Hey guys,
I got a MacBook Pro a1989 820-00850-A dead for repair. The MacBook itself was off for a month or so and it didn't power on. I tested using ammeter and it was stuck on 5v. Opened the machine and found a short on ppbus_g3h, corrosion near the right spkr_amp. removed the spkr_amp and saw short on ppbus_g3h. plugged in to power, boosted to 20v .600A and then back down to .300A. Trackpad was clicking when on .600A but no image etc.
Later, I tried again but it dropped down to 5v and never boosted back to 20V. checked board again and found ppbus_g3h shorted again. injected 1v and saw left spkr_amp heating, removed it but still same behavior. Checked around for voltages:
PPBUS_G3H: 12.20V
PPBUS_3V3_G3H: 3.3V
PP1V8_G3S: .600V
Measured around pp1v8_g3s creation circuit and the enable for the chip which creates p1v8_g3s wasn't present. traced it back to pmic. replaced it but still to no avail.
Under thermal imaging only t2 heats up and nothing else.
I got a MacBook Pro a1989 820-00850-A dead for repair. The MacBook itself was off for a month or so and it didn't power on. I tested using ammeter and it was stuck on 5v. Opened the machine and found a short on ppbus_g3h, corrosion near the right spkr_amp. removed the spkr_amp and saw short on ppbus_g3h. plugged in to power, boosted to 20v .600A and then back down to .300A. Trackpad was clicking when on .600A but no image etc.
Later, I tried again but it dropped down to 5v and never boosted back to 20V. checked board again and found ppbus_g3h shorted again. injected 1v and saw left spkr_amp heating, removed it but still same behavior. Checked around for voltages:
PPBUS_G3H: 12.20V
PPBUS_3V3_G3H: 3.3V
PP1V8_G3S: .600V
Measured around pp1v8_g3s creation circuit and the enable for the chip which creates p1v8_g3s wasn't present. traced it back to pmic. replaced it but still to no avail.
Under thermal imaging only t2 heats up and nothing else.
