820-3476 A1502 ppbus 1v

[Jeffotskie26]

this board is fully working before,
i just tooked the u7100
to put in another macbook because i dont have stock u7100
then now i have 3 pieces known good u7100
but i only getting 1v on ppbus with this 3 ic's
board boots with battery ppbus is 11.4v
with charger alone ppbus is only 1v oem/psu/original charger

PPDCIN_G3H 17.2v

u7100 basics using psu set to 16.5v
1 - 0.0v
2- 15.9v
3 - 4.1v
9 - 0.1v
12 - 3.4v
13 - 3.4v
14 - 3.3v
15 - 0.01v
17 - 1.1v
19 - 1.1v
20 - 5.4v
25 - 5.6v
27 - 1.1v

i believed u7100 is not the issue here.
what else need to be check?

 

[2informaticos]

Check for short between R7120 and L7130.
Bad solder on U7100 (pin 24) will fry Q7130 (high-side).
R/C7125 with bad solders can cause same problem.

 

[Jeffotskie26]

whoaaa!! this is very challenging
no short between r7120 and l7130
100% chip is good and no bad solder on u7100 specially pin:24
q7130 is replaced. chip 100% good
r/c7125 value/solders and traces are good.
there is no leak or missing value on u7100 all pins 1-28(compared to working board)

 

[2informaticos]

Post again pins 19 & 27 voltage.
Also post exact resistance (ohm scale, measured onboard) for R7180/81 and R7185/86.

 

[Jeffotskie26]

PIN 19 5.4V 27 1.1V
R7180 99.4K
R7181 61.4K
R7185 469.2K
R71856 331.8K

this solve by changing Q7180
just wondering,,,
i thought if q7180 is deffective can still get good voltages using fake/psu charger.
anyway big thanks to @2informaticos

 

[2informaticos]

Leakage on Q7180 is only detected by original charger; it has an embedded processor for control.
Fake charger doesn't include such expensive components.
In your case was probably internal damage on Q7180, not leakage; denoted by good resistors value measured onboard.

 

[Jeffotskie26]

no wonder i remember before when i tried measuring voltage
PPDCIN_G3H on c7185 pin1 i accidentally touch my positive prove on c7121 pin2 ground.
i believed this is the main reason.