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Dynaco SCA35 - having an output transformer rewound - should i do both?

If one Dynaco Z565 actually failed you can have it rewound if the rewinder is capable of making a faithful copy of the original design. In my opinion you do not need to replace both in this case, but it may depend on how particular you are.

If you are not confident it will be a good copy with exact interleaved winding of the original then it will be best to have both replaced commercially available clone transformers. (You should be able to sell your remaining good single Z565 for a good penny to someone in the situation your’e in.) If these clones are not close enough to the original Z656 you may need to tweak the global negative feedback network.

In the US there are a couple of Z565 clone makers but shipping to UK would make those probably prohibitive. In Europe I’m aware of only two, but both may need re-tweaking of feedback.

Thermionic Lab has an “upgrade that is not exact drop-in replacement” but I had heard they are good performers. Check dimensions for fit on this one. https://www.thermioniclab.com/en/pu...35-output-transformer-upgrade-1-veb-pair.html

I believe Magnetic Winding in the UK has a clone with 8K impedance and 23% UL ratio that sound be a good substitute. I have no personal knowledge of either.
 
Hello.
Last week I got one dynaco sca35 amp for restoration from my uncle @analogadikt
One opt was open he requested me to make a drop in replacement for this amp and i was also interested to make dyanaco opt z565 clones I opened the orignal opt and got all the geometry of winding the the amplifier was in working condition but one channel was not working because the output transformer was bad and then I made a pair of opt for this amp .as we make output transformer under the guidance of eletraprint audio(jack elliano sir) and( bud purvine sir) of o-netics they both are my guiders and big supporters i always thanks for them .
So finally after researching a lot for z565 i made exactly z565 opts the winding was really interesting and complicated too and now amp is working perfectly.all photos i have attached here thanks.

Regards
Asnain kolarkar of
Kolarkar audio research
 

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Last edited:
Great work, Asnain.

For the sake of documenting at one place , here are the other similar efforts containing some great information on the Z565's unique winding, by Richard Hughes (retailer/familyguy) and Stanko - also look at David Hafler's patents

https://www.vintage-radio.net/forum/showthread.php?p=1598882
https://audiokarma.org/forums/index.php?threads/rewinding-a-dynaco-z565-transformer.1019903/
 
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Hello.
Last week I got one dynaco sca35 amp for restoration from my uncle @analogadikt
One opt was open he requested me to make a drop in replacement for this amp and i was also interested to make dyanaco opt z565 clones I opened the orignal opt and got all the geometry of winding the the amplifier was in working condition but one channel was not working because the output transformer was bad and then I made a pair of opt for this amp .as we make output transformer under the guidance of eletraprint audio(jack elliano sir) and( bud purvine sir) of o-netics they both are my guiders and big supporters i always thanks for them .
So finally after researching a lot for z565 i made exactly z565 opts the winding was really interesting and complicated too and now amp is working perfectly.all photos i have attached here thanks.

Regards
Asnain kolarkar of
Kolarkar audio research

Do have a winding diagram of the Z565 OPT, as you unwound it - I would be interested in seeing it.
 
Yes that is the one that has been around for quite some time - just wondering what forum member Kolarkar found when he unwound one, was it the same ?
Yes the digram is perfect i used same turns same winding arrangements just did some on work leakage capacitance and inductance to match the orignal.... specs using nomex 418 insulation....

Regards
Asnain kolarkar
 
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Reactions: analogadikt