On 2019/08/23 8:44 a.m., wrote:
On Fri, 23 Aug 2019 05:01:33 -0700 (PDT), John-Del
wrote:

On Wednesday, August 21, 2019 at 7:47:11 PM UTC-4, 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.
The CRT I am using is a Russian 5LO38i. The Heater voltage for this
CRT is 5.7 to 6.9 volts and I measure only 5.1 volts.
I'm not sure how the voltage for the heater or how any of the other
voltages might affect the sharpness.
The specs for the Russian CRT has the first anode voltage at 550
volts max and the second anode voltage max at 1100 volts max. But I
measure only 250 volts for each. Could this be why the focus is not
even?
Anyway, thanks for any help.
Eric


In theory, voltages shouldn't have any affect on the focus across the face of the CRT, but in practice, all sorts of variables happen.

It's indeed possible that your problem will go away if you get the CRT close to it's designed operating voltages. At least, that's what I would do before condemning the CRT as defective.

Is there a schematic of what you built on line?
No, there is no schematic. Paul Drahn suggested to me that the CRT may
need to be degaussed. I have a demagnetizer designed for demagnetizing
tools. I'm sure it would work to degauss a CRT.
Eric


A Weller heavy duty soldering gun is also useful as a small degaussing
tool if you don't have a proper open coil one handy.

John :-#)#

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