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Toshiba TV problem?

Discussion in 'Electronic Repair' started by Forrest, Jan 5, 2008.

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  1. Forrest

    Forrest Guest

    I have a 32 inch Toshiba TV (CX32D60) vintage 1994. It developed a problem
    with the vertical aspect of the picture. It started after a local power
    failure. I, in my infinite wisdom, ran an extension cord out to the car and
    plugged it into a small inverter. Anywhooo ... now, when turned on, the
    lower six inches or so stays black until warmed up and then about the bottom
    few inches stays black. People on the screen look like cone head midgets.
    I'm a DIY type person ... do all of my own mechanical work on the cars and
    build my own computers etc. but don't know squat about TVs. I hate to toss
    it, without at least popping it open and having a look, and am sure not
    about to lug it down to a repair shop or pay to have it fixed ... especially
    considering how old it is. I somehow feel that I would get screwed in the
    deal, like a woman taking her car down to "Bubba's Auto repair" and being
    told that her muffler bearings are shot and need to be replaced. I've
    Googled around some and have come up with a few things. One is that you can
    get the shit shocked out of you, even though it's unplugged. I'm not sure
    where and what exactly has to be discharged before tinkering. Any tips on
    that would be appreciated and any thought as to what the problem with it is.
    I do have a digital volt meter. I came up with this on a web page about TV
    repair: Vertical squashed
    "This is a vertical deflection problem - possibly a bad capacitor, bad
    connection, flyback/pumpup diode, or other component. None of these should
    be very expensive (in a relative sort of way).

    If the symptoms change - particularly if they become less severe - as the
    set warms up, a dried up electrolytic capacitor is most likely. If they get
    worse, it could be a bad semiconductor. Freeze spray or a heat gun may be
    useful in identifying the defective component.

    It is often easiest to substitute a good capacitor for each electrolytic in
    the vertical output circuit. Look for bad connections (particularly to the
    deflection yoke), then consider replacing the vertical output IC or
    transistor(s)."

    So, as I said, I don't know shit from Shinola about it but can't let myself
    throw it out, without at least having a "look see". Sure would appreciate
    your time and effort for any advice or tips. Thanks in advance
     
  2. AJ

    AJ Guest

    Time to troubleshoot the vertical defelction circuit including the
    electrolytic capacitors. ESR the caps and change the ones which check out of
    tolorence.
     
  3. newbee

    newbee Guest

  4. b

    b Guest

    If You can solder and have access to capacitors then this is likely
    fixable. 99% of the time what you describe is due to one 20 cent cap!

    don't bother with ESR meters unless you plan on fixing tvs regularly,.
    just change the caps near the frame /vertical IC. there aren't many
    and they arent expensive. look for a small ish IC, usually on a metal
    heat sink with anything from 6 legs. ( older sets used a pair of
    transistors but this is doubtful in your case).

    tip: if the ic is labelled say IC 401, then change all the nearby
    caps similarly labelled , eg c405 c408 etc etc. do them one at a time
    so you don't mix them up. good luck

    -b
     
  5. Forrest

    Forrest Guest

    Thanks for the replies and advice but I haven't quite figured out how to
    start without either killing myself or trashing the TV. One or two things
    I've read say to just short out the caps and picture tube. Then I read all
    this stuff about using certain resistors to do it. Like this:

    For the CRT, use a high wattage (not for power but to hold off the high
    voltage which could jump across a tiny 1/4 watt job) resistor of a 1 to 10 M
    ohms discharged to the chassis ground connected to the outside of the CRT -
    NOT SIGNAL GROUND ON THE MAIN BOARD as you may damage sensitive circuitry.

    Do I need to go to an electronics store and buy some resistors before I
    start and if so what do I want?
     
  6. b

    b Guest

    that is just overkill. unless youre planning to remove the big line
    transformer then you needn't short out anything. just leave the set
    unplugged for a few hours or even overnight and you will be fine,
    just don't touch the big red wire going to the sucker on the tube!
     
  7. Mr. Land

    Mr. Land Guest

    More important than the resistors, I think, is to have something that
    will allow
    you to safely make electrical contact with the high voltage clip on
    the tube.
    This is usually under a large, rubber-like cap. You need something
    that will
    allow you to poke under that cap and touch the clip while electrically
    insulating
    you from high voltage, also bearing in mind that you're scraping
    against a glass
    tube (so it shouldn't have any sharp edges). Obviously (I hope) a
    long screwdriver
    is out, since its metal shaft would be bringing the high voltage
    charge close
    to your hand. All sets probably use built-in discharge circuits, but
    I never trust
    those - I just feel safer knowing I've discharged the tube myself.
     
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