PowerBook DUO 230 No backlight

[johnnyilblasco]

Hi guys,
I have an issue with the backlight on a PowerBook Duo 230. The machine works perfectly, it boots up and works with the dock station, but the internal display has no backlight. The image is there, but there’s no illumination. I tested the display with another motherboard and the screen works fine.

So the problem is definitely on the motherboard. What do you think it could be? I tried something that you really shouldn’t do because it risks causing damage, connecting the display flat cable while the machine was powered on, and when I did that, the screen lit up. It seems like something related to the backlight control logic or brightness control. Of course, I can’t find any schematics…

 

[imactheknife]

Check for bent pin if applicable in the connection. Try doing a fresh install of an os via the dock. Definitely recap the logic board if not done.

 

[johnnyilblasco]

The motherboard’s been recapped, of course.
I’ve got another donor board for spare parts, so I swapped out U17, U9, and a bunch of other 9953s around the board. The weird thing is that if I plug in the flat cable while it’s powered on, the backlight comes on, which makes me think it’s some kind of logic issue, but I’ve got no clue what’s actually causing it. Without schematics, it’s pretty hard to figure out how to fix it.