PB display flickers, but external monitor still OK

Question

Hi all,
I've just bought a faulty powerbook to see if i can fix it. It's a G4 15" 1Ghz Titanium DVI. The fault is that the powerbook display frequently becomes corrupted. it's actually a beautiful effect, but not very practical! Every few moments, minutes sometimes, the display looks as if deep colours are gradualy bleeding accross it, until it becomes unreadable. the effect is sometimes psycedelic and sometimes textured like oil on canvas!
Anyway, simply moving the angle of the display a little clears the screen and everything's visible again. At no time does the system crash or anything; if there's an external monitor conected in Display Mirroring or Extended Desktop mode it doesn't show any artifacts and continues to work perfectly. It's only the powerbook's own display that exhibits the fault.
i'm presuming therefore that the logic board is OK but that there is a loose connection somewhere (where I don't know!). Could it be the invertor board however?
does this all sound familiar to anyone?
thanks!
TiBook 1Ghz (DVI)   Mac OS X (10.3.9)   9600/350

Answer 1

Hi, efunc. If your situation is such that you could happily use the Powerbook as a very compact desktop computer with its built-in display closed and an external monitor, keyboard and mouse connected, you might be able to do so for a long time without fixing anything at all.
If you really want to use the Powerbook as a portable, you'll have to crawl inside and look around for the trouble. The fact that changing the built-in display's angle clears the problem suggests strongly that the cause is in one of the very thin, fragile cables that pass through the display hinges. These can become pinched or abraded in the very narrow passageway there (especially if the hinges are fatigued and begining to break), leading to faulty insulation and short circuits or even severed cables. There is very little room there to make any repairs, if that's the case, and cable damage is not always easy to see. Replacing the cables, one end of which is sealed inside the display bezel, is essentially impossible. A professional technician, when faced with bad display cables, replaces the entire display instead of trying to pry the bezel apart.
Because the cables are so thin, flexible and delicate, the motion of the display being opened, closed and adjusted is, in itself, very unlikely to loosen (or tighten) any of the cables' connections inside the body of the Powerbook. But a loose connection there is possible, and it wouldn't hurt to check. Complete disassembly instructions are here, and will show you where the display cable connections are located.
If you don't find a bad connection, the inverter board is the least expensive part you could replace in the hope of solving the problem. But I doubt that adjusting the screen angle would "fix" (even temporarily) a problem caused by a bad inverter, so I suspect that isn't where the fault lies.
Good luck.
EDIT: Oh, dear — I just realized that you're the very same efunc who reports a whole different set of problems with his used 1GHz Tibook in a different thread. If all those problems are occurring in the same Tibook as the display problems discussed in this thread, most of what I've said above is out the window, and the source of all the problems could be anywhere, including the logic board, or even multiple sources.
My comments above were based on the assumption that the problem you reported in this thread was the only one you were having with the affected machine. If that assumption is wrong, disregard them.