macbook A1989 820-00850

[PITERPENY]

does not turn on.
5.060v /0.060-0.310 unstable
no in DFU
PPBUS_G3H=12.30v
PP3V3_G3H=3.3v
PP5V_G3S=0v
help plz

[mon2]

Check the resistance to ground of PP5V_G3S (with no power). Do the same for each inductor on the board. The ace cd321x are also suspects. Check each LDO rail voltage. Study the cd3215 20v wiki page for the power on sequencing to achieve 20v.

[PITERPENY]

the strange thing is that it switches to 20v/0.000a if you connect a battery
PP5V_G3S=8 kohm
when removing f7000 consumption 5v/0.000a

[mon2]

Check the input current sense full path resistance on the isl controller for ppbus_g3h.

Test the smbus line voltages on the battery connector.

[PITERPENY]

replaced isl to no avail! started to carefully examine the board under a microscope and saw that the u7800 had a barely noticeable crack! replaced the u7800, 20v appeared and the macbook started charging (I still don't understand how the u7800 plays a role in the transition from 5v to 20?)! but it still doesn't start and the ssds are getting very hot!