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Zenith pict comes on bright then goes dark

Discussion in 'Electronic Repair' started by Vorlon, Mar 28, 2005.

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  1. Vorlon

    Vorlon Guest

    Hi
    I was wondering if any of you have had any experience with Zenith
    H0958x or H09c59x 9" TVs. These TVs were also modified by a company
    called PDI for hospital TV usage (PDIZ9TV-B)but doesnt seem to be a
    problem in the modifications, I could be wrong though.

    When first powered on the TV will come on full brightness then quickly
    fade to a very dim picture. The audio is ok as is the on screen
    displays but as I said the video get very dark, almost completly black
    on some. And on some of the TVs the brightness will return to normal
    after being on for about 3 or 4 min while others dont seem to ever come
    back up. But turning off tv then back on will continue to give the
    normal brightness good pict then fade away results until TV has "warmed
    up"

    Also the voltage on the high voltage anode is still present. It seems
    to be something in the video chip and associated components since the
    on screen display and menu appear normally but I havent had any luck
    tracng the problem down.

    I have recently inherited about 7 or 8 of those TVs so any help would
    be apreciated
     
  2. Guest

    Do those have the microprocessor PDI board in it? If so they have to
    be unlocked to allow video display via some computer code coming in
    through the cable.
     
  3. Vorlon

    Vorlon Guest

    These sets are only able to be activated by infared remotes and dont
    have the over the cable remote activation features. Once activated only
    chan vol and cc funtions can be accessed.
    Also I have a number of the same model purchased at the same time as
    the others that are working fine.
    And these TVs worked fine for a couple years until they developed the
    problems
    Now I am not ruling out a chip problem since the problem will either go
    away after being on for a few min or do the opposite and fade away
    after a few min. But the most common problem seems to be the come on
    for a second full brightness then dim down to a either very dark
    picture or completly black.

    I contacted PDI and they are pointing me to a capacitor but after
    changing it out on 1 of the TVs (only had 1 cap lol) the problem didnt
    change.

    Oh well back to proding and tracing to try to track it down with my
    poor schematic lol

    Thank you very much for your responce, I appreciate any thoughts.
     
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