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Monitor High Pitch Whistle

Discussion in 'Hobby Electronics' started by Bazil, May 2, 2005.

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  1. Bazil

    Bazil Guest

    A friends monitor is occasionally emitting a pretty uncomfortable high
    pitched whistle.

    You can give it a knock and it may drop the intensity a bit, but will
    often come back again later. Changing the display width also may reduce
    it for a while but he says it is still there.

    I assume it is a physical problem yes / no ?

    Any ideas on solutions?

    TIA,

    Bryan
     
  2. Bill Bailley

    Bill Bailley Guest

    The likely culprit is either the LOPT on the circuit board, or the scan
    assembly on the neck of the tube. Some people have had luck using superglue
    dotted anywhere they can see a join where ferrite pieces are clamped
    together. The glue then wicks into the joints and sets. YMMV

    Apart from the normal unplugging from all power and other equipment, be VERY
    careful to ensure there is no HV stored in capacitors or by the CRT. Not
    usually lethal, but can cause galvanic responses in muscles that tears flesh
    on sharp bits of the chassis, or even propels the monitor off the bench. An
    imploding CRT is not something you want at your feet!
     
  3. Bazil

    Bazil Guest

    Thanks Bill,

    HV points noted. How long does the glass hold charge for after switch off?

    Bryan
     


  4. I can remember picking up CRTs to put into TVs and accidentally
    brushing the ultor and getting stung........... This was outta the box
    from the mob that regunned them.........

    So I would say that the charge can last a long time.........


    Mitch.....
     
  5. Bill Bailley

    Bill Bailley Guest

    And a quick discharge does not seem to finish the job. My memory tells me I
    was stung from CRT that had been discharged, and then seemed to gather some
    more charge from somewhere. If you can keep a wire link from the ultor to
    the aquadag you will be pretty safe.
     
  6. Bazil

    Bazil Guest

    That's why I asked. Because of the nature of glass, the charge takes
    time to travel and a quick short will not discharge it.

    But I will try and be careful, and if you never hear from me again, send
    an epitaph.

    Bryan
     
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