820-2879 restoring after liquid.

[mobajer]

There was very little water corrosion, only 2 components affected:
c7564 was shorted. removed short gone.
c7541 was shorted.changed, short gone.

Macbook when power button pressed, start hdd, and charger light orange.

cooler dont spin, nothing on screen. what voltagesi test next?

 

[dukefawks]

ALL_SYS not present I guess. Go though all the rails and see which one is missing.

 

[mobajer]

Hello, i am begginer, so not easy catch everything

Do you mean i need to have voltage on: ALL_SYS_PWRGD? to have voltage on this pin, i must have all these voltages first:

P5V3V3_PGOOD
P1V5S0_PGOOD
MCPCORES0_PGOOD
CPUVTTS0_PGOOD
MCPPLLLDO_PGOOD

i was able only measure p5v3v3. P1V5S0 shows 0v, i am measuring when charger plugged, do i need to turn on mac?

 

[dukefawks]

Yes it needs to be on. You said the HDD spins up so the system is at least doing something. Just one power rail is not coming on and stopping the rest from coming on. Start with checking all the S3 ones and if all present then continue with all S0.

 

[mobajer]

how many s3 rails need to check?

enough to check these 3 main:

PPDDR_S3_REG
PP3V3_S3_FET
PP5V_S3_REG

?

 

[jadao]

First check at least if power rails are present in each state starting as Duke said from S3 and if present look further for S0.

Yes only 3 rails on S3, search for PP1V5R1V35_S3, PP3V3_S3 and PP5V_S3, no need to verify yet if S3 subrails are present at each chip, they are all tied together except if you have a bad trace or missing component, but this case is for later, you want first look for easy problems like missing rail/short circuit/bad chip, corrosion, bad looking component, single or multiple issues.

 

[dukefawks]

You check them all till you find one that is missing.