820-00165 all_sys_pwrgd 0V

[No-Clean]

Board had corrosion on U7820 all else looked fine, after replacing and repairing U7820 I am now stuck at all_sys_pwrgd 0V.

PPVRTC_G3H 3.2v
PP3v42_g3h 3.42v
Pp5v_s5 5v
Pp3v3_s5 3.3v
all_sys_pwrgd 0v
Pp5v_s4rs3 0v
PM_BATLOW_L 3.3v
PM_DSW_PWRGD 3.3V
SMC_ADAPTER_EN 3.3v
PCH_DSWVRMEN 3.3v
PLT_RESET_L 0V

 

[2informaticos]

ALL_SYS_PWRGD comes later, after RAM and PCH get power.
Do you get 3V3_SUS at least?

Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L (at same time).
If present, tehn check for pulse at PM_SLP_S4/3_L.

 

[No-Clean]

3V3_SUS = 3.3V
I do get a drop on PM_PWRBTN_L and PM_SLP_S4/3_L

Also when I first connect the charger I get all voltages for less than 1 second, even VCORE comes high at 1.8V but then goes to 0V shortly after.

 

[2informaticos]

Check if starts in SMC bypass mode.

PLT_RESET_L pulses at same time with VCORE?

 

[No-Clean]

PLT_RESET_L does pulse

SMC bypass same thing

 

[2informaticos]

Do you catch the pulse at L7820 too?

 

[No-Clean]

Yes L7820 pulses too

 

[2informaticos]

Possibly accumulated crap under BGA chips.
Start reballing SMC.
If no change, heat CPU with quality flux.

Check all PCH's power lines from page 11.
Also check all SPI Bus Termination resistors and their traces.

 

[No-Clean]

Reball SMC same thing, CPU trick did it!

Thanks!