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Sony Trinitron KV-27TW70 Tuner Repair

Discussion in 'Electronic Repair' started by GerryO, Oct 28, 2005.

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  1. GerryO

    GerryO Guest


    Picture and sound work great on our Sony Trinitron KV-27TW70, as lon
    as we use a vcr tuner routed through the rear of the set a/v inputs.
    On occasion the tuner works properly, and when it doesn't there'
    anywhere from a slightly shrunken picture to a white flat line in th

    Believe the tuner has been repaired/replaced once, after possibl
    damage by a power surge.

    Any tuner repair suggestions? Re-solder some specific connections?

    Thanks, Gerr
  2. Sounds like two totally different problems.
    A defective tuner can give you a snowy picture, total snow, or a blank
    or blue screen.
    A shrunken picture or flat line are caused by a problem with the
    vertical deflection circuit.
    If both problems seem to come and go at the same time or seem to affect
    each other then I would suspect a problem with a voltage that supplies
    both the tuner and vertical section, or loose solder joints in the
    related circuits.
  3. GerryO

    GerryO Guest

    So if power to both the tuner and the vertical section is occasionall
    interrupted ONLY when the set's tuner is being used (as there's never
    picture or sound problem when using a vcr tuner that's connected to th
    set's rear a/v inputs), does selecting VIDEO turn OFF power to th
    set's tuner, which could have a short or loose connection?

    Thanks, Gerr
  4. GerryO


    Jan 31, 2009

    Resoldered one other suspect solder joint in the area and what looked like two cracked connector post joints where the four yoke wires connect to the Main Board.

    Now I'm left with a tuner issue where the word VIDEO periodically appears on the screen, even when there is a video input present

    And the tuner, if it's used at all, repeats a continual and relatively short cycle of good picture/sound to no picture/static, with it sounding almost like there is a relay inside the set clicking ON/OFF.

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