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35" proscan problems (horizontal lines/turns off/high pitch whine)

Discussion in 'Electronic Repair' started by playstationdude, Sep 7, 2007.

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  1. Hi everyone. My friends and I got a 35" Proscan TV for free to
    replace a broken Zenith 20" CRT (the picture is green and brigher
    parts "bleed" over). I any case, the Proscan has
    problems. When i turn it on, the green LED by the power button lights
    up, but there is no image except for a few horizontal lines in the
    middle of the screen than bend a little; it looks like |) rotated 90
    degrees. After a second or so, the green led turns off and so does
    the TV. When its doing this, there is a quiet high pitched whine.
    Sometimes it will try to cycle on and off a few times before giving
    up. Does anyone have any idea what's wrong? Can we use parts from
    the 20" Zenith to fix this? I have soldering experience and basic
    electronics repair skills.
  2. Meat Plow

    Meat Plow Guest

    You won't be able to repair it with basic skills.
  3. Thanks for the vote of confidence. Seriously, does anyone have any
    ideas what I can try? I have a multimeter and an oscilloscope. Its
    going to be recycled if I cant fix it.
  4. Meat Plow

    Meat Plow Guest

    I'm just being realistic. You need more than a scope, a meter and basic
  5. Smitty Two

    Smitty Two Guest

    Start here:
  6. James Sweet

    James Sweet Guest

    That's not necessarily true, gotta start somewhere, and CRT displays are
    generally not too hard to work on. I don't have any specific advice for this
    set, but I'd start by checking all the semiconductors in the horizontal
    drive section as well as look for bulging electrolytic capacitors.
  7. James Sweet

    James Sweet Guest

    I rarely use anything more than a multimeter, basic troubleshooting skills,
    and occasionally a tip from someone here. I've fixed dozens of TVs and
    monitors over the years.
  8. Meat Plow

    Meat Plow Guest

    This part is what I had some trouble digesting:

    quote: "Does anyone have any idea what's wrong? Can we use parts from
    the 20" Zenith to fix this"
    end quote

    You in all your experience may think that these sets are "not to hard to
    work on"

    Not the case for the totally clueless.
  9. That's not necessarily true, gotta start somewhere, and CRT displays are
    The OP might be able to fix the set, but given the problem, as he describes
    it, he'll probably need to shotgun a lot of components. And that's not the
    way you usually fix things.

    Without at least a comprehensive service manual, he's likely to have
  10. You might start by posting the model number and chassis number. If you want
    a color by numbers fix you need to be more specific.

  11. Maybe just resolder the coils in the horizontal drive circuit...

    Mark Z.
  12. Meat Plow

    Meat Plow Guest

    Ok, get back with the OP and tell him how to fix it.
  13. the model number is PS35182 and the chassis is CTC170MA. Is there any
    more information i can give?

  14. Guest

    It is a CTC170 chassis.
    Even an experienced technician with the service manual would have a
    tough time with that one.

    Do a google groups search for the CTC170 chassis and see what comes

    Before you toss the set, find out if any repair shops are willing to
    pick it up for free.
  15. Did a google search and found this site:

    more specifically:
    Proscan PS35682 CTC170 cycling on an off CTC170 chassis. Unit will
    cycle on and off three times then finally shut off. Gave tech
    instructions relating to the this type of shut down complaint. The 9
    volt source was OK. The 3.7 volts that must be on pin 2 of U3101 (CPU)
    never rose above .8 volts. These two voltages are critical to the
    operation of the D.C. detect circuit. Problem was U1902 audio output
    IC on audio board.

    Does anyone know where I can get circuit diagrams for the set?
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