From: LILMARA@YaleVM.YCC.Yale.Edu (Martin Lilly)
Subject: Magnetized monitor NOT = Junk or How to Degauss
Organization: Yale University
Date: Thu, 07 Jan 93 23:34:50 EST

Thanks to everyone who replied to my plea for help regarding the
magnetized monitor. For those of you who didn't see the post, my
six year old daughter was doing "experiments" with a magnet she
got for Christmas. The "result" was an expensive color monitor with
ugly green blotches all over.
 
I was assured by everyone that it was a minor problem that could
be resolved by removing the spurious magnetic fields by a process
called degaussing.
 
My first step was an attempt to identify an internal degaussing
button inside the monitor. I couldn't find one in mine, a Seiko
CM1445.
 
On the suggestion of Arthur Dunham, I attempted to scramble the
magnetic fields using the same magnet my daughter had used.
First, I removed the monitor far from the cpu (and my thesis),
plugged it in and turned the brightness to max in order to see the
distortions. I brought the magnet in close to the screen and slowly
withdrew it while rotating it simultaneously. This creates some
interesting special effects similiar to some After Dark modules,
though I don't recommend magnets as an alternative. By
withdrawing the magnet at the correct angle, I was able to
alleviate 95% of the problem.
 
Although this was much better I wasn't quite satisfied, so I dug out
a very powerful speaker magnet I had in the basement. This
magnet is difficult to pry off of any object it's stuck to. Amazingly, I
could create monitor distortions from about 6 feet away. With this
magnet, I followed a protocol Rick McCormack sent me, which I
include here:
 
__________________________________________________________
Rick McCormack's de-gaussing procedure:
 
You have already received much advice about correcting the
problem.  If you decide to do it yourself (i.e. if you have a tape de-
magnetizer, once common to bulk erase 7-inch reels of recording
tape), it is easy to do and even easier to mess up. Proper
precautions include; take off your watch!
 
Don't do it with-in the area where your stereo and audio cassettes
andfloppies and hard drive are--move the monitor to where you
have a large clear area around it (see why in the next few steps).
 
Turn on the selected de-gausser (bulk eraser, coil, etc.) when it is at
least six feet away from the monitor. Approach the monitor from
head on, moving the de-gausser continuously in circular motionsof
about 8-12 inches, covering an area that extends about 16 inches
outside the monitors perimeter (top, bottom, both sides) and covers
past the centre of the monitor (you want to describe arcs that go, for
example, from about 16 inches above the top of the monitor to
about 2 widths of the way down the monitor surface, then swings
out to about 16 inches past the monitors side, back across 2 of the
monitors width then down to the bottom, etc.) Vary the distance
from the monitors screen--start the coil about 6 feet away, bring it
in, moving it slowly but continuously to about 2-3 inches from the
screen for several passes as described above; then begin backing off
from the screen whilerepeating theabove passes. The object is to
"confuse" the comprehensive magnetic pattern that your daughter
set up, and make it progressively weaker and more disturbed.
Finally, don't turn the de-gausser off till it is at least six feet from
the screen again.  And watch out for what is called 'duty cycle". My
bulk eraser has a 25% duty cycle, meaning it can be on for a
maximum of one minute continuously, then must be left off for at
least 3 minutes before being used again. This prevents it from over-
heating and blowing out.
 
I hope this hasn't discouraged you from attempting this simple job-
-I just wouldn't want you to do it wrong and give up. Lotsa luck
and let us know what you did and how it worked.
 
UseNet: Rick_McCormack@mindlink.bc.ca  |  A O-L: Rique
________________________________________________________
 
This worked beautifully, and I have a distortion-free monitor.
Had  it not worked I could have just taken it to a dealer
or TV repair shop for a professional degauss job.
 
Thanks again to everyone for vindicating my daughter. We
degaussed the screen together, and I'm letting her eat food again
(Just Kidding!!)
 
Martin Lilly LILMARA@YaleVM.YCC.Yale.edu
Newsgroups: comp.sys.mac.hardware