Consoles and displays

["William D. Gooch" <ai.gooch@MCC.COM>]

    Our consoles seem to be the weakest links in our systems.  A majority of
    our service calls are console-related.  Is this true for anyone else?
 
Yes.  One reason is that the picture tubes wear out over time, to the
point that nothing short of replacing the tube will help.  Also some
tubes have poorly placed fixed magnets, which causes nonlinearity that
may be impossible to tweak away.

I have a strategy which works pretty well for me.  I'm very picky about
the quality of the image I look at all day.  Whenever I have a console
that doesn't satisfy me, I call service.  I keep bugging them about it
as long as is necessary to get a good sharp, reasonably rectangular
image on my screen, even if this requires replacing the entire guts of
the console.  Once this state is achieved, I find that it will usually
maintain pretty well over time, requiring only an occasional tweak or
two (usually to improve the focus or linearity).  I never turn off my
console unless forced to, because frequent power cycling can lead to
relatively rapid degradation; however, don't unplug the console cable
at either end without turning the console power off first, as this can
damage the console.

The linearity problem seems to be somewhat inherent in the design of the
old-style Symbolics consoles (less so with the new style).  I have less
concern for this issue than you apparently do, and I'll settle for a bit
less than total perfection in this regard - but not much less.  

There is a way to display a pattern in the screen surround, e.g.:
(tv:set-screen-background-gray tv:75%-gray)


P.S.   I've noticed that the MacIvory B&W consoles we have do not
exhibit significant non-linearities (at least when they're new).