For less than a minute a speaker magnet was moved in front of my TV while on. Now the upper third of the picture is purple, the middle is normal and the lower third is green. Really horrible.
Can this be undone in someway?
Is it permanent (or for how long)?
Help
Can this be undone in someway?
Is it permanent (or for how long)?
Help
You have the option of trying to manually degauss the CRT yourself. Since the tv is basically done. If you can get a crt deguasser, use that, but a large unshielded speaker magnet will also work. With the tv on, come straight in to the middle until the color starts to change. About 1"-2". Working in a circle spiral out keeping the magnet the same distance from the front of the screen and overlap you path. When you get to outside, spiral back in to the middle and pull the magnet back straight from the screen. Try this several times and see if it works. Sometimes the deflection reduces its self over time. We have been doing this onboard Navy ships for 25 years because the onboard degausing system (which reduces the ships magnetic signature against mines) plays havok on our tv's.
Usually the picture tube should be degaussed every time you switch the TV on. But this only when the TV was completely off for a longer time.(A PTC conducts the current to the degauss coil)
If it shouldn´t resolve the problem you can use a specific magnetic coil to get rid off the magnetized areas.
It´s definitely not a permanent problem like it could happen for example when the TV falls down.
Jens
If it shouldn´t resolve the problem you can use a specific magnetic coil to get rid off the magnetized areas.
It´s definitely not a permanent problem like it could happen for example when the TV falls down.
Jens
Deguass that CRT!
This sounds like the CRT or frame of the TV may have been magnetized.
The TV set has a built in degausser (the buzzing noise that most TV's make when you turn them on) that will remove some of this each time it is turned on. Unfortunately this built in coil will only work for a maximum of a few seconds each hour, the degaussing coil is powered through a relay that is held open by a thermisistor. As the thermisistor heats up, it shuts off the relay. The net effect is that the coil will only function fully 4-5 times per hour.
If a couple of power cycles doesn’t fix this you will need an external degaussing coil. I think I once last bought one from MCM electronics for a bout $30. Its about a 12" diameter coil of copper wire that plugs into the wall. It looks real cool to wave it in front of the set while it is operating but this also increases the chances of damaging the mask.
For about half as much you can purchase a hand held tape bulk eraser. These are also great for degaussing unsuspecting "friends" wallets. A quick blast will wipe out ATM and credit card strips from about a foot away.
Worth trying, for what is likely a one-time fix, is to look around the house for any small appliance that may be emitting a mild AC field while it operates. I’ve used electric can openers and hand mixers with mild success.
For a general rule, with the TV off, turn on the degaussing coil from 3 or more feet away, slowly bring it to the affected area and wave it about for 20 or 30 seconds, slowly move it away and then turn it off. I'm not joking this really works!
Turn the set on and see how much progress you have made.
Repeat.
An other fun thing to try is turning the TV 90 (horizontally not vertically, unless you like to watch TV lying on your side) degrees while it is on. Many TV's will react to the change in orientation to the earth’s gravitational field affecting the color "purity". They then need to be mildly degaussed by cycling the power.
Hope this helps
-Dave
(a very slow typist)
This sounds like the CRT or frame of the TV may have been magnetized.
The TV set has a built in degausser (the buzzing noise that most TV's make when you turn them on) that will remove some of this each time it is turned on. Unfortunately this built in coil will only work for a maximum of a few seconds each hour, the degaussing coil is powered through a relay that is held open by a thermisistor. As the thermisistor heats up, it shuts off the relay. The net effect is that the coil will only function fully 4-5 times per hour.
If a couple of power cycles doesn’t fix this you will need an external degaussing coil. I think I once last bought one from MCM electronics for a bout $30. Its about a 12" diameter coil of copper wire that plugs into the wall. It looks real cool to wave it in front of the set while it is operating but this also increases the chances of damaging the mask.
For about half as much you can purchase a hand held tape bulk eraser. These are also great for degaussing unsuspecting "friends" wallets. A quick blast will wipe out ATM and credit card strips from about a foot away.
Worth trying, for what is likely a one-time fix, is to look around the house for any small appliance that may be emitting a mild AC field while it operates. I’ve used electric can openers and hand mixers with mild success.
For a general rule, with the TV off, turn on the degaussing coil from 3 or more feet away, slowly bring it to the affected area and wave it about for 20 or 30 seconds, slowly move it away and then turn it off. I'm not joking this really works!
Turn the set on and see how much progress you have made.
Repeat.
An other fun thing to try is turning the TV 90 (horizontally not vertically, unless you like to watch TV lying on your side) degrees while it is on. Many TV's will react to the change in orientation to the earth’s gravitational field affecting the color "purity". They then need to be mildly degaussed by cycling the power.
Hope this helps
-Dave
(a very slow typist)
Don't be rediculous!
Hi,
Of course it's not ruined.
If it's just the speaker's magnetic field that's magnetised the shadow(apperture)-grille OF the CRT it is NOT permanent.
Each time you turn on the TV (from cold), the internal de-gauss will operate, and it will improve until it gets back to normal.
If you are impatient, you can call a repair man and ask him to use a manual de-gausser. These are much more powerful.
Cheers,
Hi,
Of course it's not ruined.
If it's just the speaker's magnetic field that's magnetised the shadow(apperture)-grille OF the CRT it is NOT permanent.
Each time you turn on the TV (from cold), the internal de-gauss will operate, and it will improve until it gets back to normal.
If you are impatient, you can call a repair man and ask him to use a manual de-gausser. These are much more powerful.
Cheers,
I would try the built-in degausing coil first by unplugging the set for several munutes and then plugging it back in. If that does not handle the problem completely, try bringing a magnet near the screen in different orientations to lessen the impurity once you have moved it back away. Then try the internal degausser again to finish the job. Repeat both steps until you get it right.
I've seen a couple of tv who never got back from it. Does it have something to do with the way the tv is made.
(and even after bringing them for repair)
(and even after bringing them for repair)
Well, it's always POSSIBLE that the magnet warped or misaligned the shadow mask. And that would be permanent. But following the old physicians' dictum of, "When you hear hoofbeats, expect horses, not zebras," it's most likely degaussing and not something irreversable.
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