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GE PROJECTION TV

Discussion in 'Electronic Repair' started by LawyerKill, Nov 29, 2003.

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  1. LawyerKill

    LawyerKill Guest

    LK

    Hi I have an old(about 25 years) GE Projection TV. There is a circuit breaker
    in the back for the horizonal output circuit. I turn the TV on, get audio, but
    before I get a picture the CB pops. I checked the Filter Caps and they are OK.

    Question: If the Flyback was bad would the CB pop when you first turn the TV
    on, or pop after about 10 seconds like it's doing?
     
  2. Jerry G.

    Jerry G. Guest

    I have seen these mechanical breakers themselves go defective. You should
    find out exactly how much current the circuit after the breaker is supposed
    to be pulling, and verify that. If the current pull is too high, you can
    work from there. If it is normal, then the breaker has to be changed. I
    have seen these breakers go defective, and become easy to trip.

    The fault may be some high ESR caps in the scan outputs, or anywhere after
    the breaker. Even a cap somewhere that is going resistive (internal
    leakage) that is causing too high a current pull, can cause the breaker to
    trip. It is possible that a bias resistor on a power device is going off
    value, thus causing it to pull too much current.

    If the picture is normal, chances are that the flyback and HV module is
    okay. This has to be determined.

    To work on your set, you will need the proper training, service manual, and
    tools.

    NEVER jump that breaker. If you do, and there is a defect, then the failure
    will be catastrophic, thus doing a lot of component damage.

    Considering that the set is 25 years old, it will probably be impossible to
    find many of the specialized parts. Only the generic parts such as the
    standard resistors, most of the semiconductors, and caps would be available.
    As for transformers, custom devices, mechanical parts, and etc, these will
    be almost impossible to have. The tubes must also have signs of wear on
    them as well.

    --

    Greetings,

    Jerry Greenberg GLG Technologies GLG
    =========================================
    WebPage http://www.zoom-one.com
    Electronics http://www.zoom-one.com/electron.htm
    =========================================


    LK

    Hi I have an old(about 25 years) GE Projection TV. There is a circuit
    breaker
    in the back for the horizonal output circuit. I turn the TV on, get audio,
    but
    before I get a picture the CB pops. I checked the Filter Caps and they are
    OK.

    Question: If the Flyback was bad would the CB pop when you first turn the TV
    on, or pop after about 10 seconds like it's doing?
     
  3. Andy Cuffe

    Andy Cuffe Guest

    I would expect a shorted HOT to pop it in less than a second, but a bad
    flyback (depending on how bad) could cause this. Do you get HV? You
    can always put an ammeter in series with it to see what the current
    really is. A short, or overload on one of the flyback secondaries would
    cause this type of thing. A shorted yoke is another possibility. On a
    25 year old GE, the first thing I would do is check the soldering very
    carefully, ESR the caps and resolder any through board connections if it
    uses double sided boards.
     
  4. David

    David Guest

    Didn't GE put out a rear projection tv from a very long time ago that was
    actually an overdriven 13" tv set with a big lens? I seem to recall seeing
    someone try and bring one of those in for repair several years ago.

    David
     
  5. John Del

    John Del Guest

    Subject: Re: GE PROJECTION TV
    Dear God yes! I remember those too. The cabinets were "L" shaped as the 13"
    TV part was stuffed off to the side. The focal length must have been 10 feet!
    They had a crappy picture even when new.
    My guess is that the poster's TV is actually a Panasonic. I fixed a couple of
    GEs years ago that were.
    John Del
    Wolcott, CT

    "I'm just trying to get into heaven, I'm not running for Jesus!"
    Homer Simpson

    (remove S for email reply)
     
  6. LawyerKill

    LawyerKill Guest

    David
    LK

    That's the one, the only reason I'm trying to repair it is that I have no one
    here to help me push it out the door and onto the sidewalk.
     
  7. Steve Reinis

    Steve Reinis Guest

    Just out of curiousity, do you (or anyone) have any web resources showing
    photos of this contraption?

    Are you in a position to take and upload photos somewhere?

    Thanks,
    -Steve
     
  8. LawyerKill

    LawyerKill Guest

    Andy Cuffe
    I would expect a shorted HOT to pop it in less than a second, but a bad
    flyback (depending on how bad) could cause this. Do you get HV? You
    can always put an ammeter in series with it to see what the current
    really is. A short, or overload on one of the flyback secondaries would
    cause this type of thing. A shorted yoke is another possibility. On a
    25 year old GE, the first thing I would do is check the soldering very
    carefully, ESR the caps and resolder any through board connections if it
    uses double sided boards.

    LK

    Thank Andy, it turns on and you can hear a whine for about 15 seconds, the
    audio is loud, after 15 seconds the circuit breaker pops and the audio drops to
    about half of what it was, the screen never gets a raster.

    The breaker is OK, I checked that.

    I disconnect the voltage from the horizontal output and measure it and it's a
    nice 140 VOLT, I hook it back up and turn it on and it's about 85 volt until
    the CB goes, it's drawning 2.5 amps. I put a scope on the Horizontal output
    transistor and it looks like I'm getting the wave form that I should (The set
    came with service information). I measured all the diodes and resistors in the
    Horizontal section and they appear OK, the Driver and Output transistors check
    OK with an ohm meter.

    There's a lead coming out of the flyback and it shows 4 diodes on the winding
    where that lead is, I took it off and laid it on that side, turned the TV on
    and it started arcing about 3 inches to the chassis, so I guess I have HV.

    I'm not a TV guy, I have an FCC First Class that I got in 1969 but I went right
    into engineering(Logic circuits) and I forgot most of the TV stuff.

    Now I'm measuring my doorway and distances to the sidewalk.
     
  9. LawyerKill

    LawyerKill Guest

    Steve Reinis
    LK

    I can take a picture of it, if you want, that's no problem.
     
  10. Andy Cuffe

    Andy Cuffe Guest


    Since you have HV, the flyback is probably ok. What's the circuit
    braker rated at? As a LAST resort you could always bypass the circuit
    braker and see what smokes. Of course there's a good chance you'll lose
    the HOT, or components in the power before learning anything. One thing
    to try would be unplugging the yoke and CRT socket (so you don't burn
    the CRT screen).
     
  11. LawyerKill

    LawyerKill Guest

    Andy
    LK

    Thanks Andy. What I just finish doing was disconnecting all but the drivers for
    the HOT and the winding of the flyback for the HOT. Across the HOT there is a
    diode, an 300 pf 2kv cap, and a .0145 5% 1.5 kv Cap, that's all, and it still
    pops the breaker. Resistance checks of the caps, HOT and diode all appear to be
    good. I'm one step away from putting a 15 ohm resistor in line with the power
    supply and jumping out the circuit breaker and see which of the few parts left
    smoke.
     
  12. Steve Reinis

    Steve Reinis Guest

    If ya don't mind, I'd love to see it. It sounds like such an oddball idea -
    using a 13" single CRT for a projection set.

    You can email it to:

    Ragtop429
    @
    Hotmail.com

    I'd sure appreciate it,
    -Steve
     
  13. James Sweet

    James Sweet Guest

    They actually sold something like that commercially? Is there any more info
    out there?
     
  14. James Sweet

    James Sweet Guest

    Yeah I'd like to see this too, very strange, must have had a horrible
    picture quality.
     
  15. Steve Reinis

    Steve Reinis Guest

    LK sent me a couple photos of this monster. And what a beast it is, too!
    Very 70's looking cabinet. I'll forward them your way. I'd actually love
    to strip the guts from the cabinet and stick another pullout style lightbox
    in there just to get a functional RPTV with that great (tacky) retro look!
    The cabinet looks to be in great shape for the age.

    -Steve
     
  16. LawyerKill

    LawyerKill Guest

    LK sent me a couple photos of this monster. And what a beast it is, too!
    LK

    The cabinet is in great shape, too bad you're not in New Jersey, I give the
    thing to you, if you can get it out the door (It fits in the door way, but it's
    heavy as hell)
     
  17. James Sweet

    James Sweet Guest

    Yeah that thing is hideous, but interesting at the same time.
     
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