820-01958

[MacByte_Repair_]

Have an A2179 MacBook Air. Board number is 820-01958. There was a little sticky substance and corrosion on C7670 and C7665. Board will take anywhere between 25 and 100 milliamps and then it will cycle, but the cycles are not consistent. PPBUS_G3H is 12.29 V with battery plugged in and without battery. Have tried restoring with Apple Configurator 2, but I get stuck with Error 4005. PP5V_G3S is missing, where the corrosion occurred. Pin 12 which is the enable pin of U7650 appears to come from U7800 and is also missing. Not sure where to go from here.

 

[2informaticos]

DFU process should go on if all AWAKE and SLPS2R voltageas are steady.
Also check if SSD voltages are there, at least when trying DFU revive.

Incorrect PPBUS_G3H voltage denotes bad communication between T2 and U7000.
DFU can solve this, if is the result of T2 firmware corruption.

3V3_G3H (L7690) comes on?

 

[MacByte_Repair_]

I haven't measured AWAKE and SLPS2R or SSD yet, but I started with the easiest thing and measured 3V3_G3H at Pin 1 of L7690. I get 3.29 Volts and then itll drop to 3.23, 3.0, 2.68, 1.63, then cycle back up to 3.29. (I think this is what pulsing means?) Will update with other voltages.