MacBook Pro 15 820-2850 both fans pulsing every second

dukefawks · Jan 29, 2018

Check all rails for shorts. Does it charge a known good battery?

Cocobill · Feb 5, 2018

No, it does not charge a known good battery. In diode mode PP3V3_S5 is 0.140v. Is that normal?

dukefawks · Feb 5, 2018

.140 could be ok. What is diode mode with the leads reversed? Resistance to GND? History of the board? PPBUS stable?

Cocobill · Feb 5, 2018

Diode mode with leads reversed reads 0.515v, resistance to ground is 10.42 kOhm. History is unknown

. PPBUS is NOT stable

Cocobill · Feb 5, 2018

Resistance 17/18 is 3.5 Ohm, and 26/27 is 21 Ohm. TPS51125 looks clean.

dukefawks · Feb 5, 2018

Replace the 51125. This one is going to suck it looks like.

Cocobill · Feb 13, 2018

Replaced 51125, PPBUS_G3H is stable at 12.52V. However, it does not charge a known good battery.

dukefawks · Feb 13, 2018

PP3V3_S5 present now?