JESSA IS ALWAYS WRONG! 2012 13" Air - No Backlight

[wrbailey]

Just to confirm, I do have 0.589 diode mode from backlight output @ C9797.
I also tested for continuity to pins3/4 on LCD connector from backlight output and the continuity is there.

 

[dukefawks]

I have 8.4 volts at left side of L9701 and 0.033V on the boosting side.

That just makes no sense coils like that have near 0 resistance. It would suggest an open coil but more likely bad measurements.
You should have checked the feedback trace A5 when the LP8550 was off.

 

[wrbailey]

I remeasured... again, I get 8.4v on "left side" pin 1 and 0.05v on right side of circuit, pin 2 of L9701

I have no problem removing the LP8550 again to take measurements.

 

[wrbailey]

HAHA!!

Here is one for Rossmann!!! IT WAS THE COIL!!

OL on the bad one I removed and 0 ohms on the donor board... and the backlight comes on!!

 

[wrbailey]

All tested and all working. You can mark this as complete/solved.

Thank you!