sudden monitor geometry fault

[RdM]

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

 

[RdM]

RdM <rdm@orcon.net.nz> wrote:

: 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.
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: ) (
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:
: 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.
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[Asimov]

"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 <rdm@orcon.net.nz>

Rd> RdM <rdm@orcon.net.nz> wrote:

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.