Monitor shakes w/ UPS

Hi all,

I have a bit of a strange problem. I have a fairly new, fairly high
quality 19" monitor that sometime suffers from an annoying "shake".
Usually it's most noticible in the upper left corner, but sometimes it
occurs around the entire perimiter of the screen. I recently connected
it to a SmartUPS 700, but the problem will still occur. I even
connected a 500 joules surge protector to the outlet which the UPS
connects to, but the problem STILL occurs. I've taken the monitor to
other locations and the problem does not happen. I live in an old
building (>75 yrs old), and I'm betting the wiring is also very old.
Things like turning on the washer/dryer set this off.

What else can I do to prevent this from happening? Is the APC SmartUPS
700 simply not powerful enough to "condition" the line? I know the UPS
works in terms of being able to keep my equipment online when there is
no AC power, but it does not appear to be helping w/ preventing these
spikes/surges (correct terminology?) from reaching my monitor. For my
own knowledge, why would this be the case?

Thanks for any insight...

joe.

 

[HedgeWarden]

Joe,

We had jitter problems in our monitors when we set them on top of a
power distribution box. That was back in the eighties, and people
don't use those power distribution boxes anymore, as far as I know.
(They had a "master" on/off switch, and switches for the system unit,
monitor, printer, and a few additional units. They were designed to
sit between the system unit, usually horizontal back then, and the
monitor.)

But the 60 Hz radiation from the box was too much for the monitor to
bear.

Any-ho, look for any electrical appliances near your monitor -
flourescent light, power strip, even an incandescent lamp.

It "may be" your building wiring. However, if the wiring uses cable
(hot and neutral in a common sheath) instead of separate wires at some
distance from each other (that predates even me - called "post and ??"
or something), it is unlikely to create much of a magnetic field very
far from the wires. More likely it is something much closer to the
monitor.

Here is a clue - if the wires to-and-from the appliance or circuit are
close together, the magnetic fields cancel each other a very short
distance from the wires. If the wires are separated by a distance, as
apparently they were inside the aforementioned box, they will radiate a
60 Hz magnetic field for some distance, potentially messing with that
delicate stream of electrons hurrying from the "guns" at the back of
the CRT to the precision phosphorescent dots on the face of the CRT.

-Howard

joe_macdonald25@yahoo.com wrote:

Hi all,

I have a bit of a strange problem. I have a fairly new, fairly high
quality 19" monitor that sometime suffers from an annoying "shake".
Usually it's most noticible in the upper left corner, but sometimes
it
occurs around the entire perimiter of the screen. I recently
connected
it to a SmartUPS 700, but the problem will still occur. I even
connected a 500 joules surge protector to the outlet which the UPS
connects to, but the problem STILL occurs. I've taken the monitor to
other locations and the problem does not happen. I live in an old
building (>75 yrs old), and I'm betting the wiring is also very old.
Things like turning on the washer/dryer set this off.

What else can I do to prevent this from happening? Is the APC
SmartUPS
700 simply not powerful enough to "condition" the line? I know the
UPS
works in terms of being able to keep my equipment online when there
is
no AC power, but it does not appear to be helping w/ preventing these
spikes/surges (correct terminology?) from reaching my monitor. For
my
own knowledge, why would this be the case?

Thanks for any insight...

joe.

 

[HedgeWarden]

A short Google suggests that "knob and post" and "knob and tube" are
both correct terms for the old wiring that ran separate wires for the
hot and common. They were strung in space, in my experience, between
small ceramic insulators - in the same fashion as distribution wiring
on power poles, but on a smaller 110/220V scale. It is the relatively
large spacing between the wires that could cause stray magnetic fields
some distance from them.

The point about transformers is great. Transformers operate using
magnetic fields to transfer energy from one circuit to another. If
they were 100% efficient, no magnetic energy would escape. But they
are not. Even the relatively far weaker earth's magnetic field
influences the path of electrons in a CRT - luckly it is a static
influence and so does not create flicker. An unshielded or poorly
shielded transformer close to a CRT will wreak havock on the image.
Note that wall-warts are usually transformers in a plastic box.

-Howard