820-01987 Stuck on 5V

[brunomotter]

Hello. Got this board here. Very clean, no signs of corrosion. It negotiates only 5V with charger. Already checked for shorts, no shorts found. Replaced both CD3217, same issue. Tried replacing U7000 too as I'm not getting CHGR_EN_MVR, but same result... I'm stuck... I'm not good at this new architectures, need to study more to understand how it works. Any ideas on what to do next?

 

[2informaticos]

What about PPBUS_G3H and small coils around U7800?

 

[brunomotter]

PPBUS_G3H is stuck on 1V, how the hell I do to take off the shield that's over U7800?

 

[2informaticos]

"PPBUS_G3H is stuck on 1V"
Check diode mode to ground there.

Post U7000 basic voltages; P_IN, AUX_DET, VDDA/P, SMC_RST_IN, A/BMON.
Check resistance over C7020/23 (ohm scale).

 

[brunomotter]

Diode Mode to GND on PPBUS - 0.431

P_IN - 5V
AUX_DET - 1,289V
VDDA/P - both@5V
SMC_RST_IN - couldn't find a point that's not under the nasty shield to measure this one
AMON - 0V
BMON - 0V
C7020 resistance - 3ohm
C7023 resistance - 2.6ohm

 

[2informaticos]

All look good there; you should get there PPBUS_G3H.
Remove F7000 and check C7050 voltage.

CHGR_RST_IN is available at U/R6940.

 

[brunomotter]

U/R6940 are under the shield. Will try removing F7000

 

[brunomotter]

1.236V on C7050 without F7000

 

[2informaticos]

Then change U7000...

 

[brunomotter]

Ran out of ISL here. Replaced it two times already. Waiting for new chips to arrive.

 

[2informaticos]

Then replace Q7030/40.
First check R/C7030/40 and their traces.

 

[brunomotter]

This worked! Thanks

 

[2informaticos]

Changing Q7030/40, or found bad discrete component?

 

[brunomotter]

Changing Q703040

 

[2informaticos]

Thanks for feedback.
It may help other froum members.