Raytheon/Sonotone flyback

[Gus1969]

Hello again. This project is mine. I have a lot of appreciation for this television model, because my grandmother had one just like it, and it was the first television that I destroyed, trying to repair it. I was 17 years old. Fireworks included for the same price...
I never knew what happened. I think I bypassed all the fuses and it worked for a few hours, then smoke, boom and a new color TV gift from my Dad.
Obviously it is an american kit and I don't know who its original manufacturer is. My grandmother bought it around 1965.
The CRT is original Raytheon. The flyback is in bad condition. For years I repaired solid state flybacks with silicone. What is the best way to proceed in this case? In a hot oven and fix the wax? What kind of wax? I'm worried about the humidity inside. Thank you so much.

https://imgur.com/a/efi2YnK

[Yamamaya42]

What do you mean by “bad condition” , flybacks are the very epitome of “you can't judge a book by its cover” IE, just cause it looks awful, does not mean that it's bad, as many have pointed out here, but if it is arcing all over the place, there are ways to deal with it like removing the failed parts of the rubber “doughnut” that often carbon tracks, and using NON-VINEGAR type silicone, or my choice, High Voltage Super Corona Dope.
But always 1st rule is, if it's not broken, don't fix it!

[Alex KL-1]

Sub all H. osc caps for new ones, and the coupling cap for H. out tube, and all caps near flyback. To be sure to have correct drive for HOT for testing. Put a 10R in parallel with a 100nF cap in series with the cathode, and monitor cathode current and arcings when testing.
Then use for some minutes. I've seen flyback working good for some minutes, and smoking after some time (some internal arcing temperature dependent).

[zeno]

Must be a kit sets. looks US built but I do not recognize the
chassis or part numbers ( on PCB). So must be based on one of the
very small builders.
Often we saw tires melted away but the FBT works. Most bad FBT's
had shorted turns. Best start is be sure the H out tube has a HIGH
negative voltage on G-1 & cathode current within spec. Take it from there.
BTW RCA, GE & Sylvania used to publish "tube manuals".
https://www.ebay.com/itm/32572606269...Bk9SR9LN-azcYg

They are quite helpful and cover a LOT of things.

73 Zeno
LFOD !

[Gus1969]

Originally Posted by Yamamaya42

What do you mean by “bad condition” , flybacks are the very epitome of “you can't judge a book by its cover” IE, just cause it looks awful, does not mean that it's bad, as many have pointed out here, but if it is arcing all over the place, there are ways to deal with it like removing the failed parts of the rubber “doughnut” that often carbon tracks, and using NON-VINEGAR type silicone, or my choice, High Voltage Super Corona Dope.
But always 1st rule is, if it's not broken, don't fix it!

Hi Yamamaya42! Thanks for your reply, sure, I am 99% this flyback it's OK. (maybe I'm too optimist haha).
Next step dry it in a very low temp oven, and a slow start.

[Gus1969]

Originally Posted by Alex KL-1

Sub all H. osc caps for new ones, and the coupling cap for H. out tube, and all caps near flyback. To be sure to have correct drive for HOT for testing. Put a 10R in parallel with a 100nF cap in series with the cathode, and monitor cathode current and arcings when testing.
Then use for some minutes. I've seen flyback working good for some minutes, and smoking after some time (some internal arcing temperature dependent).

Hi Alex, in the thread "what do you drive", maybe you recognize my car.

[Gus1969]

Originally Posted by zeno

Must be a kit sets. looks US built but I do not recognize the
chassis or part numbers ( on PCB). So must be based on one of the
very small builders.
Often we saw tires melted away but the FBT works. Most bad FBT's
had shorted turns. Best start is be sure the H out tube has a HIGH
negative voltage on G-1 & cathode current within spec. Take it from there.
BTW RCA, GE & Sylvania used to publish "tube manuals".
https://www.ebay.com/itm/32572606269...Bk9SR9LN-azcYg

They are quite helpful and cover a LOT of things.

73 Zeno
LFOD !

Hi Zeno, good advices. Honestly, first time I saw to measure cathode current
was reading Videokarma restorations! After recap, it will have a "soft start".
Maybe, for work comitmments, can't work on it for some days.
Curious this set was not made for a main manufacturer. A colleague (the guy of the Hitachi I asked previously), send me via whatsapp some captures of a very similar schematic diagram. Thank you so much.