820-00281 no power, 20v, s5 cycling

[Yoel Ren]

Hi.. this macbook came in, owner say it suddenly die.
When plugged with usb c ( 96w original magsafe ), it will go from 5v to 20v, then consume20-40ma, back to 0a repeatedly. ( all port behave the same )
measured :
Ppbus : 12.6v steady
pp3v3_g3h : 3.3v steady
pp5v_s5 : 5v - 0v cycling
pp3v3_s5 : 3.3v - 0vcycling
pp1v8_sus : present but cycling
pp3v3_sus : present but cycling
smc_pm_g2_en : present but cycling

checked pp5v_s5, pp5v_s4, pp5v_s0 not shorted.
pp3v3_s5, pp3v3_s4, pp3v3_s0 not shorted.

 

[Yoel Ren]

voltage for U7650: pins 23, 22, 12, 13, 29, 21, 4.

Pin 4 - 0.00
Pin 12 - fluctuating between 3.42 and 0
Pin 13 - fluctuating between 2.0 and 0
Pin 21 - fluctuating between 3.42 and 0
Pin 22- 3.2
Pin 23 - 13.1
Pin 29 - fluctuating between 5.0 and 0

 

[2informaticos]

Check diode mode to ground on all big coils; compare with good board.
Just in case, test SMC bypass mode.

 

[Yoel Ren]

all big coil diode mode compared to good board is good.
board doesnt start in smc bypass too...
have tried reheating pch, smc, pmic , replacing tps519810A but still same behaviour

 

[2informaticos]

Remove R7643 and check again U7650 voltages.
Test the board alone on the desk.