[X4U] iMac screen problem

[Doug McNutt]

At 17:38 +0200 8/18/08, Paul Moortgat wrote:
>A friend who uses her iMac professionally has a problem with her 5  year old iMac.  It started to produce horizontal lines which start at  the bottom and move up to the top of the screen.  Sometimes it's so  bad she can't work.  She doesn't dare to restart because then it's at  it worst.

>Is it time to buy a new Mac?

Lines as you describe are often due to interference. The vertical scan rate is not far from power line frequencies and interfering signals are often synchronized that way.

Do you have another CRT display nearby? Try moving it around. Watch for things like lights, power converters, and motors nearby. Try just turning the Mac 90 degrees. The magnetic field of planet earth does make a small difference. I'd say try choosing a different scan rate for the monitor but I don't think that is possible for an integrated box from Apple.

But then the internal power converter inside the iMac can also be the source and that makes your last comment germane. Flat panel displays aren't bothered by magnetics.

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