820-3115-B green light, quarter fan spin

[Sr. Robot]

Hi, got an 820-3115-B with periodic quarter fan spin

PP3V3_S4 is 0.6v pulsing to 3.3v each time the fan spins

PP3V3_S3 is missing.

C6226 as corroded and ireplaced it. Replaced BIOS chip no change. No other signs of corrosion visible.

 

[2informaticos]

If fan spins, PM_SLP_S3_L is pulsing, as PM_SLP_S4_L too.
So you must get a pulse at 3V3_S3 and 3V3_S0.
Be sure to get pulse at pins 2 & 5 of Q7812.

 

[Sr. Robot]

Yes, 3V3_S3 and 3V3_S0 are pulsing.

pins 2 & 5 of Q7812 are pulsing too.

 

[2informaticos]

ALL_SYS_PWRGD pulsing too?
Did you try starting in SMC bypass mode?

Please, post accurate information.

 

[Sr. Robot]

ALL_SYS_PWRGD is pulsing.

It wont start in bypass mode, the fan starts quarter spinning even before i release the power on button.

 

[2informaticos]

Any pulse at L7510/20?
Check R7402/03.

 

[Sr. Robot]

L7510/20 are pulsing in the order of 0.4 milivolts

R7402/03 have correct values are traces are good.

 

[2informaticos]

Apart of VCORE, do you get pulse at all other power rails?

 

[Sr. Robot]

PP1V8_S0
PP1V5_S3_DDR
PP1V5_S3
PP1V5_S0
PP1V05_S0 all pulsing

PP1V05_SUS is stable 1.04v

 

[2informaticos]

Probably bad CPU, or PCH...

 

[Sr. Robot]

After several attempts i got the laptop to reach a steady state, disconnecting and connecting the battery and pushing the power button w/o the charger (if i do it with the charger it just quarter fans).

The fan spins steadily but there´s no chime and no image.

PPBUS_G3H 11.32v (charger only is 12.5v).

PPVCORE_S0_CPU is 0.9v

ALL_SYS_PWRGD is 3.3v

 

[2informaticos]

0.9V is not correct voltage, board is stuck.
Check RAM slots if possible.
Do you get PLT_RESET_L?

 

[Sr. Robot]

PLT_RESET_L is 3.3v on the stuck state. it is 0v on the quarter fan.

 

[2informaticos]

Try BIOS, just in case...

 

[Sr. Robot]

Tried BIOS, no change