So I have a stereo 1/4" plug and cable. I cut off a portion because I want to use it to plug a sound device directly into a project board. It yields 3 wires like expected. I was expecting 3 insulated wires or 2 insulated and one not within the overall insualtion. Instead, the outer insulation is double insulated and there are three uninsulated but varnished bundles of very fine wires, every strand varnished. Each of the 3 bundles is maybe 10 wires wrapped around some synthetic fibres. The varnish seems to be better than 5M ohms per inch. How do I get this off the end so I can solder the wires down ? Any ideas?
I unwrapped the three bundles and cut away most of the synthetic fibres for this image. I would like to unvarnish perhaps the last quarter inch of each bundle.
It can be hard depending on the type of varnish used. The easiest is the varnish designed to burn off with just heat from a soldering iron. I usually end up using "emery cloth" and taking my time, light pressure.
OK, I think I got this. I used a butane torch on low to remove the varnish (it ate a bit of wire too, but not too much). Then I took a 0.4" or so length, ran it parallel to a piece of solid wire on my solderboard, and encased them both with solder, about 4 pads worth for each line. The resistance now between the terminals on the 1/4" headphone plug and the end of the solid wire measures about 0.2 ohm. That sounds pretty good to me, is that about right? This wire is really thin so I would expect resistance from the wire itself. And now I can run that solid wire into my project's audio IC (i.e. something similar to this http://nuewire.com/info-archive/msgeq7-by-j-skoba/). Thank you for getting me to think about this is a physical solution and not some chemicals - that was where my mind was on this earlier.
If its polyurethane lacquer then beware cyanide in the fumes - a hot soldering iron will both remove the lacquer
and form a smoke plume that will tend to take fumes past your face and traces of cyanide will make your
nose sore - this can't be a desirable thing!
Even with a hot iron the polyurethane layer only peels away slowly so it takes a little patience. Other materials
may not melt back - they may char a bit (then emery paper will have an easier job removing it).
A butane torch will oxidize the wire so solder may not wet it properly - might as well use emery paper in the
first place.
Commercial approach is a hot solder pot to dip the ends in for a while I believe.
MarkT:
If its polyurethane lacquer then beware cyanide in the fumes - a hot soldering iron will both remove the lacquer
and form a smoke plume that will tend to take fumes past your face and traces of cyanide will make your
nose sore - this can't be a desirable thing!
Even with a hot iron the polyurethane layer only peels away slowly so it takes a little patience. Other materials
may not melt back - they may char a bit (then emery paper will have an easier job removing it).
A butane torch will oxidize the wire so solder may not wet it properly - might as well use emery paper in the
first place.
Commercial approach is a hot solder pot to dip the ends in for a while I believe.
Well, the proof is in the results, so to speak, right? I knew it might not be a good contact so I soldered 0.4" of the wire to my project wire, all of it encased in solder. The results is 0.2 ohms from jack to my copper. Can't I call this a success? It seems to be fine for what I am trying to do (graphic equalizer display based on the MSGEQ7 chip). When I connect a small speaker to the project leads that come out of the patch of solder and connect my iPod Nano to the jack, it actually sounds OK.
I have a thermal wire stripper. Strips any kind of wire, without nicking the copper. Works great even on magnet wires and even very fine "headphone/earbud" wires.