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PANASONIC Color problem "circle"

Discussion in 'Electronic Repair' started by Max, Apr 3, 2007.

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  1. Max

    Max Guest

    Hi all,

    Having a Panasonic television CT-27... with a color problem. There is a kind
    of big circle on the screen and the color is not right around thiscircle.
    King of purple and yellow.

    It looks like a perfect circle so I'm assuming something in the tube itself
    is bad. Shadow mask ? Problem with the Degauss ?

    Any idea ?

    Tks for you help...
     
  2. b

    b Guest

    someone probably put a speaker or other magnet against it or it is
    impact damage.try replacing the degauss posistor first.
    -B
     
  3. The built in degauss won't fix a bad case. Needs external degaussing. A
    repair shop should be able to do this.
     
  4. Was it dropped?

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  5. Max

    Max Guest

    The unit dhas not been dropped and no speaker has been put near the TV.

    Unit was OK and went bad just like that.

    You can easily see a big circle in the middle...
     
  6. Andy Cuffe

    Andy Cuffe Guest

    In that case I would say that either the degaussing circuit has
    failed, or the deflection yoke is loose and has slipped back on the
    neck of the CRT. Both of these problems are minor and will cause the
    problem you describe. Manual degaussing won't fix either of these
    problems.
    Andy Cuffe

     
  7. Guest

    in some cases moving of scan coils back can result in tube explosion.


    NT
     
  8. verni

    verni

    3
    0
    Apr 4, 2007
    have u tried degaussing with degauss ring..
    if not try an ordinary magnet to see if it corrects problem..if it does then replace degauss component inside tv( this will be the thermistor) usually located near power supply...tv's usually degauss the moment they are swithed on...however a bad degauss usually creates coulered patches around edges.. vernon
     
    Last edited: Apr 4, 2007
  9. BH

    BH Guest


    In some cases dropping a CRT onto concrete can result in breakage,
    Huh??

    Bruce
     
  10. Circular magnetic effects are usually due to the degaussing circuit
    malfunctioning or a power surge such as happens with a nearby lightning
    strike. The former is very common on Panasonic sets, could be bad solder
    connections at the degaussing thermistor or a bad thermistor.

    If it is the latter problem, manual degaussing may be needed.

    Leonard
     
  11. Max

    Max Guest

    Hi All ,

    The thermistor has been tested OK and solder joints are OK.

    How to confirm that it's not the tube ? Shadow mask ?

    Should I try to degauss it anyway ?

    Tks for you help...
     
  12. You may have had a nearby lightning strike? We see sets all the time that
    have been subjected to a surge that have the tube magnetized by the
    degausing coil to the extent that the internal degaussing cannot demagnetize
    the tube.

    The fact that it is circular indicates that the source of the magnetic field
    is likely the degaussing coil itself. A damaged CRT shadow mask will almost
    always give you adifferential symptom at the edges on one side.

    Leonard
     
  13. Max

    Max Guest

    Right on !

    I use an external degauss coil and it's OK now.

    Tks.
     
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