#31
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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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Brian USN RET (Avionics / Cal) CET- Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! |
#32
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I was curious how the Fly 283 and 284 compare.
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#33
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I had good and similar results with a nearly-failed CTC12 flyback.
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"When resistors increase in value, they're worthless" -Dave G |
#34
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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.... |
#35
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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 10:57 AM. |
Audiokarma |
#36
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Quote:
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.
__________________
Brian USN RET (Avionics / Cal) CET- Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! |
#37
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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. |
#38
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Quote:
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....
__________________
Brian USN RET (Avionics / Cal) CET- Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! |
#39
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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
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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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Audiokarma |
#41
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Quote:
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.
__________________
Brian USN RET (Avionics / Cal) CET- Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! Last edited by Findm-Keepm; 06-19-2017 at 03:10 PM. |
#42
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Quote:
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..
__________________
Brian USN RET (Avionics / Cal) CET- Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! |
#43
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Quote:
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