"Mr. Land" wrote in message
oups.com...
I agree. I don't see how a HV or focus voltage problem would mess up
the focus in only one direction (unless it's some strange interaction
with one of Sony's non-standard shadow masks or something like that,
but that seems unlikely.)

It seems more likely that, if you are somehow losing your video
bandwidth you'd get blurring like this. Something in the video
circuitry could be intermittently limiting bandwidth, so when the fault
is occuring and the electron beam in the tube is about to draw one of
the lines making up the "o" in my example, instead of the video level
jumping "instantaneously" from white to black (which requires good
bandwidth) at the edge of the "o", it rather ramps down to black. So
what you see is a fade (aka blur) from white to black instead of a
nice, sharp, crisp line.

If I've convinced you of this hypothesis, I also have some land for
sale....

Loss of bandwidth! Yes, that would do it! Thank you - new theory. It makes a
lot more sense than my mystery high frequency modulation (which would
require lots of spare bandwidth, so didn't sound likely).
The only other possibility I can think of is if they do have separate
horizontal and vertical focus (cylindrical electron lenses?) - it's just
that I vaguely recollect reading that they do. Anyone know about that?
New:
I just got hold of "Nokia Monitor Test" and checked to see if the effect
varies with the screen resolution set in windows, and it doesn't as far as I
can tell - the physical width of blurring remains fairly constant - but I
think I now have to admit that there is some blurring in the vertical
direction too, although it's not as bad. I guess that points back to the HT?
This morning also, for the first time, I left the screen blurred to let it
warm up. Just as I returned I heard a small 'pop', which coincided with the
screen image momentarily collapsing.
So perhaps the horizontal/vertical variation in blurring is just a
consequence of the aperture grill and there is some kind of HT problem where
charge is building up and that's causing the blur?
I'll leave it blurred and watch it like a hawk tomorrow morning.
Scrim