[SOLVED]820-2936 - Missing P3V42_G3H

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smiba

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Hi

Originally this macbook came in without a light on the charger, the customer did not know of any water damage but some other company told them there was corrosion (and they made and showed pictures I have in my possession as well), they 'Chemically cleaned" it (read: Drop it in the ultrasonic and call it a fix) and it worked for a good 3 months until it just crashed and never came back on again.

Just after opening I saw a very ugly looking R6995 which measured >10MOhm resistance, instead of the 1MOhm it should've. The Coil didn't look very well either, and I replaced both for good measure. Macbook worked again and kept working for a couple of days before it had the same issue again.

The board looks somewhat clean for a board this old, no signs of bad corrosion and all components are looking okay.

I found that U6990 was defective, as there was power going in but nothing coming out even though there is no short on the line and replaced U6990
It still had the same issues, but I thought that maybe I broke it with too much heat, bad soldering or just bad chip. So I tried it again with a new chip while being extra careful of its environment, however the issue stayed.

VIN(7)/EN(4) = 18.4V
VCC(8)/FB(2) = 3.74V
SW(6) = 0V
BYP(9) = 0V (Obviously)

R6995 = 998kOhm
No short to ground on P3V42G3H_SW
No short to ground on P3V42_G3H

Any idea?
 
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smiba

New member
Aha

PPVIN_G3H_P3V42G3H on R6995 is ~3.7-4.2V (Pin 1)

This should be directly tied to PPVIN_G3H_P3V42G3H if I'm not mistaken?
May I get away with soldering a wire from PPVIN_G3H_P3V42G3H from underneath the board to Pin 1 of R6995? Or should I look somewhere else for what might be pulling it down?

Bad traces to R6995.....
Just figured it out as well, read text above
 
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