Looking for a flyback for a RCA CTC 15

[jsandlin]

I finally found an RCA roundie.
The good:
It looks to be a low hour set most all tubes are still originals.
The PCB's have little to no heat damage.
The cabinet is spotless looks like it is right off the show room floor.
The CRT was replaced in 1968 with a RCA Colorama checks almost NOS with a Sencore CR70.

Now for the Bad:
The flyback is burnt.

So I am looking for a replacement flyback part numbers are:
RCA 113382
Thordarson Fly 277
Triad D304

Any help in finding one would be appreciated.

Thanks
Jim

[JohnCT]

Originally Posted by jsandlin

The flyback is burnt.

There were two types of flyback failures in those: a shorted turn which would be evident by a burned stripe around the secondary core and a burn through from the 3A3 cup to the core.

EDIT: Does the 15 have the 3A3 socket???

Back in the old days, we used to carefully scrub down the burned section from the 3A3 cap to the core and put several coats of corona dope on them. We'd do them "in frame" in the house. These would last quite a while, enough time to schedule a flyback replacement or a new TV delivery.

I haven't seen one of these in over 40 years but if it has the burn between the 3A3 and core, I'd try removing the flyback and really cleaning it up well. I'd also use the RTV that doesn't have the acetic acid in it. Might be a permanent fix.

Nothing to lose to try.

John

[Electronic M]

Originally Posted by JohnCT

There were two types of flyback failures in those: a shorted turn which would be evident by a burned stripe around the secondary core and a burn through from the 3A3 cup to the core.

EDIT: Does the 15 have the 3A3 socket???

Back in the old days, we used to carefully scrub down the burned section from the 3A3 cap to the core and put several coats of corona dope on them. We'd do them "in frame" in the house. These would last quite a while, enough time to schedule a flyback replacement or a new TV delivery.

I haven't seen one of these in over 40 years but if it has the burn between the 3A3 and core, I'd try removing the flyback and really cleaning it up well. I'd also use the RTV that doesn't have the acetic acid in it. Might be a permanent fix.

Nothing to lose to try.

John

I think you're confusing the CTC-15 with the CTC-16. The CTC-16 and most later RCAs had the stupid design where the top cap of the HV rect was molded into the flyback tire.
The CTC-15 and earlier all had a wire running 2-3" out of the flyback to the top cap connector of the HV rect. Every RCA color chassis number has a flyback a little different from the others, but the 15 is easy to identify because it didn't use a focus rectifier tube, but instead a a selenium stick focus rect.


How have you checked your original to determine that it's bad? There some faults and methods of checking that can easily fool you into thinking the flyback is shot. I've had it happen to me before.

[nasadowsk]

There was an rca tech note that said you seat the 3A3 into its socket with 1/8 th clearence. Then put the top on, and make sure its bolted down tight. Dumb design.

The focus stick I guess wasn’t ready either - they went back to a tube…

Didn’t Zenith just use a rectifier with a conventional setup? RCA seemed to make things stupid at times…

[jsandlin]

With it out of the set and on the bench the resistance from the core to the connection for the rectifier plate (3A3) measures about 200 Ohms. one side has a burn from the plate wire.

luckily one of the other members has a NOS RCA he is willing to sell.

Will post pictures when I get it in and hopefully working.

[zeno]

IIRC all Zenith rectangles with high focus used a stick rect. Later
roundies also I think but it has been a loooong time.
I like sticks myself. No more reliable but easier to fix. Always hated doing
filament winding & sockets on tube jobs.

73 Zeno
LFOD !

Originally Posted by nasadowsk

There was an rca tech note that said you seat the 3A3 into its socket with 1/8 th clearence. Then put the top on, and make sure its bolted down tight. Dumb design.

The focus stick I guess wasn’t ready either - they went back to a tube…

Didn’t Zenith just use a rectifier with a conventional setup? RCA seemed to make things stupid at times…

[damen]

I transfered the tire from a CTC15 flyback to the frame of a burned CTC16 flyback and kept the original pulse winding assembly. Worked fine, just need to remember the short plate cap lead when lifting the cage cover!

[Jon1967us]

Originally Posted by damen

I transfered the tire from a CTC15 flyback to the frame of a burned CTC16 flyback and kept the original pulse winding assembly. Worked fine, just need to remember the short plate cap lead when lifting the cage cover!

How did you get the tire off? Does the core come apart in the middle? I don’t see how you can get the tire off the core

[damen]

The RCA ones come apart quite easily. Straighten the one tab at the top of the frame above the stamped numbers and pull. Sometimes there are spacers between the 2 core pieces, have to be careful to put them back.

[nasadowsk]

Originally Posted by zeno

IIRC all Zenith rectangles with high focus used a stick rect. Later
roundies also I think but it has been a loooong time.
I like sticks myself. No more reliable but easier to fix. Always hated doing
filament winding & sockets on tube jobs.

73 Zeno
LFOD !

My only experience with a tube Zenith rectangular set was one we got from a friend, that started arcing badly one day. When you're 10 and that happens and you're alone, you don't think much beyond yanking the cord out of the wall...

ISTR peeking in the back and seeing a TALL HV box. Beyond that, I don't know what was in there...

[dieseljeep]

Originally Posted by zeno

IIRC all Zenith rectangles with high focus used a stick rect. Later
roundies also I think but it has been a loooong time.
I like sticks myself. No more reliable but easier to fix. Always hated doing
filament winding & sockets on tube jobs.

73 Zeno
LFOD !

When the HV rect winding arced out, I used to just cut away the winding and use, what they referred to as a "Solid Tube".
I assured the customer that it was less expensive to do it that way.

[Jon1967us]

Can the CTC-15 fly be converted for tube instead of the solid state focus?

[Electronic M]

Originally Posted by Jon1967us

Can the CTC-15 fly be converted for tube instead of the solid state focus?

Probably, but why would you want to?
All you would need to do to use a focus tube is add a focus winding on the flyback frame using 10KV insulation rated wire.
However every heater load on the flyback increases horizontal output cathode current, reduces HV, and increases opperating temperature of the flyback...All of which are bad things to do.

On sets with tube focus I often disconnect the focus tube heater winding, leave the tube in for appearance, and stick a cheap modern 5KV PIV rated diode in. It reduces load, heat, and stress on the flyback and horizontal system, and improves focus in most cases.
I can give you a part number for a cheap modern diode if you want.

[Yamamaya42]

not to mention. you will be very hard pressed to find a socket for a 2av2 that wont wanna arc out, not too many original ones out there...

[rcaman]

i may have one i will look shortly