TITLE
    Apple Displays: Changes In Colors Requires Degaussing (4/94)
Article ID:
Created:
Modified: 		15205
4/25/94
4/25/94
TOPIC



    What can cause the below symptoms?

    When the computer and monitor are powered on, a green an area on bottom left of the monitor changes colors depending on what is displayed on screen. Another less intense area is directly in the center of the screen. Both distortions are approximately one inch high and 3.5 to 4 inches wide.

    The display has been moved in the house and checked for any environmental factors but this didn't change anything. The monitor was left off for over 24 hours but the discolored areas didn't change.


DISCUSSION


    This sounds like a classic case of magnetic field interference. Evidently the CRT has come in contact with a strong magnetic field that magnetized the CRT screen and thus created the problem you are now having. The magnetic field could have been generated by anything from a small magnet to the electric motor on a vacuum cleaner. The cure is fairly simple. The unit should be degaussed with an external manual degaussing coil, as used by TV technicians. They can be purchased at most good electronic parts stores and cost about $30.00.


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Document Information
Product Area: Monitors-Displays
Category: General Topics
Sub Category: General Topics

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