I should have gone into more detail about my explanation.   The offending
lamp didn't actually damage the monitors but caused the disturbance.   After
replacing 2 monitors (which were OK in another location), I got suspicious
and unplugged the lamp and voila! the jittering disappeared.   This lamp was
not used (no bulb in it ) but was turned on.  I hope this clears things up a
bit.
This problem also has occurred in some mobile test stands we built which had
a blower motor near the monitor (relocated the blower motor).

Regards,
Fred Hahnel
ISO9000 Point Person PFSL


> From: Mark Rode [SMTP:[log in to unmask]]
        snip  >  however this is the first
> time I have heard of a ballast actually damaging a monitor. A halogen
> light
> does not require a transformer although a twelve volt transformer is often
> used for energy efficiency.
> It is always a good idea to keep any devices that produce a magnetic
> fields
> a foot or so away from your monitor to avoid picture distortion.
> Mark
>
> >Be sure no fluorescent or halogen lights are nearby either.  They use
> >transformers which will mess up a monitor.   I had two monitors replaced
> at
> >work because of a fluorescent lamp that was on (without a bulb in it
> yet!!)
> >and it made the monitor jittery.
> >Fred Hahnel
>
> >
> >>I have a problem with a Princeton Graphic Systems EO70 17"
> monitor.Actually,
> >> >I am not totally sure it is the monitor. Sometimes -- not all the time
> --
> >> >after operating for several hours, the display begins to jitter. It
> >>> >Bryan S. Tyson