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sudden monitor geometry fault

Discussion in 'Electronic Repair' started by RdM, Aug 26, 2003.

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  1. RdM

    RdM Guest

    My Wyse WY-782D has dveloped a scallop in the sides about 3/4 way up
    Ascii text (fixed pitch font) representation:
    ______________
    | |
    ) (
    | |
    | |
    |______________|

    There is a very slight jitter associated with the symmetrical scalloping.
    Any ideas on failing component causing this?
    Happy to replace electrolytics etc, but don't feel like a shotgun approach.
    I've inspected for dud solder joints - all appear OK.
    Thanks for any help
    Ross Matheson
     
  2. RdM

    RdM Guest

    : My Wyse WY-782D has dveloped a scallop in the sides about 3/4 way up
    : Ascii text (fixed pitch font) representation:

    Ooops!! Make that "Arial" variable font! ;=) A fixed font version below.
    ______________
    : | |
    : ) (
    : | |
    : | |
    : |______________|
    :
    : There is a very slight jitter associated with the symmetrical scalloping.
    : Any ideas on failing component causing this?
    : Happy to replace electrolytics etc, but don't feel like a shotgun approach.
    : I've inspected for dud solder joints - all appear OK.
    : Thanks for any help
    : Ross Matheson

    Here's a crude fixed font sketch anyway.
    ______________
    | |
    ) (
    | |
    | |
    |______________|
     
  3. Asimov

    Asimov Guest

    "RdM" bravely wrote to "All" (26 Aug 03 15:13:02)
    --- on the heady topic of "Re: sudden monitor geometry fault"

    Jitter or instability could be the symptom of HV arcing and so is a
    divet like yours. I don't think it is an electro. Try and observe the
    circuit traces under the FB or its vicinity in a darkened room. Any
    light blue fuzz is clear evidence, also any electric smell is a clue.
    In the past what I've seen cause the arcing, besides the obvious bad FB,
    is the pulse shaping network. Sometimes a high voltage resistor opens
    and allows the H-out pulse to get very peaky. It's the uncontrolled
    peaks that causes the arcing. Beware of high voltage and RF burns!


    Rd> From: RdM <>


    Rd> : My Wyse WY-782D has dveloped a scallop in the sides about 3/4 way up
    Rd> : Ascii text (fixed pitch font) representation:

    Rd> Ooops!! Make that "Arial" variable font! ;=) A fixed font version
    Rd> below. ______________
    Rd> : | |
    Rd> : ) (
    Rd> : | |
    Rd> : | |
    Rd> : |______________|
    Rd> :
    Rd> : There is a very slight jitter associated with the symmetrical
    Rd> scalloping. : Any ideas on failing component causing this?
    Rd> : Happy to replace electrolytics etc, but don't feel like a shotgun
    Rd> approach. : I've inspected for dud solder joints - all appear OK.
    Rd> : Thanks for any help
    Rd> : Ross Matheson

    Rd> Here's a crude fixed font sketch anyway.
    Rd> ______________
    Rd> | |
    Rd> ) (
    Rd> | |
    Rd> | |
    Rd> |______________|


    .... I worked hard to attach the electrodes to it.
     
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