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From: kenw@col.hp.com (Ken Wyatt)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Magnetic burn on VGA monitor
Message-ID: <25580004@col.hp.com>
Date: 6 Dec 90 18:28:01 GMT
References: <9012051811.AA23627@ucbvax.Berkeley.EDU>
Organization: HP Colorado Springs Division
Lines: 21

I missed all the previous explanation on how this crt became magnetized,
but allow me to relate a possibly similar experiance with my EGA monitor.

One day I tried running a magnet around in front of the crt while observing
all the fasinating color changes.  Of course, when I removed the magnet,
the most of the "color changes" remained!  It took about two months of
use before the built-in degaussing coil could finally remove all traces
of the residual magnetism.  I suspect that the process could be greatly
speeded up by using a video tape demagnetizer.  Turn on the demagnetizer,
holding it a couple of inches from the face of the crt.  Slowly (with a
circular motion) move the demag. around the crt face, keeping the distance
about two inches away.  Once the entire face has been treated, SLOWLY
start to move the demag. away from the crt surface WHILE KEEPING THE
DEMAG. POWER APPLIED.  When you get about three feet away, remove power
to the demag.  You should now be left with a fairly clear screen.  Any
residual problems will likely be fixed by the built-in demag. coil (which
is located around the perimeter of the crt face).

I caution you that I have not personally tested this technique, although
it has worked very well for color televisions and is a standard procedure
used by service persons.