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THE GUITAR PLAYERS COMMUNITY

Replacing Your Guitar Innards

This article is a guide to replacing pickups, control pots and wiring inside your guitar. Often, replacing the stock pickups on a guitar with a better quality ones that match your playing style more closely, will yield better sounds.

This article was inspired by just such a thing - the stock Ibanez pickups on my DTX120 were muddy sounding, and the wiring and pots were knackered.

Because of the many varied configurations of guitar controls and pickup wiring schematics - this is only a generalised guide and specifics will relate to the 2 humbucker / volume / tone / 3 way switch configuration.

The first question you need to ask yourself is "Do I need to replace my pickups or wiring?". The task of replacing pickups isn’t always cheap depending on the pickups you get. If it’s a case of rewiring - you risk getting your connections wrong and stopping the guitar from sending a signal to your amplifier properly. Having said that, if you have duff wiring, pots or you simply want to upgrade pickups - then keep reading.

In my case this was a yes to both points of the question. The stock pickups were pretty standard and gave a plain rock sound. The guitar was second hand and had seen better days for sure. The fret wire was worn down and it was a bit grubby - but this was minor. The main issue I had was the volume and tone pots. Both of these were dying and not giving a clear sound.

A potentiometer with a short split shaft and 3 solder lugs

Diagram of the innards of a potentiometer

The track was starting to wear out on the inner ring as well as slightly on the outer ring. The main problem was the connection between the 3 solder tags - the metal tags are pressed into place to make contact with the resistive track rings. When I had tested them with my multimeter - there was no reading whatsoever. They had to be replaced.

Next up was the wiring. The basic wires that are used by manufactures in Korea / Indonesia / China are quite thin and the shielding is poor. It’s vitally important to use good wire with a high quality shielding. We’re not talking oxygen free copper or anything silly - but it needs to be flexible multi core wire with a proper metal foil / wire screening layer. This is an example of a wire mesh screened cable. I used a cable with a plastic coating embedded with a shielding compound.

If you use normal plastic coated wire - you will get more noise and interference on your guitar. Unshielded cables act as antenna and things like computer or TV screens, radios, lights and any other source of mains power or radio frequency is going to be inducted. This inductance then is carried to your amp and you will get hums and buzzes and this is clearly a bad thing.

Other interference can be reduced by lining the electronics cavity with a copper shield or use a layer of shielding paint. We will talk about these later on.

So, once you have decided on what you want to replace, we will need to get hold of some tools. This is a list of tools that I used or think would be useful.

• Replacement pickup
• Replacement potentiometers
• Shielded wire - about 1 meter to give you some spare
• Soldering iron & solder
• Steady hand tool
• Wire cutters
• Adjustable wire strippers
• Assorted screwdrivers
• Hex nut driver
• Scissors
• Sharp knife
• Fine sandpaper
• Shrink wrap tubing
• Multimeter
• Pen & paper

Some of the tools were not necessary but I found them useful. If you trust your wiring - then a multimeter is not required. I found it helpful to identify the initial wiring problem and also to check my new connections and grounding.

I like to list where I got my parts from in these articles. Many times you see these articles and lists of things to use - but then spend days trying to source parts. Although these components are easy to find, I used www.axesrus.com because they stock a great selection of bits at a good price. Their delivery times are also very very quick. You can find all the parts I used on this page of their site: http://www.axesrus.com/axeknobs.htm I will talk more specifically about the pots you need later. There are quite a few to choose from - so just read on and then check which ones you need.

The next step is to clear a space to lay your guitar down to work on. Because it will be face down, I suggest you use several old towels to protect and support the body and neck. Lay the guitar down and remove the back plate to reveal the electronics compartment.

Make a good diagram of the existing wiring. This is essential. Make note of what wire connects where, and the colour of the wire. This will help when it comes to reconnecting the pickup wires, and especially if you are unable to find a wiring diagram online.

Next you need to unsolder the parts you wish to replace. Generally if your change both pickups, then it’s not too much more effort to redo all of the wiring. Unsolder the parts carefully as you may accidentally melt the other wires coating. It may be easier to unscrew the pots - remove the control knobs first, and then with a hex nut driver (those hexagonal screwdriver type or ratchet type tools)

A hex head for a ratchet spanner

These ensure that you don’t use a normal spanner or a set of pliers to unscrew the nut and risk damaging the finish on your guitar.

So, you’ve remove all the wires and the old pots and pickups. The next step is to clean out the cavity and think about some shielding. Cheaper guitars won’t have any shielding, and the more expensive ones will have shielding paint applied to the cavity. Most models will at least have a metal foil to line the inside of the back plate.

This image shows a copper covered back plate. Axesrus sells a shielding kit containing adhesive backed copper, heatshrink tube, and shielded wire. They also sell the shielding adhesive tape.

These tapes are great for covering the back plate, but can be tricky to properly shield the electronics cavity. Maplin electronics and the acclaimed stewmac site both stock conductive paint. Maplin has a general purpose paint for any electronics application and the stewmac site has a more guitar shielding orientated paint - however this is based in the US and the shipping can be expensive for small orders.

NOTE - If anyone knows any more online stores that stock this paint - please let me know so I can add to this list.

Stwemac conductive paint - 1/2 pint @ $28.56, 1 pint @ $52.98

Maplin conductive paint - 3 grams @ £6.99 (quite a small bottle)

With the copper tape, you need to ensure that there is a complete connection between the layers and that you ground these to the volume or tone pot casing. This ensures that the interference is channelled to the ground. This is where the multimeter is useful. If you can’t get a connection across the layers - just use the soldering iron and some solder to make a bridge across each bit of tape. There are many web pages out there that cover this is far more detail, down to getting the back plate to connect to the inner cavity forming a full shield.

OK, so now we can start to wire up the new parts. The first step here is to get the right pots. There are 2 main types in terms of electrical operation - linear and logarithmic - often shortened to lin and log - and also to just B and A type.

B type are a linear scale and A type are logarithmic.

What does this all mean you ask? Its to do with the change in resistance as you twist the dial.

This diagram shows how a pot resistance varies with the position of the control knob. The volume control pot is a linear taper type. This means that the volume change is proportional to the movement of the control. Moving the volume dial from 1 to 2 is a 10% increase in output, from 5 to 6 also a 10% increase and so on. The audio taper or logarithmic pot is use on the tone control. At the lower settings say from 1 to 6, the change in tone is very slight. Towards the 7, 8, 9 and 10 - a slight change in the tone control will result in an even larger change in tone. This allows for finer tuning compared to a linear pot or for a full out sound when the control is on full.

Just to make sure:

Volume = Linear Scale Pot (Lin) / Type B Pot

Tone = Logarithmic Scale (Log) / Type A Pot

The next step is to insert your new pickup (s) and feed the wires through into the electronics cavity. Strip away the outer plastic (about 4cm) and use a knife to cut away the foil shield to expose the ground and pickup coil wires. You may have a wire wound cable instead of the foil shield. This is usually the ground on the more basic pickups. Don’t cut this off, but instead twist it together and cover almost all of it with heat shrink - just leaving about 4-6mm exposed for soldering. Strip another 4-6mm from each of the inner cores’ shielding and twist the exposed wires together.

Next, you need to refer to your wiring diagram to reconnect all of the parts. If yours isn’t clear enough, or you want to get a more professional version - you can normally find them from the guitar’s website. The Ibanez site had the following for the Iceman / Destroyer series guitars:

This is a generalised diagram showing input and output. This can be doubled up as with a les paul style 2 volume 2 tone setup.

The diagram is easy to follow if you make the connections starting on the tone pot. First, I must make a couple of points.

1, Soldering the pots. From the diagram you can see that there are 6 connection to what looks like the side of the volume pot. This is actually a collection of ground wires from the pickups, tone pot, the switch, output jack and the bridge ground. The connections are made to the back of the pot on the metal casing. Because the pot can be easily damaged by heat, I suggest you do 2 things. Firstly, take a piece of fine grade sandpaper (finishing paper is ideal) and lay it face up on a flat surface. Holding it taught with one hand, begin to rub the pot casing over the sandpaper to clean it up. This will expose the clean metal surface with allows for a good solder connection to be made - also less time needed in contact with the soldering iron.

Oxidised "Dirty" pot on the left, sanded "clean" pot on the right

This is a photo that shows one normal pot, and one that has been sanded clean ready for soldering. The second thing to do in regards to soldering the pot is to try and hold it in a pair or pliers - or as I did - a mole grip. Don’t clamp it so you bend the casing - but just use the pliers / grips as a heatsink to protect the solder lugs from melting away from the resistrive track. Trust me on this one, it does happen, especially on the old pots. I melted the joint that connected the solder lugs and the track rendering the pot useless!

2, The second point is regarding the capacitor. Normally you can just use the old capacitor, but I wanted to explain how their value effects the sound and tone control. My Ibanez DTX120 was fitted with a 473 value capacitor which is 0.047uF (microfarads) or 47nF (nanofarads), but the schematic quoted a 223 which is 0.022uF (or 22nF). Allow me to explain the difference.

The capacitor is what separates a volume control pot from a tone control pot. A capacitor bleeds out a certain amount treble to the ground, based on the capacitor’s value. The higher the value, the more treble the cap bleeds out to the ground, resulting with more bass. A capacitor doesn’t add bass, it just simply removes a portion of the treble based on the capacitor’s value. By picking a certain capacitor value we can passively increase/decrease the amount of bass/treble our tone pot is able to dial into.

0.050uF - 0.001uF caps are used mostly on electric guitars tone pots. 0.100uF - 0.050uF caps are mostly used on electric basses. The larger the value 0.100uF the more bass your tone pot will be able to dial into. The smaller the value 0.001uF the more treble you will be able to dial into. If you are looking for the brightest possible tone, then you can remove your capacitor all together. It would render the tone pot useless though. Without a capacitor in the way, you would get the "true" tone of the pickups. The chart displays the most common capacitor values.

.005uF		Treble and bright flow thru easily
.022uF		Cuts out a small amount of bright, has good mid range, capacitor used by most players
.047uF		Beefier sounding, lots of mid and bass range, most electric guitars don’t exceed this value
.100uF		Most bass, almost all bright treble sounds are gone, used mostly in electric bass and active pickups

Because I found the sound of the guitar to be quite muddy and the tone pot added way too much bass, I replaced the 473 pot (0.047uF) with a 223 (0.022uF). You will see the capacitor codes written in many ways. Because the capacitors a quite small, manufacturers use the 3 digit code. The first 2 digits give the value of the capacitor, and the final digit is the multiplier (the number of 0’s at the end) The value is given in picofarads.

microFarads (µF)		nanoFarads (nF)		picoFarads (pF)
0.000001µF	=	0.001nF	=	1pF
0.00001µF	=	0.01nF	=	10pF
0.0001µF	=	0.1nF	=	100pF
0.001µF	=	1nF	=	1000pF
0.01µF	=	10nF	=	10,000pF
0.1µF	=	100nF	=	100,000pF
1µF	=	1000nF	=	1,000,000pF
10µF	=	10,000nF	=	10,000,000pF
100µF	=	100,000nF	=	100,000,000pF

So the 473 is a 47000pF (picofarad) capacitor or a 47nF (nanofarad) capacitor or most commonly known as a 0.047uF (microfarad) capacitor. The 223 is a 22000pF (picofarad) capacitor or a 22nF (nanofarad) capacitor or most commonly known as a 0.022uF (microfarad) capacitor.

This isn’t meant to be an electronics lesson - but it can be useful to help work out values on the existing capacitors. A multimeter is the quickest way to tell if you’re no so clued up with all this.

My replacement pickup - The Seymour Duncan SH-13 "Dimebucker"

Right, so you have the pickups in place, you have the pots clean, and the right capacitor. You can begin soldering. Don’t place anything in the electronics cavity yet as it’s easiest to solder the parts outside the guitar, then fit them in later. First, solder the capacitor to the tone pot. The helping hands tool (that thing with the 2 arms and crocodile clips) to hold the parts in place. If you have 3 arms already, then don’t worry about this. Next, connect the output jack to the volume pot. This requires some of the shielded cable.

This comes in 2 sorts. The single core stuff that I used (from axesrus) is a single metal core and a shielded plastic coat. This means I needed 2 wires from the hot tip from the guitar lead to the volume pot pin, and then a second wire from the guitar lead ground (the jack case) to the outer case (ground) of the volume pot. If you have the wire mesh shielded wires, you can use the middle core for the hot to volume, and the outer shielding to go from the volume pot case to the output jack case (ground).

Either way, you need to strip off the outer plastic by about 1cm (for the metal shield) or if you use the single core with the plastic outer shielding, then strip back about 4-6mm (a bit less as you don’t need to separate the wires). Solder these in place, remembering not to heat the pots up too much as they can be damaged.

Next, wire up the switch. my Ibanez DTX120 uses a 3 way switch that has each pickups hot output connected to one side of the switch, and the centre pin output from the switch goes to the volume pot. You can then select the neck pickup, bridge pickup, or both (with the switch in the centre position). The volume pot needs one of the solder tabs to be connected to the outer case. I use a little piece of wire that I trimmed from the capacitor legs to make a wire join. Again, use the helping hand tool to hold this on place as you solder it.

At this point it’s best to rest the pots and switch in place as this helps with soldering in the pickups.

Next, solder the bridge ground (that grounds the strings and exposed metal parts on the guitar) to the back of the volume pot. Finally, solder the hot output from the pickups to the switch, and the pickup grounds to the volume pot casing.

A good tip - if the wires get a bit tight, you can always solder to the back of the volume pot - but be careful of the capacitor. Have a friend clamp the capacitor leg that connects to the tone pot case so that it acts as a heatsink - and you won’t damage it. It’s also sometimes easier to apply a little solder to the back of the pot case before heating the wire and soldering in place.

The final step is to fit the pots and switch back into the cavity, and tighten up the screws. Remember to use the washer on the other side of the guitar so that when you tighten down the screw - it rubs against the washer and not the guitar finish. At this stage you can also test the connections (volume and tone pot cases, bridge etc to the output jack case) to make sure your wiring is sound. Replace the back plate and plug in the guitar.

The finished guitar with new back controls. The bridge will be replaced later (also in black!)

The SH-13 Dimebucker pickup

Other wiring diagrams can be found online by simple searching for your guitar model on google i.e. Les Paul wiring diagram etc. If you have any problems when you plug the guitar into your amp, you need to go back and check each connection in turn with the diagram. Check that the pickup hot and ground are wired the right way around and also the output jack hot tip and ground.

Good luck with any similar projects, and feel free to ask for help on the forums. We’re only too happy to assist.