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-   -   Restoring a RCA 21CT55 (http://www.videokarma.org/showthread.php?t=268390)

etype2 01-21-2017 12:57 PM

Restoring a RCA 21CT55
 
https://visions4netjournal.files.wor...2/img_2449.jpg

Well over a year ago, we purchased a 21CT55 from the Early Television Foundation. It has been a long haul, 470 days and the restoration is completed.

Steve McVoy, Dave May, Bob Galanter, Kevin and Mike Doyle (edit: I left out Walter) all members of this forum helped with the restoration. I want to thank them very much. It could not be done without your help.

You can see screenshots along with a chronological accounting of the restoration from day one at this link:

https://visions4netjournal.com/vinta...p-carousel-967

Moderators, apologies for the large screenshot. Can you reduce the size?

walterbeers 01-21-2017 02:40 PM

Very good job. Looked at the pictures on the visions link, and the color is great. I have a 21CT55 also that I restored, and is working as well.

etype2 01-21-2017 02:52 PM

Thanks Walter. I forgot to acknowledge you. You also helped me isolate the power switch problem.

I followed your 21CT55 restoration thread. Was inspired.

jr_tech 01-21-2017 03:25 PM

Wow! Wonderful restoration and documentation of the restoration of one of the very most desirable of the milestone color sets!

jr

walterbeers 01-22-2017 04:37 PM

Out of curiosity what was the problem with the power switch. If I remember right we chatted online and you said it was dead completely. I suggested the power switch and some of the places you could check it out without pulling the chassis. Was it the switch itself as I suspected? If so did you find a replacement switch with volume control? Also is your cabinet the original finish? Looks really good in your first photo. Mine was really sun faded, (especially the top and one side), so I finished it with Minwax stain. I really should have had the cabinet professionally refinished, but was afraid to remove the 21AXP22 as I didn't want it to go to air. Sanding and stripping the cabinet (with the CRT in place) also felt very risky because of the vibration if I had left the CRT in the cabinet. Maybe someday I'l be brave enough to remove the CRT and take the cabinet to a pro refinisher.

Tomcomm 01-22-2017 05:29 PM

Welcome to the 21CT55 club. I would like to see some full screen size, screen capture shots. I assume your included screen shots were thru the full RF/IF systems, right? It would be interesting if you could compare them with your computer monitor screen shots. Seems you have some color aliasing contamination in the small detail. Looking forward to your further screen shots.

etype2 01-22-2017 05:41 PM

Walter,

You were right, it was the power switch that failed. We found out the switch was a replacement sometime in the set's history. It was incapable of handeliing the high current on power up. The switch had a 3 amp rating but the transformer was drawing higher current. Mike suggested we install a relay to draw the current and lessen the load on the switch which was replaced to the correct value. This was done to preserve the switch for long life. I'm so glad we did because the room light dims briefly on power up. The brightness control and volume control which were integrated with the power switch were retained.

The cabinet was in good shape. There was one scratch on the side which was touched up without refinishing the entire cabinet. The safety glass was removed and the CRT and glass were cleaned. I share your concern and the CRT was never removed during the restoration.

I need to refinish the brass around the safety glass. I don't want to remove the glass if possible. Do you know of a good product I can use to remove the patina? I tried Brasso and it had no effect.

etype2 01-22-2017 05:54 PM

Quote:

Originally Posted by Tomcomm (Post 3177080)
Welcome to the 21CT55 club. I would like to see some full screen size, screen capture shots. I assume your included screen shots were thru the full RF/IF systems, right? It would be interesting if you could compare them with your computer monitor screen shots. Seems you have some color analysis contamination in the small detail. Looking forward to your further screen shots.

Tom,

In the link I provided, (within the image carasel) you can click on a tab to see the full resolution shots. I used a non-pro camera, an iPhone 6 Plus to capture the shots. The signal was OTA converted to analogue with a converter box. I'm still planning to adjust a bit more and create a video. I followed your treads on the 21CT55 and that CRT produces about the best color CRT screenshots I've seen from an old "roundie". The original CRT (21CT55) was replaced with a newer tube, right?

etype2 01-22-2017 05:55 PM

Quote:

Originally Posted by jr_tech (Post 3177027)
Wow! Wonderful restoration and documentation of the restoration of one of the very most desirable of the milestone color sets!

jr

Thank you very much JR. :-)

Electronic M 01-22-2017 09:16 PM

Quote:

Originally Posted by etype2 (Post 3177081)
I need to refinish the brass around the safety glass. I don't want to remove the glass if possible. Do you know of a good product I can use to remove the patina? I tried Brasso and it had no effect.

That is odd...The same trim was used on the CTC-4, and I polished that trim on my CTC-4 with brasso. Did you forget to shake the bottle before using or forget to scrub?...I had to scrub mine vigorously with a discarded toothbrush to polish the tarnish off.

etype2 01-22-2017 10:23 PM

Quote:

Originally Posted by Electronic M (Post 3177094)
That is odd...The same trim was used on the CTC-4, and I polished that trim on my CTC-4 with brasso. Did you forget to shake the bottle before using or forget to scrub?...I had to scrub mine vigorously with a discarded toothbrush to polish the tarnish off.

I tried with a soft cloth. I good try your meathod or maybe a Dremel tool with fine sandpaper, then seal with varnish?

ohohyodafarted 01-23-2017 12:36 AM

Quote:

Originally Posted by etype2 (Post 3177096)
I tried with a soft cloth. I good try your meathod or maybe a Dremel tool with fine sandpaper, then seal with varnish?

The only way to get good results refinishing the brass is to remove the trim and work at it with successively finer grades of steel wool or scotch bright. The brass has a lacquer coating, that was sprayed on at the factory. Brasso will not do anything unless the brass is bare naked. Then Brasso can remove the tarnish. If you try to remove the lacquer coating using Brasso and a soft cloth, you will be expending many needless hours of labor

Removing the brass trim is easy. Behind the crt bezel you will find tensioning clips that hold the trim in place. Remove all the clips that hold the trim tabs in place. Then you can push the trim tabs forward, through the crt bezel and the trim frame can be easily removed.

If you try and clean the trim with Brasso with the trim in place, you will end up with Brasso in all the crevasses, and then there is still the problem of having to apply a new coat of clear lacquer to prevent future tarnish. No, varnish is not the correct product to use.

Click on the "Brass Refinishing" link under "MY Methods" section at my web site or click below

http://antiquetvguy.com/WebPages/MyM...finishing.html

etype2 01-23-2017 02:42 AM

Bob,
I found out quickly about the Brasso getting in crevices as well as a soft cloth not working. Thank you for the suggestions.

Kirk 01-23-2017 08:50 PM

Great Job! Went to your website and saw the pictures....I just started working on my 21CT55 again....you cant beat seeing Spock on a 21AX!

benman94 01-24-2017 02:11 PM

etype2,
You might consider Bob's method of removing the old lacquer, but instead of using Brasso to polish the brass, use MAAS polish. I do brass instrument repair and restoration (I specialize in higher end pre-war Conns) and MAAS is the polish I always use before either silver plating or hitting the horn with new nitrocellulose lacquer.


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