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LCD gives irritating high-frequency sound !

Discussion in 'Electronic Repair' started by [email protected], Jul 5, 2007.

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  1. Guest

    Can anyone tell me what electronic component I should replace if a
    computer 17" LCD-monitor gives a irritating high-frequency sound? I'm
    not a genius in electronic but I can solder and maybe repair a 4years
    old teriffic lcd screen.

    Also I like to know if a LCD has also the dangerous hi-voltages like
    the old TV's?

    Samsung SyncMaster 171N

    Thanks you!
  2. Meat Plow

    Meat Plow Guest

    Probably the SPMS. Takes more than soldering skill to troubleshoot those
    and they do have some lethal voltages.
  3. Meat Plow

    Meat Plow Guest

    errrp SMPS :)
  4. Guest

    Probably the SPMS. Takes more than soldering skill to troubleshoot those
    thanks, but what is the SPMS and how does it look like?

    Also how can I safely remove the high voltages without damage the
    electronics or me ;)
  5. PhattyMo

    PhattyMo Guest

    The SMPS is a "Switch Mode Power Supply",it may be "internal" to the
    monitor,or it might be in the little "power pack" for it (varies by
    model.My monitor has it internal -no "power pack".)

    You can generally tell the SMPS section by the small ferrite
    transformer,and a large capacitor (400V,100uf,perhaps.) *Discharge that
    capacitor before you even think about poking around inside!* (don't
    short it out though!)
    High voltage hurts,at the least..and worst case,can be !LETHAL!

    Another possibility is the CCFL inverter for the backlight.
    Again,High voltage on the output side (the side that goes to the
    backlight tube(s).) There is likely a small 2KV 100-1000PF capacitor in
    series with the lamp(s) might want to discharge it also (short it
    with a screwdriver -DO NOT use this trick on larger caps -big BANG,and
    lots of sparks!)

    Those are about the only possible sources of 'whine' in an LCD
    monitor,that I'm aware of.
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