820-00923 A1706 NO POWER

[Jeffotskie26]

Hello got this macbook with VR0V9_IND_TBT_X and VR0V9_IND_TBT_X full short to ground, fan spins high
but no brain. no display no usb activity.
after removing u2800 is removed. short circiruit is gone.
i took u2800 from a1708 donor board and put properly the macbook still cant on
no fan spin no usb activity.
ppbus 13v
usb meter 20v 0.96-1.15amp looping.

 

[2informaticos]

Do you get CPU core voltage?
Did you test the board without U2800 soldered?

 

[Jeffotskie26]

u2800 removed
PPVCC_S0_CPU 0V 0.008 diode to ground.
CPU issue?

 

[2informaticos]

CPU core rail has low value as normal.

Do you get voltage on other big coils?
Check pages 73/5/6.

 

[Jeffotskie26]

L7700 0.03v
L7900 1.2v
L7960 0.9v
L8000 1v
L8020 1.8v
L8050 1v

 

[2informaticos]

So you have missing ALL_SYS_PWRGD.
Check the power good signals at U7800 (1 OF 10), at page 74.

 

[Jeffotskie26]

CPUVR_PGOOD 3.3v
P5VS4_PGOOD 3.0v
P1VSUS_PGOOD 3.3V
P1V0PCH_PGOOD 3.3V
P1V8SUS_PGOOD 3.3V
PVCCIO_PGOOD 3.3V
P3V3SUS_PGOOD cant find testpoint
cant see what else to check

 

[2informaticos]

"CPUVR_PGOOD 3.3v"
This implies correct CPU core voltage; impossible without ALL_SYS_PWRGD!!!

PLEASE, post accurate information.