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Rainbow colours all over screen! Degaussing failed! Is my TV broken for good?

Discussion in 'TVs' started by jonhead34, Oct 17, 2006.

  1. jonhead34

    jonhead34 Member

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    Hi all

    Just over a week ago, my 32 inch Hitachi CRT widescreen TV (new around 2002) suddenly developed vivid rainbow colours all over the screen in a circular pattern. The picture can still be seen but only through the rainbow!!

    Having done some research on the web, I assumed that this was a classic case of magnetisation, probably caused by a magnetic toy. I removed any obvious causes (speakers, etc) to no effect. My next step was to buy a heavy duty degausser from ebay (please see link below): -

    http://cgi.ebay.co.uk/ws/eBayISAPI....00035116819&rd=1&sspagename=STRK:MEWN:IT&rd=1

    ...this arrived this morning but has barely any affect at all. When the degausser is held very close to the screen, you can just about see a very, very minor movement of the patterns, but these always spring back to the circular pattern, and despite following all instructions, it has no lasting affect whatsoever.

    Does anyone have any idea of any other steps I could take, or would you say that the TV has simply come to the end of its time.

    The only nagging doubt I have about the degausser is that it comes with an American plug, but I have a UK to USA adaptor, so I have no reason to believe that it's performance is compromised.

    I would like to thank you in advance for reading my post and for any help you may be able to offer.

    Many thanks

    Jon
  2. JayCee

    JayCee Active Member

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    What's the model no taken from the rear label?


    If you had read the ad carefully you should have spotted it's for the USA market and rated at 120v...we use 240v here in the UK so I wouldn't be surprised if it went o/c with a "phut" the first time you plugged it in and that is why it's having no effect.
  3. jonhead34

    jonhead34 Member

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    Many thanks for the reply JayCee and for considering my problem.

    The model is: C32WF535N

    I did indeed read the ad carefully and was careful to ensure that my USA to UK adaptor (Tacima SC 5327) transforms the voltage from 240v to 120v, as indeed it does. The eBay ad (link in original post) states:-

    "International buyers: This coil WILL work on all international sets, but you may need to buy a current/voltage adapter. It is corded to work on US 120 VAC."

    I can also confirm that the coil did no go o/c with a "phut" because, as stated in the original post, it does have a noticeable affect, but unfortunately only a small one, and the colours quickly spring back into place. I have since tried the coil again, and exactly the same thing was observed. It's as though the coil simply isn't strong enough to overcome the magnetism, but it is advertised as heavy duty, so surely it really should be able to do this?

    I appreciate your post and appreciate any further thoughts from yourself or any other posters.

    Many thanks

    Jon
  4. JayCee

    JayCee Active Member

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    Apologies I didn't realise the adaptor you bought was the proper step-down transformer type.
    Worst-case scenario is a faulty crt...but...it could also be a faulty or dry-jointed degaussing thermistor which is known in the TV Servicing trade as a "PTC"...these are fitted to every TV and are responsible for degaussing the set at switch-on from the mains...these regularly go faulty in all makes of TVs.
    Due to the risk of electric shock/death I would not encourage you to have a go yourself at checking this but to call in an experienced TV engineer...if it is just a faulty PTC you are looking at a modest repair charge.
  5. red16v

    red16v Member

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    But even if the internal de-gaussing circuitry was faulty might we not have expected the external de-gausser to have provided a cure ?

    In my experience - very pronounced circular areas of very severe purity is an internal fault on the crt. I must admit though that on two occasions I have witnessed this on a set the fault has gone away by it own accord - no one was more surprised than me. I'm not optimistic that the crt will cure itself in your case ( I wish) and I think you may have to consider a new crt. Regards, yt.
  6. jonhead34

    jonhead34 Member

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    JayCee and red16v

    Many thanks for your informed advice on this issue - it really is appreciated. red16v's words "very pronounced circular areas of very severe purity" pretty much exactly describe what I am observing, and the degausser is barely having any effect at all, so perhaps I'm looking at a faulty CRT.

    Come to think of it, the incident happened very suddenly and without any obvious external stimulus, suggesting that something suddenly "went" inside the set as opposed to have being caused by an external agent.

    I may persevere for a week or two just to see if it rights itself as red16v has observed before, will probably give the degausser another few tries just in case, and may get a repair man in to have a look too. Inidentally red, you say you have seen a situation like this right itself on 2 occassions. I would be interested to know how many cases you have seen that have not cured themselves - I guess a few more! Did those cases simply have to be discarded?

    If all else fails, I guess this will be the perfect excuse to get a new LCD flat panel - it is just persuading the wife that will be the hard part!!

    Further posts welcomed.

    Many many thanks!

    Jon
  7. red16v

    red16v Member

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    Hi, I'd say in 25 years I've seen no more than 4 in total. The very severe rings (on the sets I've seen) are centred on the centre of the crt itself - a sort of set of waves/ripples of bands of very very severe colour errors.

    Generally simple purity errors are around the outside of the crt and usually the centre of the crt is the last place you'd normally expect to see purity errors.

    My thoughts at the time was that something had either short circuited inside the crt or some debris inside the crt had become dislodged and set up a short circuit. Under the circumstances the short circuit might un-short itself or the debris might eventually get 'blasted' off from where its sitting - in time. If it's convenient I wonder if it might be worth grabbing hold of the set (with the power off) and perhaps trying rotating/turning it upside down etc in an attempt to dislodge the short/debris etc. You will not do the tV set any harm in trying this but don't over do it or you might dislodge the circuit boards inside. Perhaps some gentle smacking of the case? No harm in leaving it/trying it for a couple of weeks - with it switched on of course - I doubt the fault would go away unless the crt was hot. Regards, yt.
  8. zircon3035

    zircon3035 Member

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    Jon,

    My opinion is that the shadow mask of the c.r.t. has probably moved out of position, so that it will be impossible to get correct purity and landing.

    Several years ago I saw the same effect on a Panasonic TX-2200. The set was owned by an elderly woman, so she hadn't dropped it and there were no kids about to stick magnets on it.

    When you try to degauss the c.r.t., you are simply wobbling the shadow mask about, which accounts for some 'effect' but no cure.

    Sorry to be the bearer of bad tidings.....

    Ian
  9. jonhead34

    jonhead34 Member

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    Hi again

    Many thanks for the further advice guys, much appreciated again. It is sounding rather terminal at the moment for the set at the moment isn't it unfortunately! At least I got well over 4 years good use out of it, which isn't too bad in this day and age I guess.

    I will try some of the moving/smacking suggestions offered by red as a last resort and perhaps a few more attempts with the degausser, but from what has been said, I'm not holding out too much hope at the moment. I will just have to put up with watching psychadelic TV through the rainbow until I can afford a new set!!!

    Cheers

    Jon
  10. hamster

    hamster Member

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    There are three possible reasons:
    1 Failure of degauss
    2 Shadowmask damage
    3 Deflection coil out of position (too far back on tube neck)

    The second two are likely caused by a drop, or just possibly the coil becoming loose (but they normally have a screw clamp.) A degauss failure usually doesn't give a ring shape though.

    TO check your degauss wand works - use it with the set switched on, and you will see the patterns change as you wave it.

    They are hard to use, but switch the wand on, start in a rotating movement around th front of th escreen, getting wider as you step back. Do around ten rotations until you are around 6 foot back, then turn the wand to 90 degrees from the tube and switch off.

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