Soldering Varnished Transformer Wire

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Ray P
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Soldering Varnished Transformer Wire

Post by Ray P » Thu Jul 05, 2018 9:40 pm

I need to solder some Slagle autoformer volume controls to PCBs; no problem with most connections as they're via pins but for two of the connections I need to solder some thin/delicate flying leads from the autoformers. The flying leads are very fine varnished transformer wire. I need to clean the varnish off in order to solder them but I'm nervous of scraping it off given how fine they are. Any tricks for removing the varnish without needing to get too physical?

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Dave the bass
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Re: Soldering Varnished Transformer Wire

Post by Dave the bass » Thu Jul 05, 2018 9:53 pm

I've used heat from the iron before to burn the varnish off, I've also use a blade to scrape insulation off to but go gently.
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Mike H
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Re: Soldering Varnished Transformer Wire

Post by Mike H » Thu Jul 05, 2018 9:57 pm

If like what Danbury used to use, will melt and burn off at 400°C, he had a machine to dip the wrapped terminals (with still enamelled wire) into a very hot solder bath, which melted off the enamel then the solder er, soldered it.

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Re: Soldering Varnished Transformer Wire

Post by RhythMick » Thu Jul 05, 2018 10:08 pm

I use a scalpel. 2 techniques.Both require a gentle touch.

If you get the wire flat you can roll it while RESTING the scalpel blade on the wire - no weight or force. Using this I've been able to cut through the varnish and pull it off without nicking the wire. However if the wires are from the autoformer they may not roll.

Other technique is to scrape towards the cut end, scalpel facing back.

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Mike H
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Re: Soldering Varnished Transformer Wire

Post by Mike H » Thu Jul 05, 2018 10:17 pm

I think the problem here the wire is EXTREMELY thin.

I've doen Litz type stuff that's bad enough.
 
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IslandPink
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Re: Soldering Varnished Transformer Wire

Post by IslandPink » Thu Jul 05, 2018 10:30 pm

I've worked with litz in bundles (36/48 and 140/40 ) for speaker and hook-up wire.
It just seems to need a bit of bare wire at the ends to get things started, then a hot soldering iron at 400°C+ which boils/chars off the polyurethane.
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