820-00165 brain dead?

[Kyle93]

Arrived with no power from minor liquid damage around SMC and clock area. Replaced U1900 U8500 and reballed SMC. Board now powers on with fan spin but only draws 0.175-0.230 miliamps for 8-10 seconds...then powers off then stays on continuously drawing a steady 0.235 miliamps. No chime but fan spins. Replaced SMC to rule out but same symptoms. Also swapped bios for testing but same issues.

What to check next?

 

[2informaticos]

Check all SPI Bus Series Termination resistors and their traces.

Did you check for USB activity?
Do you get all voltages from pages 57/58?
PLT_RESET_L goes high?

 

[Kyle93]

Termination resistors are good. No USB activity

all coltages present pn 57/58

PLT_RESET_L 3.3v

PCH side of CPU gets very warm while board is on. CPU side isn't nearly as warm.

 

[2informaticos]

If you don't see other liquid sign, could be crap accumulated underneath CPU, or RAM.
You can try heating the chips with quality flux.

Are you sure test BIOS is good?

 

[Kyle93]

ram and CPU area were spotless on arrival. Only minor liquid damage on small section of board mentioned.

Could it be bad CPU?

 

[Kyle93]

known good bios from working board tried with same symtpoms

 

[2informaticos]

Check the board alone on the desk.
Disconnect any flex and other device; including SSD and airport card.
Just use onboard USB port to monitor activity.

 

[Kyle93]

Board is already alone on the desk. On board usb has no activity.

 

[2informaticos]

Could be damaged CPU, or just a simple corroded resistor.
Liquid spill problem is always nightmare...