820-00923 not turning on

[drmacbookth]

Hello, I have an 820-00923 that came in dead, looks clean no liquid damage. It had a short on PPBUS. after injecting power (removed all FDMF chips) I found a short on U8000, replaced it and now I have 13.07 on both sides of F7000. On L7030 I get fluctuation from 8.4-8.6v but there is no short. On charger I get 20V, 0.04A. Not sure what to check next. Could it be CPU already died from short before?

 

[2informaticos]

First of all, welcome to the forum!

Very likely dead CPU.
Injected voltage goes directly into CPU, through 1V0_SUS.
Do NOT do this ever again!!!
So many times explained WHY NOT in the forum, and people still doing this .

CPU could be already fried because of shorted U8000 (on high-side part).
But you've eliminated the lowest chance of being still good...

 

[drmacbookth]

Hello, I have been in the forum before but lost my login details.

From what I understood is that if I remove all high-side mosfets I could inject voltage? How would you suggest to find a short on PPBUS otherwise if board is completely clean? Is there anyway we can measure resistance to see if the CPU is dead?

 

[2informaticos]

If you get the same ohm value (to ground) on PPBUS_G3H and one big coil (not only from CPU), guess what that means???