RCA Projection TV in Central Europe

[centurion]

Projection TVs are completely unknown in my country. I bought the first one a few years ago. More appeared after it. One of the most interesting and most damaged by moisture is RCA 9PC41. I've had it for several years. I recently discovered that CRT has good emissions. I started its renovation. So far everything is going smoothly. Currently, I have my first technical question regarding the high-voltage capacitor. What is the brass ring on one of the capacitor poles for?
Greetings from Poland

Adam

[ChrisW6ATV]

Welcome to Videokarma!

I wish you well with your RCA TV restoration. I do not know the function of that ring on the capacitor, but if it all fits together properly, I would not be concerned about it. Perhaps it is related to arc-suppression or noise elimination in some way.

[centurion]

I won't worry about it. A bigger problem is the average condition of the high voltage transformer. For now, I'm reviewing the entire horizontal deflection system. There are several 500pF/10kV capacitors. Some have no ring. Some have rings and they vary in diameter. I think the function of these rings is not entirely trivial. But I will check it soon - I hope.

[bandersen]

Here are some photos of mine. Maybe that will help?

[Phil]

Those are anti-corona knobs or rings. The voltage at those points is very high and so the pointy end on the doorknob capacitors they used would tend to develop corona at those points. I wish you good success. On the chassis of that type I have worked on 75% had back flybacks. They tend to run hot. It appears to me they used the same flyback they used in the 630 with the addition of extra filament windings. I would like to replace the rectifier tubes with solid state replacements to take some of the load off the transformer, but have never found a matched set of three.

[centurion]

Brass caps can actually eliminate the risk of electric arc formation. Everything has a reason. High-voltage capacitors are arranged very widely on the board to further eliminate this risk.
My horizontal deflection module is exactly as in the photo/does this set work?/. Unfortunately, the condition is much worse. This was, as I know, a universal part used in many other RCA sets. In Europe, Philips modules with different optics and an oil rectifier box were common.
I have some Russian valve equivalents, so that makes the job a little easier. E.g. 1B3GT = 1C7S.
This is my start on this forum. I think I will find help here in restoring my other US TVs. I have several models from the 1940s and early 1950s.
Thank you for your comments so far.

[bandersen]

Previous owner says it worked last he used it and it has been partially recapped. I'm in the process of restoring it and have not attempted a power up.

[Electronic M]

I've got a 648PTK I've electrically redone (still could use mirror resilvering). The HV boxes in these tend to attract dirt and look ugly, but dirt doesn't necessarily mean damaged.

I've heard of some people installing solid state tripplers from 70s US SS color sets in these for better HV....Mine worked well enough that I didn't bother with that.

[centurion]

My optical system has to spend a lot of time in the rust remover. The mirror absolutely requires a new coating. There is a lot of work.

Upgrading the EHT circuitry and semiconductor components can improve image quality, but I personally prefer to keep the old "spirit" of the device. It seems to me that yellow capacitors are enough of a novelty in a tube device. Today, the biggest problem with old TVs is probably the cathode ray tube. In my country, a few years ago, you could buy old picture tubes and valves from military warehouses from the 1960s. Today this is no longer possible. I have one Russian tube that can theoretically replace the original RCA one/5TP4/. If I successfully complete the renovation of the RCA, I will experiment with another CRT.

It will be nice to see the image on another 648PTK or RCA 9PC41

Adam

[tvdude1]

I have new 5TP4 CRTs for these sets if needed.

[centurion]

Thanks.

I sent a message.

[peter scott]

Just today I came across an early RCA projection set that I hadn't seen before.
It looks like TRK 12/120.

Peter

[centurion]

Originally Posted by peter scott

Just today I came across an early RCA projection set that I hadn't seen before.
It looks like TRK 12/120.

Peter

This photo is of average quality. The screen aspect ratio is similar to a projection TV screen, but I believe this is a "standard" TRK12. I have this model at home. I measured the mirror. Its dimensions are 51x36 cm. After opening the mirror, looking horizontally, we obtain a shape as in the photo, close to a square. For comparison, I measured the mirror of a pre-war Marconi. Its dimensions are 74x38 cm. When we observe the mirror horizontally, we definitely see a rectangle. By the way, this is an interesting difference between the pre-war US/GB production.

Adam

[peter scott]

Thanks Adam, You are correct. I was confusing the mirror for a display screen.

Peter

[Electronic M]

I've got a TRK-12 as well. I got the radio working around Christmas and decided to wait on the TV half until after I finish a 21CT55 client refurbishment project.