A Confession
 

Well after working on my RCA ctc4 Seville a whole year nearly I finally got a good picture. I made a nice repro back for it and added "dressing" coats of lacquer to minimize the heavy scratches. I was ready to put it in the living room- AND THEN THE FLYBACK BEGINS ARCING. I encased it in electrical tape and 1/4" of silicone which worked well- for a few hours. Then high voltage plummeted- the arcing appears to have been merely hidden now it reads 10K ohms instead of 550 :tears:

Okay I admit I was running it at 217 milliamps current as that was as low as I could get it (high voltage about 22.5 kV) and I had no idea the RANGE was 170-220. And I know very well how impossible these are to find. BUT of all places I figured I let it be known here I'm very happy to buy a parts chassis to get one. This was/is going to be a major centerpiece and I'm willing to invest, and it will help me remember to ask here about the amperage rather than rely on the original service manual. This is a late model chassis I have currently I'm fairly certain- #2746056 and still has the original steel CRT.

No hurry-I can't make the convention this year but any leads from there too appreciated- THANKS! :sigh:

Aw man. That's such a nice set. I quite like the looks of the 21-CT-55 series. I know how it feels to finally get something working and then it goes and breaks again out of the blue. I hope you find a good flyback!

Thanks, it sat outside on a porch 1980-2008 and this was a bit hard on components.

There's no 21-CT-55 series, just one set. The 4 had different models, this is one of them. Fwiw you might be able to unwind the HV doughnut and use a tripler off the HO tube plate cap, the museum did something like that and it worked.

Darned, what a disappointment after all the work you have put into it. 217 MA might be a little high, but not excessive by any means. My 21CT55, (CTC2B) about the lowest I could get it was around 210 ma. It still works great (at least for a set that old), but I'm always afraid of leaving it on for hours, as I don't want the same thing to happen to it. Heat and humidity are killers of those RCA flybacks. Good luck in finding a replacement. Keep checking the different sites on the web, surely someone has an old chassis somewhere that has a good fly on it. It seems to me that there was someone around my area (Omaha), that had either a CTC4 or CTC5 with a necked tube that was in pretty bad shape. I'll ask my friend Jamie if he remembers anything about who has it.

I AM SO DOWN FOR THAT BLESS YOU. Will investigate, thanks.

EDIT- Can't find info on museum website though so far.


John H.

As my good friend John Folsom (aka Mr. Early Color TV) told me when I first got into this hobby......."It's all about the spares" I am sure there are people out there who probably have a good used spare, however the minute you sell your only spare, that is when you will need it to fix one of your sets.

It is a rare part indeed. Attached are photos of my NOS spare, the improved version. (probably worth it's weight in gold)

You are correct, your Seville is a "late production" set. However that does not necessarily mean that the flyback is the new improved version. The original flyback design was very problematic. Many many failures. That prompted RCA to redesign the flyback and the replacement was far more reliable. The original version flyback was stock #100409 and it will have the RCA drawing number 1106237-1 stamped on the frame in black ink letters in the same place you see in the photo.

The improved flyback is stock #101959A and will have the RCA drawing #1106237-2 as shown in the photo of my spare.

I have discovered over the years, that you need to buy backup sets that are in poor condition, so that you will have a source of spare parts for the sets that are worth saving. I do not subscribe to the notion that ALL sets should be saved. If a set is a POS then use it for parts and canabalize it so that a nice quality, or rare set, may live again.

Your Seville is a rather common variety 4. Spend some money and buy a high end 4 (Director model or better) and keep the chassis from the Seville as a parts set. That may be the only way you will find a replacement flyback. You can then keep or sell off various parts from the Seville as you desire.

I just finished restoring a CTC4B chassis that is going into my Cheltenham. The HOT current draw on this properly restored chassis is running a cool 175ma, so this is not an impossible current specification.

I truly feel your pain. It has happened to most of us at one time or another. All is not lost, there is always hope that you may get lucky and find a replacement, however it may take quite some time and more than a little luck. Perseverance is the key. Hang in there and just keep looking. Eventually you may find a parts chassis and if lucky it will have a good flyback. Unfortunately the flyback is the first part to be canabilized. That's why I say you should set your sights on another complete set, preferably a Director or better.

That's one good looking TV though. The other day I was reading an old thread where someone had a flyback failure in a 21CT55 and managed to fix it somehow. Maybe the same procedure (whatever it was) could be used on this CTC4. Of course now I don't remember whose thread that was. It was whoever owns the 21CT55 with the hacked up cabinet. Maybe read through that old thread. Sorry I don't have a link.

Also, you could get lucky and find the problem is very close to the outside layers of the HV winding. If it is near the outer diameter, you could unwind a few outer layers till you get to the defect, and just re-coat with wax and use the flyback with a few less turns on the HV winding. You would have a bit less HV at the crt, but it's worth a try if the defect isn't too far in from the outside. You could probably remove 10% of the turns and still have enough HV to operate. I think you would still be able to operate at 20KV. Cross your fingers and hope you find the defect very near the outer edge.

I have been able over the years to resurrect bad flybacks. You will generally find the insulation has cracked or else the is a carbon track across the insulation.

I would ascertain where the arc is by examining the flyback when briefly plugging in the set. That is if the carbon track is not immediately obvious. You could then remove the flyback and give it a thorough investigation. You most likely can remove the carbon track and then seal it with glyptol or silicon and it will as good as new.

Nothing is lost trying and there is a lot to gain.

Two ways to think about that mentality. One is I'll hoard everything I can find and never sell anything so that IF I come across something that needs parts I, and I alone, will have the spare parts I need. My island will be full of the fruits of my hoarding, but I will be alone on it. The other way to look at it is if I have a spare part you need and I don't then I sell it to you. Murphy's law dictates that yes I'll need that part minutes after I let it go, but such is life. My island becomes not so full of shiny things, but full of other people and we all benefit. I love that this hobby is full of people who think closer to the latter than the former. Everyone is free to keep and share whatever they feel fit and I'm not advocating antique television socialism, but good for those people that do let (some) precious parts go to others.

while not a color set it give the idea of the tripler
this is me messing with a BW tv:

https://www.youtube.com/watch?v=li-kxlpA0mU

this guy has lots of great videos on flybacks:

https://www.youtube.com/watch?v=tVK2ZoiT9uA

Don't give up too fast on the one you have

Myself I have found spare parts in reserve act as a talisman where you'll never need them :) Seriously though I have always relied upon the kindness of strangers.....

John H.

Me too.

John,

I am sure you have life insurance to care for your new baby in the event of your demise. Having spare parts is a form of insurance against decreased value of an operationally restored collection losing significant value when a rare part goes bad. This is not about hoarding, it's about a type of "insurance" we choose to have in order to feel comfortable. Some collectors are happy to just look at non-operation sets. Others of us want our sets to actually work, (it's about the WOW factor that occurs when non collectors see our collections). But there is very high risk in turning on a set that could go poof at any moment. So we try to have "insurance" against the heartbreak that is sure to come sooner or later. Some parts are easy to get, some are total "unobtanium" and others are just so rare that the only way to get one is to buy an entire set just to get one part you need.

As for me, I am in the middle. I both share, and retain of my parts spares, as most all of us do. Last month alone a Porthole fly and a Moto Yoke. Your implication that there are "hoarders" among us who never share anything, is rather insulting. I don't know anyone in this hobby who is that selfish.

In the end when a collector dies and passes on his estate, there will be an opportunity for everyone to share in the "insurance parts" the deceased collector saved for us. "All things must pass" George Harrison

In the meantime there will be those who have and those who do not. That is just the way life is. We all covet stuff that we don't have, that doesn't mean the people that have those things are bad or selfish, it means they are successful in their endeavor. And when success becomes looked down upon, we end up with Socialism.

Yep. The same rings true for any kind of collectable device. I collect 35mm and 70mm film prints. When the movie theaters started converting to digital projection at a rapid pace about 3-4 years ago I ended up picking up many of the same model projector that were headed for scrap metal recycling. There's really not much that can go wrong with a projector head short of gears wearing out over time and the intermittent movement wearing out and failing. Once that happens, the machine is useless. While finding a company that can machine gears is not terribly difficult, there are really no longer any companies left that have the tooling and expertise to manufacture parts and rebuild an intermittent. Hopefully the 4 intermittents I have will last the rest of my life.

I don't think any one of us is 100% on the side of either of the two extreme examples I gave. I am certainly not suggesting that anyone should be looked down upon because they choose not to give things away at will. As I said in my last post "anyone is free to keep or share anything they see fit." There are things in my collection that I'm not offering up for grabs! What I am saying is that the more people we have in this hobby the better for all of us. I don't think I would be a tv collector if it weren't for the generosity of this community. When we let porthole fly's, Moto yokes, and spare 15GP22s go to others we keep people collecting and that infects others. Just this week I let go of another rare picture tube to another young collector because he needed it for a family set. This was no only my only spare, but it left me with a broken CRT in my set. Someday a 7EP4 will come around again and maybe then I'll have one to replace mine. In the meantime another collector will have the joy of watching a set that means a lot to him, and that means a lot to me to help him.

Sorry to go so off-topic. Moderators edit if you see fit.

Well I have known more than one radio collector anyway who has let $100K or more of incredibly rare sets molder to dust in leaky sheds and tents being unable to get highest eBay value for them. This is nothing that benefits people or is a matter of selfish there, it simply is a way some people think really. OTOH I've had dozens of near strangers help me and I have returned the favor as I can.

I certainly have no intention of giving up on it before 2026 anyway.

John H.

I did a partial trade for my CT-100 with good 15GP22 this week. Why? Partially because I was rather ambivalent toward totally restoring it, partially because a potential move overseas would be complicated by a CT-100, but mostly because the individual that wound up with my set is hellbent on getting his 15G based set operational.

I also traded away a 1955 Hoffman Colorcaster. Why? Because the other collector seemed to like it more than I did, and he had something he was looking to get rid of that I wanted.

In both of these trades, the other collectors and I walked away very happy. I can't think of anything better than that. I would rather be known for my generosity and willingness to help others when I can, than hoard sets and have them rot in my basement. I have found in my few short years in this hobby that my approach has paid off for me numerous times. To each his own I guess...

Hey wait a minute, I think I do that :scratch2:

Mine live in the basement too, but it's a finished basement so they rot a little slower :stupid:

So did you watch the videos? The key is to not watch a set until catches fire. As soon as arcing is happening that is the time when you still have a chance to fix the FLY. Based on your resistance readings you may be too far gone but there is no reason not to investigate.

So why not make an adapter socket, and substitute a common 7JP4? :scratch2:

jr

In general, a 7JP4 won't sub all that well for a 7EP4, the difference in HV is too great. The 7EP4 needs about 2 or 3 kV, a 7JP4 is around 6 kV I think. A 5BP4 is a better sub, being electrically identical, despite the smaller screen, and actually cheaper than a 7JP4. A 7GP4 would probably work though...

I'm a stickler for originality. I've seen 2 7EP4's for sale in 5 years so another one is due to come up in 3 years or so.

I watched every video containing the word flyback on YouTube before even beginning to restore the set. I repeatedly followed the instructions given- encasing the flyback in non-acidic silicone twice. It suppressed the arcing but not internally.

John H.

Indeed, that was when the idea of using the hot wax and the vaccum to draw the moisture out before encapsulating it come up.

I think another option would be to use low heat and a desiccant to further draw the moisture out, although I think Shango's hot wax is the best.

I suggest you remove the silicone and examine the paper windings. When you orig did the silicone did you note any black marks showing burns on the paper insulator?

On my CTC-4 the wax on the fly was fine so I never touched it of added any silicone, but I was careful to have the H osc., and drive good before connecting the output tube to the fly...Once I did I IMMEDIATELY adjusted the linearity control for minimum cathode current.

IHMO using silicone and such on a fly is something you keep in your back pocket till it appears to be needed.

Slightly off topic but still relevant, an experienced RCA technician once told me that when you power up a TV for the first time, you want to let it run in short increments. 5 or 10 minutes at a time, then 20 to 30 minutes at a time. This will help to slowly cook out the moisture content in the flyback. It's a much better than turning the set on and leaving it on and all the moisture causes the flyback to arc and stuff.

I think that paragraph just about blew my mind... you have the ability to project 35 and 70MM FILM at HOME!? WOW! I thought that hobby was for eccentric millionaires :)

in the hot wax video you can hear my commentary about running a low voltage DC current to cook out on a really hard to find (like a CT-100 fly) and or doing the desiccant low heat alternatives. On flys that are not as hard to find I just tend to leave them be unless there is a problem. The idea of short term use makes since, both the internal heat and heat from tubes would be good. However if there is a chance the set has seen high humidity (which is always a chance since we rarely know the complete history) then I think at a minimum the FLY should be cooked slowly (FLY jerky) to dry it out before use and restraint on sealing it up least the moisture be trapped.

I hope the OP will open it up and see if he can find a carbon trace, there is still a chance the fly can be salvaged. If not the quadrupler (pretty sure you would need that vs a tripler) may work.

I absolutely will be closely examining and unwinding the flyback as possible. Details on how the quadrupler mod works though would be appreciated- not exactly sure where the last few turns of the old HV donut (with the taps) gets connected.

John H.

Here's the thread on ETF detailing the tripler: http://earlytelevision.org/hoffman_c...storation.html

I believe he just connected it to the output tube plate cap, but you might ask Steve himself since he's the who did it. He pops in from time to time.

Another thought: if the transformer defect is part way in the donut, you might be able
to stop unwinding there and use a doubler rather then tripler of quadrupler.

I suggested a quadrupler yesterday to somebody over at vrat across the pond.
I should check to see their response.

Definitely look into the tripler approach. My CT-100 is running that way, since mine came with a bad flyback and I was not able to find a source for a replacement. See here:

http://videokarma.org/showthread.php?t=260010

Basically, you remove enough of the HV winding to eliminate any possible shorts or arcs (also OK to simply completely remove it), and the tripler connects to the top of the primary of the flyback -- same place as where the anode of the horizontal output tube connects. You need to keep the flyback connected, since it supplies current to the yoke, etc. The tripler takes care of the actual HV generation.

You may find the tripler actually works a little better than a real flyback supply. HV stability may be a bit better, for better focus stability, etc.

I have been depressed about this but this has cheered me immensely, thanks to everyone! By June I should have this working.

But am I correct that the non-shorted remainder of the original flyback high voltage donut is left entirely out of circuit? Thanks.

John H.

"You may find the tripler actually works a little better than a real flyback supply. HV stability may be a bit better, for better focus stability, etc. "

For those who would accept a bit of non-originality, tucked away, there
is a simple cheap, effective panacea for focus instability: Zener diodes.
Just install a long chain of 200V Zeners from the focus pot down to ground.
I did this and it works great. I measured the correct focus voltage and
set the total Zener voltage so that the focus control was about 1/4 or 1/3 of
the way up from the bottom.

I don't want to derail the OP's thread too much so I'll keep it brief. Yes it's not only possible to collect and project 35 and 70, it isn't as expensive as you think if you are patient and have good contacts. It took me a long time to work up to the 70mm however. I mostly bought prints in the 90's from a now defunct classified ad magazine called "The Big Reel". Prints averaged from $150-$350 usually back then. I bought a WWII era "portable" 35mm projector and could only run one 20 minute reel at a time. In 2008 I acquired my first dual gauge 35mm/70mm machine and started accumulating the sound processors for the different kinds of audio tracks. That machine also allowed me to use large enough reels to hold an hour of film so only one re-thread per show. Now I have a full blown system with platters and and everything but my print collecting days are pretty much done and I sit on my 45 or so titles I've kept. The magazine is gone, and what titles get put on ebay are being "panic bought" by film archives and "eccentric millionaires" Just last week a print of Raiders of the Lost Ark got bid up to $4585. Ridiculous. That used to be a $350-$500 title not too long ago. Maybe I'll make a thread on the subject in another subforum.

tip
 

This Tech Tip from Worked for me years ago, could be a new idea for you, I am not sure what set that I tried it on its been awhile
I have problems with windows 10 and this site, I try and rotate but it still loads sideways

Hi!

Sorry, but in my opinion the best way would be rewinding the donut. Has anybody ever tried that or finding a company who is able to do so. If not what are the reasons?
O.k. the diameter of the wire is real thin but on the other hand if it was possible winding a HV coil 60 years ago it should still be possible today- or am I wrong?

Greetings Josef