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Zenith Pip System 3, blank screen, but sound and menu work

Discussion in 'Electronic Repair' started by majesus, May 24, 2007.

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  1. majesus

    majesus Guest

    I got a Zenith TV with a blank screen problem.

    WHen cold, the TV would start fine, then after a few minutes, th
    picture would blank out (a blank screen.) The sound still works, an
    the menu, volume, channel info can still be displayed on the screen
    but I have picture. The problem use to be fixed by powering off/on th
    tv. The blank screen would come on intermittently.

    Well tonight, the picture went blank, and I couldn't get it back on. S
    I let the TV sit off for 20min off while I did some googling on the ne
    searching for an answer (that's how I found this forum.)

    After 20min, when I turned the TV on, it worked for another 10minutes
    then went out blank again after a minute or so. I haven't been able t
    get a picture back since.

    I am thinking it is a bad cap (just a case), I'll take it apar
    tomorrow and test some di-electric caps around the board with my scope

    Anyone have suggestions that maybe the cause of the problem?

    The Zenith TV is a PIP SYSTEM 3, Model SR2573DT, serial 522-454-80230
    It was built in 1995.

    Thank you
     
  2. Art

    Art Guest

    Suspect failure in video processing circuit, get out the scope and trace the
    video from the demodulation circuits through to the jungle ic. Other
    alternative is send the main board into PTS for rebuilding.
     
  3. majesus

    majesus Guest

    Thanks for the info

    Can I get a schematic for it to trace the inputs/outputs of the Vide
    circuit?
    Here is some more info if it helps:
    Service Manual CM-147/C-11(A)
    Chassis (C11 from Z-tips). The Main board has a sticker with: 9-1551
    Thanks
    majesus18 @ gmail.co
     
  4. R!

    R! Guest

    I had a lot of problems with the voltage regulator and bad solder
    connections in the pip modules. Some of them can be troubleshot by using
    one of the video jumper interconnects to temporarly bypass the pip
    module. You would need a diagram to find these the Y (brightness) and C
    (color) are looped through the pip module,

    Y------- ------- Y
    CH - PIP - CH
    C------- ------- C

    The above is greatly simplified...

    R!!
     
  5. majesus

    majesus Guest

    Found it!!! THanks guys for the help.

    It was the Comb Filter which is part of the video's circuitry
    Initially, on my first examination of the component DL2200, everythin
    looked fine. So I did a wiggle test by turning the TV on and tappin
    and shaking DL2200 with a wooden spoon. Nothing happened. But when
    started doing some measurements with my scope, as I touched pin2 wit
    the probe's tip. The picture on the TV screen came back on. AHA
    SUCCESS!!!

    So I resoldered all five pins of DL2200 as well as others around th
    problematic area. The TV works great now. :) I'm very pleased.

    If anyone does have the service manual (or any other relevan
    schematic) for chassis C-11. I would thank you immensly if you coul
    email it to me (majesus18 at gmail.com). I would like to have it fo
    reference in case I ever need it again.

    For other people/members, here is a schematic I used. It has a simila
    comb filter and is good starting point ot give you an idea on how th
    circuit is setup. FYI, this circuit is for chassis CS, models
    H27E46DT, H27E46DT8, H32E46DT & H36E46DT.

    Going to go watch a movie on my fixed TV. :)
    Cheers,
    Maj

    [image
    http://i48.photobucket.com/albums/f223/majesus/coupons for rfd/DL2200.jpg
     
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