Many people get a bit daunted when the first see a CTS full size push/pull switch, even if they have wired cheap push/pulls before.
These are lovely quality and nowadays the only ones I sell, but with their 'circuit boards' and plastic shrouded backs they look very intimidating.
First the theory: A coil is shunted or turned off (tapped is actually the wrong term) by shorting the link wires between the two humbucking coils to ground. You can
do a 'partial tap/split' by putting a resistor between the link wire and ground, the wiring principal is the same.
Our aim is to have the coil link wires (in the case of my wiring colour code at Oil City, the green and white wires on a four conductor output) simply connected together when the push pull switch is pushed in. However when the switch is pulled out we want both wires to be shorted to ground (in other words a pot back).
The first obstacle with a CTS push/pull is you can't get to the pot back because of the sexy plastic shroud that covers the switch mechanism. Never to fear, there is plenty of the pot side exposed, so it's to that we will make our ground connections. I say connections, because of course when you install a switched pot it's pot side must work as a normal volume or tone as well as it's switched side doing its own little job totally separately and independently,
The CTS push/pull pot has six possible connections into it's circuit board and thence to its poles. It is in effect two separate switches with three poles each, enabling you to split two humbuckers at once with one switch, or just to use one half and split one humbucker.
Lets just look at one half of the switch: The theory with any switch like this is that one pole is common, or always connected, so when activated by pushing or pulling, one or other of the other poles is connected to 'common'.
Soooooooo we want common connected to ground, and both the white and green coil link wires connected to one of the other poles When the switch connects the white and green together to ground the pickup will be split, when it is in the other position the link to ground will be broken.
Helpfully the CTS circuit board has 'common' marked with a 'C' so we start by connecting termanal C1 to the pot casing and hence ground.
Right ... wiring the split. The first thing to know is that when the CTS switch is pushed in, terminals C1 and 2 are connected, when pulled out, terminals C1 and 1 are connected. this is just for the 'left' side of the switch
The right side has C2 connected to 4 when pushed in, and C2 connected to 3 when pulled out ... if we used this side of the switch instead the same wiring rules apply, We ground C2 and connect the series wires to 3 ... but we won't be using it here.
We know we want the white and green wires to be grounded when we pull the switch out, so we must connect the white and green together and then connect both to terminal 1.
To recap: when the switch is pushed in C1 is connected to nothing but ground, when the the switch is pulled out, C1 and 1 are connected and thus both shorted to ground ... coil tap/split done!
Of course the red, black and bare braid from the pickup are connected as normal to the volume pot ... and job's a good-un.
Just some practical points about wiring this up: I find it much easier to put a short
link wire from the white and green wires to terminal '1' , remembering to shrink tube insulate the connection before connecting the other end to the circuit board (rather than try and jiggle both tiny wires into one tiny wiring eyelet).
I also always wire up these switches on the bench rather than in the guitar ... far too little room in there!
Hope this was helpful :-)
PS ... next I will show wiring in a phase reversal switch on a CTS pot :-)