Degauss coil. Symptoms list?

gozer5454

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So I think I may need to degauss a couple of my monitors. I have a 19" 7000, a 25" Magnavox TV, and a 27" k7400. All of them have a small region somewhere on the screen which shows a small pink zone.

The 25" and 27" not only have this spot but will do a slow shift between red hues and green hues then back to red hues and so on.

Are these two common symptoms for needing a degaussing coil? If so, I was hoping to buy a coil from twisted quarter, but I'm hoping I can just use the smaller size. Will I really have to buy the larger coil for my 25" and 27" tubes?

What other symptoms might a tube have to require this act?
 
There is nothing magic about a degaussing coil. It's simply a handheld AC powered coil of fine wire, and when in use, it produces an alternating magnetic field. It can be then used to demagnetize (degauss) picture tube shadow masks.

All color monitors and television sets have a built-in degaussing coil. It fires when the set is powered up from cold. It's fairly low power, but it will take care of most light magnetism. So, if you power up the set, it should degauss itself - you don'y see it, since it fires before the tube warms up. After it fires, you'll need to turn off the set, and let it be for 20 minutes to a half hour, then next time you turn it on, it'll do it again. This assumes, of course, that the degauss circuit is working in the particular monitor/TV...

If manual degaussing is required, then you use the degaussing coil. Most handheld coils are a foot in diameter or less. You don't need different coils for different size tubes, you just move the small coil around.

You can buy a coil, or you can make one by using the degaussing coil from a junked TV set (use one from the biggest junk set you can find). Just coil it up smaller, and put a cord on it. Beware that TV coils are only intended to be used for a few seconds - it'll get hot, and if you leave it on too long it will melt. You can also wire two coils in series to increases resistance and make more stable.

NEVER try to use a permanent magnet for degaussing - too strong a magnet can permanently magnetize the shadow mask, or even bend it.

From your description, it does sound like those monitors need degaussing. But if degaussing doesn't fix it, then you may have a purity problem related to misadjustment. Display solid red, green and blue screens - if there are blotches of the wrong color in them, and you can't clear it with degaussing, you might need to adjust the purity ring on the neck, or try rocking the yoke - one of the rubber wedges might have fallen out.

-Ian
 
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