A1708 820-00840 no backlight (logicboard problem, not flexgate)

[drdream]

Hi all,

I was wondering if you could guide me a bit, as I am not experienced.

I am actually working on a MacBook A1708 820-00840 with no backlight.

I ruled out the flexgate issue, because I have a few working board and displays.

Here are the readings I wrote down so far:

- F8400 13.1V / 13.1V (in/out)
- R8402 13.1V / 10V
- C8401 13.1V
- C8410 13.1V
- C8412 13.1V
- C8414 13.1V
- C8413 13.1V
- C8466 to C8468 12.83V (which is abnormal)
- C8475 12.83V
- R5455 0.0V
- R5459 0.0V
- C8473 to C8469 12.83V
- D8410 13.1V / 12.83 (here I saw that I need +/- 45V, but I got only 12.83V instead)
- C8474 12.83V

I replaced the following parts:

- F8400 (as the first reading were lower on the output) (I replaced it with a fuse from a MacBook A1466 and it seems to work fine as I have 13.1V on both sides)
- U8400
- D8410
- Q8401
- R8431
- Flex connector MB to LCD

Any help would be much appreciated.

Thank you.

[mon2]

Re: A1708 820-00840 no backlight (logicboard problem, not flexgate)

Check the lid_open voltage to ground when the clamshell is open and when it is closed.