Member Avatar for GreatSilverWyrm

my Viewsonic A90F has had strange white flickering lines near the bottom for about 6 months now

they're worse right when I turn the monitor on, but I'm still unable to expand the screen any lower than about half an inch above it's physical maximum

I've turned off all electronic devices around it to no avail, so, I don't think it's interferance


running it at 1280x1024 @ 75 hz
off of a nVidia Geforce 6800 GT 256

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  • Latest Post Latest Post by vicec64

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The symptom set — white, flickering lines confined near the bottom, worse at cold start, and an inability to move the raster fully down even with geometry controls — points less at external RF interference and more at the monitor's internal vertical-deflection or power-delivery stages. and raised external checks earlier; those are useful to isolate the fault to the monitor, but the behavior you describe is classically caused by time-dependent component failure inside the CRT chassis (for example, failing electrolytic capacitors or a weak vertical drive stage).

Practical next checks and observations to narrow it down:

  • Make the artifact easier to assess: display a uniform full-screen color (black/white) and try a couple of refresh rates and resolutions. If the line is fixed to the screen regardless of source image or graphics card settings, the fault is internal.
  • Watch how the fault changes as the set warms up. Improvement with temperature strongly implicates aging electrolytic capacitors or marginal solder joints.
  • Do a careful visual inspection (power unplugged and case removed only if comfortable): look for bulged or leaky caps on the power/vertical boards and for cracked solder joints around the neck/yoke connector. Those are low-cost fixes compared with replacing large components.
  • Service-level checks: measuring DC-rail voltages and vertical-output waveforms will confirm a weak ramp or offset, but this requires an oscilloscope and experience with CRT safety.

Safety and outcomes: CRTs contain lethal high voltages. If the inspection points to bad caps or a failed vertical IC and there is no electronics experience, seek a qualified repair shop. Re-capping or replacing a vertical output IC can restore full vertical travel in many cases, but for an older A90F the repair-vs-replacement cost should be considered.

For background on the components and failures mentioned, see the Cathode-ray tube overview and notes on electrolytic capacitor aging: Cathode-ray tube, Electrolytic capacitor, Flyback transformer.

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Member Avatar for vicec64

Try degaussing the monitor in the monitor's controls, and you can also try another power supply if you can dig one up (if degaussing doesn't work). Believe it or not a marginal/faulty PSU that migh not deliver enough juice on your +12V rail can cause screen artifacting or symptoms like you describe.

Member Avatar for WhitieTheCracke

if you have another pc try the monitor on that pc that way you will know if it is actually the monitor or your ps,video card. then let us know what's up.

Member Avatar for vicec64

Try degaussing it.

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