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Toshiba colour problems

Discussion in 'TVs' started by Grev, Feb 15, 2002.

  1. Grev

    Grev
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    Help ! I purchased a Toshiba 3798DG from Germany 7 months ago, it's an excellent large screen TV, but the colour system seems to be playing up. It's multi system, ie PAL, NTSC, etc and the manual recommends using the auto setting.
    The picture has started displaying a green tinge or sometimes a reddish pinkish tinge. I have tried setting the picture system to PAL but the result is the same.
    Before I call out the TV technicians and incur a whopping bill ! any ideas ?
    Thanks in advance
     
  2. JPC

    JPC
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    Sounds like it may be something with the CRT but without more information its impossible for any one to help you.

    Is this tinge all over the screen?...... can it be seen on Black & White material?...... does it flick on and off?....... when its there can you see a drop in focus or resolution or coloured edges to outlines?............. does it happen more when the set has been on for a while or can it happen anytime?.....

    If you can answer some of these questions then maybe we can give you an idea what it is.

    Regards
    JOHN P C
     
  3. Kirthen

    Kirthen
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    Grev,

    What you describe is identical to what happened to my 37" Grundig a few years back when I repositioned the set - it turned out to be Earth's magnectic field, believe or not!

    The Grundig Manual states that the Earth's Magnetic field can affect the TV's colour purity depending on the installation direction of the set. Colour purity errors are colour aberrations occurring as coloured zones on the picture screen. Leaving the TV on standyby will increase the intensity of the colouring over time.

    The best solution is install the TV set in a west/east direction and use the degussing function. On the Grundig, this occured every time the set was switched on using the button on the TV - not the remote.

    Hope this helps

    Kirthen
     
  4. Doubledoom

    Doubledoom
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    Instead of leaving it on standby. Turn it off over night. Do this for a few days and see if you get any improvement. The degaussing may be all it needs (which it gets on the older Tosh sets when you turn it off)
     
  5. Grev

    Grev
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    Thanks for the replies.
    I did leave turned off completely (though not at the mains switch) overnight. Turned on this morning and the discolouration occured immediately, though last night after the TV had been on for a few hours it had gone away, and perfect picture once again. I'm checking today how long it may take to correct itself.

    On closer inspection the symptoms are:-
    Uniform discolouration all over screen.
    The sky programme bar at the bottom of the screen when changing channels etc, where should be blue is a darker greeny colour.
    Whites seem to be a greeny tinge.
    Human faces seem to take on a darker pinky colour.

    The position of the TV has remained constant for last 6 months. No new wiring or electrical equipment has been moved near which could cause interference.
    I've tried adjusting the manual contrast, brightness, colour etc, doesn't alter the base discolouration.

    Grev:confused:
     
  6. Grev

    Grev
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    Quick update on the colour probs, if there is anyone out there that can offer further advice. The colour has just returned to normal, that's just over an hour since TV turned on and discolouration occured.
     
  7. JPC

    JPC
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    From your latest discription this is something more serious than ironisation from the earths magnetic field.......

    Its either inter electrode problems on the CRT or a decoder problem......

    Its fairly obvoius that heat is a factor....... Making me bias towards inter electrode tracking on the CRT base between the control grid and red and grean cathodes..... or a dry joint on the CRT base plug.

    If it is a tracking problem it can be blown clear (very easly) with a CRT rejuvinator.... eny engineer worth his salt will carry one with him.

    You could just try one thing yourself...... if you feel confident enough!..... and that is to make sure the plug on the CRT base is pushed securly into place.... a poor connection here would fit your description of symptems very nicely.

    Otherwise.........

    If it is still under warrentee you *must* get it sorted out now!
    As it is a problem that could get progressivly worse and eventualy become permenent........

    Regards JOHN
     
  8. Grev

    Grev
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    John, thanks for your latest reply. When you mentioned about dry joints or the plug on the CRT being not seated correctly, I thought I'd try a quick 'knock' of the TV. The problem appeared again at turn on time. A quick rap on the side of the TV mad the picture ok again, it then went 'bad'. Another knock produced good results, which remained. It has now been good for a day and half.
    I may take the back off and check the seating.
     
  9. JPC

    JPC
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    Grev
    This shows your CRT is most likely OK!
    Be very carefull about going near or touching the High Tension connector going to the back of the fat part of the CRT...... This can retain a charge of about 50,000 volts on a tube that size..... (even after it has been switched off).....

    This connection does have loads of insulation on it and you will recognise it straight away as it is very thick......

    There won't be enough current there to kill you, (Ive had loads of belts off these in my time) but it can make you jump......

    If you confine your attention to the neck of the tube, the seating of the plug and its components, you will be perfectly safe.

    I would say a little prod around with an insulated proder like a wooden chop stick will reveal the problem very quickly for you.

    Check that all connecters are good and tight especialy any Red Grean & Blue cathode wire connectors.
    especialy the Blue one.

    Regards JOHN
     
  10. JPC

    JPC
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    Unless of course you have a bad heart or pace maker!
    JOHN
     

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