Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

tv degaussing

Status
Not open for further replies.

Gaston

Member
i just bought a 32" ge television (crt) from the pawn shop. there is no date on it but i guess its from the late '90s. the upper right corner has a purpleish hugh to it. am i correct in assuming that this tv has a degugausing coil? and could the problem be something else?
 

sheldonstv

New Member
yes the veiwing area of the screen does somtimes get magnetized...if you switch the set on from cold it should dissappear,if not it is an easy repair to put the set right-any service engineer at yr local tv repair shop(like me) can repair it for you.dont attempt it yrself if you dont know how.....
 

killivolt

Well-Known Member
Most repair shops usually have a degaussing coil of some sort. We had one that was built from an old steering wheel and a switch.

Basically Iron core electro magnet.

I would just wand it and if it was going to take it would otherwise the customer would return with the set for repair or another wand over of the degaussing coil.

Back then we had plenty of work and little reason to not establish customer relations.

Try calling around to see if someone in your area have one and are willing to do it for you.



kv
 

HiTech

Well-Known Member
Some of those large CRT sets have user operable switches to compensate for magnetic fields. Check if your does. If you cannot get ahold of a degaussing coil you could try a small magnet and carefully bring it close to the problem spot, swirl it around and slowly remove it. This has been known to work but not nearly as effective as a degaussing coil.
 

HarveyH42

Banned
What would a degaussing coil do to an LCD screen? I got a few dead pixels, two red, one blue that never change, on a 22" monitor. Not a big deal, hardly notice them...
 

fernando_g

New Member
The magnetic coil ONLY works for CRTs as the electron beam is deflected magnetically.
For LCD screens, there is no beam deflection mechanism.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
The magnetic coil ONLY works for CRTs as the electron beam is deflected magnetically.

That's not what deguassing coils do though :D

It's nothing to do with CRT's been magnetically deflected (even though they are), it's to do with the shadow mask, a thin sheet of metal full of holes that makes sure each beam only hits the correct coloured spot on the front.

If this sheet gets magnetised, it bends, and this makes the beams hit the wrong colours - because the metal is so thin (and full of holes) even the earths magnetic field causes it, try rotating a TV while it's ON.
 
Last edited:

killivolt

Well-Known Member
That's not what deguassing cpoild do though :D

It's nothing to do with CRT's been magnetically deflected (even though they are), it's to do with the shadow mask, a thin sheet of metal full of holes that makes sure each beam only hits the correct coloured spot on the front.

If this sheet gets magnetised, it bends, and this makes the beams hit the wrong colours - because the metal is so thin (and full of holes) even the earths magnetic field causes it, try rotating a TV while it's ON.

Great trick. Fine time for me to find that one out.:rolleyes:


LCD's, Plasma's. Is all the stuff now day's.

Yet I still have my 19" crt TV at home. I have little use for expensive large TV's, I'd rather spend all that money going to the movie's.

Pop Corn, Friends. Time away from what worries you.

Maybe I would spend it on a very large Computer Display.




kv:)
 

picbits

Well-Known Member
I bought a new Toshiba CRT quite a few years ago. It was brought up from the factory in Plymouth by the in-laws in the back of their Vectra. Unfortunately the screen was right next to one of the rear speakers and 270 miles later I had a nice discolouration in various parts of the screen.

The engineers at Toshiba (kindly) sent me one of their degaussing coils on loan so I could sort it out. The instructions were to start a meter or so from the set and keep moving it in a circular manner and backing away from the TV until there was no effect on the picture (and repeat this until the colours were back to normal).

It was a bit of a monster coil - weighed an absolute ton !!!
 

Bob Scott

New Member
If you cannot get ahold of a degaussing coil you could try a small magnet and carefully bring it close to the problem spot, swirl it around and slowly remove it. This has been known to work but not nearly as effective as a degaussing coil.

You are more likely to magnetize the shadow mask than to demagnetize it.
 
Last edited:
You don't want to use a permanent magnet or you will magnetize the shadow mask ^ as Bob Scott says. I've degaussed my TVs with a transformer connected to a high power resistor (to make power flow magnetically through the transformer), then move the transformer closer to the area until you see it affecting it, then move it away slowly, repeat until fixed. This is all the degauss thing is anyway. The key is AC on the magnet not DC.
 

HiTech

Well-Known Member
A standard technique in the distant past (for when you hadn't got your deguassing coil), but aren't soldering guns long gone now?.
Still widely available here in the states.... in fact I have a dual heat range, 325 watt model that I sue often.... you know like when a tin coffee can rips open or the truck frame develops a crack needing repaired!! LOL

As for the replies on using a permanent magnet damaging the shadow mask, that's not entirely true. If done carefully when no DG coil is available, one can experience success. I've done it plenty of times to old CRT arcade videogames. The games are literally shoulder to shoulder (or cabinet to cabinet) to each other and DG coil just wreaks havoc on the neighboring units. I've also used a tape head demagnetizer with a pin-point probe to correct small color abberations in CRT corners. As for the PM magnet, I'm not talking about using one from a 12" woofer!
 

Sceadwian

Banned
That's a neat trick using a heating coil as a quick and dirty degauser.
 
Status
Not open for further replies.

Latest threads

Top