Macbook 820-02773 Board short when trackpad connected

[MalodicOne]

Original fault was customer spilled milk on unit, no corrosion was found on the board. Took mainboard out of original case and LCD and swapped it into the fully functioning case and LCD.

Shorts show up all over the board when trackpad is connected only. Trackpad is used and fully functioning from another unit of same model. Voltage injection causes trackpad connector to get hot but nothing else, swapped on board connector to rule that out, same issue. Diode reading on IPD_MCU_INT_CONN is higher then reference board @ .935 expected is .803. Shorts show up on PPVBAT_AON_CHGR_REG and PPBUS_AON_PORT5V_VIN_ISNS and a few other areas,

I've replaced a few component attached to IPD_MCU_INT_CONN to rule those components out and still same thing, im kind of stuck at this point.

[ugamazing]

To confirm...you're using a proper 2022 M2 A2338 trackpad/cable and NOT a 2020 A2338 M1 trackpad/cable, correct? Check part numbers to confirm. Big issue with parts vendors.

[reformatt]

Good point. Some trackpad cables (like the one on the old A1534) were asymmetric, and had broad copper connections for the main power rail and ground. I once had a similar thing on that model because customer had torn the cable, ordered another but had put the cable in upside down, shorting all the data lines etc together on the other side!

On this one, you have 5 pins on one side for PPBUS_AON so that's the only thing that makes sense to me.

[MalodicOne]

This is what i originally though as well, I will double check this today. I also asked the client to bring me a new trackpad for this model specifically. They brought it to me like this an di do not have a spare to test with so they are bringing me one today.

The ppbus AON lines are the ones shorting all kinds of stuff on this unit so what you are saying totally makes sense.

UPDATE: part number is 821-02853 which is for a late 2020 year model. thank you for bringing this to my attention.

[ugamazing]

Glad you got it sorted! Very common issue a few years back as many parts vendors did not specify or differentiate 2020/M1 vs 2022/M2. Lot of headaches for retail guys.