For this project, I am converting a two humbucker guitar with one volume and one tone into one that has a volume for each pickup and no tone control.
This is my favorite setup for guitar wiring because:
1. I rarely use the tone knob on any guitar.
2. I like to keep one volume on zero so the toggle switch becomes an on/off, and can also be used for stuttering, killswitch-type effects.
3. I like to keep the neck pickup at a lower volume for cleaner sound coming through my tube amp, and the bridge pickup on ten for more output at the flick of a switch.
The guitar in this case is a Jagmaster, but this would also work on many other 2 pickup/2 knob guitars that have a 3 way toggle switch.
The whole process took about an hour.
-40 Watt pencil type soldering iron (maybe overkill, but works fast, and I'm not worried about frying any capacitors for this one).
-Needle nose pliers.
-Soldering probe tool thing (has paid for itself a thousand times)
-Razor blade (for stripping the ends of wires)
-Alligator clip extra pair of hands thing (also paid for itself many times over)
-Lead free rosin core solder
-Wet rag (to wipe soldering iron tip)
Step 1: Make Diagram
The way I think about a volume pot is: signal goes in one side, comes out the middle tab, other side is grounded. Reverse the order of the input and the ground, and the knob turns the opposite way.
With this kind of three way switch it's easy too look and see what's connected. Just make sure it's not upside down.
The picture I drew below leaves out the wire that grounds the whole thing to the bridge itself. It also doesn't show that I bend the grounded tab on each pot up so that it and any wire connected to it are soldered to the casing.
Step 2: Disconnect, Clean
If you are new to soldering, the key is patience. Also, if you touch the hot soldering iron, your skin will burn into bubbling blisters that hurt really bad. After burning myself a few times years ago, I learned to respect the tool and to be very careful, and haven't burned myself in many years. BE VERY CAREFUL WITH THIS DANGEROUS TOOL. It will burn the palm of your hand so bad, you will lose sleep because it feels like your hand is in a jar full of poisonous jellyfish.
To remove a wire: get a tiny bit of solder on the tip of the iron, hold it to the connection and wait until the solder melts, then use a probe or pliers to remove the wire. To clean the contact, you can use desoldering braid, or get the contact hot, push the solder through with a probe, let it cool and snip off the little spike of solder with wire cutters.
To connect a wire to a contact: If you stick the wire through and then fold it around and twist it on, it can be hard to remove later, so I usually just stick it through, or maybe put it through and bend it. I usually just touch the contact with the tip of the iron with a tiny bit of solder on it, and wait a while, until the wire itself is hot enough to melt fresh solder. Don't just touch the solder to the iron and drip it on, it wont bond to the metal. The solder should dry to a shiny silver if you did it right.
To connect a wire to a pot casing: I hold the stripped end of the wire to the casing using the tip of the iron, wait a while, touch solder to the wire (not the iron) and build up a little puddle of solder. (This can take a while, and can take forever with smaller wattage soldering irons. Using the big 40W iron it usually takes less than a minute, but be careful, that thing will melt the plastic off any wire that comes near it.) Before removing the iron, I hold the wire down in the puddle with the probe tip so that the wire doesn't move at all while the solder is cooling. If the puddle is shiny when it cools, that's good. If its dull gray, that's not so good.
Step 3: Prep, Solder
Not all brands of pickup use the same color coding system. These are Seymour Duncan pickups, but if you are using DiMarzio, Gibson, or anything else, be sure to go online and look up the color codes.
Step 4: Test, Organize
If everything works, pat yourself on the back, do a little dance, and carry on.
If it doesn't work, then troubleshoot while still plugged in to the amp. An extra wire to use as a test connector can work wonders.
If you even suspect a part is bad, throw it away and replace it. It's not worth spending hours troubleshooting for some crappy 3 dollar part.
The real test is when you have put the guitar back together and strung it, and tuned it, and are jamming on it. If the electronics go out then, you'll have to stop playing, cut the strings off, take the guitar apart, troubleshoot, solder...
Better to do it right the first time. So take your time on each and every move that you make.
Put some music on, or have someone to talk to in the background, but don't ever hurry.