I have a Titanium PowerBook G4 here (DVI model), and it seems to be suffering from some backlight issues. On startup the backlight is on, but it flickers. When I touch the brightness button to brighten the screen up (it is very dim) the backlight completely shuts off. I performed a software restore, to no avail. I opened up the machine and tried to look for the display cable, which I think is the thicker one going into the left side (facing the screen) hinge. The cable looked a little crimped, so I straightened it out. It still has the same issues. Any ideas?
I feel your pain but I don't think there's any easy way out of this. If any part of the cable or screen assembly is damaged then you're looking at a full screen replacement and that's probably more money than your machine is worth. Nevertheless, a screen replacement on your own is possible and you can find decent prices from reputable vendors on eBay.
Be aware that it is technically challenging as you need to open up the bottom and basically remove all the internals of the machine piece by piece and then put it all back together. I've done a hinge repair and a full top case replacement on my 550 so I can give you advice and links if you're interested but this type of work is not for the faint of heart. The first thing I would suggest is go find out how much a new or used replacement screen will cost you. Then decide if you want to DIY.
What you should do is, with the machine running, pull of the keyboard. Look in front of the trackpad for a cable that is squeezed between the topcase and the frame. (sorry cant remember the colour, but its easy to spot). Give it a wiggle and see if it affects the screen. If so, use some tape to wrap that cable as it passes under the topcase. This is a longshot, but you never know. Beyond that, as mycatsname is suggested any screen component will require a total screen replacement. I've also seen this caused by Motherboard or Inverter board failure.
I'll give it a shot. I think it might be the cable running inside the hinge. Again, the screen works fine, but the backlight doesn't. It's almost like no data is running back from the screen to tell OS X what the brightness is at, because when I press the "brighten" button (F2) the bezel server shows the brightness level is "2 notches", when, by my eye at least, it's half. Then in a little while, the backlight comes back on, on its own.
What you should do is, with the machine running, pull of the keyboard. Look in front of the trackpad for a cable that is squeezed between the topcase and the frame. (sorry cant remember the colour, but its easy to spot). Give it a wiggle and see if it affects the screen. If so, use some tape to wrap that cable as it passes under the topcase. This is a longshot, but you never know. Beyond that, as mycatsname is suggested any screen component will require a total screen replacement. I've also seen this caused by Motherboard or Inverter board failure.
Wow! I never thought I'd see my trackpad cable fix make it as far as the ehMac help board. I have to step out of my MCNI alter-ego here and ID myself as the author of that fix. Marc Posner has kindly blogged the fix on his site and there have been a number of threads on the Apple Tibook discussion forum (this is that lastest).
Unfortunately I don't think that this is the cause of your problem. There has only been one report (out of the many confirmed fixes I've heard) that had some sort of screen problem along with all the other symptoms of the abraded trackpad cable (random hangs - often caused by pressing the left command key, hangs on wake form sleep, three beep errors at start up with no memory chip defects, flaky track pad).
Your symptoms sound to me like the screen cable might be damaged or pinched since anything that might move the cable - changing the screen angle, plugging a DVI cable into the back panel (which might wiggle a loose motherboard) - seems to trigger the symptoms. Do you also see the same thing when you plug a different type of cable in (e.g. USB, FQ etc.)?
If there any history of "trauma" to your machine? Have you ever dropped it? Are there any cracks in the case?
One thing you could do would be to take it to a very good Apple service centre and ask them to take a good look at it. Agree on some reasonable amount of time (i.e. one or two hours of labour) as the max you are willing to pay to try to find the answer and see what they find.
Well you see, this isn't my machine. I just got it for an amazing price used. It looks like its been banged up a bit. I checked the display cable and put a bit of electrical tape around it to try and fix that issue, but no avail. Also worth noting, a "frying" noise emits when I change the angle of the screen, and when it flickers.
PB G4 (Titanium) suffering from backlight issues
Linear Mode
