820-3476 Green/orange light but no pwr on.


Good afternoon.

I got an 820-3476 that did not turn on: ppbus gave 0.60V.
I reballing SMC and it turned on but it had a graphics error: the system detects 15mb on the graphics card and 42 "on the screen.

I have tried 3 SMC's from donor boards and none works: it only gets started with smc bypass.
I connect the charger, green light, orange light, fan rotates 1-2 seconds and stops.

ppbus_g3h - 12.52V
PP3V42_G3H - 3.41V
PPVRTC_G3H - 3.41V
PP5V_S5 - 5V
SMC_LID - 3.41V
PP3V3_S5 - 3.32V

Thanks in advance.


I did what you told me but I couldn't see anything abnormal.

Add that when I connect the charger, PM_SLP_S4 / S3 / S0_ L, they give me 3.3V until the fan stops (1-2") and they drop to 0V.


Staff member
If board boots in SMC bypass, there is an error with a SMC sensor.
Should be current, or voltage sensor.
Post a picture of HWMonitor with these sensors.


Finally, I have been able to solve it thanks to 2informaticos.

There was no communication between R7151 and R7150: I jumper and it starts, but the fan turns at maximum; I run an ASD and it tells me there's a problem with the fan but nothing else.

SMC replacement (had replaced 3 before) and the MacBook works 100%.

It can be considered solved.