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How To Convert A Pot To Allow Bypass


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I did this tutorial for someone and thought i would post it here as well:

Ok this is a usual mod to do if you think your guitar will benefit from having no tone pots. it basically means the tone pot will be bypassed when turned on full.

It can also be used as a neck adder volume on a strat. If you use a normal pot for this then you will need to keep playing with the extra volume control. If you do this mod so the extra volume control is removed from the circuit at the start of its travel the 5-way switch will function as normal!

ok, so here is a pot:


notice the four tabs holding it togther - the first job is to bend them back:


the evrything comes apart nicely:


notice th bit with the solder tags and the carbon track in the middle of the picture - thats the bit we need to change. When the pot is turned up full the metal springy bit attached to the pot shaft contacts the carbon track near the first tag and as it is tuned down that moved towards the 3rd tag.

if we want to bypass it we need to break the contact between the carbon track and the metal springy bit. nail varnish works quite well

here is a tone pot modified to be bypassed when turned on full:


the nail varnish is applied to the section close to the 1st tag. Notice i also mark the outside of the pot so i dont mix this up with an unmodified one.

the tone pot can be wired as normal and will be fully bypassed when turned to the 9/10 position

use traditional nail polish (smells nicely of apple drops) rather than cheap plasticy flexile stuff. It will last longer.

this mod can obviously be reversed with nail polish remover. It will ventually wear out but not for a good long while if you let the nail polish dry really well before putting the pot back togther

right, i said this could be used to make a neck adder switch.

Fistly you will have to modify the pot slightly differently - because if you use this one you will never be able to turn the neck pickup up full. So instead we will apply nail polish to the other end of the carbon track - this will mean the neck adder volume is bypassed when turned down and the strat will function normally (apart from the missing tone)

once you have the modified pot you need to unwire both tone controls from the strat.

Rewire the one you want as master tone so it attaches to the 1st lug of the master volume pot rather than the switch.

Now attach a wire to each of the first two lugs on the modified pot. One of these wires will be attached to the 5-way switch where the neck pickup attaches, the other will be attached to the 1st lug of the master volume pot doesnt really matter which way round it goes.

So with the neck ader volume turned down you have normal strat opperation with master volume and tone. then if you are in any of the first 3 settings (bridge, bridge/middle, middle) you have the neck adder volume control to gradually bring in the neck pickup. It will always be on till you turn it down again and switch opperation returns to normal

Ok, i have tested the modified neck adding volume pot and it works well. There are some taper issues that mean that most of the adjustment is in the second half of the volume pots travel but that is fairly common for volume controls anyway! You can buy a version of this from rothwell that has a 'custom made Reverse Log Taper Potentiometer' that should function a little better in that respect.


here is stock strat wiring, i havnt drawn all the earth wires to keep it clear,


This is wired so the middle tone pot affects the neck pickup and the end tone pot affects the mid pickup. the tone pot for the mid pickup shares a capacitor with the neck pickup tone.

the first job is to remove two wires to disconnect the mid pickups tone pot:


This tone pot can then be removed and modified like i described above.

the tone pot is then re-installed and two new wires are put in. i have done these in green for clarity:


notice one goes to the neck pickups tag on the pickup switch and one goes to the volume control.

This is the basic mod completed. You now have an extra control that allows you normal strat operation when turned down but allows you to add the neck pickup to other selections when you start turning it up.

I just had a look at the rothwell neck adder fitting instructions and this is as far as they go.

the problem at this stage is that you have a tone pot that only affects the neck pickup so i want to convert it to a master tone. There are two ways to do this. the first way would be to disconnect the tone control from the switch and re-attach it to the master volume pot - but we already have two wires there so its getting crowded. the other way is to connect a couple of tags on the switch like this:


if you dont want the bridge pickup to have tone then just connect the two tags near the end of the switch rather than all 3! I would do this extra stage with the rothwell neck adder as well


You now have master volume, master tone, 5-way switch that operates normally and a neck volume to add neck pickup if you want it but is bypassed by turning it down

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