820-01598 no power

[Kyle93]

This arrived with a strange no power. Without battery takes 20v and around 150miliamps. On thermal cam U7710 and u8110 were getting warm. Replaced both but no change except they do not get warm now. Also cannot get it into dfu mode

The trackpad also clicks in the case but nothing comes on the internal lcd or external monitor and no caps lock

 

[2informaticos]

Check diode mode to ground at L7702 and L8102.
Compare with good board.

 

[Kyle93]

L7702 0.024 both boards. L8102 0.087 bad board 0.056 good board

 

[2informaticos]

Just in case, compare all coils.
Don't forget SSD's ones.

Do you get all SLPS2R and AWAKE volatges?
Try external switch method, to force the machine in DFU.

 

[Kyle93]

All coils compared looked good.

Tried external switch method, ran dfu revive which finished with no errors however no changes

 

[Kyle93]

What should be checked next?

 

[2informaticos]

If no important data, try DFU restore.
If need data, can be saved in DFU mode, by an Apple authorized workshop.

 

[Kyle93]

DFU restore completes successfully however the board still does not fully boot

 

[2informaticos]

Still no voltage on the coils?
Tested the board alone on the desk?

Do you get all G3S voltages?

 

[Kyle93]

pp3v3g3s 3.3v
PP1V8G3S 3.3V
PP5VG3S 5V

L7030 is 12v during the first few seconds of power but then drops to 7v and stays there until unplugged

 

[2informaticos]

L7030 is irrelevant.
Still no voltage L7702 & L8102?

Trigger PMU_ONOFF_L and check for drop pulse at PCH_PWRBTN_L.

 

[Kyle93]

no voltage on L7702 & L8102 board alone on the desk

There is a drop pulse at PCH_PWRBTN_L

 

[2informaticos]

Check for pulse at PM_SLP_S3_L (at same time).

 

[Kyle93]

no pulse on PM_SLP_S3_L when triggering PMU_ONOFF_L

 

[2informaticos]

Then check PCH's basic signals: PM_BATLOW_L, PCH_RTCRESET_L, PCH_INTRUDER_L.
Do you get L7690 voltage?

 

[Kyle93]

PCH_BATLOW_L 3.2V

, PCH_RTCRESET_L 3V

PCH_INTRUDER_L 2.7V

L7690 3.3V

 

[2informaticos]

Looks like bad PCH/CPU...