wavy display on a 3B1.

[Jeffery Small]

This is a request for help from some of you UNIX-PC hardware gurus out there.

I have three 3B1 machines which were recently relocated to a new site.  On two
of these machines, I am now experiencing "screen wave" - a distortion in the
display which looks like a wave running across the screen.  The frequency
which I observe this condition has been increasing and now I experience this
every few minutes typically.

The power at this new site is not as clean as my previous location and I
occasionally see dimming of the lights.  I have always been impressed with
the stability of the power supply in this unit and I am experiencing no
operational problems (other than the screen wave) with any of them -
even when I measure a significant voltage drop on the line.  However, the
wavy screen does not correspond to the power fluctuations which my eyes
register (from observing the lights).  In fact, I've never been able to
observe ANY screen wave at the same time I saw the lights dim and I can't
watch both screens at the same time to see if the condition occurs in sync.
I put an analog volt-ohm meter on the line and am getting about 116-117 VAC
and I see no variation in the voltage during periods when the screen waves -
but possibly the meter is not responsive enough to register rapid fluctuations?

So, on to my question:

Does anyone have any past experience with this condition which would indicate
whether the the problem is most likely with the external power (and I need
some line conditioning) or might possibly be a dying component (power supply,
capacitor, etc) which has proven in the past to be the cause of this type of
problem and should be checked/replaced?

Any help, hints or suggestions will be greatly appreciated.
--
Jeffery Small    (206) 485-5596            uw-beaver!uw-nsr!uw-warp
C. Jeffery Small and Associates                                    !cjsa!jeff
19112 152nd Ave NE - Woodinville, WA  98072           uunet!nwnexus