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Static problem

Discussion in 'Electronic Repair' started by [email protected], Jul 25, 2005.

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  1. Guest

    I apologise if this has been covered to death, but I couldn't really
    find any information specific to my problem.

    I have a problem with my 1984 Zenith TV set. When I first turn it on,
    all I will get is static from anywhere from 30 seconds to 10 minutes.
    After this clears up I have no problems with the TV set as long as it's
    on.

    I read something about bad grounds, but the article in which I found
    this information applied to Sonys with the 2 tuning knobs.

    Mine's got a number pad where you punch in the station and press enter
    instead of rotating the knobs.


    Any help is appreciated!


    73,

    Tim
     
  2. Guest

    Well, I pulled the tuner unit out of the set, and what immediately
    caught my eye were tiny "scratches" in the underside of the circuit
    board. It looks like someone was careless in the manufacturing process,
    as these are everywhere, crisscrossing the traces and the board. In a
    few places I noticed some of the traces were covered in a thin layer of
    solder. No doubt the scratches in those areas were so bad they broke
    the circuit, hence the need for the solder.

    I cannot believe something made in the USA would be put together so
    sloppily.



    73,

    Tim
     
  3. kip

    kip Guest

    Why ??
     
  4. NSM

    NSM Guest

    It's been repaired before - possibly on the production line. Those cuts are
    made for testing.
    Huh?

    N
     
  5. Guest

    Well, I patched the worst of the traces and the TV set didn't act up,
    but I'm not going to declare a victory until I've used the TV set for a
    while and observed its behaviour.

    Supposing my problem isn't gone, where would I look next?

    The tuner part was surprisingly easy to remove and disassemble, and
    other than the scratched traces nothing looked out of the ordinary. No
    bulging caps, scorch marks, loose wires, etc.

    ----

    I fear this might take the topic on a path I never intended it to go,
    but anyway.....

    In my experience, American products have been well built (barring cars)
    and last a long time, such as old radios, TV sets, furniture, etc.

    I personally avoid chinese products because their quality is so poor
    it's a miracle anything from there made it to the US in one piece, let
    alone work for 5 minutes after its arrival.

    In a nutshell, I expect (and these expectations have mostly been met)
    American products to be far superior to those cheaply made in
    sweatshops in foreign countries. If my TV were made anywhere else, I
    would not be surprised with my findings.



    73,

    Tim
     
  6. NSM

    NSM Guest

    The 'static' is probably better known as snow. At this point you really need
    a signal source you can inject into the IF strip to localize the problem.

    N
     
  7. Andy Cuffe

    Andy Cuffe Guest


    A good start is to resolder every connection between the board inside
    the tuner and the metal shield. Bad connections tend to develop there
    due to the thermal expansion of the shield every time the set is used.
    Most of the Zenith sets I've seen from that time period needed to have
    the tuner resoldered. The ones around the edges are usually the
    problem, but don't overlook the connections in the middle of the
    board.
    Andy Cuffe

    <-- Use this address until 12/31/2005

    <-- Use this address after 12/31/2005
     
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