A1466 820-00165 - 0.11A draw, S0 Rails present but not turning on.

[it-solve]

Hi Guys,

I am having Macbook Air A1466 which has no obvious liquid damage. Seems like decided to die out of nowhere
I can feel the board warms up such as its working but no fanspin or USB activity.

Not sure in what order to provide readings so just grabbed an example from other posts. Let me know if you like me to provide more

PP3V3_S0 = 3.3V
PP5V_S0 = 5.16V
SMC_PM_G2_EN = 3.41v
PP5VP3V3_VREF2 = 2.02v
PM_SLP_BUF_L = 3.3V
P1V8S3_PGOOD = 0.186V
P5VS4RS3_PGOOD = 0.186V
P1V05S0_PGOOD = 0.186V
ALL_SYS_PWRGD = 0.186V
P5VS0_EN = 3.3V
P3V3S0_EN = 3.3V
PM_SLP_S4_L = 3.349V

Haven't seen anything like this.
Any input would be appreciated.

Cheers

 

[2informaticos]

First of all, welcome to the forum!

"ALL_SYS_PWRGD = 0.186V"
All the other mentioned power good signals met there; no need to specify them anymore.

One power supply from S3, or S0 state has missing voltage, or its power good fails somehow.
Post the voltage on all big coils, as first step.
Also check U1950 and Q8150 for corrosion.

 

[it-solve]

Thanks for the speedy reply.

All big coil voltages seemed alright apart CPU Phase ones, hence skipped them. Here they are:
L7630 - PP1V05S0_LL = 1.06V
L7430 - PDDR_S3_REG_L = 1.21V
L7560 - PP3V3_S5_REG_L = 3.35V
L7520 - P5V_S4RS3_REG_L = 5.17V
L7130 - PPVBAT_G3H_CHRGR_REG = 8.59V

L7320 - CPUVR_PHASE2 = 0.01V
L7310 - CPUVR_PHASE1 = 0.01V

No Corrosion on U1950 and Q8159, replaced them just in case still same response.

Poked around U1930, PM_SLP_S3_L is 3.3V
I wonder where ALL_SYS_PWRGD is drained.

Thanks again.

 

[2informaticos]

You can try removing Q8150 first; is a redundant protection, not really needed.
Next, remove power good resistors, one by one; keep R8167 in place!

 

[it-solve]

That was brilliant 2informaticos. Thank you very much.

P1V8S3_PGOOD - after R8166 removed and line was fluctuating around 0.5V
P5VS4RS3_PGOOD - after R8165 removed and line was fluctuating around 0.5V
P1V05S0_PGOOD - After R8164 removed the fan spins. Resoldered it back all working.

Not sure what have caused it but u7600 seems to be okay. I wonder why it was not sending PGOOD signal and instead was pulling ALL_SYS_PWRGD down. it had around 0.3Vdc


Thanks again.