820-3115 no post

[Bizb9l21]

Hey all,
I have a 820-3115-b that was worked on, I have no history for it .

Found a lot of flux by the keyboard ic and EFI chip was definitely removed and resoldered.
It powers on , fan spin , green light, won't beep without ram .
Did SMC reset, did pram ,no visible water damage.
Removed EFI chip , made a backup and worth chip with good working bios of same exact model board.
Got a file with clean ME from some other thread here at badcaps but still same result.
Any ideas where I can start diagnosing this issue?
Thanks

[mon2]

Re: 820-3115 no post

What is the voltage to ground of PPBUS_G3H (F7040) ?

[Bizb9l21]

Re: 820-3115 no post

Hey , it's 11.40v

[mon2]

Re: 820-3115 no post

What is the voltage to ground of PP3V42_G3H ?

The PPBUS_G3H a low voltage.

Remove fuse @ F7040 and measure again at the ISL side (producer).

reference:
https://www.logi.wiki/index.php/Powe..._List#820-3115

[piernov]

Re: 820-3115 no post

Machine is in S0 state, relevant power rails must be measured not random things.

[Bizb9l21]

Re: 820-3115 no post

Thank you guys for your help, is there a weather fall flow I can follow to check voltage across rails and report back to you ?
Can it still be a bad ME that needs cleaning that is putting this board in this state and pulling the voltage down?

[leovalpo]

Re: 820-3115 no post

measure the ground resistance of the rails (red probe of the multimeter grounded to ground and the common probe reads the component), in the list attached as an image is the voltage reference value.