Connect with us

wierd colors!

Discussion in 'Electronic Repair' started by Reck, Sep 22, 2005.

Scroll to continue with content
  1. Reck

    Reck Guest

    wow something wierd happened. lightning struck a house right across the
    street from me, sounded like a bomb went off. scared the bajeezes out
    of me. anyway i was watching TV at the time with my panasonic TV (not
    sure what type or how to find out), now there are inverted patches of
    color on the corners of the screen. it looks like sombody screwed up
    the tint on 3 of the corners of the screen. how do i fix it? do i have
    to buy a new TV now? somebody please help!
     
  2. 3T39

    3T39 Guest

    Hello, Reck!
    You wrote on 22 Sep 2005 01:42:15 -0700:

    R> wow something wierd happened. lightning struck a house right across the
    R> street from me, sounded like a bomb went off. scared the bajeezes out
    R> of me. anyway i was watching TV at the time with my panasonic TV (not
    R> sure what type or how to find out), now there are inverted patches of
    R> color on the corners of the screen. it looks like sombody screwed up
    R> the tint on 3 of the corners of the screen. how do i fix it? do i have
    R> to buy a new TV now? somebody please help!

    The lightning has knocked out the de-gauss circuit and the shadow mask has
    become magnetised. It's a straitforward fix if you have it done. No need to
    throw away the set, shouldn't cost a lot.



    With best regards, 3T39. E-mail:
     
  3. Dave D

    Dave D Guest

    Possible, but not especially likely IMHO.
    A lightning flash can generate a big enough electromagnetic pulse to
    magnetise the shadow mask. It might clear up on its own after a few on/off
    power cycles. OTOH, it might need a proper degauss with a degaussing tool.

    Dave
     
  4. Dave D

    Dave D Guest

    Lightning generates a magnetic pulse which affects the shadow mask in your
    tube. In very simple terms, the shadow mask is a very fine metallic mesh
    just behing the front of the screen which guides the electron beams onto the
    correct colour phosphor dots. When it becomes magnetised, the electron beams
    are 'pulled' slightly and fall onto the wrong dots, creating the patchy
    effect.

    Luckily, there is a device inside your TV called a 'degaussing coil'. When
    you power on the set from cold, you may hear a buzz or surging noise. That
    is the coil automatically removing any residual magnetic field from the
    shadow mask. It is necessary because a shadow mask can become affected by
    other means than lightning strikes, such as nearby magnets, like in
    loudspeakers.

    Unfortunately, a very large magnetic field can severely magnetise the shadow
    mask to such a point that the built in degaussing coil is too weak to remove
    it in a single, or even several, cycle(s). Also, a lightning strike can
    damage TV circuitry so as 3T39 mentioned in his post, there may be physical
    damage to the degaussing circuit.

    However, the good news is that even if the degaussing circuit is damaged,
    the repair should be trivial and not expensive. Conventional degaussing
    circuits are theoretically far less susceptible to lightning strike damage
    than the rest of your TV's circuitry, so the fact the TV still otherwise
    works OK bodes well.

    Try a few on/off power cycles (switching it off properly, not standby) and
    see what happens. To do this you need to power on from cold, switch off,
    leave for a few minutes and repeat. See if this makes the colour patches
    fade. On powering on you may hear a slight momentary buzz or surge, which
    will be the degaussing coil working to remove the magnetism from the tube.

    If this doesn't work, (it might take several on/off cycles, or the patterns
    may fade themselves over several days) contact a TV repair shop and get it
    degaussed, and repaired if there's a fault.

    Dave
     
  5. Guest

    If you carry the set into the shop, it can be degaussed in literally
    less than one minute.

    H. R.(Bob) Hofmann
     
  6. Guest

    If you carry the set into the shop, it can be degaussed in literally
    less than one minute.

    H. R.(Bob) Hofmann
     
  7. James Sweet

    James Sweet Guest

    I'd first turn it off and let it sit for an hour or two then turn it on,
    repeat a few times if necessary, then take it to a shop if it's still messed
    up.
     
  8. I recall a poster here from years ago who had a set that had a purity
    problem when placed in a particular corner, and it was determined that
    the steel-beamed building in which he lived had been hit by lightning
    at one time.

    A soldering iron will perform a degauss, won't it?

    Tom
     
  9. jakdedert

    jakdedert Guest

    A soldering *gun* will do a passable job...big high current transformer.
    An iron is useless for this.

    This is a fairly common problem with nearby lightning strikes and almost
    always takes care of itself with repeated on/off cycles (if it hasn't
    done so already).

    jak
     
  10. Darn...was thinking gun, typed iron. :)

    Tom
     
  11. jakdedert

    jakdedert Guest

    Figgered you did...just couldn't stand the thought of some newbie going
    to Rat Shack, purchasing a $10 iron, waving it around in front of his
    set and wondering why it didn't work.....

    <G>

    jak
     
  12. Ken Weitzel

    Ken Weitzel Guest


    Hi Tom...

    You're forgiven :)

    There'll be a penalty, however :) Your penalty shall be to explain
    for the benefit of the op just how to go about using it as a degausser.

    Can't shake the image of someone pointing the gun at the crt and
    firing off shot after shot after shot... :)

    Take care.

    Ken
     
  13. :)

    Let's see...holding the gun sideways to the screen, plugged in, hold
    trigger in while moving the gun in circles, first close to the screen,
    then moving it farther away. Is that right?

    Tom
     
  14. Mike

    Mike Guest

    [/QUOTE]
    So I've wasted half a can of butane trying to degauss my monitor
    with this Portasol iron then?

    Dammit.

    ;)
     
  15. jakdedert

    jakdedert Guest


    So I've wasted half a can of butane trying to degauss my monitor
    with this Portasol iron then?

    Dammit.

    ;)
    [/QUOTE]
    Well, at least you probably 'did' get rid of the weird colors....
    <g>

    jak
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-