820-00165 PP5V_S4RS3 pulsing.

[macRepairAmb]

Have this board that wasn't powered up and had corrosion. Cleaned up the corrosion and replaced damaged R8156.
PP5V_SR4RS3 pulses, so does ALL_SYS_PWRGD, PPVCC_S0_CPU, PLT_RESET_L and all the big coils.
SPI Bus Termination resistors good
I removed J6100 and also flashed know good BIOS with same result.

Any suggestions.

 

[2informaticos]

Does it stay on in SMC bypass mode?

 

[macRepairAmb]

No.

 

[2informaticos]

Remove Q8150 and test the board again.
Also test removing U8130.
Be sure no corrosion at U1950 and surrounding resistors.

 

[macRepairAmb]

Pulsing still present with Q8150 and U8130 removed. Also confirmed no corrosion under U1950.

 

[2informaticos]

Heat CPU with good flux.
May be just a problem caused by accumulated crap between its balls.
You should also reball SMC...