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Hitachi DP 27 chassis

Discussion in 'Electronic Repair' started by [email protected], Jun 6, 2007.

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  1. Guest

    Now this is really driving me nuts, and the first thing tomorrow it
    gets stowed and we can make some money maybe.

    OK, set comes in, shuts down immediately, with scope I find offset in
    the convergence output, a pretty healthy one.

    I pulled all that out of circuit, even the module.

    Now I am troubleshooting the shutdown, it has everything, I know the
    current shutting down the HV is from RN10. I have persued that, but no
    matter what I disable, there is still votage at the cathode of DN09 (I
    think, but that's the one that clamps the pulses to the trigger input
    of the HVOT driver IC an M625 something).

    Intermittently the SMPS on the right (from the back of set) cycles
    intemittently. I assure you the STKs are gone, I literally took them
    out.

    Now when this is happeneing, the SMPS cycles on and off, and the light
    for the -28 stays lit well after you unplug it, but then the
    convergence ICs have been removed. Now, the light next to it must be
    for the +28, it would seem logical. That one drops like a rock when
    the SMPS shuts down.

    What else runs off the +28 ? Also there is the smell of heat, but I
    have let it run until it happened and then just about touched every
    component on the chassis. The CRT sockets are already unplugged.

    This thing is running me around here, I think it would be useful to
    know what else runs off that +28, I have all kinds of things unplugged
    left and right, and even though I can smell the heat, I can't seem to
    find it. I have run my finger around that chassis and the warmest
    thing is the jungle IC, and it ain't hot, just warm. It probably runs
    off the other part of the power supply anyway.

    So what all else does the +28 feed in that thing ?

    Any help appreciated, it is late, I must go.

    Be well.

    JURB
     
  2. Guest

    Oops, I think that is DP24 chassis, not 27.

    Sorry.

    JURB
     
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