How to wire up a CTS push/pull switch for coil split

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TheGuitarWeaselTheGuitarWeasel Frets: 3650
edited August 2017 in Made in the UK
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 :-)

Ash

 PS ... next I will show wiring in a phase reversal switch on a CTS pot :-)  
Professional pickup winder, horse-testpilot and recovering Chocolate Hobnob addict.
Oil City Pickups  ... Oil City Blog

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  • MegiiMegii Frets: 875
    Cheers - I have a guitar with push-pull coil split for both pickups, that needs rewiring, and I may as well upgrade to CTS pots while I'm at it, so this is highly useful, thanks for posting! :)
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  • Megii said:
    Cheers - I have a guitar with push-pull coil split for both pickups, that needs rewiring, and I may as well upgrade to CTS pots while I'm at it, so this is highly useful, thanks for posting! :)
    Trying to put a simple 'doing your guitar's own electrics' series here ... I get asked loads of questions all the time, and I'm trying to put the most frequently asked things up for the forum's benefit. Switches are the cause of headaches for a lot of folks.

    I think a soldering hints and tips article with links to good solder supplies and 'how to chose a soldering iron' might be useful. 
    I also plan to try and answer some of the series/parallel and pickup phase questions I get asked a lot, talk about changing your own pickup covers (I do a lot of repairs to pickups where owners have botched this one), 
    Professional pickup winder, horse-testpilot and recovering Chocolate Hobnob addict.
    Oil City Pickups  ... Oil City Blog

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  • impmannimpmann Frets: 7353
    Ash,

    Its not very clear with these CTS pots how you solder in the cables... there doesn't appear to be much access room for the iron so how do you do it (other than 'carefully')... otherwise they look the bomb, far nicer than the Alpha ones.

    Thanks for sharing.
    Never Ever Bloody Anything Ever.

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  • AlegreeAlegree Frets: 354
    I don't think there's particularly a secret to soldering onto the silly eyelets on the board.
    I think it's a really stupid design personally - I far prefer the import design.
    Alegree pickups & guitar supplies - www.alegree.co.uk
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  • Alegree said:
    I don't think there's particularly a secret to soldering onto the silly eyelets on the board.
    I think it's a really stupid design personally - I far prefer the import design.
    I much prefer the eyelets especially if you're trying to a Jimmy Page style - grounding them is nice and easy....my only complaint is getting four of them into a Les paul cavity can be a struggle!
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  • impmann said:
    Ash,

    Its not very clear with these CTS pots how you solder in the cables... there doesn't appear to be much access room for the iron so how do you do it (other than 'carefully')... otherwise they look the bomb, far nicer than the Alpha ones.

    Thanks for sharing.
    Hey, I manage it by using a thin solder tip. You'll struggle using a standard chisel too - think mine is 1.5-2mm chisel so it's actually more like a biro pen nib.

    but you're right, still have to be careful 
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  • TheGuitarWeaselTheGuitarWeasel Frets: 3650
    edited August 2017
    impmann said:
    Ash,

    Its not very clear with these CTS pots how you solder in the cables... there doesn't appear to be much access room for the iron so how do you do it (other than 'carefully')... otherwise they look the bomb, far nicer than the Alpha ones.

    Thanks for sharing.
    it's not really too hard: you need to wire as much of the harness outside the guitar as possible, but that is true of any harness really. I wire the connections to the 'circuit board' first, from the top with the pots mounted on one of our custom cut spacing boards, I'd recommend anyone else use some thick cardboard with holes for the pot shafts. I then make any interconnections between the pots, adding cap/caps etc while I can still get all around the assembly. The final connections are made once the harness is installed. These are usually the pickup inputs, any selector switch connections and output wires to the jack. With scratchplate/control plate mounted harness designs like Strat and Tele this is pretty much a doddle, but a Les Paul etc requires a steady hand. One dodge I use is to have a roll of aluminium foil to hand, and tear off bits as I need them, to wrap and protect other wires while I solder.

    True full size push pull are a pain when space is limited, but that inconvenience is more than made up for by their superb quality over the 'import' mini pot cheapies. You will also find that the the CTS full size push/pull pots are vintage taper and 7% tolerance.


    Professional pickup winder, horse-testpilot and recovering Chocolate Hobnob addict.
    Oil City Pickups  ... Oil City Blog

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  • impmann said:
    Ash,

    Its not very clear with these CTS pots how you solder in the cables... there doesn't appear to be much access room for the iron so how do you do it (other than 'carefully')... otherwise they look the bomb, far nicer than the Alpha ones.

    Thanks for sharing.
    it's not really too hard: you need to wire as much of the harness outside the guitar as possible, but that is true of any harness really. I wire the connections to the 'circuit board' first, from the top with the pots mounted on one of our custom cut spacing boards, I'd recommend anyone else use some thick cardboard with holes for the pot shafts. I then make any interconnections between the pots, adding cap/caps etc while I can still get all around the assembly. The final connections are made once the harness is installed. These are usually the pickup inputs, any selector switch connections and output wires to the jack. With scratchplate/control plate mounted harness designs like Strat and Tele this is pretty much a doddle, but a Les Paul etc requires a steady hand. One dodge I use is to have a roll of aluminium foil to hand, and tear off bits as I need them, to wrap and protect other wires while I solder.

    True full size push pull are a pain when space is limited, but that inconvenience is more than made up for by their superb quality over the 'import' mini pot cheapies. You will also find that the the CTS full size push/pull pots are vintage taper and 7% tolerance.


    Are they really vintage taper? I've bought a few and noticed the tolerances ranges from 1%-7% but could work out the taper on a multimeter. Agree they are superb quality 
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  • impmann said:
    Ash,

    Its not very clear with these CTS pots how you solder in the cables... there doesn't appear to be much access room for the iron so how do you do it (other than 'carefully')... otherwise they look the bomb, far nicer than the Alpha ones.

    Thanks for sharing.
    it's not really too hard: you need to wire as much of the harness outside the guitar as possible, but that is true of any harness really. I wire the connections to the 'circuit board' first, from the top with the pots mounted on one of our custom cut spacing boards, I'd recommend anyone else use some thick cardboard with holes for the pot shafts. I then make any interconnections between the pots, adding cap/caps etc while I can still get all around the assembly. The final connections are made once the harness is installed. These are usually the pickup inputs, any selector switch connections and output wires to the jack. With scratchplate/control plate mounted harness designs like Strat and Tele this is pretty much a doddle, but a Les Paul etc requires a steady hand. One dodge I use is to have a roll of aluminium foil to hand, and tear off bits as I need them, to wrap and protect other wires while I solder.

    True full size push pull are a pain when space is limited, but that inconvenience is more than made up for by their superb quality over the 'import' mini pot cheapies. You will also find that the the CTS full size push/pull pots are vintage taper and 7% tolerance.


    Are they really vintage taper? I've bought a few and noticed the tolerances ranges from 1%-7% but could work out the taper on a multimeter. Agree they are superb quality 
    They are a 30% taper as far as I'm aware, which takes them into vintage territory. The smoothness is what makes me recommend them and the really good, positive feel of the push/pull mechanism.  
    Professional pickup winder, horse-testpilot and recovering Chocolate Hobnob addict.
    Oil City Pickups  ... Oil City Blog

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  • Ah ok didnt realise that. No i think they are great, really smooth action, not too loose or to stiff (don't like either) ad the push pull works a treat. Cheers Ash.
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  • TheGuitarWeaselTheGuitarWeasel Frets: 3650
    edited August 2017
    The soldering iron tip I use for wiring to eyelets ... and indeed any fiddly work. This fits on the iron belonging to my usual digital temperature  regulated soldering station ... but I have other cheapo irons that have this sort of needle point tips fitted. 

    Professional pickup winder, horse-testpilot and recovering Chocolate Hobnob addict.
    Oil City Pickups  ... Oil City Blog

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  • normula1normula1 Frets: 257
    TheGuitarWeasel said
    One dodge I use is to have a roll of aluminium foil to hand, and tear off bits as I need them, to wrap and protect other wires while I solder.


    That's a very good tip. In 35+ yesrs of wielding a soldering iron I'd never thought of that. Wis awarded.
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  • TheGuitarWeaselTheGuitarWeasel Frets: 3650
    edited August 2017
    normula1 said:
    TheGuitarWeasel said
    One dodge I use is to have a roll of aluminium foil to hand, and tear off bits as I need them, to wrap and protect other wires while I solder.


    That's a very good tip. In 35+ yesrs of wielding a soldering iron I'd never thought of that. Wis awarded.
    Thank you :-) My dad was a rocket engineer ... he's 90 now ... but he taught me that one when I was a kid. Handy for when you are heating shrink tube in tight spots too.
    Professional pickup winder, horse-testpilot and recovering Chocolate Hobnob addict.
    Oil City Pickups  ... Oil City Blog

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  • GagarynGagaryn Frets: 1290
    normula1 said:
    TheGuitarWeasel said
    One dodge I use is to have a roll of aluminium foil to hand, and tear off bits as I need them, to wrap and protect other wires while I solder.


    That's a very good tip. In 35+ yesrs of wielding a soldering iron I'd never thought of that. Wis awarded.

    Seconded! I'll be doing this from now on, no more scabby melted wires to show me up as the useless amateur that I am!
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  • Glad to be of help ... 
    Professional pickup winder, horse-testpilot and recovering Chocolate Hobnob addict.
    Oil City Pickups  ... Oil City Blog

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