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 Post subject: RCA flyback question
PostPosted: Mar Thu 15, 2018 2:38 pm 
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Location: Southwestern,Ontario Canada
I picked up a Garod TV/Radio combo. The only evidence of any harm is the flyback. Looks like a mouse enjoyed chewing on the outer edge of the circular winding. I had posted a wanted to buy on another forum and a kind forum member responded that he had one available. I don't have it in my grubby little hands yet, but my question is: The picture shows the top left corner of the one I am getting. It has the phenolic board broken out of this area. This area also has a critical attachment point (solder rivet). If I am careful and unsolder the wires from the one I have, and disassemble the entire iron "core" area to get down to the actual "core". Does anyone know if the phenolic board is securely attached (some form of compound) or is the entire form "floating" freely on the iron core. Can I swap this board without to much trouble ? Has anyone actually taken one down to this "level" or just swapped out the whole flyback. It looks like the wire attachment board is just 90 degrees to the circular insulator that runs through the winding. I hate to think that I can't swap it out. The picture of the chewed flyback does not show the back area, of the 2 large rivets and wires but it is identical to the one with the broken corner piece.
Tony


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 Post subject: Re: RCA flyback question
PostPosted: Mar Thu 15, 2018 3:43 pm 
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Location: Dallas, TX
I don't know that flyback, but if the portion of the board of the replacement one had a terminal on the missing piece it might have ripped off the wire attached to it. That would be a big problem. Some of those wires are very thin.
From your picture of the original flyback it doesn't look very bad. If only some wax is missing it isn't that big a problem.

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 Post subject: Re: RCA flyback question
PostPosted: Mar Thu 15, 2018 3:46 pm 
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I'd be tempted to just add a piece of phenolic to that corner using epoxy, and put the missing terminal on that. Or perhaps using the Dremel tool, cut that side or the upper terminal area off the bad one and use it for the repair without any disassembly of the good unit.

Yes, you can disassemble those flybacks if you are careful and patient. The wires are very fragile though and the fewer of those you disturb the better off you are.

The original flyback is obviously damaged too much to be repairable where the wires are chewed through on the winding.

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 Post subject: Re: RCA flyback question
PostPosted: Mar Fri 16, 2018 12:30 am 
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Joined: May Sun 07, 2017 11:35 am
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Location: Belrose, NSW, Australia
That wax nibbling doesn't look terminal to me. I'd be doing a tidy hot-melt glue repair before worrying about changing it out.
Run a bead of hot melt around the periphery of the overwind and smooth it off with a hot air gun. A bit of skill needed here but you can make it look like the original.
A smooth surface is desirable to avoid corona from the 15,000 pulse that appears on the outside rim of this winding.

Consider replacing the EHT rectifier filament winding, it's a very common source of failure and can quickly destroy an otherwise-good flyback if it breaks down.

If you do disassemble the core, take care you don't lose the paper spacers on the ends of the ferrite legs.
That sets the "air gap" and it is very critical in a flyback. Don't double them up either...

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 Post subject: Re: RCA flyback question
PostPosted: Mar Fri 16, 2018 1:05 am 
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Location: Albion, CA, USA, 95410
irob2345 wrote:
That wax nibbling doesn't look terminal to me. I'd be doing a tidy hot-melt glue repair before worrying about changing it out.
Run a bead of hot melt around the periphery of the overwind and smooth it off with a hot air gun. A bit of skill needed here but you can make it look like the original.
A smooth surface is desirable to avoid corona from the 15,000 pulse that appears on the outside rim of this winding.
.


I was wondering if it is ruined too. But I wouldn't use hot melt. During my high voltage phase (Tesla coils, plasma generators etc) I found that high voltage corona eats hot glue. It just kind of evaporates away. Might have been just the type I had, I suppose. I would use HV silicone or corona dope.


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 Post subject: Re: RCA flyback question
PostPosted: Mar Fri 16, 2018 1:55 am 
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Location: Lafayette, CO
My recommendation is to either replace that phenolic board (use the original one from your set) or replace the entire FLY1 as they aren't uncommon (yet). Craig


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 Post subject: Re: RCA flyback question
PostPosted: Mar Fri 16, 2018 3:45 am 
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Location: Belrose, NSW, Australia
I know they used to make hotmelt glue from animal bones but AFAIK it's been synthetic for some time now. I've had no such trouble with it.

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 Post subject: Re: RCA flyback question
PostPosted: Mar Fri 16, 2018 5:24 am 
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The resolution in that photo is not good enough to see if any of the wires in the winding have been severed. I tried enlarging it and could not tell. Try looking at the winding with a magnifying glass and see if you can tell for certain. If no wires have been cut then try insulating the winding and see if it will work.

What is attached to that solder rivet that is missing on the new flyback? Is there a wire from one of the windings that attaches there? If so, is that wire in good condition on the new flyback?

I would not take the new flyback apart. Just cut the corner of the board off of the old flyback and glue it on to the new one. Don't try to match the broken part of the new board exactly. Just overlap the piece of board from the old flyback over the corner of the new board

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 Post subject: Re: RCA flyback question
PostPosted: Mar Fri 16, 2018 2:09 pm 
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Location: Southwestern,Ontario Canada
Thanks for all the suggestions about a fix. The mouse has most definitely eaten through a few of the fine wires, so a swap is the only way to go. I currently don't have the replacement flyback in my possession (I had it shipped to a friends place). I will know more when I get it. I figured if I was gentle enough with the fine wires I could swap it (provided it wasn't glued to the flyback itself). As for the status of the wire and lug that is in the broken off area, I'm hoping it is still there. The seller said that it tested good, he didn't elaborate on the broken area where the solder lug has broken out. The lower existing lug goes to the grid cap of the 6BG6 and the missing one goes to the cap of the 1B3GT HV Rectifier. I had contacted the ETF about a flyback and they said they were out. The seller was the only one that responded to my WTB ad. I really didn't know where else to get one. Strange thing about this set is the High voltage section just sits in the middle of the chassis with no cage or shielding what so ever. I'm not sure how many other sets are like this. If it did have a cage around it, I'm sure the mice could not have gotten to it. Funny thing is, the chassis is spotless and there is no evidence of mouse pee or droppings anywhere. Just on this one area of the flyback.
Tony


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 Post subject: Re: RCA flyback question
PostPosted: Mar Fri 16, 2018 3:08 pm 
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Sorry to hear about your flyback. Hope the replacement works. For anyone curious, here is what one looks like dissasembled.

I'm not sure about the comment above referring to paper spacers ? I didn't find any.
Image


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 Post subject: Re: RCA flyback question
PostPosted: Mar Fri 16, 2018 3:32 pm 
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Location: Southwestern,Ontario Canada
Excellent Bob !! Just what I was looking for. You wouldn't happen to have any close up pics of the opposite side where the flat section attaches to the "tubular" section of transformer itself ? I see these were taken on May of 2015. Your level of documentation on every aspect (no matter how seemingly insignificant) is great. Keep up the good work, it is appreciated. It gives me hope I've got something to work with.
Tony


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 Post subject: Re: RCA flyback question
PostPosted: Mar Fri 16, 2018 5:18 pm 
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Location: Dallas, TX
Tony F wrote:
Thanks for all the suggestions about a fix. The mouse has most definitely eaten through a few of the fine wires, so a swap is the only way to go. I currently don't have the replacement flyback in my possession (I had it shipped to a friends place). I will know more when I get it. I figured if I was gentle enough with the fine wires I could swap it (provided it wasn't glued to the flyback itself). As for the status of the wire and lug that is in the broken off area, I'm hoping it is still there. The seller said that it tested good, he didn't elaborate on the broken area where the solder lug has broken out. The lower existing lug goes to the grid cap of the 6BG6 and the missing one goes to the cap of the 1B3GT HV Rectifier. I had contacted the ETF about a flyback and they said they were out. The seller was the only one that responded to my WTB ad. I really didn't know where else to get one. Strange thing about this set is the High voltage section just sits in the middle of the chassis with no cage or shielding what so ever. I'm not sure how many other sets are like this. If it did have a cage around it, I'm sure the mice could not have gotten to it. Funny thing is, the chassis is spotless and there is no evidence of mouse pee or droppings anywhere. Just on this one area of the flyback.
Tony

The missing terminal would be the HV secondary output. The secondary is wound with very thin wire. That end of the secondary would be coming off the outer edge of the winding, which happens to be were the mice got at the original flyback. I don't quite see how the fellow said that the flyback tested good when an important terminal is missing. BTW in a TV the top tube caps are the plate connection and carry dangerous high voltage unlike the grid caps in an early radio where they are at near ground. Touch a plate cap with the set on and you will wake up across the room on the floor, if you wake up at all. I suppose you know the black core material is brittle, about like glass.

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 Post subject: Re: RCA flyback question
PostPosted: Mar Fri 16, 2018 5:26 pm 
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Tony F wrote:
...You wouldn't happen to have any close up pics of the opposite side where the flat section attaches to the "tubular" section of transformer itself...



Thanks, I do what I can. I went through all the photos from that project and I don't see any of the other side. However, I do have video footage that might show what you're interested in.

https://youtu.be/BtWcvmtba5E?t=17m2s


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 Post subject: Re: RCA flyback question
PostPosted: Mar Fri 16, 2018 6:13 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Southwestern,Ontario Canada
Funny,.. I watch a lot of your videos , but I must have missed this one. Now I guess I'll have to watch all of this Westinghouse series. Interesting how a lot of different manufacturers used the same RCA flybacks and yolks. I like how easily it all came apart.
Cheers
Tony


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 Post subject: Re: RCA flyback question
PostPosted: Mar Fri 16, 2018 7:18 pm 
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Yes, Admiral used them in many models too. Probably figured RCA did all the R&D and used them for a design reference.


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 Post subject: Re: RCA flyback question
PostPosted: Mar Sat 17, 2018 2:44 am 
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If you need a fine wire to extend one from a flyback or other coil, take some lamp cord and strip some insulation off. Separate out one strand of wire. I find that one strand is often about the right size.

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