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Color bleeding on 19" Toshiba TV

Discussion in 'Electronic Repair' started by pdp11tech, Dec 7, 2007.

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  1. pdp11tech

    pdp11tech Guest

    I have a transistorized Toshiba 19" color TV that I purchased in 1984.
    It has worked quite well over the years, but recently has been
    exhibiting a symptom which I would describe as a horizontal "bleeding"
    of color under certain conditions.

    Specifically, bright images on the screen (such as white shirts,
    brightly-lit windows, white lettering, etc.) will exhibit a bluish
    bleeding or tearing effect, always horizontally to the right of the
    bright object. The picture is otherwise very good and stable, with
    good contrast, color, and brightness.

    Is this likely to be cause by some kind of adjustment out of whack?
    Components (maybe condensers?) going bad? As mentioned, this is a
    transistor set so I know it's not a weak tube causing the problem.
    Thanks for any help with this!
     
  2. Deke

    Deke Guest

    picture tube (CRT) showing signs of age, IMO.
    Time for a new TV. After 23 years, I believe you've got your money out of
    the Toshiba.
     
  3. But it can possibly be adjusted to work OK a while longer. The screen grid
    adjustment on the FBT may help, and the user brightness, contrast and color
    controls can be adjusted down a bit.

    Mark Z.
     
  4. pdp11tech

    pdp11tech Guest

    Actually I don't really think of the Toshiba as all that old, it's my
    newest set and I have older ones (vacuum-tube type) that are still in
    regular use.

    I don't care much for those strange new futuristic flat sets, and the
    Toshiba fits perfectly in my home entertainment center -- guess I'll
    have to keep an eye out for a good used TV that's similar.

    Thanks for your input...
     
  5. Try replacing the electrolytic caps on the video driver board. It doesn't
    cost much and it's not difficult.
     
  6. pdp11tech

    pdp11tech Guest

    Actually this set has just a single circuit board in the bottom of the
    chassis. (I've gone into it before to tweak the vertical height which
    started shrinking a bit a few years ago.) Replacing the electrolytics
    is probably not a bad idea, though, they're pretty likely to be drying
    out at this point and starting to cause problems.
     
  7. :>
    :> Specifically, bright images on the screen (such as white shirts,
    :> brightly-lit windows, white lettering, etc.) will exhibit a bluish
    :> bleeding or tearing effect, always horizontally to the right of the
    :> bright object. The picture is otherwise very good and stable, with
    :> good contrast, color, and brightness.

    : picture tube (CRT) showing signs of age, IMO.
    : Time for a new TV. After 23 years, I believe you've got your money out of
    : the Toshiba.


    No, as someone else mentioned, it's time to start pulling electrolytics. I'd
    bet the CRT is fine.

    The description of the problem I remember quite well, flaring, comet tails,
    color bleeding off one edge, always going in the same direction. Don't
    remember working on Toshiba's but remember the problem was common on
    Panasonics and Quasars in that period (early/mid 80's).

    They were probably the 1st generation that used video jungles, complex large
    scale ic's to near do everything from take in from the tuner and spit out
    RGB.

    I'd try to narrow down odd ball caps around anything that looks like the
    video processor ic, 1uf at 160v or 200uf at 3v, anything that is marked that
    seems lop-sided with rating vs. voltage or visa versa.

    I remember it was harder to find (at that time) the replacements over which
    one was bad.

    Just saying it's more likely a problem in the video stage rather than power
    supply, horizontal/high voltage sections or CRT and related convergence
    controls.

    But I do agree, with it at the quarter-century mark at age, I wouldn't put
    that much effort in it, rainy day project at best.

    -bruce
     
  8. Meat Plow

    Meat Plow Guest

    If you have some time to kill that's a very good idea.
     
  9. Dave

    Dave Guest

    If the picture tube is still bright, and has good color balance, i.e. no
    missing single red, green, or blue, the tube is likely fine. The age of the
    TV really doesn't mean anything with regards to tube life if the set has had
    infrequent use.

    If you've got a few hours, I'd replace all of the electrolytics. It'll
    likely cost you less than $20 in parts. If you'd rather a newer set, you
    can pick up a new-ish CRT set for practically nothing these days at any pawn
    shop or secondhand store. I was at the dump the other day and they had
    hundreds of new-looking sets on pallets, shrink-wrapped slated to go to some
    recycling facility... people actually throw out perfectly good televisions
    because they want a flat-screen. The current TV in my livingroom, a 27"
    Toshiba, was put out by the curb on garbage day. I picked it up, replaced a
    $5 regulator and a handful of caps and it's been working perfectly ever
    since.

    You say you do not like "those strange new futuristic flat sets". To each
    their own, but if you give them a look I think you'll find the picture
    quality is better than most CRT's. They also use less electricity and take
    up much less space. Probably generate less heat too. Unfortunately,
    they're not particularly user-serviceable.

    Your statement harkens up memories of 'me old grandpappy and his dislike of
    "them newfangled iron horses and moving pictures." I don't mind certain
    aspects of technology, but still enjoy the glow from my tube amplifier in a
    darkened room.

    Dave S.
     
  10. pdp11tech

    pdp11tech Guest

    That's the problem exactly.
    Same with this set, it has a single circuit board in the bottom with
    what I would consider to be an amazingly small number of components
    for a color television.
    Sounds like a plan, or maybe I should just recap the whole set,
    probably wouldn't be much money and just an afternoon's work with a
    soldering iron. Will have to pull the back off and take inventory of
    the electrolytics.
    It will be less work than trying to revamp my entire home
    entertainment unit for a TV with a different form factor. :) Also I
    hate the idea of discarding something that probably just needs minor
    repairs. I am still seeing new CRT-type sets around for sale that
    would fit, but they look like cheap Chinese junk that would probably
    last about six months and would be pretty much unrepairable.
     
  11. pdp11tech

    pdp11tech Guest

    I just like to stick with what I'm familiar with and works well.
    (Since you mention it, I have vacuum-tube equipment as well that I
    still use and keep in repair.)

    Thanks everyone for the suggestions, I'll have to take a look at
    replacing some or all of the elecrolytics in this puppy...
     
  12. clifto

    clifto Guest

    Depends. Given a good video source, I agree. But HDTV is so full of nasty
    digitization artifacts that I would rather watch an NTSC signal from 100
    miles away with rabbit ears. I am not exaggerating.
     
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