Hi,

I have a ibook g3 ( dual-usb ), starting it I can hear the chime booting sounds and that the hd works but no images on screen.

I tried to see if it works on external video, but it gives no signal, so I'm sure about the logic board failure problem.

But, yes there is a big doubt: when i boot up the ibook the display is totally black, like when your ibook is off.

I have a look at inverter cable, and i saw that a wire was broken, I fixed it and tested with a multimeter and the cable works fine.

I tested also the data cable and it works too.

So I'm starting to think about the way that the lcd have not power, and the only thing that gives power I suppose to be the inveter, because when i turn on the ibook I can't see any light on the back of the ibook.

So the first task to solve is:

- if I have the logic board failure problem, should the backlight still works or not?

there are two cables (the display cable and the inverter cable), and they work independently. If the inverter cable is bad then you should still have a picture but it will be real dim since you don't have a backlight. If the display cable is broken, you would just have a white screen.

If you are not getting a picture at all it is usually going to be the logic board. It could possibly be the LCD but that is rare for them to just stop working at all.

I'm quite sure about the logic board because i've tested with an external monitor and I have no image on it too.

My only doubt is: with the logic board trouble should the backlights work or they are off due to no images data?

I've tested both inverter and flat data cable with a multimeter and them seems ok.

I've already had the logic board replaced on my G3 iBook once, and it is gone again. The first time, the logic board was covered by Apple, but no such luck this time. Apple said that if there is not a pic when you connect to external display they were 99% sure that it was logic-board related.

Saw an ad for this site in MacLife, and I'm hoping to be able to replace that logic board myself...my daughter will be ecstatic!

My Girlfriends ibook LCD backlight just went out. The ibook still boots up and is visible if you shine a light on it. I hooked it up to an external monitor and it works fine. So I'm sure the logic board is okay. Would replacing the inverter be the first thing to try?

Generally if the backlight goes out all the sudden its the inverter board. If it was more of a gradual thing especially when moving or bumping the display makes it better or worse it is an inverter cable problem.