820-3023 ppbus 8.40V is ok?

[MDY]

820-3023 ppbus 8.40V is ok?
I have this board pretty clean. No liquid damage with ppbus 8.40. Not power. Customer says this air sometimes shutdown randomly and finnaly never power again.

 

[dukefawks]

Fine. Check voltages on R1800/1/2/3 both sides.

 

[MDY]

All 4 resistors are between 3 and 3.3V both sides.

 

[dukefawks]

The usual PP3V3_S5? Check for shorts on all rails, corrosion? Green light ok? Charges battery?

 

[MDY]

Green light appear only with original 85W adapter. With no geunine no green light. Also with 85W adapter green light is faintly. I need dark room to see it. Same charger in macbook pro and all compatible green light is easy to see. That means something? Tomorrow will check S5 and battery too.

 

[dukefawks]

That means you have no green light. Check with known good IO board and cable first.

 

[MDY]

I have another working board with ram problem here and already interchanged IO boards and all the same.

 

[dukefawks]

Come on engage brains, green light issues have been discussed so many times. ACOK? SMC_RESET? Trackpad disconnected?

 

[larossmann]

No light on the charger is the first issue to solve.

1) is CHGR_ACOK present on pin 14 of U7100?
2) are the PP3V42_G3H, SYS_ONEWIRE, and SMC_BC_ACOK pins on J4700?
3) Did you try a known good DC in board and DC in cable?

99% of the time it is a bad cable between dc in board & logic board, or burned pins on the connector for PP3V42_G3H, SYS_ONEWIRE, and SMC_BC_ACOK.

 

[MDY]

Ok, lets start gain. I do have good green light. Before I wasnot connect flex cable well between main and io board.

SMC_ADAPTER_EN - 3.38V
PP3V3_S5 - 3.31V
PP5V_S3_REG - 5V
PPDDR_S3_REG - 1.50V

I also have 1.5 and 1.05 power supplay. What I miss is PPVCORE_S0_CPU_REG - 0V

I checked EN - pin1 U7400 and it is 2.5V. Should be 3.3V
This mean U7400 is bad? Should I replace MAX15092?

 

[larossmann]

r7402 good?

 

[MDY]

Yes, it is 90K
Area arround look ok

 

[MDY]

Only thing I found bad was CPUVCCIOS0_RTN from U7600 to the resistor. Before repaired this corroded trace I missed PPCPUVCCIO_S0_REG
After repair this trace I have PPCPUVCCIO_S0_REG stable at 1.05V
Only thing I miss now is CPU supplay and dont understand what more could be happend. No more corrosion found in the board.