Screen over-exposing/blurring/distorting

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Level 1

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Screen over-exposing/blurring/distorting

Hi - in the last few days my iMac G3 (400) screen has started playing up. The symptoms are that it starts getting very bright/white so that the screen becomes almost impossible to see; on-screen boxes start stretching and blurring to one side. If I switch to other programs, the fault remains, but the problem isn't there all the time.

I was wondering if my CRT is dying?

Has anyone else had anything similar? Any clues as to the cause or what can be done about it?

Thanks

Steve

Message was edited by: Sam's dad

iMac DV SE 400, Mac OS X (10.4.10), External Lacie HD

Posted on Aug 31, 2007 5:34 AM

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Answer 1

Aug 31, 2007 11:31 AM in response to Sam's dad

It sounds like the CRT is dying. However, if you seldom fully shutdown the iMac, you may want to do so, because starting up after causes the CRT to degauss.

http://docs.info.apple.com/article.html?artnum=25339

This sounds more serious than simply a need to degauss, but who knows...

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Answer 2

Sep 10, 2007 5:01 AM in response to Sam's dad

Hi Sam's Dad

Chances are that it's not the screen but the circuitry that drives it and the cost of repairing it is now probably more than the mac is worth.

However, you can get round it by plugging an external monitor into the VGA socket hidden under the little oval panel at the back of the iMac (only the very basic models don't have this).

Cheers
Donna

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Answer 3

spudnuty

Level 5

7,128 points

Sep 10, 2007 6:58 AM in response to Sam's dad

Well clearly something is going bad in the high voltage section or PAV. It's the board on the top under the CRT. My solution for this is if the CPU speed is 400 or above, I've dropped the logic/down converter board into a 350 machine.

As Donna says sometimes when this fails the VGA output will be unaffected and the iMac will still run with an external monitor but there will be no resident video. The VGA spigot is on all the FireWire iMacs 400 and above.

Richard

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Answer 4

Oct 9, 2007 5:11 AM in response to spudnuty

Hi
I've the same symptom on my machine.
I could work without any trouble (after some days not plugged) but suddendly the screen "moves " until beeing troubled and dark. Near everytime, it makes boging (buging?) the machine.
Futhermore, I ve changed the battery two years ago and from yesterday day and times are removed each plugging off.

I checked the firmware (ok), and the static electricity.
I wonder how turn to 350 MGH from my 400 MGH speed.
Can you explain?
Harmfull thanks

Groseille

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