On Sat, 24 Aug 2019 14:47:21 -0700 (PDT), wrote:

On Saturday, 24 August 2019 21:24:56 UTC+1, wrote:
On Fri, 23 Aug 2019 13:30:31 -0500, Jon Elson
wrote:
On Thu, 22 Aug 2019 12:11:57 -0700, etpm wrote:
On Thu, 22 Aug 2019 13:38:15 -0500, Jon Elson
wrote:
On Wed, 21 Aug 2019 16:47:10 -0700, etpm wrote:

So I built a kit that uses an electrostatic deflection CRT for the
display. It all turned out very well except the display is much more
in focus on one side of the screen.
Do they use true differential deflection signals, or unipolar (ie one
plate of each deflection pair is held at a constant voltage)? If
unipolar, it can cause this type of trouble.

Jon
I dunno Jon. How would I tell? Measure voltage to ground and see if one
or both changes?
Eric

If they have a centering pot that drives one deflection plate, and some
amplifier that drives ONLY the other plate, then that is single-ended
deflection drive. if they have differential amplifiers that drive both
plates in opposite directions, then that would be differential.

A scope could show that both plates are driven, but not sure a DVM would
give a definitive reading.

Jon
I tried swapping the X axis connections to the CRT and the out of
focus conditionn swaps too. So it is not the CRT. I'll contact the
contact the kit supplier and see what he says.
Thanks,
Eric

We already knew it's not the crt at fault. Another poster that asks and gets the correct answer, but remains entirely lost.
Hogwash. I went back and read all the responses to my posts about this
CRT. Most likely the CRT was not at fault but this was not known for
sure. Now I know for sure the CRT is OK. Your reply does nothing to
enlighten anybody. You have not posted anything useful. Why is that?
You posted "Presumably the electrode voltages aren't staying the same
as the thing sweeps across the screen." That's all you posted. Should
I take what you presume as being true in all situations? In any
situation? Why? And why did you presume what you did? How do I check
what you said? I'm trying to learn, what are you trying to do? If I am
lost then why not show me the way? When people ask me questions about
machining I try my best to help, often with several explanations
because some folks don't get it as easily as I do when it comes to
machining. Please, if you can't bring yourself to help then don't
waste your time responding to my posts, especially since I won't be
wasting any more of my time reading yours.
Eric