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  #31  
Old 10-19-2015, 05:06 PM
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Quote:
Originally Posted by Kevin Kuehn View Post
Missing the Fly 284 that was for the CTC 9 and late 7?
Yeah, I'll add it and the 352. My point was to show how different the flybacks are, and how difficult it would be to adapt one to another chassis. FLY312 and 308 look close, but if you want color, you've got to use the original. I made a mistake and put the wrong fly in once, and it wouldn't even light off. Even after swapping leads (the windings have different pinouts), I could get it to light off, but with a drive line, no color, and no AGC. 'Twas a 34-dollar mistake - had to spend that to get the correct flyback after a weeks wait.

The OP is working a CTC16 with a questionable fly - and no fly except the RCA/TRIAD/Thordarson/Hallordson exact replacement will work. Me? I'd work to prove it wasn't the fly first - by checking cathode current, 6BK4 current, and the drive to the 6JE6, as well as a swap out of the tubes with known good ones. Then, start unloading - focus rectifier, boost diode, and 3A3/cup. Good drive, good 6JE6, good cathode current, and still low HV? Probably the fly, but still plenty to check.....
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  #32  
Old 10-20-2015, 10:27 AM
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I was curious how the Fly 283 and 284 compare.
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  #33  
Old 10-20-2015, 02:21 PM
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Quote:
Originally Posted by andy View Post
I've had some luck removing the outer rubber covering from RCA flybacks that were arcing and recoating with silicone. The rubber seems to degrade and become conductive in some cases. Obviously, this won't work on flybacks that were allowed to arc for a long time.
I had good and similar results with a nearly-failed CTC12 flyback.
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  #34  
Old 10-20-2015, 02:58 PM
Alastair E Alastair E is offline
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I wonder if--

Your flybacks, (Line Output Transformers) are suffering a damp-coil condition like some British Bush/RBM B/W sets.

The HV Overwind was a pitch covered/wax impregnated coil in a doughnut shape, and some years of dis-use,--especially with a set stored in a damp barn or basement would allow moisture to creep into the coils via tiny cracks that appeared in the pitch/wax over the years since it was made, causing low EHT (HV) and worse still, falling EHT as the transformer warmed up, to the point the picture would expand and eventually completely disappear and the horiz-out bottle plate glow under the stress.

A period of 'cooking' the HV overwind coil by passing current through it carefully monitoring the heat in the coil to around 100-120 deg C for some hours, (I usually leave 'em overnight at this temp on the 2 or 3 Ive done) cures the issue.

Some guys have had success by storing the complete transformer in/on central-heating system hot-water storage tanks for some months...
--I prefer my method--Much quicker!

--A good coating of the insulating-varnish of your choice then seals it all up keeping the coils dry....
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  #35  
Old 10-20-2015, 08:08 PM
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Ancient Rca ctc2b FTB replacement

Ancient Rca ctc2b FTB replacement

I've been there, done that from Nov 30, 2010 to Mar 10, 2015. Used an RCA 117426 FBT.
This FBT was used in the CTC16 and CTC20. To me it was a major effort to get it right
in 80 days, elapsed time. The result was a transplant that produced screen shots eqivalent
of my original FTB. That quality is near 1986 Sony SS comb filter quality today.

This exercise is well documented in the included VK "RCA 21ct55 #8802877 is dead" thread.
It is long technicaly and somewhat contentious but good reading.


http://www.videokarma.org/showthread.php?t=249148

Last edited by Tomcomm; 10-21-2015 at 11:57 AM.
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  #36  
Old 10-20-2015, 09:56 PM
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Quote:
Originally Posted by Tomcomm View Post
Ancient Rca ctc2b FTB replacement....

I've been there, done that from Nov 30, 2010 to Mar 10, 2015. Used an RCA 117426 FBT. This FBT was used in the CTC16 to CTC20....

Um, the 117426 was used only by the CTC20.

See the whole lineup:
http://www.videokarma.org/showpost.p...79&postcount=9

I'd hate to see someone buy a 117426, only to find it doesn't work.
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  #37  
Old 10-21-2015, 09:01 AM
DaveWM DaveWM is offline
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if you want to try, you can find off brand flybacks (not listed above) that can be subbed. Its not easy but can be done. As an example I transplanted an entire fly tire for a Magnavox to a Sylvania. They were both RCA clones, but the Magnavox mounts the fly on the left side of the chassis (view from rear). It was still a clone circuit wise. The Sylvania was more I direct clone, both of the CTC-15 circuit.

If you review the schematics you can look for circuits that are basicly the same.

Funny thing was before I did the Swap of the Maggie fly I used some odd ball Admiral IIRC tire. The set worked but was just a bit down on horz power (the sides would not quite fill out and the HV had no head room. I tried increasing the screen current but it was really just not enough plate load from the fly. It would work fine if I bumped the line up to about 128vac. the cathode current was about 150ma max so the tire ran stone cold. I even considered just leaving it that way just to not worry about flybacks. I still have that transplanted fly somewhere as a spare for any CTC-15. Oh I think the orig fly was for a 19" Admiral portable.
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  #38  
Old 10-21-2015, 10:15 AM
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Quote:
Originally Posted by DaveWM View Post
if you want to try, you can find off brand flybacks (not listed above) that can be subbed. Its not easy but can be done. As an example I transplanted an entire fly tire for a Magnavox to a Sylvania. They were both RCA clones, but the Magnavox mounts the fly on the left side of the chassis (view from rear). It was still a clone circuit wise. The Sylvania was more I direct clone, both of the CTC-15 circuit.

If you review the schematics you can look for circuits that are basicly the same.

Funny thing was before I did the Swap of the Maggie fly I used some odd ball Admiral IIRC tire. The set worked but was just a bit down on horz power (the sides would not quite fill out and the HV had no head room. I tried increasing the screen current but it was really just not enough plate load from the fly. It would work fine if I bumped the line up to about 128vac. the cathode current was about 150ma max so the tire ran stone cold. I even considered just leaving it that way just to not worry about flybacks. I still have that transplanted fly somewhere as a spare for any CTC-15. Oh I think the orig fly was for a 19" Admiral portable.
That's what I like about having the tire schematic - you can match the electrical characteristics, and hope the mechanical will follow. Years ago, I tried a Muntz color flyback tire on a CTC16 with mixed results - I had HV, but the rest of the windings were either out of phase or not quite right, leaving me with no color and poor AGC. The similarities among the early colors to RCAs helps - a Philco, Packard Bell, Olympic or other clone fly might work electrically - I've just never gone that far. I've got 11 RCA tube flybacks, all for different chassis, and just dreading the day I might have to use my spare flyback for my CTC16.

On a side note, Horizontal Efficiency coils, focus coils, and Chroma coils are another area I'm stocking up on spares. Still available, but a finite supply nonetheless....
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  #39  
Old 10-21-2015, 01:02 PM
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The more I read, the less and less I want to even tinker with this thing anymore. Maybe I should have stuck with Solid State, hah
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  #40  
Old 10-21-2015, 01:07 PM
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21ct55 FTB replacement

It seems there is some concern the CTC20 I used was not used in the CTC16 and therefore not interchangeable for swaps. I checked the dc resistance of the ctc20 tire versus the ctc16 tire I have as spares. Well for all concerned, they were identical. Both flys had the same lug arrangement and the same added cores for aux signals. Only the mounting plate holes were different, but who cares! Really, if a failed ctc16 or ctc20 can be saved by drilling s few holes and rearranging some pickoff coils I certainly would go for it.

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  #41  
Old 10-21-2015, 01:47 PM
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Originally Posted by Tomcomm View Post
It seems there is some concern the CTC20 I used was not used in the CTC16 and therefore not interchangeable for swaps. I checked the dc resistance of the ctc20 tire versus the ctc16 tire I have as spares. Well for all concerned, they were identical. Both flys had the same lug arrangement and the same added cores for aux signals. Only the mounting plate holes were different, but who cares! Really, if a failed ctc16 or ctc20 can be saved by drilling s few holes and rearranging some pickoff coils I certainly would go for it.

Re-read your original (now edited....with the correction) statement - you stated it was used in the 16 TO 20, not true. 117426 may work with the 16.

As to the pinouts, significant differences between the two, with different pin 5, 7 and 8 - tire may be similar, with close resistance of the secondary winding, but the pinouts will have to be dealt with.
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Last edited by Findm-Keepm; 06-19-2017 at 04:10 PM.
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  #42  
Old 10-21-2015, 02:11 PM
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Originally Posted by Arcanine View Post
The more I read, the less and less I want to even tinker with this thing anymore. Maybe I should have stuck with Solid State, hah
Yeah, the mortality of old round-tube color sets may be upon us, with the dearth of available flybacks and CRTs. There are probably several dozen flybacks/CRTs held by collectors, but getting them at a reasonable price may be problematic, and make a set beyond economical repair.

My saved searches on eBay for vintage roundie flybacks have yielded only one roundie Fly in 2 years - and that was just days ago - glad it went for cheap to one of us V-K'ers..
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  #43  
Old 10-21-2015, 06:10 PM
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Quote:
Originally Posted by Findm-Keepm View Post
Yeah, the mortality of old round-tube color sets may be upon us, with the dearth of available flybacks and CRTs. There are probably several dozen flybacks/CRTs held by collectors, but getting them at a reasonable price may be problematic, and make a set beyond economical repair.

My saved searches on eBay for vintage roundie flybacks have yielded only one roundie Fly in 2 years - and that was just days ago - glad it went for cheap to one of us V-K'ers..
Well. I am not giving up quite yet.
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