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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 17th Feb 2009, 2:05 pm   #21
FRANK.C
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Default Re: Bush TV22 restoration: mission impossible!

Quote:
Originally Posted by Top Anode View Post
No doubt the original designers work hard to give some leeway in the design, but does anyone know the typical voltages between strands?
I am sure that someone on here can answer your question definitively. But as a guess I would think probably 3 to 4 volts between strands and 500 to 600 volts between each layer on the overwind.

Frank
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Old 19th Feb 2009, 6:59 pm   #22
Giulio Maiocco
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Default Re: Bush TV22 restoration: mission impossible!

Hello to everybody,

the last few days I was submersed with works to do urgently, so no spare time to post a reply, sorry!

Rich - Thank you, Sir! The tube is very strong, and I already have a better still spare CRT in my lab, so I should be set for a very long time.

Andy - You guessed right, this set won't leave my collection for a very long time, there is really too much work and patience in it to sell it, and I cannot give a monetary valutation to the very large number of hours spent on it!

Tas and Frank C - I'm really happy and proud too about the final results, better than what I expected, it is already on it's "predestinated" shelf, a turn of the volume knob and it's ready(after the warm-up time, of course!) to watch some TV shows.

Chipp1968 - I think these little sets give out a really good video, despite the limitations, for sure, as you said, these are really impressive!

Des - I'm happy you appreciate my work, I always try to do my best on every thing I repair, I'm not always successiful, but this time it seems I reached my goal!

Top Anode - I usually have tons of patience for these "oldies", but this time that particular TV22 required even more patience to have it working again. The final results convinced me my efforts were worth the trouble!
About your question, I don't know how much voltage can withstand the old enamelled wire, but for the modern insulations, a safe value should be around 600V, as the minimum perforation voltage is between 2000 and 2400V, this is for a double enamelled magnet wire! Of course, the lower the voltage between turns and layers, the better

Cheers

Giulio
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Old 27th Feb 2009, 5:53 pm   #23
Ed_Dinning
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Default Re: Bush TV22 restoration: mission impossible!

Hi Giulio, Just back from holiday and seen you excellent thread on Bush LOPT. I have rewound several of these where the primary had gone, but had little sucess with the EHT secondary, so I'll give your method a try. I did attempt a replica on plastic wastepipe as a formers and using modern lams. The primary worked fine when using the turns date given in the Red books, but the EHT overwing had too much self capacitance without wave winding, needing a negative value of tuning cap to get the correct EHT.

I have re-wound many of the blocking oscillator transformers. I usually add paxolin cheeks to the existing bobbins and random wind without paper insulation, but using grade 2 wire. I use polyester tape between pri and sec.

Ed
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Old 9th Feb 2018, 6:08 pm   #24
Dickie
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Default Bush TV22 LOPT overwind

Sorry to drag this topic up yet again. Being faced with a LOPT with an o/c EHT overwind, I wonder if anyone has tried to emulate Giulio's method here;
https://www.vintage-radio.net/forum/...ad.php?t=37396
I note Ed Dinnings last post on this and wonder if a layer-wound coil is practical, given the impossibility of finding wire for wave-winding. I guess if anyone had achieved success we would all know about it!
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