> But I'm a bit sceptical about the backlight theory. > > But I've put a Picture of my screen online. So you can see what I mean. > Unfortunately I have shot this picture too early. So there is only a bit of > the top darkening. But it really gets worse when running the PB540 for some > hours longer. > > http://www.webkreativ.de/temp/pb540_lcd.jpg > > I think the question that still remains is: Is it the too hot backlight > causing the darkening or the exhausted LCD? And has anyone yet tried to ask > Apple what the problem might be? > > Well. A last question: Tom - You wrote that i.e. DigiKey has these > backlights. I took a look at their page but there was only a lot of > confusion for me. Because I have no idea which one might be the right one. > Do you know which backlight I would need for the Powerbook 540? Or does > anyone else? Because if I could organize some. Why shouldn't I give it a > try... > > Thanks, > Kai
You have every reason to be skeptical about anything I say! Thanks for the photo of the screen, because it clears up a few things. It definitely rules out any problem with, say, the connectors (which can be unreliable, as Sionnach notes, and cause many display anomalies -- but not this one). >From your photo, it is almost certainly some problem with either the backlight not getting its light evenly distributed to all parts of the display (was this thing ever dropped?), or a thermal problem that causes the liquid crystals to stop polarizing correctly. If the thermal problem is caused by the CCFL tube, things should improve if you turn the brightness off, and let it sit for a few hours. If the display is ok when you turn the brightness back up, then it's likely a tube related thing. If not, open up the display, and try aiming a desk fan at the affected areas, and see if that helps at all. And examine the display carefully to see if anything has gotten knocked out of alignment. Inside the LCD panel assembly, there is a translucent sheet whose job is to disperse the backlight evenly (it may be hard/impossible to see anything other than the edges of the sheet; look around near the CCFL). If it's loose for some reason (or curling up at its edges as it heats up), that might cause what you're seeing. Overall, I think the cause itself is pretty simple (light not getting to the right part of the display, or parts of the display overheating), but finding out what it is another story... The most reliable way to get the right CCFL lamp is to measure its dimensions, and use that as a guide. If you get lucky, a knowledgeable sales associate at JKL or DigiKey (see http://www.lowendmac.com/bookrev/02/1227.html) might already have a cross-reference with the right part number handy. Me, I'm never that lucky. I'm looking forward to the next episode in this continuing saga... --Cheers, Tom -- Prof. Thomas H. Lee Center for Integrated Systems, CIS-205 420 Via Palou Mall Stanford University Stanford, CA 94305-4070 http://www-smirc.stanford.edu 650-725-3709 ph, -3383 fax -- PowerBooks is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Enter To Win A | -- Canon PowerShot Digital Cameras start at $299 | Free iBook! | Support Low End Mac <http://lowendmac.com/lists/support.html> PowerBooks list info: <http://lowendmac.com/lists/powerbooks.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/powerbooks%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
