The cable on a pair of headphones suffers more abuse than most audio cables. It is exposed to far more repetitive movement that many, it has to be reasonably thin and not too heavy. As many a newbie studio tech used to find out, the design also makes a headphone cable the devil’s own job to solder to.
Diagnosing Intermittent Headphone Problems
Careful flexing of the cable and listening to the fault usually shows than the break is close to where the cable exits the plug. The good news is that a repair doesn’t have to lose much of the cable.
If the fault isn’t at the plug end, unfortunately the next most likely place is where the cable enters the earpieces. This isn’t usually so easy to rectify, as either the headphones have to be partially dismantled, or there is another moulded plug which usually can’t be replaced with a generic part. If the headphones can be dismantled, then cutting off a length of the cable at this end and resoldering can follow the same principles as described for the plug end.
Double Check Other Possible Faults Before Replacing the Headphone Plug
Of course, with gear where a 3.5mm headphone jack is mounted to the circuit board of something like an Apple iPod it is possible that the intermittent contact is a cracked or intermittent joint in the player. It is always worth double checking that the fault is in the headphone plug by testing with another sound source.
Finally, dirty contact can be eliminated by cleaning the plug with isopropyl alcohol and a tissue or switch cleaner.
Repairing a Headphone Cable the Easy Way
Some studio headphone makers like AKG, Sennheiser and Beyer know that the cable is the weak link, and make demountable cables with a connector at the headphone end too. The easy way to fix these is to simply order up a replacement and swap it out. However, it is not for everybody.
How to Prepare The Headphone Cable for Soldering
If the fault is at the moulded plug, cut that off with about six inches to spare, and slide the replacement plug shell over the cable, and perhaps consider some heatshrink of rubber sleeving strain relief too. Strip the outer insulation About an inch or so. Slip a silicone rubber sleeve (which won’t melt with the heat of soldering) over each signal conductor, and untwist the strands, which should reveal the synthetic core. Tease this apart and trim with a pair of cutters, so just the enamelled strands remain.
The enamelled coating can be flared off with a lighter flame. This must be done in an area of good ventilation as the polyurethane enamel combustion products can irritate the respiratory system. Bring the lighter flame to the strands for only a fraction of a second, else the wires will heat up and melt down into blobs (see picture). Alternatively try to scrape off the insulation with some wet and dry sandpaper.
Once the insulation is off, twist the wires together and they can be tinned as a regular stranded cable, and the jack plug soldered together as normal.