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zenith avi tv issues

Discussion in 'Electronic Repair' started by Bob in PHX, Feb 8, 2005.

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  1. Bob in PHX

    Bob in PHX Guest

    To All,

    My Zenith 27 inch avi tv is exhibiting the following symptoms


    #1 the red gun seems to fail every now and then, causing all colors to be
    green ...This happens at startup and does not clear, unless the tv is turned
    off for a number of hours... Power cycling does not fix it.

    #2 If you were to divide the screen into fourths (horizontal bands) the
    second from the top band goes all fuzzy when the brightness is turned up,
    but only on white or sky shots... with the brightness turned down, it works
    fine....

    Any ideas??????
    I friend of mine suggested that Zenith made some really crap CRTs from the
    late 80's till the late 90's and suggested that a CRT rejuvenator might fix
    the issues. I have an appointment setup with a buddy who has a
    rejuvenator.... we will see if that helps... in the mean time,,, any other
    ideas...

    Bob in phx
     
  2. Guest

    #1. Bad solder connections on the 3 video output transistors on the CRT
    board.

    #2. Bad picture tube.

    Both very common on this Zenith TV unfortunately.
     
  3. Bob in PHX

    Bob in PHX Guest

    ok, its fixed, but I did more then one thing to fix it...

    1. removed back and took off crt card. I found some discoloration around the
    three color gun resistors. I resoldered all three resistors.
    2. found some weak/dry soldering on the large color gun transistors on the
    same board. Resoldered these connections
    3. gave the crt tube pins a shot of pro gold / deoxit. replaced the board.

    I then cranked the old girl up and look no more green tint to everything.

    But the 1/2 to 3/4 horizontal band was still fuzzy. I looked closer and
    decided that maybe a tweet of the focus on the flyback was in order.... Well
    that was all it took. No more green and perfect picture!!!!!!!!!!!!!!!!!!!

    Now to lift it back to on top of the file cabinet in my office, of course, I
    had to buy the 4 drawer cabinet,,,, didnt I......

    Bob in phx
     
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