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  #16  
Old 10-17-2015, 01:19 PM
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Quote:
Originally Posted by Username1 View Post
Looks like at some point someone will have to begin rewinding flybacks from burnt
out ones.... It's gotta be easier than rebuilding a picture tube..... People with good
spares should measure all important parameters like resistance, inductance, and
all that good stuff, wire diameter, and begin keeping records, so when a rewind is
attempted it can be compared to NOS specs.....

.

.
I know the Thordarson guide I have has resistance specs, maybe windings.

The achilles heel of RCA has always been the flybacks, and i made sure I had a spare lined up for any set I owned, except for a CTC76 XL100 set. As little as I run my CTC16, the only failure has been the focus coil and a seized efficiency coil.
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  #17  
Old 10-17-2015, 02:00 PM
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Quote:
Originally Posted by Findm-Keepm View Post
I don't think that is all - the donut is the primary and the secondary, so what generates the HV?

Solid State HV module - care to elaborate?
I think what he means is why can't a modern fly back be made to work in antique sets? A solid state high voltage section instead of what the sets have now.
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  #18  
Old 10-17-2015, 02:07 PM
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Quote:
Originally Posted by Findm-Keepm View Post
I don't think that is all - the donut is the primary and the secondary, so what generates the HV?

Solid State HV module - care to elaborate?
By dough nut I believe he means the outer HV winding. On some sets where the HV winding has been fried (and all else is fine) I've heard of some success being had in disconnecting the HV winding and driving a trippler ('solid state HV module') off the H out tube plate to get HV.
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  #19  
Old 10-17-2015, 02:15 PM
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Quote:
Originally Posted by Arcanine View Post
I think what he means is why can't a modern fly back be made to work in antique sets? A solid state high voltage section instead of what the sets have now.
That would be quite a feat of engineering! SS yokes are quite different from tube ones, and the tube sets have things like dynamic convergence, and synch pulse windings that most SS flys lacked.....Making up for those differences and incorporating something like that into the existing circuits would be a challenge even for a team of the best of us.
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  #20  
Old 10-17-2015, 02:58 PM
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There are some limits to what you could do here..... For starters, you could probably
only easily adapt tube to tube H output things, first drive coil winding voltage, which
gets you into the ball park for output voltage, same with current. And there are all
those other taps mentioned above. Tube circuit impedance's, don't forget the yoke is
also part of that circuit too.... There is lots to think about here.... Better to rewind a correct
part that has failed, than to try and re-engineer a 1/8 of a tv to fit in a part that may not
last too long when yer done....

.
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  #21  
Old 10-17-2015, 03:45 PM
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The hv tripler would make the hv in place of the secondary, donut while yes the primary stayed intact. I think someone here on karma already posted that that very thing was done but don't remember who, it was awhile ago. There has to be a simpler why other then rewinding a primary not to mention a secondary, donut.
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  #22  
Old 10-17-2015, 08:56 PM
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Quote:
Originally Posted by timmy View Post
The hv tripler would make the hv in place of the secondary, donut while yes the primary stayed intact. I think someone here on karma already posted that that very thing was done but don't remember who, it was awhile ago. There has to be a simpler way other than rewinding a primary not to mention a secondary, donut.
You're probably referring to this thread, where a fella in England describes how he replaced a HV winding with a tripler (although in a B&W set).
See post# 18.
http://videokarma.org/showthread.php...winding+flyack

Some translations of terms would probably help:
'Overwind' = HV secondary, 'donut', 'tire'
'EHT' (Extreme High Tension) = HV to CRT anode
'LOPT' (Line Output transformer) = Flyback xfmr.
'Line Output Valve' = Horiz. output tube

Note that he had to add some capacitance to the primary to compensate for the capacitance lost due to the missing 'donut'.

Earlier posts in the thread describe the perils and pitfalls one would encounter trying to actually rewind a flyback.
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  #23  
Old 10-17-2015, 10:05 PM
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Well I didn't think there was that much involved seeing as I thought the secondary , donut only made the hv for the crt anode to have the 23 kv for the crt to conduct in the way it was designed for. I also thought the primary was responsible for certain voltages via induction as well as geometry.
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  #24  
Old 10-17-2015, 10:24 PM
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It would be nice to have some concrete results - all I'm hearing is "I believe," "I think" and "I've heard"...

A schematic of the mod, a screenshot, and a narrative would be nice.

I have dug out bad HV rectifiers from potted flybacks ('twas nice to have a dentist office next door with an underused Xray machine) and I've seen an doubler added to generate HV in a Conrac color monitor with a bad (internal arcing) potted doubler. That one was in an ATE station aboard the USS Theodore Roosevelt and our NDI shop Chief did the Xraying. We used a doubler originally used in a Xerox machine, after first frying a Tektronix doubler from an oscilloscope - it didn't have the current capability. The arcing caused tearing of the raster, and with text being the primary display, it made it unusable.

To try a tripler in a tube RCA with the usual 6JE6, 6DW4, and 6BK4C would be problematic - coming off the plate of the 6JE6 would provide HV only - no horizontal sweep, and coming off the top end of the primary would add capacitance ( a tripler is all caps and diodes, with a possible resistor if a focus tap is provided) - you might be able to use a doubler in lieu of a HV rectifier if the HV is low, but regulation might cause issues - shunting a doubler would take a bit more current through the 6BK4C, and I dunno what that might do. A donut swap from a good flyback might work, but I've never seen two RCA flybacks with the same donut (PRI/SEC) schematic - I'll post the Thordarson schematics to show what I see...

RCA flybacks, as some have mentioned, provide much more than just HV - they provide Horizontal sweep to the yoke, focus voltage, sync pulses to the Chroma circuits, and convergence signals for the set. True they all operate at 15,750 Hz or so, but inductances, winding counts, and resistances all differ, making it all but impossible to easily swap out.
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  #25  
Old 10-17-2015, 10:30 PM
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Seems like Tom Albrecht was experimenting with triplers, in a Philco projection set for one. Seems like he tried one in a color set too, but I can't recall the details.
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  #26  
Old 10-18-2015, 12:05 AM
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And it probably worked, lol.....
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  #27  
Old 10-18-2015, 12:27 AM
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A little math here guys...

A TRIPLER is NOT going to give enough HV for a color tube from the H-out line. They normally are driven with between 8-10KV, to give out about three times that. BUT the h-out pulse is around 5-6KV I believe...and that will ONLY give at BEST 18 or so KV...NOT NEARLY enough..

Now--a QUADRUPLER--MIGHT work...they get about a 7KV pulse and give out 4 times that or so.. SO driving with 6KV might give 24 or so KV..while likely WOULD be enough...

There are still a few ECG 536A and ECG 550 Quads out there floating around...

It might be a good experiment...but I am NOT sure how well it will work...if at ALL, as others have stated...regulation, geometery and all else might be a real problem...
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  #28  
Old 10-19-2015, 10:39 AM
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As promised, here are the RCA Flybacks, from CTC7 to CTC31, minus the CTC12 (Fly273) and the CTC20, a FLY352, the oddest of them all.
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Last edited by Findm-Keepm; 09-29-2017 at 06:38 PM.
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  #29  
Old 10-19-2015, 12:43 PM
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Missing the Fly 284 that was for the CTC 9 and late 7?

Last edited by Kevin Kuehn; 10-19-2015 at 12:48 PM.
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  #30  
Old 10-19-2015, 02:43 PM
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Last edited by andy; 11-20-2021 at 03:23 PM.
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