Vladimir Zworkin's 21CT55 Restored and On Display

[Electronic M]

Originally Posted by Kirk

I have the one they built to plug in where the ballast tube goes- its the same circuit as the one that is "built in" to the 21CT55 that we have running. It came with a hand-drawn schematic, done by David Neegard, the 87 year-old Engineer from RCA.

I will dig it all out and hook it up to a working CT-100 chassis that I currently have on the Test Jig.

Once I know it's OK, I would be happy to share the info with whoever wants it.

Stay Tuned!

Kirk

Thank you.

Originally Posted by Penthode

How much is your supply varying? Do you have aluminum house wiring?

If your supply varies so much that you need a regulating transformer, maybe you should contact your electricity utility.

It's probably more than 10V throughout the year (sometimes throughout the day) but the main reason for the voltage regulating transformer is voltage dips. There's a big industrial park about 3 blocks away. When we moved in several times a minute the grid would have sharp instantaneous dips (reminded me of welding) that would cause SUBSTANTIAL blooming in all my tube era TVs. I used to think something was wrong with my sets until I ran 3 sets at once and watched them bloom in sync with each other.
It's not as bad as 10 years ago, but on 4 figure sets with unobtainium flybacks that the H output cathode current is very sensitive to B+ variations caused by line voltage changes I 1.) don't want to risk damage, 2.) don't want distracting Blooming.

I think it's all copper, but everything is backstabber (which is kind of trash IMO), and this is a 1970s Belinski home (the home inspector had some choice words for some of the non-electrical construction choices to give you an idea of their standard level of craftsman ship here) and it went through a significant change order mid-build, and the previous owner was a small engine mechanic that modified some stuff. I don't own the place so I don't have a say in the matter. At least if it burns down it's more likely to be mice chewing the wiring than what's here.