This sounds like an SMC_LID issue. Tried known good DC in board and flat cable?

 

[2informaticos]

3437 board starts after two power cycles, so is normal.

Change U7701, possibly corrosion on its FB solder...

 

[[email protected]]

Dear Sir, Thanks for your replay, I've tested it with two other known working dc in boards. same result.
SMC_LID on keyboard connector pin 1 shows 1.5v

 

[[email protected]]

ok thanks for your help

 

[JohnB8812]

Please don't use comments we won't see it. If SMC_LID is 1.5 volts no matter what DC in/cable you're using, you have an issue with that data line. Inspect J9500, trackpad connector, and around the SMC for corrosion

 

[2informaticos]

Disconnect trackpad and LIO flex cables.
If SMC_LID is still low, check C4834 and R5171.
If stays at 3V without LIO board connected, check lid sensor from LIO...