820-00165 (missing PLT_RESET_L) quick 200mA S0 bounce.

[KC Micro Tronix]

no evidence of water damage on this board. Quick S0 bounce pulling 200mA for 1/4th a second.
The only thing I have found is a missing PLT_RESET_L signal. Should be 3.3v prevent SMC_RESET but the 3.3v never shows. It comes out of the mystery box U500.

Not sure what to check from this point.

 

[2informaticos]

Any pulse at VCORE?
Platform reset is not released untill power on sequence is completed.

 

[KC Micro Tronix]

All the CPU rails come up during the S0 state,
all the 3v3 switches come on and operate normally. Even the .9v switch.
I can't see anything wrong with any of the rails. Resistance is all good.

 

[2informaticos]

Did you try new BIOS?

"It comes out of the mystery box U500."
Who?
PLT_RESET_L is controlled by PCH...

 

[KC Micro Tronix]

CPU , PCH. Same U500 mystery box.
I have not tried another bios. but I will..

 

[piernov]

Pm_pch_syspwrok?