Most Reliable Headphone Fix

Ever since I have a smartphone, I am ridiculously obsessed with listening to music. Unsurprisingly I bought and broke quite a few headphones over the years. To save a bit of money, I always tired to fixed them. Usually the cable is broken right before the connector, as it is the most mechanically stressed part. It's super easy to fix this, but it is tricky to make the fix last long. With every broken pair I took the chance and improved the design, making it more reliable and simpler to build. My current pair broke a few days ago, so I took the chance to document my latest version for you!

The headphones used in this instructable are the Sennheiser MX475, my personal favorite, but it works with any other pair as well. On avarage these last about 9 months, and with each repair they are usable for about 6 additional months. And it doesen't even cost much! The material is worth a few cents and it only takes about half an hour of your time for this fix!

Tools:

• side cutters, high quality (I like the german brand "schmitz", amazon.de)
• front cutters, cheap
• pliers, fine
• tweezers
• soldering station, temperature regulated, with fine tip (0.4-0.8mm)
• desoldering pump
• hot air rework station
• hot glue gun
• file
• solder fume extractor (my diy version)

Consumables:

• solder, 1mm thick, preferably with lead (lower soldering temperature and more reliable joints) (amazon.de)
• flux paste (more aggressive than the usual liquid kind I use) (amazon.de)
• solder iron cleaner, dry brass/copper recommended, but wet solder sponge is ok, too
• hot glue (I like pattex brand, amazon.de)

Materials:

• broken headphones, preferably with round cable (I fix the MX475 in this instructable) (amazon.de)
• heat shrink tubing, 2mm diameter (depends on the thickness of the headphones' cable)
• solid copper wire, 0.8mm diameter (the kind used for the mains installation)

The links included show the products I've actually used, not just a similar product. Unfortunately I could not find identical products on amazon.com, so just use google translate and find a similar, locally available product.

Slowly wiggle the cable to figure out where the broken area is. Cut through the cable so that the cable attached to the actual headphones is fine.

Take the other piece with the connector and use the front cutters to carefully dismantle the inner, metel part. You should be left with a part that looks like the one in the image above. Note down to which wire is soldered to which ring.

Desolder the remaining wires and remove the old solder with the desoldering pump. This works especially well when you add a little fresh solder beforhand. If you like, you can also use desoldering wick instead. If you use a vice to hold it while soldering, add some cushioning material to prevent scratches; I like to use a cheap, dry soldering sponge for this.

Cut off 3.5-4cm of solid copper wire and use some pliers to bend one end to a small loop like shown above. The loop should fit tightly on the last metal ring. If you have, round nose pliers will be very helpful. On the straight end are some sharp edges, remove them with a file.

For a solder joint with good mechanical strength the solder must completely fill the gap between connercot and copper wire. You'll notice that adding more solder does not necessary help a lot, if it doesn't flow into the gap.

For a good solder flow you'll need 3 things:

1. high quality solder, preferably with lead
2. flux, I like to use a rather aggressive paste for this kind of work
3. the right temperature

Out of this three things the last one is the trickiest: You need to heat up both, the copper and the connector quickly and evenly, without burning the plastic. I usually set the soldering station to 320°C. For good heat transfer the tip must be clean and freshly tinned.

1. Add a tiny amout of solder to the connector, use flux to spread it evenly. Clean the flux residue up afterwards.
2. Test fit the support wire, if it doesn't fit anymore you may need to remove some molten plastic with the utility knife.
3. Apply new flux.
4. Place the support wire over the connector hold the iron where the gap in the loop is.
5. Progressively add solder until all metal is covered evenly. Don't move the soldering iron, let copper wire do the heat transfer.
6. Let it cool.

Warning: You absolutely want to have a solder fume extractor for this. Not only is this kind of flux even worse than the normal stuff, but melting or burning plastic will release toxic fumes. Under no circumstances look directly on top of the connector, the rising fumes will cause a intense burning sensation in your nose and eyes. I'm no expert, but there's no way this could be healthy.

Before you do anything slide an about 2cm long piece of heat shrink tubing over the cable. Later it harder and it's easy to forget :)

Strip off the insulation about 8mm of the insulation of the cable. For cheap cables you might get away with a pair of sharp sidecutters, but for the silicon cable of the MX475 I needed to cut the insulation with a utility knife.

The color on the wires is actually lacquer and insulates the conductors from each other. The easiest way is simply to burn it away. No, not with a lighter, but with a soldering iron set to maximum temperature (450°C). Tin about 2-3mm of each wire.

First solder the ground wire to the last metal ring. When the support wire is cooled down push the heat shrink tube over it. This will provide enough support so solder the remaining two wires. Solder them according to the notes you've taken earlier.

Gently connect this still fragile connector to a device of your choice. It's super helpful to have left/right balance setting for this. Are both speakers working as they should? If not, find the problem before continuing.

Power up the hot glue gun and wait till the glue is melted. Meanwhile shrink the heat shrink tube. Place a 'blob' of hotglue over the end of the connector. It does not need to be pretty at all, well take care of that in the next step.

Whack up the hot air rework station to the maximum airflow and set the temperature just high enough to melt the hot glue. Hold the metal part of the connector with some pliers and slowly turn it in the airstream. You should expect that excess hot glue will drip. When you are satisfied with the looks, give it some time to cool off, or it will stick to anythingit touches.

Over time the hot glue will crumble and the cable might break again. In that case simply remove all hot glue, desolder the wires and continue from step 6.

Congratulations, you're done! Rock on! :D