MACBOOK A1534 820-00244 Logicboard Dead

[felix27]

Hello,
I want to fix a 2016 12 Inch Macbook which has a dead Logic Board.
USB-C and Battery section seems to work, trackpad clicks, but all cpu Voltages, (VCORE, CPUSA) are 0V, CPU stays cold.
PPBUS_G3H, 3.3V and 5V Rails seem normal. PM_SLP_S3_L is present but CPU_VR_READY is not.

Thanks for your help!

[felix27]

ALL_SYS_PWRGD is also present, so i guess, either U7800 or U7100 have some sort of problem. But resistance on the ALL_SYS_PWRGD line is normal, it is not shorted to gnd.

[mon2]

What is the current draw? Working at 20v?

Power cycling or steady voltage & current draw?

[felix27]

I do not have an USB ampmeter, but imput voltage is steady at 20v measured at C3101

[felix27]

PPVCCIO_S0 is only 0.84V and PM_PCH_PWROK is not present.

[mon2]

What is the exact voltage to ground of PPBUS_G3H? (measure @ white fuse F7040)

[felix27]

PPBUS G3H is 8.8V

U3900 gets warm (not extremly hot). Is that normal?

Could my EFI-Firmware be the Problem?

[PITERPENY]

as they said on one site “probably a bad CPU)”

[mon2]

https://boards.rossmanngroup.com/thr...o-power.60238/

[felix27]

Thing is, I don't even get vcore and all resistances seem normal. My CPU stays completly cold and CPU VRM isn't even turning on. The PCH doesn't create PM_PCH_PWROK but there is SPI activity on the ROM IC, so the PCH isn't completly dead either.

[felix27]

I looked at the schematic again and PM_PCH_PWROK isn'r even generated by the PCH. All Voltages that depend on U7100 are gone, even PPVCCSA. Could just U7100 be dead?