820-00850 short on PPBUS

[arnonabuurs]

Hi guys, this 820-00850 has no liquid spil and 0V and shorted on PPBUS. I put 1v in PPBUS line but nothing heats up. Before ramping up the voltage, how you usually look for shorts on these? I believe if I put to much power in I can short the CPU?

Edit see attached image found this, looks like a tiny bit of corrosion, that might be rip CPU I guess.....

 

[2informaticos]

Probably dead CPU, after saw the picture.
But you've just injected AGAIN voltage on PPBUS w/o checking for shorted high-side MOSFET.
WHY???

Compare exact ohm value on PPBUS_G3H with the value on CPU coils.
If you get 0 ohm, then remove power chips from CPU; starting with the one in picture.
Check when PPBUS_G3H short goes off.

 

[arnonabuurs]

I injected 1v, cpu gets 0.9-1.5v, how can it blow up from 1V? I replaced the bad chip now I have no more short and 12.29 on PPBUS

I have not seen any video from Louis on how to repair these boards so sorry if I dont follow the correct procedure, been reading up a=on the forum on how to find shorts for these boards and canot find any clear instruction, how am I supposed to figure it out...

 

[arnonabuurs]

Tried with another charger and got Apple logo so this one can be closed

 

[2informaticos]

https://boards.rossmanngroup.com/fo...ering-if-there-any-schematics-or-sub-for-this

I already told you do NOT do that here
https://boards.rossmanngroup.com/forum/board-repair-troubleshooting/52630-820-00923-not-turning-on
and you've got upset, instead of properly use search function.
The above result is from this list
https://boards.rossmanngroup.com/se...e&searchJSON={"keywords":"shorted+high-side"}

And there are more usefull posts
https://boards.rossmanngroup.com/fo...ess-of-an-820-00923-direct-short-on-ppbus_g3h
https://boards.rossmanngroup.com/fo...-00840-no-power-ppbus_g3h-was-short-to-ground

Remember, the forum goal is to assist online repair process.