820-01700-A - Coffee dropped - PPBUS line short

[samstown]

Hello,

I've got this Macbook for data recovery, customer dropped a cup of coffee.

Motherboard is 820-01700-A. Where should I start looking ?



Thanks
Sam

 

[2informaticos]

All USB-C ports have the same behavior?
Which areas have been affected by liquid?
Is the machine detected in DFU mode?

 

[samstown]

Thank you for your answer. Yes, all port takes 0.04 amp, coffee on top of keyboard, around touchbar. No it's not detected in DFU, I've followed your URL and I successfully put MBP in DFU in the past.

 

[2informaticos]

I forgot, you've mentioned short at PPBUS_G3H.
What is the exact ohm resistance to ground?
Compare the value with the readings on all big coils.

 

[samstown]

Thank you for your quick reply.

I am getting 0v and 0 ohm on all big coils.

 

[samstown]

as all ports have same behavior, could it be SMC chip ?

 

[2informaticos]

You cannot get 0 ohm on all big coils.
Did you check without charger, nor battery connected???

I was asking about "exact resistance"...

 

[samstown]

yes, only the board, nothing connected. Is it not the way you want ?

 

[2informaticos]

Is impossible to get 0 ohm to ground on all big coils!

Please, post resistance to ground (ohm scale) on all big coils...

 

[samstown]

ok, I hear the beep but value is 3.2 ohm

 

[2informaticos]

3.2 ohms to ground on CPU core coils look good.
But there are many other coils to check.

You still didn't post exact value from PPBUS_G3H; we need something to compare with...

 

[samstown]

And PPBUS_G3H = 8.6

 

[2informaticos]

Looks like you have short between PPBUS_G3H and L7330.
This points to bad U7370...

 

[samstown]

thank you, so this is CPU power supply, is it worth trying to repalce it ?

 

[2informaticos]

8.6 ohm is not really short, CPU can still be good.
Of course, there is a big chance to be dead, but nothing to lose; just change U7370 and try.

If possible, after U7370 is removed, compare diode mode to ground with good board.

 

[samstown]

After removing U7370, I saw short was on CPU. Dead MBP. Thank you for your help anyway.

 

[2informaticos]

Did you check the value on similar good board?
8 ohm may not be short in fact...