MacBook Air A1932: no power, no fan spin

ciup

New member
MacBook Air (Retina, 13-inch, 2019) A1932
Part Number: 820-01521

Problem: does not turn ON, no light on LCD, no fan spin
Board: looks pristine, no liquid damage or corrosion

Power on USB PowerMeter with battery disconnected:
5.12V/7mA when power connected to USB-C port A
5.08V/300mA when power connected to USB-C port B

Voltages:
PP20V_USBC_XA_VBUS: 5.16V
PPDCIN_G3H: 0V
PP3V3_G3H_RTC: 0V
CHGR_EN_MVR: 0.08V
PPBUS_G3H: 0.054V

Fuse: F3000 and F3010 good

Resistance measurements:
F3000 to GND: 28Kohm
F3010 to GND: infinite
 

2informaticos

Administrator
Staff member
First of all, welcome to the forum!

Looks to have a problem at USB-C ports, as doesn't have same behaviour on both ports.

Post diode mode to ground at R7020, F7000 and L6960.
BTW, red probe connected at ground!
 

ciup

New member
The PP20V_USBC_XA_VBUS is supposed to be 20V the moment the USB-C power is connected to port A. But instead of 20V, there is only 5.16V.
Looking at the schematics, by design, there is no circuit connected on the PP20V_USBC_XA_VBUS that can change/control the voltage from 20V to 5.16V.
This means that the problem must be on PP20V_USBC_XA_VBUS (9 decoupling capacitors, D3300, D3301, inside U3100 or inside Q3100). The problem cannot be after the Q3100 (N-MOSFET), meaning the problem cannot be on PPDCIN_G3H or the circuits on that bus.
Do you think my logic is correct?
 

2informaticos

Administrator
Staff member
USB-C ports will switch to 20V after PPBUS_G3H appears.
Even more things need to happen also.
Once CD3215 chip receives VBUS, it should open corresponding Q31/200 MOSFET; PPDCIN_G3H must receives 5V from input, as first step.

You probably need to change both CD3215 chips.
 
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