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Maxim these days is 'takes a high school education to fix it, college education to break it.'
lol
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Evolution... |
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Last edited by andy; 12-07-2021 at 01:32 PM. |
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I don't know what the core is for the RCA John Folsom is rewinding, but if it's ferrite, MO=Fe2O3 or the ilk, the ferrite has a high electrical resistivity and shouldn't suffer that type of failure. John |
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Last edited by andy; 12-07-2021 at 01:32 PM. |
Audiokarma |
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Powdered iron I can believe. It would be pretty strange for ferrite to change that much. Not that strange things don't happen.
However, I was surprised to see the large range of conductivity for various ferrites spanning six orders of magnitude. This table gives the properties and normal uses for ferrites and powdered iron. http://www.ferroxcube.com/prod/assets/sfmatgra_frnt.pdf John |
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I don't think the ferrite cores on these vintage flybacks suffer from any changes in electrical resistance with heat. I believe they were fired like a ceramic, though maybe not at that extreme of temperature. Their only weakness, literally, is their brittleness.
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John Folsom |
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RCA 21CT55 #8802897 is Dead
Hi Tom , If you were to sell your 21ct55 how much would you ask for it ? I am looking for one of these sets in any condition and am looking to get an idea how much I might have to spend if one comes across my path. Thank's , Dave
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What are 21CT55s Selling For?
Dave..........I assume you know the condition of mine from reading this thread? There is no cabinet so its value is strictly as a laboratory test bed for various "experimentation". Presently I"m using the CTC2B chassis to determine what's involved in making it accept Component 400 line video in addition to its present standard 270 line Composite video. This is the only roundy I have. I have no intention to ever sell it. I would suggest you inquire of VK members Steve Kissihger or Bob Galanter or John Folsom what they paid for theirs or what they think a 21CT55 should go for. Lotsa luck...........Tom
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I paid
My 21ct55 was a steal at $975. I got very very lucky on this purchase. It had a very dead 21axp22. The crt was the original and was from what we believe was probably the first production run of 21axp22's. They used a 20 pin stem left over from production of the 15gp22's, to mount the electron gun assembly. I had the crt rebuilt at a cost of $500. Later the flyback took a crap and I was lucky that my best buddy John had a spare for me. Cabinette needed to be refinished too.
But based on the rarity of this set, I would probably say it is worth more than a working ct100 with a good crt. But that is only my opinion. I think that CT55's are vastly under appreciated. Everyone wants a ct100, of which there are many more. I think there are only about 8 or so CT55's known to exist. Steve Kissinger paid more for his. But his was in better condition. FYI: last year I acquired a 1st generation 21" Sylvania color set. Upon close inspection I discovered that it uses the same flyback as the 21ct55. Both sets were produced at about the same time. And both sets are equally rare.
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Vacuum tubes are used in Wisconsin to help heat your house. New Web Site under developement ME http://AntiqueTvGuy.com |
Audiokarma |
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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 !
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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?
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Ken, email sent. Long and short, I do not have any spare parts. George Stevens Co. still has some gears and cams available, but they are expensive. The gears for the machine are non-standard, so are not available from the usual gear sources.
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John Folsom |
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First Signs of Life
Just finished installing the new FBX sub-chassis circuitry into the CTC2B chassis. No dynamic conversion, chroma keyer, color killer, chroma blanker pulses from the FDX are connected. Focus out of range, linearity, screens, gray tracking not adjusted.
Power input is 115vac, B++ adjusted for 378v producing 860v boost, Ultor is adjusted at min of 28kv, max is well over 36kv! HOT cathode reads 128ma. The big ultor voltage with a tiny HOT current indicates I need a HOT that matches this new FBX, namely a 6JE6A replacing the original 6CB5? I have to order one and its socket & cap. The premature screen shots indicate I’ve got a long ways to go on this one to approach this 21CT55's previous posted shots. Last edited by Tomcomm; 01-12-2011 at 05:42 PM. |
Audiokarma |
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