Chuck,
Let me dig back to my EE days...
On an analog monitor (CRT) the electron beam is deflected in the X and Y
axes by deflection coils (electromagnetic) or plates (electrostatic). Each
deflection signal is theoretically a sawtooth to move the spot linearly in
one direction and then fly back fast for the next line/frame. Theoretically
the slope of that sawtooth waveform would have to be dead straight.
Due to non-linearities in the deflection and the need to deflect according
to the screen shape (non-hemispherical) some 'deflection linearity' circuits
are built in to 'correct' it. And they're not perfect and they can drift.
Goodness knows how this is achieved in modern CRT monitors - probably the
deflection is managed by a D/A converter - but certainly yours ain't right.
Maybe there's a menu control (I've got one on my Trinitron monitor, under
the option set called "geometry" but it only does vertical linearity -
mine's set to 66 fwiw :-) - or maybe there's knob to adjust it inside (you
remember the TVs of the 60's with all those knobs on the back?!)
So there is one advantage of an LCD monitor - the linearity is built in,
pixel-by-pixel....
Not much help, eh?
Jez
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