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Sylvania TV Problems

Discussion in 'Electronic Repair' started by William R. Walsh, Sep 12, 2003.

  1. Hello all...

    Model number RAC128WA03, marked as being made by North American Philips in
    Knoxville, TN. Says "Sylvania" on the front panel.

    This is a set I keep on my porch...and when the weather is bad, the set
    comes indoors because the porch is enclosed but unheated and uncooled. It is
    a nice little table set in good condition and it has been kept pretty clean
    over the years.

    Problems:

    The picture occasionally becomes sort of a soft but pronounced cyan (blue)
    in color. The shift isn't so bad that all other colors are forced away, but
    some colors simply do not appear. When the color control is turned
    completely off and a black and white picture is displayed, the syptom still
    appears in a way that seems to shift color temperature. This is something
    the set only started doing recently and a hard whack on the side may or may
    not fix it. At the very least it will produce an attempt at switching to the
    proper colors. I reckon this is bad solder or marginal parts more than
    anything else. Is there anything specific I should be looking for?

    The next problem seems perhaps a bit more serious and certainly affects
    viewability more than the first problem. Periodically the set acts like the
    screen (G2) control on the flyback is being slowly turned up just until
    white lines appear softly on the screen. Along with this effect, the picture
    on the screen will get brigher and brighter. After a second or so of
    displaying the bright picture with faint white lines, the set reverts to a
    normal picture and the process happens again. I'd say it is repeated about
    every 5 seconds. This problem never goes away as long as the set is powered
    up, but it won't start until the set has been running for --say-- 30
    seconds.

    I have had very good performance from this set, and I like the way it looks
    and works, so I'd like to repair or get an idea of what is wrong if at all
    possible. Thanks in advance to anyone who can give any ideas or thoughts!

    William
     
  2. Jerry G.

    Jerry G. Guest

    There may be a cold solder joint(s), in the video processing or CRT bias
    paths to start with. The changing of the brightness may be the high
    voltage multiplier. In your set, it is most likely integrated with the
    flyback transformer, and all are replaced as a module.

    You can try to rotate the G2 or bias pot back and forth a little in case
    it is sitting on a sort of intermittent spot, but more than likely the
    HV multiplier section is bad.

    --

    Greetings,

    Jerry Greenberg GLG Technologies GLG
    ==============================================
    WebPage http://www.zoom-one.com
    Electronics http://www.zoom-one.com/electron.htm
    Instruments http://www.zoom-one.com/glgtech.htm
    ==============================================
    "William R. Walsh" <>
    wrote in message Hello all...

    Model number RAC128WA03, marked as being made by North American Philips
    in
    Knoxville, TN. Says "Sylvania" on the front panel.

    This is a set I keep on my porch...and when the weather is bad, the set
    comes indoors because the porch is enclosed but unheated and uncooled.
    It is
    a nice little table set in good condition and it has been kept pretty
    clean
    over the years.

    Problems:

    The picture occasionally becomes sort of a soft but pronounced cyan
    (blue)
    in color. The shift isn't so bad that all other colors are forced away,
    but
    some colors simply do not appear. When the color control is turned
    completely off and a black and white picture is displayed, the syptom
    still
    appears in a way that seems to shift color temperature. This is
    something
    the set only started doing recently and a hard whack on the side may or
    may
    not fix it. At the very least it will produce an attempt at switching to
    the
    proper colors. I reckon this is bad solder or marginal parts more than
    anything else. Is there anything specific I should be looking for?

    The next problem seems perhaps a bit more serious and certainly affects
    viewability more than the first problem. Periodically the set acts like
    the
    screen (G2) control on the flyback is being slowly turned up just until
    white lines appear softly on the screen. Along with this effect, the
    picture
    on the screen will get brigher and brighter. After a second or so of
    displaying the bright picture with faint white lines, the set reverts to
    a
    normal picture and the process happens again. I'd say it is repeated
    about
    every 5 seconds. This problem never goes away as long as the set is
    powered
    up, but it won't start until the set has been running for --say-- 30
    seconds.

    I have had very good performance from this set, and I like the way it
    looks
    and works, so I'd like to repair or get an idea of what is wrong if at
    all
    possible. Thanks in advance to anyone who can give any ideas or
    thoughts!

    William
     
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