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  #31  
Old 04-19-2016, 06:02 PM
DaveWM DaveWM is offline
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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.
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  #32  
Old 04-19-2016, 07:57 PM
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Hagstar Hagstar is offline
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Originally Posted by DaveWM View Post
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.
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  #33  
Old 04-20-2016, 07:54 AM
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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.
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  #34  
Old 04-20-2016, 10:18 AM
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dtvmcdonald dtvmcdonald is offline
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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.
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  #35  
Old 04-26-2016, 01:41 AM
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Tom Albrecht Tom Albrecht is offline
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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.
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  #36  
Old 04-28-2016, 08:17 AM
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Hagstar Hagstar is offline
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Quote:
Originally Posted by Tom Albrecht View Post
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.

Last edited by Hagstar; 04-28-2016 at 09:04 AM.
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  #37  
Old 04-28-2016, 09:12 AM
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dtvmcdonald dtvmcdonald is offline
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"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.
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  #38  
Old 04-29-2016, 01:46 PM
sweitzel sweitzel is offline
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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.
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  #39  
Old 04-29-2016, 07:01 PM
wiseguy wiseguy is offline
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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

Last edited by wiseguy; 07-19-2016 at 01:00 PM.
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  #40  
Old 05-01-2016, 04:11 AM
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Josef Josef is offline
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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
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  #41  
Old 05-22-2016, 05:20 PM
matt99 matt99 is offline
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Just wanted to point out this ctc4 flyback on eBay.
http://www.ebay.com/itm/RCA-CTC-4-5-...YAAOSwVcFXOf~p
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  #42  
Old 05-22-2016, 06:07 PM
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Quote:
Originally Posted by Josef View Post
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.
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  #43  
Old 05-26-2016, 03:13 PM
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Josef Josef is offline
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If an used and untested flyback goes up that much, rewinding should be definitely worth a try or maybe more attempts.

Greetings Josef
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  #44  
Old 06-26-2016, 03:48 PM
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Hagstar Hagstar is offline
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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.

Last edited by Hagstar; 06-26-2016 at 04:40 PM.
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  #45  
Old 06-26-2016, 04:48 PM
tom.j.fla tom.j.fla is offline
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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.
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