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A television question

Discussion in 'Hobby Electronics' started by Ian Sutherland, Feb 27, 2004.

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  1. Hi folks, I have been given a Sony 21" Model KV-2184AS. will be ideal
    for watching the cricket in the workshop. Supposed to have an
    intermittent/uneconomical to repair fault. I watched the last couple
    of 1 day finals (8 Hrs. plus) with no sign of a fault. Next switch on,
    no sound, no pic. It had a snowy raster, & speaker hiss. Also on
    screen display's functioned. Absolutely no sign of sound or pic or
    sync. bars, nothing!!

    Did this for next 5 or 6 switch on's, was about to take it down from
    the wall bracket, switched on, & operation normal. (1 week later,
    still functioning.)

    When it was dysfunctional I gave it a couple of thumps, no effect.

    Does anyone have a circuit diag. they could copy & post to me? I'm
    in Adelaide, & happy to pay any costs involved.

    To me it doesn't seem irrepairable, hopefully just tuner power
    supply or something else as easy to diagnose.

    My background is retired electronics tech, speciallizing in
    industrial controls.

    T.I.A Ian Sutherland.

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  2. James

    James Guest

    Being a Sony I'd say probably the tuner itself. Haven't worked on them for a
    while now and can't recall that model precisely, but in a lot of the smaller
    sony sets around the 10year old mark the tuners were bloody unreliable. If
    your lucky it might be a generic get from WES for $30 job.

    James
     
  3. Bob M

    Bob M Guest

    Hi Ian,

    Sounds like an intermittent antenna connection into the tuner. Follow
    the signal feed into the tuner, looking for a cold/cracked solder
    joint. I have to use a magnifying glass these days but be patient and
    you will find it. Over the years, thermal stresses cause this fault
    often. I am in the process of tracking down a similar issue on my Sony
    32" TV. My problem is in the cabling connections that connect the
    video output of the tuner to the main chassis (picture goes very dark
    with only slight amount of red coming through). Been at it for a while
    (a little vibration and the fault goes away) but I know I will
    eventually find it.

    Best of luck and happy hunting!

    Cheers from Canada

    Bob M.
     
  4. Resolder IF module and around the tuner.

    Rudolf
     
  5. Hi folks thanks to those that replied, & cheer's to Bob in Canada.
    I didn't want to do a blanket solder, but would have preferred to
    have found the fault. That struck me as being too hard, looked at all
    the solder joints on the main board & they looked O.K. Desoldered the
    tuner module, removed the screen shields & boy what a mess. 43
    inductors, 86 leads & about 50% were bad solder joints, particularly
    cratering around the lead. Dozens of surface mount component's but
    they all looked O.K. There were 2 resistors on the board & both had a
    crack right around 1 lead, on 1 of them I could see the crack get
    bigger & smaller as I moved the lead with tweezer's, this resistor was
    on the B+ line.
    Resoldered all leads except suface mount & reinstalled. Perfect pic. &
    sound. Before the resolder, the set was running on a small indoor
    antenna with a snowy pic, now, same antenna, no snow at all, must have
    increased the sensitivity as well. I hope it's fixed, and thanks again
    for the help.

    While the main board is out, should I remove the I.F. module or let
    sleeping dogs lie?
    Cheer's, Ian Sutherland.

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