820-4924 PPBUS 4V

[ajdoc]

Board has liquid damage here and there - came from another shop.
Is working, it see battery, works fine on battery but won’t charge it.
There is battery charging symbol.

Tested with genuine 85W charger, known good battery and DC IN.

Resistance between 17/18 and 27/28 on U7100 is correct.
Resistance on R7151/52, R7150, R7150, R7121/22 is correct.

R5380 and R5381 is correct as well.

Replaced U7100 but still same issue.

PPBUS_G3H without battery 3.9V-4.1V
PPBUS_G3H with battery, no charger 10.55V (battery got around 30% of charge)
PPBUS_G3H with battery and with charger 10.55V

R7112 is fine and got good traces.

Any idea why PPBUS is only on 4V?

 

[2informaticos]

Post U7100 voltages (no battery, only charger); pins 1, 2, 3, 9, 12, 13, 14, 15, 17, 19, 20, 27.

 

[ajdoc]

1 = 0.004V
2 = 17.9V
3 = 4.33V
9 = 0.67V
12 = 3.40V
13 = 3.35V
14 = 3.35V
15 = 0.08V
17 jumps between 3.9V-4.1V
19 = 5.48V
20 = 5.48V
27 = 17.55V

 

[2informaticos]

"9 = 0.67V"
Post exact ohm resistance measured directly between pins 27/28.

Replace C7125 and Q7130.

 

[ajdoc]

"Post exact ohm resistance measured directly between pins 27/28." = 20.8 Ohm
"Replace C7125 and Q7130." solved the issue

Thank you very much for help