How this Guide Came About
I got a call one day from my friend who plays bass guitar in a band. He had called because at the gig he did the night before he had got a string stuck underneath the bobbin of the pickup and now it was not making a sound through his amplifier. Instantly I knew what had happened, the string had severed the fine wire that makes up the coil of the pickup. We succeeded in fixing it in a DIY style, here is how we did it.
I need to put a little disclaimer here, I will not take any responsibility to any damage that you do to your guitar. It is not me doing the job and it is one that requires absolute patience and attention to the task at hand for several hours. I can advise you as much as you like, feel free to ask me stuff, but if it is broken it is not my hands, not my fault.
Types of Pickup
This tutorial describes a single coil pickup, not a humbucker. If you don't know the difference then I suggest you look it up because there are some specific complications in the case of the humbucker. If you do know the difference and want to attempt it, good show! If you do you will need a counter. I have not described how to set one up here as it is not so critical on a single coil pickup.
Before you start you will need to acquire some fine magnet wire. You can find this online and if you shop around you can get a fair price, bear in mind that copper is expensive. Make sure that the wire you buy is enamelled, or varnished if you prefer. You will probably want your winding to last forever, so I recommend that you get some quick drying epoxy resin such as araldite. Use this after the job is finished to give your coil some armour.
Out With The Old
Obviously the first step is to remove the pickup. This is different for every guitar but anyone who knows how to handle a screwdriver and a soldering iron will have no trouble. You should keep hold of any small flex wires and take note (AND A PHOTO) of how the fine magnet wire is joined to the flex wire. You will need to reproduce this join later on. Also take note of how much space the coil takes up in the bobbin, perhaps even mark it with a sharp blade.
If the damage is only shallow you may be in luck. If the wire is not potted in glue you can unwind the wire until it is coming off in one piece for a long way and all traces of damage are removed. Then you reconnect the flex wire to the magnet wire as mentioned before. If the wire is potted in glue or the damage is deep then you need to cut the coil out and rewind it from scratch. This is the situation that my friend and I faced.
To remove the coil you will need a sharp knife, a scalpel is best. Have a bowl underneath the coil to catch the copper wires as you cut and peel them out. When you get to the core take note (AND A PHOTO, really, it helps) of how the flex wire is connected as before.
You should now have two sets of notes about connections, a bowl full of fine copper magnet wire, two pieces of flex wire and an empty pickup bobbin.
In With the New
Reconnect you new roll of magnet wire to one of the pieces of flex wire that you removed previously. Try to keep any colour codes the same. I find that the easiest and neatest way to make this connection is to strip about 10mm of the flex and clip the old solder off. Then I carefully coil the end of the fine magnet wire around the exposed copper flex fibres. I then apply heat to the flex fibres with the soldering iron and the solder directly to the fibres. When the heat is sufficient the solder will melt and flow along the fibres by capillary action. As it does this it will melt and burn off the enamel on the magnet wire that was previously wrapped around. A coating of quick drying epoxy carefully applied to the join will ensure that there are no short circuits.
While the epoxy dries it is time for you to set up your winding machine. This is the fun part, you get to design and build a machine to wind your coil. I built mine by taping 2 beer cans to a table and making a hole in each big enough for a pencil. By using two of the same type of can, and by making the hole in a recognisable part of the beer cans print you can ensure that the pencil stays level. You need to find a way to mount the bobbin in a battery powered drill and used this as the drive mechanism/motor. You may need to use some items such as a stool and some books to bring the arrangement to a comfortable level.
Firstly put the flex wire in as it was originally (refer to your notes and your photo) and wind the fine wire onto the bobbin ten times by hand.Tape the flex wire down to stop it flapping in the way then gently press the trigger until the bobbin starts moving. Grip the wire between your thumb and forefinger and slightly strengthen your grip until the wire being wound on to the bobbin is taut. DO NOT grip too tightly or the fine wire will snap and you will need to start again.
The actual winding process is a bit gruelling. As your coil grows be sure to move the wire back and forth so that it builds up consistently. When the coil is at the marks that you made in the bobbin it is finished. Solder the other flex wire onto the end of the magnet wire as before and restore it to its original position (check your notes).
Now Test It
If you want it to last forever, mix some epoxy resin and apply it liberally (but also carefully) to the coil. You may want to test it before you do this. To test the pickup attach the flex wires to a 3.5mm jack socket (just twist the wires on as this is a temporary measure) and connect this to your computers microphone socket. Use some recording software to make an audio track and place a mobile phone speaker right next to the pickup's poles. Play some music through the mobile phone. The music should be recorded into the computer. This is because the speaker in the phone works magnetically, so the close proximity of the speaker to the pickup causes a current in the pickup coil due to the disturbance in the surrounding magnetic field.
If the audio software does indeed record the music then congratulations, you have wound a guitar pickup. Mount this back into the guitar and play some rock and roll!