Mike,
Ya got me. Question #1
How can anyone change the phase on a single coil single pickup? You would have to switch the two wires coming out of the pickup. What would that do with a single single coil pickup? Not much other than increasing the hum. The reason being: the outer wrap (The end of the coil that is on the outside of the wrap) is hooked to ground. Why? Because the outer wrap now acts as shielding. If you put the inner winding to ground, then the outer winding is exposed to electrical fields since it hasn't any shielding. In order to use a phase switch, you have to have a second pickup. One would be wired normal. The other would go between normal and reverse. Phasing requires one signal to be compared to the other. The second pickup is either in phase with the first pickup, or out of phase with it.
Question #2
What the heck is a single coil pickup doing with a 5 way switch? Is it a single hum bucker?
Just a thought. Your repair guy is making up terms.
First you can split the pickup IF it is a hum bucker. There are a couple of methods to splitting pickups. One is to parallel them pos to pos neg to neg. (Actually there is no positive or negative since a pickup generates an AC voltage, but for the sake of simplicity, call the ground most point of the coil negative, and the outer most wrap positive) . Another is to simply kill one of the windings by cutting it out of the circuit, thus turning it into a single coil pickup.
If you add a second (neck) pickup, you can put in a switch that does what I said in #1 concerning phasing One of the coils would remain as is, while the second coil would have its wiring flipped (reversed) through a switch that would allow you to chose between a reverse coil or a normal coil wiring scheme. That would be called a phase switch.
Unless you have a Varitone in your Axe, I have no idea what a 5 way switch is doing in a single coil (pickup) guitar. Enlighten me please.
I am going to Google your guitar to see what you have.
HEY! That is a single coil.
No way can it be phased or split. Is your tech ignorant or is he blowing smoke? Now if you add a second pup you can change phasing between the two. But you still can't split them. Even if he were to rewind the coil into two windings, phasing them against each other would only cancel the electromagnetic energy when they were out of phase and there would be "0" output in the out of phase position. Your pickup would in a sense be canceling itself.