Marantz model 18

Gepetto

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Generally each is wound as a separate winding, center taps often as bifilar wire for symmetrical performance. Junctions are made under the wrap that goes around the coils as a final assembly step.
 
laatsch55

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So, what do the junctions look like Joe? Is the wire that is brought out soldered to the winding itself at the right place? Crimped? ?????
 
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This is proving to be a very interesting thread, I did not realize transformers could be so seemingly complicated
 
laatsch55

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Not to mention.......mysterious........a lot of things go on in there we can't see....sneaky b@#&^$#s.....
 
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calman46

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I was reading about the bilifar wire a few days ago , I'll have to back track my web searches . I knew each coil had to have its own CT,but how to do it . So I need to learn about the bilifar wire method and look into the separate scope winding .This is looking like it might happen. Merry Christmas !! I have my Phoenix Holiday CD in .
 
oldphaser

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"Transformer Winding"

You might find these links interesting:

https://ludens.cl/Electron/trafos/trafos.html

http://www.dicks-website.eu/coilcalculator/index.html

http://www.soundstage.com/maxdb/maxdb071998.htm

http://www.geofex.com/article_folders/xformer_des/xformer.htm

http://www.electronics-tutorials.ws/transformer/transformer-construction.html

http://www.bryston.com/PDF/newsletters/Bryston_Newsletter_V8_4.pdf

http://www.academia.edu/9832634/Winding_Transformers_Introduction_and_Line_Power_Transformers

http://www.audioxpress.com/article/Power-Transformers-for-Audio-Equipment

Ed
 
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laatsch55

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What does wire size have to do with it? Strictly amperage dependent? The older PL 700's had HEAVY solid wire coming out, the later stuff smaller stranded stuff, and then finally a single center tapped stranded..I know tannins aren't wound with stranded...
 
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calman46

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Great links thanks .
This is what I'm thinking about doing . Making a transformer with 5 secondary windings and 1 primary (orignal has 2 in parallel) . Each (secondary) will be a separate winding with a CT, except for the two 6.3VAC windings. I start with the smallest secondary coil and work out to the largest and then the primary . Using 18GA magnet wire for all windings(for now) which is rated for over 2 amps. The receiver has a 250w rating and has a 2.5amp primary fuse. Do I really need to know how much amperage each winding could draw ? .
If I can do it this , I will need to know if all these windings will fit in the original core .I need to practice winding first and maybe make one of those transformer kits . What do you folks think ? doable ?
 
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calman46 said:
Great links thanks .
This is what I'm thinking about doing . Making a transformer with 5 secondary windings and 1 primary (orignal has 2 in parallel) . Each (secondary) will be a separate winding with a CT, except for the two 6.3VAC windings. I start with the smallest secondary coil and work out to the largest and then the primary . Using 18GA magnet wire for all windings(for now) which is rated for over 2 amps. The receiver has a 250w rating and has a 2.5amp primary fuse. Do I really need to know how much amperage each winding could draw ? .
If I can do it this , I will need to know if all these windings will fit in the original core .I need to practice winding first and maybe make one of those transformer kits . What do you folks think ? doable ?
Click to expand...
Standard practice is to start with the highest power windings first, against the core. That keeps the I2R losses to a minimum due to shorter length of a turn nearer the core than farther out in the winding stack. Keeps heat in the transformer to a minimum. Lowest power windings to the outside diameter.

A lot of thought goes into winding a transformer and the last step is vacuum varnish impregnation to keep the windings from vibrating and making noise.
 
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laatsch55 said:
What does wire size have to do with it? Strictly amperage dependent? The older PL 700's had HEAVY solid wire coming out, the later stuff smaller stranded stuff, and then finally a single center tapped stranded..I know tannins aren't wound with stranded...
Click to expand...
Yes Lee, I2R loss is what it is about for low frequency transformers. Very high power transformers are wound with wide foil windings.

I am sure that PL gradually worked the cost aspect of the transformer hard which is why you saw degradation in the wires coming out of the transformer. Value engineering setting in.
 
laatsch55

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Gepetto said:
Yes Lee, I2R loss is what it is about for low frequency transformers. Very high power transformers are wound with wide foil windings.

I am sure that PL gradually worked the cost aspect of the transformer hard which is why you saw degradation in the wires coming out of the transformer. Value engineering setting in.
Click to expand...
I've scrapped some 50-100kva stuff and they are usually rectangular wire wound on it's small side....
 
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calman46

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I'm not taking this build lightly ,so there will be more questions. I read its real import to kept the primary insulated from the core .At first I thought to wind the primary first just because it was the primary . More reading is needed and supplies . The wire and insulation tape aren't a problem , its the bobbin . I could make one but pre made one would be better .
I need figure out if the new windings will in the old iron before I start winding it .
 
Gepetto

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calman46 said:
I'm not taking this build lightly ,so there will be more questions. I read its real import to kept the primary insulated from the core .At first I thought to wind the primary first just because it was the primary . More reading is needed and supplies . The wire and insulation tape aren't a problem , its the bobbin . I could make one but pre made one would be better .
I need figure out if the new windings will in the old iron before I start winding it .
Click to expand...
Always a challenge. The window defines what you can do. Plus you are not machine winding so your space efficiency will be lower than machine wound.
 
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calman46

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Things have changed . The add on scope- coil didn't pan out. There is a picture of a unit with the add on but that's it doesn't give any more info. Its an old post of a French audio site .There is an "as-is" 18 on ebay
 
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