CRT Rebuilding in Poland - Videokarma.org TV - Video

AlekZ · #1 11-15-2020, 03:18 PM

Hello everybody,

This is my first post on this forum.
I have been collecting CRT repair equipment and materials for some time.
I also saved a lot of literature that was thrown away at my job. For now, I practice on damaged small CRT's (up to ca. 10''). For now, the procedures are somewhat simplified. I do not use screen metallization, but I can make a damaged screen by sedimentation.

Some of the tests (not all) are described in Polish:

https://www.youtube.com/watch?v=Df8RT4BM6U0
http://www.pwl.mikrokontroler.pl/tv_...rt_regen_e.htm

I can try to translate my descriptions into English if anyone is interested.

Recently I've been trying to build my own electron guns. I am particularly interested in electon guns with an ion trap. The additional product of these attempts is the construction of a home- made monoscope

:

http://www.pwl.mikrokontroler.pl//tv...p/monoskop.htm

Best wishes,

Alek

old_tv_nut · #2 11-15-2020, 05:06 PM

Very interesting. Welcome to VK!

Electronic M · #3 11-15-2020, 11:19 PM

Welcome.

It looks like you're doing well at rebuilding.

If you start taking on work replacing depleted cathodes in early color CRTs like the 21FBP22 and 21AXP22 I (and many others) could probably give you some business as I have been stockpiling examples with worn out cathodes.

AlekZ · #4 11-16-2020, 01:24 AM

Thank you for your nice replies.
These color CRTs are unknown in Poland. Our color television started practically in the 1970s. First, we imported color cathode ray tubes from the USSR, then we launched a factory (Unitra Polkolor) under the RCA license in Piaseczno near Warsaw. I was lucky enough to be at this factory in 2007, not long before it closed.

It is not my goal to compete with the US project (Early Television Foundation CRT Rebuilding Project).

Let's talk about the technical side of this issue.

As I can see, the 21FBP22 and 21AXP22 are CRTs with a delta electron gun.
I tried to search the internet for photos of the electron guns of these CRTs, but I can't see the construction well. If it is possible to remove the cathode without destroying the Wehnelt electrode cup and the "sticks" holding the electron gun, then I think it is possible to repair such cathodes. In some Polish black and white picture tubes the cathode can be easily removed.

After removing the cathode, it will be necessary to remove (mechanically and chemically) the old layer of hydrated (after air entrainment) barium, calcium and strontium oxides from the cathode surface and apply a new layer. For the lack of any other option, not by spraying, but by careful painting. I have recipes for emission pastes. I have practically tried some of them and they are good. Unfortunately, activating such a cathode may be more difficult than activating a completely new one. This is because the old cathode nickel core may have fewer reducing impurities.

The cathode filament will also be replaced. The manufacturing technology of filaments is quite difficult (cataphoresis, hydrogen sintering, etc.). I've done some trials on this topic and the results are encouraging. When making a heater, it would be nice to know its length and diameter of the tungsten wire, so as not to do a lot of painstaking experiments. I think that making whole mechanical parts (cathode cups, Wehnelt electrode cups, etc.) would be too expensive. Parts from damaged electron guns must be used.

Electronic M · #5 11-16-2020, 05:17 PM

If you wanted to start rebuilding CRTs as a business I don't think anyone would be bothered including the ETF.

The ETF has been accumulating CRT rebuilding equipment for over a decade and have been trying to get rebuilding going for over 6 years IIRC. Their main issue is there is nobody that lives local to the museum willing to learn and do the work... They did have Nick Williams (he goes by miniman82 on Videokarma) who learned the process and was going to move to Ohio and run the effort at the museum, but in the last few years he bought his own rebuilding equipment and IIRC indicated he was going to rebuild CRTs himself independent of and in competition with the museum.

Many collectors I have spoken with don't expect the ETF to ever offer a rebuilding service to collectors. Most of those collectors also wish they could pay someone to rebuild their CRTs. As far as I have seen if a viable rebuilding service becomes available it will have collector support and patronage regardless of who owns the service. Collectors were sending CRTs to (now closed) RACS in France to be rebuilt after the last American rebuilder retired.

bgadow · #6 11-18-2020, 08:48 PM

I have a gun assembly from a 21FJP22 which was "necked". I've been saving it just for a conversation piece. If it were to do you any good for experimentation I could ship it to you.

AlekZ · #7 11-19-2020, 12:59 AM

That's a good idea. I could compare the construction of this electron gun with the Soviet ones and think carefully about how to replace the cathode and heater.

AlekZ · #8 10-17-2021, 03:05 PM

I am currently building several instruments. Here is a vertical glass lathe that will repair 14 '' and 17 '' picture tubes.

AlanInSitges · #9 10-18-2021, 01:06 PM

What a cool project. I wish you lots of luck with this! I think if you can get to the point of rebuilding 15GP22 and 21xxP22 tubes you would have your hands full.

AlekZ · #10 10-19-2021, 11:23 AM

These color picture tubes do not exist in Poland. Our color television started late, around 1970. The color picture tubes we use are the Soviet 59LK3C, 61LK4C. At the end of the 1970s, we started to produce the A56-701X picture tube under the RCA license.

For now, my work is focused on the regeneration of black and white picture tubes, for the earliest TV sets that were in Poland. The cathode-ray tubes used there were the Soviet 31LK2B, 35LK2B and the Polish 35MK1, 35MK21, 35MK22, AW36-80, AW43-80 and the like. For training purposes, I try on much newer 20mm cathode ray tubes, similar to the A31-310W.

jhalphen · #11 11-28-2021, 05:48 AM

Hi to all,

@AlekZ: you might be interested to see the "photo report" i did on CRT rebuilding at RACS/France circa 2012. Every major step of the process is described.
RACS re-screened & aluminized every CRT except if the customer did not want it.
In the case of some Pre-War CRTs with low EHT (5/6KV) aluminization would reduce brightness too much.

https://app.photobucket.com/u/jhalph...b-ded825d8e562

Best Regards
jhalphen
Paris/France

AlekZ · #12 11-30-2021, 04:26 PM

jhalphen

Thanks for interesting pictures!

Josef · #13 01-03-2022, 01:52 PM

Hi AlekZ,

your project sounds very interesting for German and Austrian collectors an many others too I guess

If you plan setting up a business I suggest not only to rebuild CRTs but als eye tubes. A new or like new EM34 can easily bring between 50 and 100€.
Anyway keep us informed.
If you rebuild a AW43-80 you should also be able to rebuild

https://www.radiomuseum.org/tubes/tube_mw43-64.html

or the even rarer

https://www.radiomuseum.org/tubes/tube_mw53-20.html

what should be a nice business or at least keeping our hobby alive

Good luck and all the best from Austria

AlekZ · #14 01-08-2022, 04:29 PM

Thank you for your nice post. There will be a lot of water in the Vistula before I get enough practice... . Besides, I suspect that not every repair will be successful. You have to take into account that there may be a leak in the anode lead (I've seen such cases) or the glass may break due to stress. I advise everyone not to throw away damaged picture tubes as long as the screen cone with the piece of neck is intact. There may still be a chance for such CRTs. Let's save old picture tubes!
Currently I am working on the topic of phosphor P4 (white). Perhaps I will try to make it myself. Below are some test photos of the various phosphors I have.

Josef · #15 01-26-2022, 01:29 PM

Quote:

Originally Posted by AlekZ

Thank you for your nice post. There will be a lot of water in the Vistula before I get enough practice... . Besides, I suspect that not every repair will be successful. You have to take into account that there may be a leak in the anode lead (I've seen such cases) or the glass may break due to stress. I advise everyone not to throw away damaged picture tubes as long as the screen cone with the piece of neck is intact. There may still be a chance for such CRTs. Let's save old picture tubes!
Currently I am working on the topic of phosphor P4 (white). Perhaps I will try to make it myself. Below are some test photos of the various phosphors I have.

I fully agree and I'm also going to forward this thread to the Austrian collectors community. Of course I cannot promise anything but the more interested people know about you and your ambitions, the bigger the chances are being successful and save old CRTs