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Zenith projection TV ZB4685T no green.

Discussion in 'Electronic Repair' started by Mike, Aug 13, 2004.

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  1. Mike

    Mike Guest

    I have found one of these projection sets, I liked it because of the bose
    and dolby sorround.

    The set had a very dim picture, it was out of focus, and there was
    no green period.

    The back of it was missing, and I found the model number on a sticker.

    I fixed the out of focus problems, and I turned the picture off from 0 to
    give a great picture. It has a great purple picture, but no green. there is
    absolutely no raster at all on the green tube. The filiments are lighting in
    all 3 tubes, and HV is there.

    I pulled out the CRT neck board, and with other zenith sets I worked on,
    alot of the color problems are open resistors on the CRT neck board.

    I checked every component on the neck board. All of the transistors are
    good, and no shorted/open diodes, and every resistor tests within tolerance.
    Im thinking its in the video output board.

    Any ideas? is this a common problem, anyone know? I tried cranking the G2
    all the way up, it makes no difference. Still no green raster.
  2. Mike

    Mike Guest

    uh oh. little help please.

    for testing purposes, I moved the CRT board from the blue, and just plugged
    it in the green tube, yes, i know the green tube will now recieve the blue
    signals, but the tube still isnt comming on.

    either the tube is bad, or the HV is missing from the tube. any ideas?
  3. Art

    Art Guest

    Did the green tube produce a raster when the bleu crt board was attached??
    If so then trouble shoot the green crt board for failure of component parts
    or check with Zenith to see if the board is available.
  4. Mike

    Mike Guest

    nope. no raster still. its either in the HV block, or the tueb is gone.
  5. Mike

    Mike Guest


    I switched the anode leads on the block, and still no green. The tubes gone.
    I never thought tubes fail to no emission like that. Wouldnt the set shut
  6. Mike

    Mike Guest

    this time , I looked streight into the lense, and there is emission. its
    really really really faint.
  7. Mike

    Mike Guest

    ok. I had another zenith TV that had the exact same to the number, green
    CRT. The deflection board failed in it some time ago, and I didnt feel like
    fixing it.

    Anyway, I pulled out the CRT, and put it into this zenith. The green is now
    back to working order.

    The problem is, the picture is way too wide and tall, (raster blooming). you
    can hear the wining in the flyback, and the picture will bloom in and out
    sorta small, but you can notice it. IF you see a phone number in an ad, it
    runs off the screen. The red is perfectly focused, and the green and blue
    will NOT focus all the way. Green is a little bit worse focus wise than the
    blue. Red is perfectly focused. Any ideas?
  8. Art

    Art Guest

    Change the HV block and the focus pack. Check the deflection and PCC
  9. Mike

    Mike Guest

    i resoldered the entire HV and sweep module, the blooming is gone, and the
    flickering is gone. the picture is perfectly stable. The red is perfectly
    focused, and the blue is perfectly focused, but the green is still out of

    I tried flip-floping focus leads, and its still out of focus. I dunno what
    the deal is here.

    anyway, the raster is way too large. you cant even see the ticker on the
    weather channel at the bottom of the screen. its cut off.

    anyway, i googled it up, and found an entry that there is a cap that would
    cause this on the sweep board, and I replaced the cap. it made things a
    little more stable, but still no change in the size of the raster.

    its a 46inch screen, the picture is teh size of a 60inch.
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