820-3462 A1425 NO POWER

customer say lastime can power on fan was spinning so fast until the macbook dies.
no sign of corrosion sometimes have green light most of the time dont have light on magsafe

PPBUS_G3H 12.26v
R7020 16V

1 0v
2 16.3v
3 3.9v
6 3.4v
9 0v
12 3.4v
13 3.3v
14 3.1v
15 0.1v
17 12.28v
19 5.5v
20 5.5v
27 16v


Staff member
Looks like no communication between SMC and U7000.
Magsafe light behavior points to SMC related issue.
Check SMC_RESET_L first.
Try known good DCIN board also.
smc reballed nothing happens ppbus still 12.26V
i have osci but i dont know yet how to use it,
can give a little knoledge how to use it?


Staff member
If can't confirm oscillation, check for DC voltage at Y5010 pins; should get around 1-1.2V DC.
If 12MHz oscillation is there, SMC should work; change it, if not.