820-00840 short to ground PPBUS

[iClub]

Good morning, this mac is shorted on the PPBUS, we applied voltage to identify the component and identified that the U7410 was causing the short. I replaced it, PPBUS now with 13V, however, there is no activity on the USB and it won't turn on.
Imagine that the CPU died, right?

 

[tcampbell34]

Yea 13v went to the CPU from the shorted U7410, so the CPU is dead.

 

[2informaticos]

Small chance that CPU was still good.
If you injected voltage into PPBUS_G3H, you've also injected directly into CPU core.
I cannot imagine someone still does this, after so many times explained on the forum how NOT to do that.
You MUST first check if any high-side MOSFET is shorted, or not.

90% of cases, CPU is dead after high-side MOSFET found shorted in CPU power supply.
But if you inject voltage over shorted one, then 100% CPU got dead!

 

[iClub]

So how should I identify a short in the MOSFET without applying a voltage to the PPBUS?

 

[2informaticos]

READING the forum...
"so many times explained on the forum"

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