RCA 21CT55 #8802897 is Dead

[ws407c]

Thank's Tom , Bob for your replies I currently have 2 CTC-16 , 1 CTC-16X and a CTC-12 , 2 of which have rebuilt tubes from Scotty and perform quite nicely . I wish to do some sort of black level clamp/ dc restore to one of them and am very curious as to how the CT-100/21ct55 performs as to black level responses. I hope to find a 21CT55 someday and will keep a constant look out for one in hopes to have one as my daily watcher.Thanks again guy's !

[Robert Grant]

Originally Posted by ws407c

Thank's Tom , Bob for your replies I currently have 2 CTC-16 , 1 CTC-16X and a CTC-12 , 2 of which have rebuilt tubes from Scotty and perform quite nicely . I wish to do some sort of black level clamp/ dc restore to one of them and am very curious as to how the CT-100/21ct55 performs as to black level responses. I hope to find a 21CT55 someday and will keep a constant look out for one in hopes to have one as my daily watcher.Thanks again guy's !

In the meantime, if you find your new 21CT55 leaves you with no room for one of the 16's, let me know

[miniman82]

Originally Posted by ws407c

I wish to do some sort of black level clamp/ dc restore to one of them and am very curious as to how the CT-100/21ct55 performs as to black level responses.

FYI, I did some research into black level resto on CTC based sets (I have a 9, a 7 and a 4). I ended up running into an old service document that said black level on those chassis was reset during every blanking period when the blanking tube went into effect. So in theory no resto should be needed, but perhaps the restoration effect of the blanker is not what it should be?

[old_tv_nut]

Originally Posted by miniman82

FYI, I did some research into black level resto on CTC based sets (I have a 9, a 7 and a 4). I ended up running into an old service document that said black level on those chassis was reset during every blanking period when the blanking tube went into effect. So in theory no resto should be needed, but perhaps the restoration effect of the blanker is not what it should be?

CTC-4 and later had only partial DC restore in the luma. All chassis had DC restore in the chroma, which is necesary to prevent the color tracking drifting in the opposite direction of the most prominent color in a scene.

In the CT-100, DC restore was done on the individual R,G, and B drives, so both luminance and chroma were DC restored.

[Tomcomm]

I have an RCA schematics book that covers all chassis from CTC2 thru CTC20. I zeroed in to each schematic and examined just the circuitry from the HOT thru the FBX to the output that the FBX drives. I was amazed at the lack of similarity of all their horizontal driver circuitry! It was like each year RCA had a contest among its engineers who could make the most circuitry changes from last year! This convinced me that hobbling in a look-a-like FBX from another RCA into my CTC2B was impractical and injurious to my or any other person's mental health. I am even more convinced that John’s approach of replicating the original FBX on his pro coil winder is the only way to go.

However, I will entertain the swapping-in of a different RCA FBX into my CTC2B as a far-out “plan B” backup. Has anyone in this forum performed this swap or knows of any successful swap on a early delta-gun, magnetic converged roundy? Also, are there any RCA CTC4 thru CTC20 FBX available out there, NOS or used, besides the CTC20 at Moyer?

[Tomcomm]

Although my only roundy is a non-functional 21CT55 and I didn't watch the Rose Parade in SD or HD I still feel compelled to comment on this year's Rose Parade screen shots. The OTA screen shots on Bob's thread so far have been mostly taken from premium CTs which conform perfectively with NTSC WB IQ standards. These roundys were undoubtedly driven at their antenna terminals with quality ATSC to NTSC converters. It seems a shame the "pure restoration dictate" precludes chassis modifications which permit direct external composite video inputs at ther first video amp inputs. How many forum members are using ext-video to evaluate their CT's ability to properly demodulate composite video and process it to the CRT without the degradation of marginal RF tuner and limited bandwidth IF amplifiers?

My CTC2B chassis is not constrained by the "restoration" consideration and has never processed the deceased NTSC RF/IF programmed inputs. It has always performed as a pure composite video monitor, driven from DVD, Laser Disk, S-video VCR, C-Band Big-Dish and 4DTV Digicypher. At the time of its flyback meltdown, I was in the process of modifying it to accept Component Video which should extended its baseband luminance and chrominance to a full 5mhz or 400 lines vs the 3.3mhz or 264 lines of NTSC Composite Video. Now if only I can get a replacement flyback that would converge as good as my original CTC2B, I can proceed.
Tom

[kwyant]

John,

I am looking for gears and cams for a George Stevens 225 winding machine, can you help? I noticed a previous post with a picture of a gear and cam assortment. I have the same picture I was wanting to know if you know of any one with any of these gears and cams? I am in the process of trying to purchase some. Let me know if you can help or know of any one with gears and cams to sell.

These are the parts I am currently looking for:

1. Driver Gear - 37
2. Driven Gear - 76
3. Cam - .75
4. Idler - 1
5. A-115-T A series driver gear
6. A-111-T A series driven gear
7. Z-.600 Z series cam
8. 1:1 idler cluster
9. A-691 wire guide arm
10. A-697 nylon wire guide wheel
Thanks, Have a Happy New Year!

Ken Wyant
Current Controls Inc.
353 South Brooklyn Avenue
Wellsville, New York 14895
Phone: 585.593.1544
Facsimile: 585.593.1713
"E" mail: [email protected]