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CRT Degaussing Program

For Those of Us Who Don't Have a 'Degauss' Button
  [vote for,

I've had my monitor for as long as my computer, 6 years. I've been able to add some good, worthwhile upgrades to the computer, but not my monitor. This wouldn't be much of an issue, except that (perhaps because of the speakers sitting next to it) its image is a bit skewed.

I don't have a degaussing button. My monitor was made *just* before the advent of said. However, I know a teeny-weeny about how it works, and it seems a program could be made which would degauss it from the software end.

I know LCD's are taking over the market. I'm considering one myself. But some people just won't give up their CRT's. Someone is going to end up getting mine when I get an LCD. So maybe someone can write this program. I know I'D appreciate it.

galukalock, Mar 10 2003

External Degausser http://www.datadev.com/dc13.html
[Corona688, Oct 04 2004]

use a drill http://www.woil.ws/fixmonitor/
[wtanaka, Jun 03 2007]


       I don't think that's going to work... the electromagnets that divert the electron beam are both a) not in the right place and b) not powerful enough to degauss your monitor. If you REALLY want to degauss it, you can get yourself an external degausser device - technicians use 'em for messed TVs and the like. Just keep it the heck away from any hard drives, audio tapes, and floppy disks you have!!
Corona688, Mar 10 2003

       What about those that DO have degauss functions? Shirley they don't put much more powerful electromagnets in *just* for that, Shirley?
galukalock, Mar 10 2003

       With built-in degaussers, they have a sort of compromise... they drive a somewhat smaller coil at *very* high power for a second or two, using a thermistor to prevent it from overheating and burning out. Since it's right inside the monitor, a very short distance from the parts that need to be degaussed, it doesn't have to be anywhere near as powerful as an external one.
Corona688, Mar 10 2003

       There you go. A brief, strong signal with the right modulation might activate the main coils in a regular monitor the right way.
galukalock, Mar 10 2003

       Sorry, wouldn't work. The main deflection coils are around the neck of the tube; the degauss coils are around the front, near to the shadow mask. (I'm more familiar with the CRT as it applies to TVs, but monitors are fundamentally the same.)
angel, Mar 10 2003

       Degaussing coils in TV's?!
galukalock, Mar 10 2003

       Yep. All CRTs work the same way.
phoenix, Mar 10 2003

       What I meant was, 'There are auto-degaussing TV's?!'
galukalock, Mar 10 2003

       All colour TVs, and all colour monitors (CRT ones, that is) have degaussing coils. TVs and monitors without degauss buttons do it automatically when you first turn them on - most of them emit and audible THUNK when they do it.   

       You can get an extra degauss cycle by turning the monitor off and on again - but you have to wait for the thermistor to cool down before turning it back on again, or it doesn't do anything.   

       An undegaussed CRT doesn't look skewed - that's a different problem. What happens is that the colours go completely loopy, with an otherwise (almost) undistorted image.   

       [Corona688] "Since it's right inside the monitor, a very short distance from the parts that need to be degaussed, it doesn't have to be anywhere near as powerful as an external one."   

       Sorry, no, not so. The components that needs to be degaussed are many and various, and the degaussing coil runs all around the face of the tube. The field from it is quite strong initially, dropping away rapidly (10% after 0.1s, 1% after 0.2s, and so on - or thereabouts).   

       It's certainly not strong enough to upset a hard drive from outside the hard drive case (the motors in the drive itself have much stronger magnets) - floppy disks and audio or video tapes could conceivably be at some risk, but probably not.   

       You're right about the thermistor - it's not just to stop it burning out, it's to stop the coil running continuously, which would be a terrible waste of power - and prevent you seeing any picture, too. Degaussing requires a strong alternating field that gradually diminishes to zero - a coil in series with a suitable thermistor does the job beautifully.   

       [angel] is correct.
Cosh i Pi, Jun 03 2007

       If you have a CRT TV or monitor with built-in degaussing, you can hear a buzz and thump as it turns on, as [Pi] points out. Plus, any other CRTs nearby will be affected, and their images will wiggle a bit.   

       I haven't seen a hand-held degausser in ages, but a strong magnet and some practice may work, instead.   

       A software program probably wouldn't do a thing toward degaussing. It's an image, it's at the wrong end, and a few other things.
baconbrain, Jun 03 2007

       Weren't the military developing this for wide-range degaussing?
MaxwellBuchanan, Jun 03 2007

       I've been on a U. S. Coast Guard ship as it went through a Navy degaussing range, so I know there is military degaussing, but that's about it.
baconbrain, Jun 03 2007

       [baconbrain] You can do a reasonable job of degaussing a screwdriver with a strong magnet and a bit of practice, but I challenge you to degauss a TV or CRT monitor that way! 8~)   

       Fortunately the psychedelic mess you'll inevitably make (try it - it's really cool!) will clear itself in two or three restarts from cold.   

       Not all colour tellies or monitors make any noticeable noise degaussing, but they ALL do it on switch on - apart from some of the ones with separate degauss buttons. A CRT telly or monitor without degauss is virtually useless - certainly no point having colour, other than for pure psychedelia.
Cosh i Pi, Jun 03 2007

       My first color TV used tubes, and had a circular screen (about 10" diameter). It had to be degaussed once or twice a year -- I used a soldering gun. The technique is to place the gun close to the screen, pull the trigger, then slowly move away. Might have to do this a few times starting from different places on the screen.   

       I got rid of this TV when replacement tubes began costing more than I paid for the entire set!
Optiker, Jun 03 2007


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