...But It Works

It definitely ain't pretty, but it works...

The molded plugs manufacturers place on electronics items drive me crazy. It seems they always fail. Yesterday, I was walking along, minding my own business when all of a sudden, the audio started cutting out sporadically on my Koss Plugs.

by adjusting the angle at which the cord left the molded plug, I was able to make it through my walk, but I knew it was just a matter of time and frustration before one or both channels failed completely.

Being the cheapskate that I am, I didn't want to just go purchase a new set, so I decided to try to effect a repair.

After a fair amount of Googling, I found a great little site - Headwize - that had a wonderful fact filled FAQ with a critical tidbit related to repairing headphone cords:

Why can't I splice/solder/repair headphone cords from Sony (and some other brands)?

The wires in Sony headphone cords are insulated with a lacquer coating, which must be removed to make an electrical connection. Most low-wattage soldering irons are NOT hot enough to vaporize the coating. Here are some options:

Dip the wires in alcohol and ignite with a match. The ignited alcohol should burn off the insulation. (Note: I have received email that merely heating the wires with a match or cigarette lighter (without any alcohol) works equally well.)
Put the wires on an aspirin tablet and apply a soldering iron to the wire and aspirin until the aspirin melts. Aspirin is an acid that should dissolve the insulation.
Try a high voltage soldering iron if available which will burn off the insulation while soldering
Use a pocket knife to gently scrape off the insulation
Dip the wires with a lacquer solvent until the coating dissolves
With any method involving a solvent, make sure there is adequate ventilation and avoid inhaling any vapors released by the process. After burning or dissolving the insulation, wipe the wires clean of any residue before soldering.

Well, the match trick, sans alcohol, worked like a charm.

Soldering those tiny little wires proved to be a bit of a challenge, but I finally got them to hold tight. Getting the lengths of those tiny little wires such that I could minimize the possibility of shorting the wires (I wasn't sure how much of the lacquer insulation remained on the exposed portions) was also challenging.

I guess I might have overdone it a little bit with the heat shrink tubing - I used four layers - but hopefully, the connection will remain secure for a while - I wanted to provide enough mechanical support to minimize the strain on the solder joints as I connected and disconnected the plug from the jack, give me something I could "grip," and provide some measure of strain relief.

Actually, the fourth layer of heat shrink, and the reuse of the original strain relief tailing was prompted by a thermal discontinuity in the insulation covering the wires (in other words, I melted the insulation with the heat gun while I was shrinking the tubing). I had planned for the first two layers, and so had placed them on the wire, upstream of the plug, prior to soldering the wires. Unfortunately, I had not planned for an additional layer to cover to boo-boo. In order to get the heat shrink over the plug, I had to use a larger gauge than would shrink down to the size of the wire. The solution was to reuse the strain relief portion of the original molding to fill the void.

Hopefully, the repair won't fail on today's walk - otherwise it might prompt me to transform the plugs into airborne individual aural audio reproduction devices...

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Posted by David at March 10, 2005 01:27 PM