Successful Rebuilt of a 15GP22 at ETF

[yagosaga]

Hi folks,

on the last ETF convention, a successful rebuilt of a 15GP22 by the French company RACS was demonstrated. Who attended the presentation, how was the rebuilt done, and which problems are still to solve?

Some photos are kindly provided by old_tv_nut:

http://www.flickr.com/photos/4200284...7623940164614/

Kind regards,
Eckhard

[Steve McVoy]

Hi Eckhard,

The main difference between the successful (so far) rebuild by RACS was the use of frit glass to seal the junction between the glass and metal at the front of the tube. The rest of the rebuild was normal. So far the tube doesn't leak, and displays a nice picture. We will watch it for the next few months to see if it continues to work.

Here is a page with pictures of the original tube, the rebuilt tube, the frit glass seal, and the tube in operation:

http://www.earlytelevision.org/2010_...tion_RACS.html

Jerome Halphen is taking two of his 15Gs to RACS to be rebuilt. If they work, RACS will be ready to accept tubes for rebuilding. They have promised to provide a price for this soon.

[kx250rider]

That's VERY encouraging!!!! I hope however, that if indeed successful in the long term, we can get someone in the USA to do it. I'd hate to think of the nervous breakdown I'd suffer, mailing a 15GP22 to & from Europe. And I have the feeling that the FAA would have a problem with us buying an extra seat, and flying the tube by hand. I did that with a prewar Andrea TV (domestic flight in USA), but that was pre-9/11.

Charles

[colorfixer]

I for one am optimistic that with the frit application from RACS, the puzzle might be solved.

Something occurred to me: On the 15G' the red phosphor is much less efficient than that of the green and blue. This was corrected by driving the red gun harder to make up for the lesser light output of the original red. Since the red gun is being driven harder, it serves to reason that it would wear faster.

Since the gun is being redone as part of the rebuilding process, could the red gun be built heavier or with greater output relative to the other two, so that it lasts longer? Surely technology in electron gun construction has progressed over the last 60 odd years to allow for better lifespan and better emission. (ducking for cover)

[jr_tech]

Originally Posted by colorfixer

I for one am optimistic that with the frit application from RACS, the puzzle might be solved.

Something occurred to me: On the 15G' the red phosphor is much less efficient than that of the green and blue. This was corrected by driving the red gun harder to make up for the lesser light output of the original red. Since the red gun is being driven harder, it serves to reason that it would wear faster.

Since the gun is being redone as part of the rebuilding process, could the red gun be built heavier or with greater output relative to the other two, so that it lasts longer? Surely technology in electron gun construction has progressed over the last 60 odd years to allow for better lifespan and better emission. (ducking for cover)

Dispenser Cathode, perhaps?

http://www.semiconassociates.com/products/crt.aspx

jr

[Eric H]

Steve, in the pictures there are some blemishes in the center of the screen, is that from debris that got into the tube or is it just dirt on the screen?

[Steve K]

I know that you mean the other Steve but I can answer that. The three spots in the center are from contamination inside the tube. These spots were really not noticable when viewing something other than color bars. The rest of the spots are due to the fact that we forgot to clean the inside of the safety glass when we put the tube in!

Steve

[David Roper]

I was standing around during setup. I recall some lamentation expressed about not having taken Windex to the safety glass ahead of time. There certainly aren't any dark spots on the phosphor plate.

EDIT: Steve, that is news to me. I didn't notice it at all and am surprised nobody commented on it.

[akent36]

I think you'll find that Semicon's dispenser cathodes would cost way over $100 each in small quantities.

[jeyurkon]

Originally Posted by akent36

I think you'll find that Semicon's dispenser cathodes would cost way over $100 each in small quantities.

Considering the cost of just shipping a CRT to RACS, that might not be so unreasonable.

John

[colorfixer]

I agree, since the point is one doesn't want to rebuild this tube more than once- due to the risk of stresses on the tube, and more importantly the cost. What's another $100 if it means greater longevity and a better result.

[yagosaga]

Hello,

you have to see the 15GP before rebuilding:

http://www.earlytelevision.org/images/15G-before.jpg

This is the worst candidate of all candidates for rebuilding. It is a CRT with a broken neck, and it is absolutely incredible that this tube came back to life and that the phosphors were not damaged by oxygen of the air. Absolutely incredible!

Kind regards,
Eckhard

[jhalphen]

Good day Gentlemen,

Some of my pictures of the 15G's original condition as it was entrusted to my care exactly one year ago.

Best Regards

jhalphen

Philadelphia, PA

[jhalphen]

Hi again,

ETF 2010 Pictures, my shots.

Best Regards

jhalphen
Philadelphia, PA

PS: Any TV collectors at the Kutztown/PA Radio Meet this upcoming weekend?
I will be there & wear my ETF "dog tag".

[bgadow]

Just amazing!