CTC21 Flyback Problem
 

So I was watching this set this evening and I heard a strange sizzling sound, oh sh!t. I was near the set and was able to shut it down after a few seconds, just as the picture was starting to shrink (tale tale sign of HV failure), and it stank up the room pretty good. I waited for it to cool and took a look in the HV cage and saw this:

https://live.staticflickr.com/65535/...afa4093a_c.jpg

HV rectumfryer:

https://live.staticflickr.com/65535/...80a1d309_c.jpg

So a nice arc trail in a dirty HV cage and a nasty wart on the fly :thumbsdn:

What (besides a dirty cage/socket) would cause this? and assuming the fly isn't shorted or open, should I coat it with HV silicone or something to repair the "boil"?

HV rectifier and focus rectifier test ok, my tester can't test the shunt regulator, but it doesn't LOOK shorted

Carbon tracking. That rubber tire has become conductive. its arcing from the secondary core to the HV rectifier cap. Its savable but needs the tire pulled off and resiliconed with an electronics RTV. Do both sides.

Shango066 Has a good video on this.

https://youtu.be/l-b7LskuTYInd

And this

https://youtu.be/BUnPkymnxUw

I did this before on a CTC-17 with good results. discharge the CRT and remove the anode cap before doing this thou. I didn't. Learned the hard way...

Check for I believe 580 ohms between h output plate cap and flyback plate cap to the HV rectumfryer.

I have a feeling that the elements of time get trapped behind the tire from HV static pulling and dust becomes conductive.

The only time those F/B's failed was a summer time. Good old 115876.
I was started to use Thordarson replacements with the cast Silicone tire. :thmbsp:

A 'nuther example of why to never, ever leave a vintage TV running unattended, even for a minute. 'Specially color. :nono:

Thanks for the tips:thmbsp:

I'll ohm it out tonight to make sure. I don't think its shorted because I caught it within a few seconds, as I was crouched down next to the set, heard it sizzle, saw the picture shrink, and punched the knob.

We'll see about which method I use to repair, all of Shango's methods seem to work 100%. I especially like deep frying the donut in wax one :D

That would be optimal. Part of the reason is that the wax starts to dissipate and drip down the donut on to the core in this allows moisture and element intrusion into the fly back windings in then any kind of crap causes carbon buildup.

Just make sure that the secondary is still tight to the core.

If you look at my recent post on my CTC 16 that I picked up, You will notice in one of the pictures that there's a lot of wax that had left the secondary winding. Eventually this will become a problem with me as well. Is there a lot of wax underneath yours?

Secondary ohms out okay (618 ohms, spec is 660 ohms), no wax drippings to be seen. Me thinks the rubber is tired lol

Yep. Sounds like your on the right track. Peel that thing off and look for copper windings showing if any. Also carefully clean any carbon deposits off the ring.

Kudos if you can restore that to proper operation. Back in the day, it woulda been an instant writeoff and replacement called for.

I never liked RCA design with their flyback. Your picture showed what always happened when they failed. Hence why I preferred Zenith as I thought them more reliable. But they had high tripler failures so maybe what I thought was less repairs was really a wash when comparing apples to oranges. But for all the Sonys I have around I must say they were pretty hard to beat in picture and repair quality. Yes I am biased toward Sony. 📺

Zenith didn't implement tripplers on their their tube sets AFAIK (unless the 4 tube hybrids had it, never owned a 4 tuber despite having most of their other chassis). So you were comparing apples to oranges.....RCA had tripplers in their SS sets just like Zenith and they sucked just as bad as any other trippler in any other set.

We were an RCA dealer/warranty station. Saw very few OEM RCA tripler failures. Most triplers we replaced went into Zeniths, Magnavoxs and Sylvanias.(same with yokes)

There's little wonder to why modern ones are potted in epoxy. Mine has the rubber tire over it and silicone around the secondary. So it's going to be re-coated in silicone when I get around to it.