View Full Version : A Confession


Hagstar
04-18-2016, 09:39 PM
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:

TUD1
04-18-2016, 09:48 PM
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!

Hagstar
04-18-2016, 10:04 PM
Thanks, it sat outside on a porch 1980-2008 and this was a bit hard on components.

miniman82
04-18-2016, 10:12 PM
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.

walterbeers
04-18-2016, 10:14 PM
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.

Hagstar
04-18-2016, 10:21 PM
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.

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

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


John H.

ohohyodafarted
04-18-2016, 11:29 PM
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.

matt99
04-19-2016, 12:24 AM
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.

ohohyodafarted
04-19-2016, 01:50 AM
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.

Penthode
04-19-2016, 02:38 AM
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.

vts1134
04-19-2016, 08:15 AM
...the minute you sell your only spare, that is when you will need it to fix one of your sets...

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.

DaveWM
04-19-2016, 08:49 AM
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

Hagstar
04-19-2016, 08:52 AM
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.

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.

vts1134
04-19-2016, 09:40 AM
...I have always relied upon the kindness of strangers.....

John H.

Me too.

ohohyodafarted
04-19-2016, 12:23 PM
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.

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.

sweitzel
04-19-2016, 01:11 PM
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.

vts1134
04-19-2016, 01:52 PM
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.

Hagstar
04-19-2016, 01:56 PM
J . 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.


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.

benman94
04-19-2016, 02:10 PM
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...

vts1134
04-19-2016, 02:23 PM
... hoard sets and have them rot in my basement...

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

benman94
04-19-2016, 02:25 PM
Mine live in the basement too, but it's a finished basement so they rot a little slower :stupid:

DaveWM
04-19-2016, 02:25 PM
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.

jr_tech
04-19-2016, 02:55 PM
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.


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

jr

benman94
04-19-2016, 03:02 PM
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...

vts1134
04-19-2016, 03:05 PM
So why not make an adapter socket, and substitute a common 7JP4? :scratch2:

jr

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.

Hagstar
04-19-2016, 04:49 PM
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.


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.

DaveWM
04-19-2016, 05:07 PM
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?

Electronic M
04-19-2016, 05:33 PM
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.

TUD1
04-19-2016, 06:28 PM
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.

maxhifi
04-19-2016, 06:59 PM
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 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 :)

DaveWM
04-19-2016, 07:02 PM
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.

Hagstar
04-19-2016, 08:57 PM
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.

miniman82
04-20-2016, 08:54 AM
Here's the thread on ETF detailing the tripler: http://earlytelevision.org/hoffman_colorcaster_restoration.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.

dtvmcdonald
04-20-2016, 11:18 AM
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.

Tom Albrecht
04-26-2016, 02:41 AM
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.

Hagstar
04-28-2016, 09:17 AM
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

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.

dtvmcdonald
04-28-2016, 10:12 AM
"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.

sweitzel
04-29-2016, 02:46 PM
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 :)

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.

wiseguy
04-29-2016, 08:01 PM
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

Josef
05-01-2016, 05:11 AM
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

matt99
05-22-2016, 06:20 PM
Just wanted to point out this ctc4 flyback on eBay.
http://www.ebay.com/itm/RCA-CTC-4-5-7-Flyback-Transformer-/401121971713?hash=item5d64bb8e01:g:MeYAAOSwVcFXOf~ p

old_tv_nut
05-22-2016, 07:07 PM
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

Possible, but you may get a different high voltage or different "stiffness" (variation with current) of the high voltage from the original, as it may vary with the dielectric constant of the potting compound, which affects the resonant frequency of the secondary. The difference in stiffness will not be a great worry in a set that uses a shunt regulator.

Josef
05-26-2016, 04:13 PM
If an used and untested flyback goes up that much, rewinding should be definitely worth a try or maybe more attempts.

Greetings Josef

Hagstar
06-26-2016, 04:48 PM
Well after being busy for months I finally removed all but 1/4" of the flyback "tire" on the CTC4, isolated the loose end, and then hooked up one of these to the horz. output as suggested here-

http://www.nteinc.com/specs/500to599/pdf/nte523.pdf

BUT up firing up the tripler promptly split open with a loud crack. Back to the drawing board- was I not supposed to ground the "Reference" terminal? That's what I saw on nearly every diagram, can't see it working without such. I had horz. output cap voltage to IN and obviously the orange high voltage lead to the terminal on the bottom of the high voltage rectifier tube which I left out. Thanks for feedback, this is all a bit experimental obviously. Perhaps tripler was simply defective or not high enough rated? My best guess is arcing somewhere overloaded it milliamp-wise. But the high voltage "rail" (at rectifier socket) reads infinite to ground.

John H.

tom.j.fla
06-26-2016, 05:48 PM
Which tripler did you use? A D.C. input and D.C. ground will go BOOM! You need a unit that has an A.C. input (read cap in the input) and D.C. ground. Something like a ECG/NTE 500A will work, that's the one I use for getting around the bad H.V. winding. All the best, Tom PS: Try to find a print copy of the NTE semiconductors replacement guide,they are a wealth of information.

Hagstar
06-26-2016, 06:15 PM
Which tripler did you use? A D.C. input and D.C. ground will go BOOM! .

I used an NTE 523...hmmm...this has a capacitor in ground lead.....appears identical to 500A.

John H.

Hagstar
06-26-2016, 08:14 PM
Here's the diagram of the NTE523 I used, I did order a 500A replacement, actually a bit cheaper.

Hagstar
06-27-2016, 04:47 PM
I did a postmortem on the tripler and it appears to have arced from the unused Focus voltage pin to the cage. I thought the distance, shrink tube, and 200K resistor in series would eliminate that risk, but.....

Tom Albrecht
06-27-2016, 07:26 PM
"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.

In fact I also did exactly that when I restored my CT-100 a year or two ago. A bunch of 200 V zeners in series to make a 2 kV zener. Works splendidly!

tom.j.fla
06-27-2016, 08:29 PM
If using a tripler with a built in focus divider, connect a 66 meg. H.V. resistor from the pot term. to ground, puts a load on the divider gets rid of arcs and you get a bleeder resistor on the H.V. All the best, Tom

miniman82
06-28-2016, 12:40 PM
I probably have a few of those laying around if you need them. Also a few 100 meg ones, left over from the photo CRT experimentation.

Hagstar
06-29-2016, 04:58 PM
If using a tripler with a built in focus divider, connect a 66 meg. H.V. resistor from the pot term. to ground, puts a load on the divider gets rid of arcs and you get a bleeder resistor on the H.V. All the best, Tom


Thanks Tom. I believe you but how does this prevent arcs? Hair of the dog principle :) ? Bleeder resistor value principle I grasp....
EDIT - I see you must mean it would prevent arcing from the focus pin by providing a safe super high resistance path.

John H.

Electronic M
06-30-2016, 08:00 PM
Thanks Tom. I believe you but how does this prevent arcs? Hair of the dog principle :) ? Bleeder resistor value principle I grasp....
EDIT - I see you must mean it would prevent arcing from the focus pin by providing a safe super high resistance path.

John H.

Without the resistor the focus pin is at ~25KV and can arc to anything grounded within ~2-3"....With the resistor to ground that pin is at the designed value of ~4-6KV and probably won't arc more half an inch... That pin is meant to be the output of a voltage divider...Take away the bottom half of the divider and things go WAY out of design spec.

tom.j.fla
06-30-2016, 09:18 PM
Tom C. thank you for clearing up my comment from post #50. I do better in face to face conversion, again thanks. Now if you loose the focus network in your CTC-4 use a 25 meg or maybe 50 meg focus pot from the control pin to ground and move the focus lead to focus pin on a tripler with the divider network built in, with a ECG500A use a focus control network from a CTC63 or CTC66 instead it has the top and bottom resisters built in. All the best, Tom

Hagstar
07-01-2016, 11:20 PM
HOUSTON WE HAVE STABLE HIGH VOLTAGE AGAIN. Plus no blooming etc. with brightness control changes. A million thanks to this forum. "Neutering" the tire of the flyback last weekend took some worrying. Finally I just snipped through most of it and found the end again and unwrapped another couple hundred turns, securing the end in some shrink tubing and silicone.

This time I snipped off the unused Focus pin and buried the stub in a 1/2" mound of silicone.

One day I may find that NOS flyback but at least I have a working set and less hissing or :smoke: to watch out for.....

John H.

DaveWM
07-02-2016, 04:35 PM
Curious, did you consider using the tripler supplied focus voltage for the set?

Hagstar
07-02-2016, 04:50 PM
Curious, did you consider using the tripler supplied focus voltage for the set?

I saved that option by leaving a stub of the pin. But I wanted to keep the set as original as possible and retain the separate focus diode.

John H.

DaveWM
07-03-2016, 02:00 AM
understood. Now you need to post a pic or better a video of the working set!!

Hagstar
07-04-2016, 04:29 PM
understood. Now you need to post a pic or better a video of the working set!!

Only static convergence here so far-

http://hagstar.phanfare.com/7138833

John H.

Hagstar
07-06-2016, 10:17 PM
So when I did check the high voltage with the new tripler what is it? 22 thousand volts, just like before. It's stuck on that value. Does anyone get a 25 kV out of these? Not that it seems to matter too much.

But I do have to add a bleeder to stub of the focus pin- it manages a bit of corona for a moment under the RTV blob covering it to the cage as is, have 66 meg resistor coming.

John H.

DaveWM
07-07-2016, 12:41 AM
shunt tube? does the HV adjustment work? when you say stuck to you mean max?

Phil Nelson
07-07-2016, 02:17 AM
HOUSTON WE HAVE STABLE HIGH VOLTAGE AGAIN.Pardon my slowness, but could you describe in a little more detail exactly what you hooked up and where? Might be useful for anyone needing to do this in the future.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Hagstar
07-07-2016, 07:54 AM
shunt tube? does the HV adjustment work? when you say stuck to you mean max?

Well it can be adjusted up to 22.5 kV, control works but adjusts exactly as before with flyback working- 21-22.5 kV. By stuck though I'm more referring to the way all reports I've seen say other CTC4 owners get this same slightly low max high voltage. It's true I haven't unhooked shunt tube to check that system- will do so.

John H.

Hagstar
07-07-2016, 08:03 AM
Pardon my slowness, but could you describe in a little more detail exactly what you hooked up and where? Might be useful for anyone needing to do this in the future.



Well as described early in thread I removed most of the old flyback "tire" (down to about 1/4") and insulated the loose end. This was tricky as it was too burned to unwind and that would take months- I clipped the tire deeply through all layers and found the end far down instead. Then I hooked up the tripler IN pin to the horz. output voltage terminal top of the assembly. The OUT is a thick insulated red wire- I soldered this to the terminal in the plexiglass cup beneath the high voltage rectifier. The REF(GND) pin I grounded. F (focus) will receive a 66 meg at 6000 volt resistor to ground to keep the voltage there sane. That's about it. The tripler fits easily with wire ties to the side of the high voltage cage.

John H.

DaveWM
07-07-2016, 08:18 AM
used a tripler not a quadrupler correct?

Hagstar
07-07-2016, 04:02 PM
used a tripler not a quadrupler correct?

It was a tripler yes, of course this is not literal though. Triplers don't use 3 stages for TV use, this was a 6 stage and there are 5 stage ones also. The waveform from the horz. output is so uneven that's what's needed to multiply the voltage 3 times. A quadrupler would put it near 30 kV, well above spec 25 kV.

What I used- http://www.ebay.com/itm/112011512150

John H.

miniman82
07-07-2016, 06:07 PM
Well it can be adjusted up to 22.5 kV, control works but adjusts exactly as before with flyback working- 21-22.5 kV. By stuck though I'm more referring to the way all reports I've seen say other CTC4 owners get this same slightly low max high voltage. It's true I haven't unhooked shunt tube to check that system- will do so.

You're not talking about mine then, all my early color sets make an easy 25kv. More if you aren't careful... Only sets I was never able to get more out of are the CTC-5's of course (my Wingate tops out at 22.5 no matter what I do), and some of the other RCA's like the 7's and 9's. Some of their later sets had better HV production, but those used compactron output tubes not octals.22/22.5kv isn't bad though, as long as it isn't sagging or blooming on high brightness scenes you'll be OK. Voltage is only one piece of the pie, have to have the current as well or it won't perform.

On the shunt regulator adjustment, you should be able to pull a full 1ma on the shunt tube's cathode with brightness all the way down. If it's higher than that straight off the bat, you may have to play with the grid circuit resistance to get it in spec. Not at all uncommon, the Silvertone I'm working on right now had a badly drifted 6BK4 grid resistor that caused hv to sag all the way down to 8kv. Changed out that resistor, boom got a full 24kv without breaking a sweat.

DaveWM
07-08-2016, 01:06 PM
It was a tripler yes, of course this is not literal though. Triplers don't use 3 stages for TV use, this was a 6 stage and there are 5 stage ones also. The waveform from the horz. output is so uneven that's what's needed to multiply the voltage 3 times. A quadrupler would put it near 30 kV, well above spec 25 kV.

What I used- http://www.ebay.com/itm/112011512150

John H.

how do you know it put it near 30kv? is that assuming its being driven as it was designed vs how you are using it in this application?

Hagstar
07-08-2016, 03:27 PM
how do you know it put it near 30kv? is that assuming its being driven as it was designed vs how you are using it in this application?

Well the tripler is putting out 3 times the input voltage, 4 times would be near 30K. I would assume they are designed the same but the quadrupler would have 2-3 extra stages. As for design they are doing what they were designed to do as far as I can see- replace flybacks by turning horz. output voltage into high voltage- weren't they used this way originally at factory?

John H.

old_coot88
07-08-2016, 04:56 PM
John, where you said:
Then I hooked up the tripler IN pin to the horz. output voltage terminal top of the assembly.
...does that mean it's going to the plate of the H out tube?

DaveWM
07-08-2016, 06:22 PM
Well the tripler is putting out 3 times the input voltage, 4 times would be near 30K. I would assume they are designed the same but the quadrupler would have 2-3 extra stages. As for design they are doing what they were designed to do as far as I can see- replace flybacks by turning horz. output voltage into high voltage- weren't they used this way originally at factory?

John H.

I have only seen SS triplers used in SS circuits, so comparing the output of a SS horz transistor to the plate of a horz out seems like there could be some difference in the voltages applied to the tripler. On top of that I cant say for sure but I think they were attached to a winding on the fly back that was not at the same level as the horz out from the SS or tube if so used. So the fly could have been adding some beyond the horz out level.

Regardless IF you are maxed at 22.5v with no shunt current, and you are in the experimenting with using triplers to replace flybacks, then it would seem at least worthy of trying a quadrupler IF you want to get more HV. I suppose there maybe some other limits as to what you are getting out as far as power in/power out, but without trying I don't know if I would say it can't work. One last thing, 30kv is about where old flyback systems maxed out anyway, so if 4 times would be 30k you would be right on target for unregulated voltage.

Hagstar
07-10-2016, 04:58 PM
John, where you said:

...does that mean it's going to the plate of the H out tube?


Yes, see photo of flyback in question earlier in thread. The top tab terminal goes to horz. output cap.

John H.

old_coot88
07-10-2016, 08:30 PM
John, you indicated there's about a quarter-inch of the old HV winding (tire) still intact with the end tied off. Does the winding still have continuity? If so, possibly you could feed the tripler from the tied-off end, thus boosting the voltage going to the tripler. Just a thought. :nerd:

Electronic M
07-11-2016, 10:47 PM
Well the tripler is putting out 3 times the input voltage, 4 times would be near 30K. I would assume they are designed the same but the quadrupler would have 2-3 extra stages. As for design they are doing what they were designed to do as far as I can see- replace flybacks by turning horz. output voltage into high voltage- weren't they used this way originally at factory?

John H.

An AC-DC multiplier is defined by it's number of diodes. A doubler has 2 diodes, a tripler has 3, a quadrupler 4, a quintupler 5, and so on. Thus a quadrupler can ONLY have one more stage than a tripler.

30KV unregulated should be fine...Some sets can hit 40KV if you disconnect the CRT and HV reg.

As long as you are not drawing more than about 1mA through the regulator with the CRT dark and the HV set to roughly 25KV, all should be well.

Hagstar
07-11-2016, 11:02 PM
An AC-DC multiplier is defined by it's number of diodes. A doubler has 2 diodes, a tripler has 3, a quadrupler 4, a quintupler 5, and so on. Thus a quadrupler can ONLY have one more stage than a tripler.



Here's a "Six stage tripler"- http://www.moyerelectronics.com/BVModules/ProductTemplates/MoyerProductTemp/Product.aspx?productid=4b69f578-eeca-47f7-977c-83adfcdcb456

I'm sorry but this is incorrect for TV high voltage use and already covered earlier. That is quite true in pure science world. In TV use here a tripler is defined entirely by function. It is not at all like a textbook tripler based on stages, it's just what does the job of multiplying voltage times 3. In this case they don't work like in textbooks because of the irregular nature of the horz. output wave. As I explained before a "tripler" in this use NEVER has 3 stages, and quadrupler never 4. Triplers are in fact 5-6 stages. Here's a 5 stage tripler schematic I posted earlier in thread similar to the one I am using which has one more stage. These are not my ideas- they are data from forums explaining TV triplers. Normal rules regarding triplers don't apply in this case. It is not defined by the number of diodes.

Hagstar
07-11-2016, 11:15 PM
UPDATE- I devised a corona free method of measuring high voltage (no there is no rubber cap on the lead to the CRT you can slip it under) and lo and behold I measure 22-24 kV out of her now. I didn't see the leakage robbing my voltage before where the tip of the probe met the (empty) rectifier socket contact. I sleeved it with 2 layers of shrink tubing leaving just the tip and voila- 24 kV which I adjusted per the specs down to 23.

John H.

Hagstar
07-16-2016, 10:06 AM
WHERE IS MY DEGAUSSING COIL??? I'm not going to do it with the soldering iron again.....BUT best image so far, mostly converged- https://www.youtube.com/watch?v=NGVm4AnomuU&feature=youtu.be

EDIT- 11 AM Sat.- found it, a Walsco 2592 with Lafayette labeling.

John H.

Hagstar
07-22-2016, 06:34 PM
Better video- https://www.youtube.com/watch?v=LfC28hSYOf8&feature=youtu.be

Hagstar
10-03-2016, 10:11 PM
Can someone offer clues as to why NONE of my horizontal phase coils seem to do anything? I can't seem to get any decent dynamic convergence and this appears to be the reason. The amplitude and tilt controls all seem to function normally. Stripped slug threads is my only guess.

John H.

tom.j.fla
10-04-2016, 12:55 PM
Make sure that all the drive signals are there, using a good scope. if you don't have one you should get one. There are are three good books on the down load page at SMC Electronics that will give insight on there use. Eric H. if you would be so kind, post the link and instructions to get the pdf's would be great(thanks Eric). All the best,Tom.J