820-01521 - Heavy Liquid 5V 0.247A after clean

[it-solve]

Hi Guys,

I am repairing this Macbook Air which had quite of liquid damage with major corrosion around
PPVIN_G3H_P5VG3S line - 12.30V
CC7D6
CC7D7

PPVIN_G3H_P5VG3S line - 12.30V
CC77D4
CC77D5

C3200 - PP3V3_G3H_RTC - 3.2V - 0.45Vdc
C3208 - P3V3_UPC_XB_LDO - 0.341V - 0.49Vdc

I could not find exact values, but those seem to be filtering caps.

After cleaning and replacing a couple of those capacitors. I have a consistent 5V 0.247A and heating up T2 chip

PPBUS_G3H - 12.27V
PP3V3_G3H - 3.28V
PP5V_S5_LDO - 0.0025V - 0.48 Diode
PP3V3_S5 - 0.0025V - 0.35 Diode

Any suggestions where to start?

 

[2informaticos]

Bad news if T2 heats when board off.

Check first if you get ALL LDO voltages on CD3215 chips.
Compare diode mode readings on their LDO rails.

 

[it-solve]

Had a feeling it is going downhill.

U3200 which had major liquid damage
PP3V3_UPC_XB_LDO - 3.27V - 0.513Vdc
PP1V8_UPC_XB_LDOA - 1.812V - 0.5308Vdc
PP1V8_UPC_XB_LDOD - 1.809V - 0.494Vdc
PP1V1_UPC_XB_LDO+BMC - 0V - 0.522Vdc

U3100 with no liquid exposure
PP3V3_UPC_XA_LDO - 3.17V - 0.504Vdc
PP1V8_UPC_XB_LDOA - 1.801V - 0.530Vdc
PP1V8_UPC_XA_LDOD - 1.709V - 0.494Vdc
PP1V1_UPC_XB_LDO+BMC - 0V - 0.523Vdc

Apart than 1.1V not being present, all others point to healthy CD3215 chips, right?

 

[2informaticos]

Could even be T2 firmware issue.
But is strange, as you don't get 1V1 LDO.

 

[it-solve]

After that much liquid, must be something related to the liquid. Some of the mentioned caps above I could not replace with exact value, but that should not be an issue right? They are filter caps.


So give up?

 

[2informaticos]

Before giving up, you can try DFU restore.
But I still suspect liquid damage...

 

[it-solve]

Thanks for the advice.

I never really had luck with the DFU restore.
Probably because I could not find a USB-C cable with all pins available.

Tried multiple ones, including genuine ones with no luck detecting second mac in DFU