[eurokrn]

I've had my 20" iMac G5 for almost a month now. It's been working great up until last night when all of a sudden the upper half of the screen went dim (about 30-40% darker than the bottom half).

It stays like that until I shutdown, wait a few minutes, and then restart. It'll be fine for a few more hours and then the same thing will happen again.

I'm wondering if this is an overheating issue due to the design. Anyone else have this problem yet? Obviously, I'm fully covered by the warranty, but I i'll be pissed if I have to wait a long time to get my Mac back. =(

[psmith2.0]

How odd. But, considering recent history, not a surprise.

This year's "white spots", I guess.

[eurokrn]

Just found out something.. my screen went half dim again and I let it sit there for a while (went away for about half an hour) and the display went into suspend mode while I was gone. I moved my mouse and the display came back and the screen was normal again. So I guess the problem doesn't require a reboot/shutdown of the system. As long as you shut the display off for a few minutes, I guess it comes back. Sounds more and more like an overheating issue.

[Quagmire]

Doesn't the new LED lights tell you about screen problems? If, so check them out. Maybe they will tell you something is wrong with the LCD and apple can send you a new one and you do the repair yourself.

[Phil]

LCD screens use miniature flourescent lamps for backlighting the LCD. On large screens, there will be 2 lamps. The lamp circuits are driven by inverter circuits that convert low voltage to high, which then fire the flourescent tubes. These circuits do produce heat which can cause a marginal electronic connection to fluctuate bad/good. Your display probably has a defective connection in one of the inverter circuits.

[FFL]

^^^^^Good post.
Phil knows of what he speaks...

[psmith2.0]

That would be something covered by Apple, right? They'd either have to fix it or give him a new machine.

[alcimedes]

yep, he's covered, but it's a bitch to lose your computer while they fix your display.

although, the LCD is supposed to be replaceable in this model (user replaceable) so they might actually have parts on hand, although this early on that might be a bit much to expect.

down the line though, i'd expect display problems to be fixed with relative ease.

[eurokrn]

Thanks for the info. I plan on calling customer support and getting a timeframe on how long a repair will take. It's been holding up since my second post above but who knows when it'll happen again.

[bassplayinMacFiend]

Originally Posted by pscates2.0 How odd. But, considering recent history, not a surprise. This year's "white spots", I guess.

As someone who was bitten by the white spot bug and now owns a 20" iMac G5;

Don't Say That!!!

Thank you for your consideration.

[InactionMan]

Originally Posted by Phil LCD screens use miniature flourescent lamps for backlighting the LCD. On large screens, there will be 2 lamps. The lamp circuits are driven by inverter circuits that convert low voltage to high, which then fire the flourescent tubes. These circuits do produce heat which can cause a marginal electronic connection to fluctuate bad/good. Your display probably has a defective connection in one of the inverter circuits.

So that's what the inverter does. I was trying to figure that out. It's one of them user replaceable parts. Though if it's only a month old Apple best fix it for you.

[davey-nb]

My 20" started coming out of the dimmed state with half the screen dark, half light. Only a reboot would bring it back. It would sleep and wake fine for maybe a day and then do it again.
The Apple specialist I finally spoke with had me boot up into the terminal and reset the firmware, zap the pram, run disk repair and repair permissions. Since then it's never given me the half light/half dark screen again.

Got the new 17" yesterday. Bought it for my wife. It booted right up and looked great. However, after an hour or so the screen began to occasionally flicker slightly. Then, about an hour later it went completely dark.

After a lengthy session with the Apple support I went thought the diagnostics they recommended. They came up with the conclusion that the inverter is bad (L3 remains lit). Apple will be sending me a new one.

I have been a Mac user since 1985 and this is the first major hardware issue I have ever had. Bummer

[eurokrn]

Just wanted to follow up... like wgeorge said, mine also turned out to be a bad inverter. Apple shipped a replacement inverter to me and I was able to replace my faulty one in 5 minutes. Works great now.