magnet distorts tv screen


  #1  
Old 01-27-01, 02:41 PM
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Our 9 year old put a fridge magnet on the t.v. screen causing green colour to concentrate where magnet was applied. Problem compounded when another magnet was sweeped across the top of the t.v. screen. We now have a wide band of mauve and green across the screen. Is this something we can fix ourselves.

A few years ago, we had a similar situation. We called in a tv repairman and was told magnet polarized??? colour due to speakers being too close to screen. He waved a magic wand and charged $$$$$ too much!!!!! Is there something we can use that would have the same effect as this wand he waved?

Thank you for any help and suggestions.

Frustrated.
 
  #2  
Old 01-27-01, 03:12 PM
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I had the same thing happen to me, in my case , 8 hours of being turned off and it corrected itself. If your tv should have a degausing button , push it, if it doesn't then either time will cure it, or it likely need to be degaused, THE MAGIC WAND the repair guy had before.

If you have another tv to use, or can do without the tv for a few hours, see if it corrects itself. If not then try one more time and this time unplug it (I'm not sure the instant on feature of some tv's keeps a charge on the tube, so that is why I say also unplug it if you need to try a second time) see if it will correct itself first. How long , can't say, when you go to bed , turn it off, and don't turn it on until you come home from work the next day (assuming you are a day worker).
 
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Old 01-27-01, 05:36 PM
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Thanks for the suggestion. I'll give it a try.

 
  #4  
Old 01-28-01, 07:01 AM
Smokey
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Good Morning, mdmj:
Sadly but true that you can magnetize a television screen with a magnet. Kids love to take the refrigerator magnets and make pretty colors on the screen.

The magic wand you spoke of is nothing more than a large coil of wire plugged into household AC (Alternating Current). AC and the wand (also call a degaussing coil) provide a magnetic field that changes polarity 120 times a second and effectively depolorarizes a magnetic spot on a TV screen.

In your case, you can duplicate the effects of the wand with a simple device called a Weller Soldering Gun. Most folks have an electric soldering gun laying around the house for odd jobs. Do this:
1) With the TV on, plug in the soldering gun and hold the pistol body against the glass of the picture tube.
2) Turn on the soldering gun with the trigger switch and move the gun around the screen in a circular motion giving attention to the specific area that is magnetized.
3) THIS IS IMPORTANT: The tip of the gun will heat up rapidly so you have only about one minute of operation using this method. WHEN YOU HAVE COMPLETED THE CIRCULAR MOTION with the unit, keep holding the trigger and move the soldering iron at least three feet away from the screen.
THEN RELEASE THE TRIGGER and let the tip cool.
4) Wait a minute and repeat as many times as it takes to remove the magnetism from the picture tube.

When the gun is on and against the screen, you will it generate a magnetic field of its own. Again, this field is changing polarity 120 times a second. Thus, it will cause a non-polarized magnetic spot on the screen and will break up any polarized magnetic spots on the screen. But, you have to move the gun away from the screen when you turn it off.

This is an old TV Repairman trick and used it for many years when I didn't have a "wand" handy.

Smokey
 
  #5  
Old 01-28-01, 12:30 PM
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To Smokey

Thank you for the suggestion. I'll ask my husband when he gets in if he has a soldering gun kicking around the house. Will let you know if it works.

I'll keep my fingers crossed!!!
 
  #6  
Old 01-31-01, 07:13 PM
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To Smokey

Just to let you know we tried the soldering gun. It did eliminate alot of the affected areas. We only have one small area close to the center (where original magnet was placed) and a little across the very top edge of the t.v. It is definitely an improvement. Thank you for the suggestion. We will retry again at a later date to see if we can still minimize the remaining areas.
 
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Old 02-01-01, 03:05 PM
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Good evening, mdmj:

I'm glad the "helpful tip" helped to solve your problem. As I said, I used to run service calls for RCA some years back and often I would find myself in front of a TV that had this problem. I used my old "trusty" soldering gun a lot of times to eliminate magnetic spots on the face of the picture tube. LOL

Good luck and happy viewing. Come back to see us now and then.

Smokey
 
  #8  
Old 02-01-01, 05:35 PM
spike
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Most color TV sets have a built-in degaussing coil that operates for a couple of seconds every time you turn on the set from a cold start. Cold start means the set must have been off for at least several minutes. It is not as instantly effective, however, as a hand held degausser or soldering iron. Usually it takes several on-off cycles to get rid of bad magnetization.
 
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Old 02-01-01, 08:30 PM
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To Smokey and Spike

I don't know whether our tv would have this built in degaussing coil. I guess I should have mentioned that our tv is a 28" Sony which I bought new in 1985. It's almost 16 years old but it's been a great tv, no problems, great colour and still keeps on going and going and going.....

This magnet episode has caused the only problem we've ever had with this tv set. I hope we can make the last of the residual spots go away because it is driving me crazy. The original placement of the magnet has a diameter of approx. 1" circle where there is still a purple hue showing on any skin tone that plays on that spot.

Thank you once again.

 
  #10  
Old 02-03-01, 06:37 AM
Smokey
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Good Morning, mdmj:
What Spike said is true. All television sets since about 1964 have some variable of an degaussing feature built into the circuitry. For normal situations such as moving the set to a new location (crossing the lines of the earth's magnetic field will magnetize a picture tube), these systems are usually adequate. In the case of a severe magnetism (i.e.: the kids and the refrigerator magnets), it would take months of operation to finally resolve all of it.

Another ploy you might try is using an cassette tape demagnetizer on the affected spot. It doesn't produce a very big magnetic field but it could be sufficient to remove one isolated spot on the screen. The procedure is the same: touch the demagnetizer to the spot, turn it on, rotate it around in a circular fashion, then move it away from the screen about 3 feet, and turn it off.

Smokey
 
  #11  
Old 02-03-01, 09:48 PM
spike
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Good evening all,

Not to cause a scare, but a cautionary note. I once saw a handheld tape eraser scramble the mask on a color monitor picture tube. In this tube, the mask consisted of a grid of fine wires apparently, and the field of this particularly powerful eraser when held right up to the face of the screen caused these wires to distort. The result was a patch of fine dark vertical lines that wouldn't go away. So just be a little cautious if the eraser seems to have a strong field, say if it sticks hard to a piece of iron when activated.
 
  #12  
Old 02-04-01, 05:21 PM
Smokey
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Good evening, Spike:

I believe the tape demagetizer you are eluding to was one of the old units that was used for 1/4" audio tape reels. It had some nasty field coils in it and exhibited quite a magnetic field. After all, it took a lot of degaussing to clean a 14" reel of audio tape.

But, the device I referred to is for demagnetizing cassette tape deck heads and is quite small. Chances are slim that it will cause any problems unless someone turns it off while it against the glass on the picture tube. If used as I indicated, it is quite harmless and will solve isolated color problems caused by residual magnetism on the tube face.

Smokey
 
 

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