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Very old monitor repair

Discussion in 'Electronic Repair' started by CIP, Mar 2, 2005.

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  1. CIP

    CIP Guest

    Hi everybody,

    I got an very old monochrome monitor that is dead.

    It's an NEC BU-1201M(E)-1 from about 1985

    It had an burnout fuse on the main board, replaced it but the screen remains
    black. Audio works. When I switch it on the first second the end of the CTR
    lights up but then it gets very dim or even no light at all. I can hear the
    HV make a little hunnimg noise.

    It's a monitor from a computer that controls a factory. The monitor was
    turned on in 1985 and never turned off, but when not in use the screen was
    cleared. The video input is NTSC

    Checked the power transistors (h/v) and they are ok. Transformer is ok.

    Anybody any tips?
  2. Aidan Grey

    Aidan Grey Guest

    NTSC is standard North American TV video. What you have essentially is a
    TV being used as a monitor.

    You should be able to be able to cheaply buy a replacement TV type monitor.
    place to check is video security monitors. A security camera being recorded
    on a
    VCR is using an NTSC signal. The video monitor for such a task would
    probably be
    a drop in replacement for your defective monitor.

    Note that even if you could repair this monitor, it will not be reliable at
    its age. A brand
    new monitor will give you the reliability needed for a factory environment.

    Aidan Grey
  3. Clint Sharp

    Clint Sharp Guest

    The HV shouldn't hum, it should whistle, you can check for operation of
    the flyback transformer by holding a neon screwdriver close to the
    transformer, it should glow on a monochrome unit if it's running.
    Replace it, if it's in a factory it's needed! You could probably replace
    it with a 12" PAL Unit and get away with it with a couple of minor
    tweaks to the frame rate and line sync. supply chassis
    monitors as do many other 'industrial' electronics component suppliers.
  4. James Sweet

    James Sweet Guest

    Don't forget that there might be special mounting considerations.

    Also I would not nessesarily expect a modern TV to last anywhere near as
    long as that monitor did, if the image was still reasonably good I'd repair
    it personally.
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