Teach me about degausing.

SilverDuck

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I have a 27" K7000 std res monitor that Chad just rebuilt for me. I got it home, hooked it up, and my tube is all sorts of crazy rainbow colors. I can move things around with a magnet enough to realize that the chassis is fine, colors are vibrant...but my tube is screwy. I can shift things with my magnet to where 3/4 of the screen is good, but still have major issues.

Recommend me a degausser tool and give me some basics on using it.

Thanks
 
I picked mine up from Bob Roberts. I find it quite simple to use.... Hold the unit a couple of feet above the monitor screen (parallel to it) push the button to energize it and using a circular motion, slowly move the unit closer to the screen until a couple of inches away, then use the same motion pulling the unit away from the screen then let the button go. Should take about 30 seconds to complete. This procedure works well for me.
 
It could be a magnetized frame or the internal components of the tube could be magnetized or interferrence from a local magnetic source. You can't really verify any of that until you try and degauss it.

Have you tried rotating the cab to see if the picture clears up some?
 
the monitor is sitting on a resin-top table (my test bench). When I connect the degaussing circuit that is attached to the monitor, it blows the chassis fuse ASAP. Is that a clue of something?

The colors are worst around the edges, and better in the center. Is that a clue?
 
All color monitors and televisions have degaussing coils built-in because the picture tube's shadow mask gets slightly magnetized by external sources very easily. The picture can be quite horrible. If the degaussing coil on your set blows the chassis fuse, then there is something wrong with either the degaussing circuit on the chassis or the coil itself. This is usually caused by a faulty degauss posistor/thermistor, or the coil is shorted.

You can use a manual degaussing coil to clear up the problem on the bench, but the picture will become discolored the next time the monitor is moved (the earth's magnetic field affects it too).

Don't use strong permanent magnets to try to clear up the problem. You risk bending the shadow mask inside the tube. If you damage this, then there is no fixing the tube. To degauss a tube you need an *alternating* magnetic field - not a fixed one.

Lacking a degaussing coil, you can use a large soldering gun held near the face of the screen with the trigger held down, a handheld bulk tape eraser, an electric drill, or some other source of an alternating magnetic field. You can also use the coil from a junked TV set, powered directly from the mains (just be careful, it'll heat up fast!).

-Ian
 
All color monitors and televisions have degaussing coils built-in because the picture tube's shadow mask gets slightly magnetized by external sources very easily. The picture can be quite horrible. If the degaussing coil on your set blows the chassis fuse, then there is something wrong with either the degaussing circuit on the chassis or the coil itself. This is usually caused by a faulty degauss posistor/thermistor, or the coil is shorted.

You can use a manual degaussing coil to clear up the problem on the bench, but the picture will become discolored the next time the monitor is moved (the earth's magnetic field affects it too).

Don't use strong permanent magnets to try to clear up the problem. You risk bending the shadow mask inside the tube. If you damage this, then there is no fixing the tube. To degauss a tube you need an *alternating* magnetic field - not a fixed one.

Lacking a degaussing coil, you can use a large soldering gun held near the face of the screen with the trigger held down, a handheld bulk tape eraser, an electric drill, or some other source of an alternating magnetic field. You can also use the coil from a junked TV set, powered directly from the mains (just be careful, it'll heat up fast!).

-Ian

Will my cordless drill work? If so, how do I do it?
 
Will my cordless drill work? If so, how do I do it?

It *might*. I've had limited success using a cordless drill. An electric (wall powered) drill would be a much better choice. But, the general procedure is:

Hold the drill sideways, a few feet from the screen, and pull the trigger and hold it down. Move the drill in circles, moving towards the screen. As you get toward the screen, the colors should change and move around. Get right up to the screen, and work your way back away from the screen (at least three feet) before shutting off the drill. If you didn't get much color changing as you got near the screen, it's not powerful enough.

Same procedure with any degaussing coil, really. I personally use one scavenged from a 27" or so TV set, coiled up upon itself to be about four inches in diameter and wound with tape. I simply patched on a power cord. Kept meaning to fit a momentary switch but never did. I just plug the cord into an extension, and stand on the extension, and hold the cord in my hand. When I get far enough back, I pull on the cord to unplug it. It works perfectly for degaussing, but you can't leave it plugged in for more than a few seconds (gets hot).

-Ian
 
If the monitor is sitting horizontally and looks messed up, try turning it vertical - or vice versa. I often times have a monitor on my bench that looks fine in one orientation, but turned 90 degrees looks like crap and degaussing doesn't do any good. But once I put it in the game, even turned, it looks fine....
 
I bought a heavy duty degausser at Fry's. It's a big circle and you plug it in, step back about 6 feet from the machine, and slowly walk towards it and get very close to the screen and do a few circles and then step back again.

Most of my monitors seem to degauss themselves but a few need this thing from time to time.
 
I am able to get this one to about 98% with only a few bad spots. Good enough for me.

It is a 27" tube, and I think the chassis is only good for 25". I can't get the width to go wide enough.
 
I have a degausing coil, but I still use one of my "part magnets" (use it to hold spare screws and stuff like that). It's just a magnet from and old 6X9" car speaker... I come in with it's edge facing the monitor, flip it so it's parallel with the monitor, then I do a few circles slowly backing away, then I flip it on edge again... works well enough in a pinch. Saves me from having to run an extension cord and helps my "hard drive" paranoia when the machines are "too close" to any other machines that have hard-drives.
 
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