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Macbook Air A2179 820-01958 Liquid Damage

C

CRC2018

Member
So I have an 820-01958 in for fixing now - was liquid damaged but customer neglected to tell us this before we opened the device and found it.

So we had liquid damage and a burned port going to the type c ports - we also had liquid damage around the top CD3215 controller.

I've replaced the type c ports and the port which they connect to. I've also cleaned up the area around the CD3215, replaced some missing resistors and also pulled off the CD3215 and reballed it (was liquid damage underneath). Put everything back together and now if the battery is not connected i'm getting a 5v 0.25a current draw and nothing further (PPBUS_G3H is 12.3V seems low to me). With battery connected i'm getting 20V and 0.00a current draw and PPBUS is only 10.3V. Device is not recognized in DFU mode. Not sure where else to go with this one as it all seems clean every other part of the board - even around the second CD3215 is very clean can see no issues there. The 1.8v, 1.1v and 0.9v sleep voltages appear present and stable.
 
2informaticos

2informaticos

Administrator
Staff member
Check for liquid signs on audio board and touch ID.
You can try to force SOC_FORCE_DFU line to 1V8_SLPS2R using 10-47K resistor.
No need touch ID for power button, in such case; in fact, keep audio flex disconnected.
 
C

CRC2018

Member
No liquid on either touch ID or audio board both clean. All testing I did so far was with those two disconnected anyway - only had the charger alone or the charger and battery connected.
Looking at the power on sequence it gets up to PP3v_G3H which is present and stable at 3V. PP5V_G3S is missing and there is no enable signal going to it. Thermal cam shows the T2 is heating a tiny amount when power is applied (Maybe 3-5 Degrees higher than rest of board)

I'm unsure if this is a case of dead T2 or the PP5V_G3S Circuit is damaged - I notice a lot of pins under the CD3217 which was corroded are connected to PP5V_G3S. Presumably if the PP5V_G3S isn't being generated then the enable signal would turn off automatically. No shorts are visible on PP5V_G3S.
 
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