RE: Monitor degaussing help wanted

Hi Joel,

I can think of a couple things that could cause this other than magnetism.
The most prominent is a purity problem that's external and can be repaired,
whether it be spinning the purity rings (magnets) or adjusting the yoke
position. The other one (which isn't a good sign) is that the aperture
grille (shadow mask) could be damaged. This happens with rough handling or
extreme temperatures. I had a DEC HR-290 20" monitor look like this after
it was dropped just a couple feet.

I don't have much of a suggestion here except to try the purity rings and
yoke to see what you get. It'd be nice if all it needed was a good
degaussing!

HTH,

John

-----Original Message-----
From: Joel Rosenzweig [mailto:Joel_Rosenzweig@Agilent.com]
Sent: Monday, July 24, 2000 1:58 PM
To: rasterlist@synthcom.com
Subject: RASTER: Monitor degaussing help wanted

I have a Wells Gardner K7200 monitor that is brand new, but 7 years old. I
picked it up a few weeks ago at a flea market. I powered it up, but was
disappointed to see that the picture was covered by a whole wavy rainbow of
colors. My first guess was that the monitor needs to be manually degaussed,
given the amount of the distortion. I have a degaussing coil from Happ
Controls, and used that the degauss the monitor. I used the procedure
outlined by Randy Fromm.

Here's Randy's description:
"Whether it's storebought, salvaged, jury-rigged or homemade, the method of
using your coil to degauss a picture tube is the same. The CRT can be
degaussed with the monitor on or off. I like to have it on so I can see the
results right away. Besides, it's neat to see how the powerful magnetic
field of the degaussing coil distorts the picture. Start at the center of
the CRT. Hold the momentary switch closed while moving the degaussing coil
in a spiral across the screen. When the spiral extends well beyond the edge
of the picture tube, move it away from the CRT, turn the coil at a 90 degree
angle and release the momentary switch to turn off the coil. Turning the
coil at the end is simply a precautionary measure to assure that the
magnetic field of the degaussing coil doesn't have any effect on the CRT at
the moment the coil is shut off. In practice, I don't find it to be
necessary. Likewise I have found that degaussing the front of the picture
tube is generally all that is necessary; "The Book" says you also should
degauss the sides and top of the CRT and chassis."

Unfortunately, when I plugged the monitor back in, it looked just as bad as
it had before. My degaussing procedure seemed to have had no effect. So,
here are my questions... given my brief description of the display
characteristics, was I correct to diagnose this as a degaussing issue? If
it's something else, have any idea what it is? If this is still a
degaussing issue, are there any tips for improving my technique?

Specifically, how long should I take to degauss the monitor? 1 minute?
Should I make rapid spirals around the monitor face or slow paced ones? I
was holding the coil so that the "O" was parallel to the face of the screen.
That is, the monitor is facing horizontally on my workbench, and the "O" was
being held straight up and down. Is that correct?

If degaussing doesn't fix the problem, what do I check next?

Thanks for your help,
Joel-

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Received on Mon Jul 24 15:03:47 2000