A2337 short on audio board

[thatsjayb]

Hi,

I have an A2337 when the charger is connected to the laptop is taking 5.14 volts, 0.05A and 0.25W.

The only place i found a short was on the bottom caps of the audio board but when i remove the heatsink the short is gone and the macbook works perfectly fine! could this be a bad cpu/ram ?


Any help would be appreciate it
Thanks

 

[2informaticos]

First of all, welcome to the forum!

"when i remove the heatsink the short is gone"
Do you mean the metal cover of that connector maybe?

You should inspect audio board/flex for corrosion.
Check M1 data lines corresponding to that connector.

You should try DFU, just in case.

 

[thatsjayb]

Thank you,

I mean when I remove the actual heatsink the one above the processor and the memory ram.

The audio board is brand new and the computer is now working ok without the heat sink.

I will now check the M1 data lines on the board.

Also what exactly I should try in DFU mode ?


Thank you

 

[2informaticos]

Forget DFU, if machine works.

Put back heatsink and look around screw holes for any damage sign.

 

[thatsjayb]

Forget DFU, if machine works.

Put back heatsink and look around screw holes for any damage sign.

Hi,

I did a visual inspection under a microscope and everything seems to be working ok. I put back the heatsink and the MacBook stopped working, after I removed it again and now it works fine.

Looks like whenever the heatsink in on there is a short to ground on PPBUS_AON but when I remove the heatsink the short is gone which makes me believe that either a component under the heatsink might be touching the heatsink causing the short or perhaps the A2 pin under U0600 on the top left or maybe the pressure from the bracket might be interfering with a component connected to the PPBUS_AON line causing it to short to ground when the heatsink is on.

Really hope you can guide me to find the issue and get this board fixed.


Thank you

 

[2informaticos]

What is resistance (ohm scale) to ground at PPBUS_AON?
Check it disconnecting charger and battery; allow 10-15s to discharge remanent voltage.

You may have a problem inside board.
Pressure caused by heatsink screws may cause short between the copper layers.