Okay...
So a "really easy" question turned into a major exercise in mental aerobics. Not that I'm complaining, becuase I've been OOW since this whole COVID thing started (thanks, big oil company that cut its CAPEX budget by 20% as a result), so mental exercises are welcomed.
Anyway....
I sat down this morning after the dog woke me up at six and started sketching based on a
Fender 5-way "super-switch" (see photo).
In my wiring diagram. I've drawn the switch as if looking at it mounted on the pickguard, and you are looking at the underside of the pickguard, as you would be soldering the thing up. So Bank A is on the metal side plate side, nearest the guitar neck, with the output lug also nearest to the guitar neck. Bank C C is the bottom left, nearest the metal side plate with the common or output lug to the bottom left. I think you can figure out for yourselves where banks B and D are for yourself, if not please put down the soldering iron and step away from the work bench.
Pickup Selection:
Bank C is used to control the outputs to the volume pot. In positions 1 (bridge only) and 2 (bridge and middle) the bridge hot (black on an S-D humbucker) is connected via C-1 and C-2 to C-COM, then to the volume pot. The neck pickup is not connected at all. In positions 4 (middle and neck) and 5 (neck only) the neck hot (black) is connected via C-4 and C-5 to C-COM. In position 3, neither the neck or bridge are connected at all.
To control the middle pickup I've used Bank D. The middle pickup hot is connected to D-2, D-3 and D-4 then to D-COM. D-COM jumps to C-COM. So in position 1 (bridge only) and position 5 (neck only) the middle pickup hot is completely disconnected as it should be. In all three other positions the middle pickup is hot. You only get bridge plus middle in position 2, however, as the bridge is only connected in positions 1 and 2. You don't get the middle in position 1 because the middle hot isn't connected to position 1. Similar logic applies to positions 4 and 5.
For all pickups, the grounds go to the backs of the volume or tone pots - green and bare for the humbuckers, black for the single coil.
Auto Coil Splitting:
For auto coil splitting I've used Bank A. I selected Bank A simply because it makes wiring up the middle and neck tone control neater. The red and white "middle" wires for the bridge pickup are connected to A-2, the red and white for the neck pickup to A-4. A-COM is connected to ground, so in positions 2 and 4 only the red and white wires for the bridge and neck pickups, respectively, get grounded and so the pickups get coil split.
Bridge Tone Control:
The bridge tone pot is easy. Just wire it in parallel to the bridge hot input on the switch, job done. It works in positions 1 and 2, where it is needed, and since the pickup isn't connected in positions 3, 4 and 5, it doesn't do anything to the overall output in those three positions.
Middle and Neck Tone Control:
This is the tricky bit.
We need to connect the middle and neck to a common tone pot without creating a short on the switch that makes the middle or neck permanently active.
The way I came up with is as follows. There may be other / better ways, but I THINK this works.
The middle pickup is permanently connected to the middle/neck tone pot via a jumper from D-2, D-3 and/or D-4 to B-COM and then out to the tone pot. Middle tone control only comes into play, however, when the middle pickup is active via bank D and the jumper to Bank B, i.e. positions 2,3 and 4, i.e. when it's wanted. In positions 1 and 5 the middle pickup connection is dead, so it doesn't contribute to the overall tone (I think).
The neck pickup is connected to the middle/ neck tone via a jumper from C-4 and/or C-5 to B-4 and/or B-5 (both 4 and 5 must be connected at each end). In positions 4 and 5 the neck pickup is activated via Bank B, in positions 1, 2 and 3 on Bank B it's disconnected.
