If you don't want to send your guitar to the shop every time something goes wrong, it pays to learn how to set up an electric guitar. By its very nature, a guitar's portability makes the neck susceptible to a variety of environmental factors like temperature and humidity. These can easily disrupt the tuning and the intonation. Also, changes in string gauge can throw the pressure balance out of equilibrium, causing unwanted side-effects that can thwart your guitar's playability. To set up an electric guitar, you first need to know some basic terms and common issues that can disrupt a guitar's playability.
Action: The action is the amount of force needed to bring the guitar string to the neck in order to produce a clear pitch. High action means a greater distance between the string and the neck, and that the the guitarist must apply more pressure to produce a clear pitch and vice versa. The action is adjusted via the truss rod that runs through the center of the neck. You can adjust most truss rods with an allen wrench at the head stock. A guitar neck is bent slightly and convexly. To lower the action and make the guitar easier to play, reduce the depth of the curve. Do this by small increments and gradually, as abrupt increases or decreases in pressure are never good for a guitar neck. To increase the action, increase the depth of the curve.
- Intonation: The intonation is one of the most vexing issues to guitarists. Play a C Major chord near the head stock and then play the same chord at the eighth fret. Are they the same? If not, you may have an intonation problem. Before worrying about making adjustments to the guitar, make sure that you have a new set of strings. Old strings tend to lose their uniform nature in places where they are most commonly played. Once you have a nice set of strings, look down the surface of the neck from the butt of the guitar to see if the neck is warped. A warped neck can cause intonation problems as well as fret buzzing. From here, you can replace the neck.
- If the neck is okay, locate the bridge. On a Fender, the bridge is segmented into six different moving saddles so that each string length can be adjusted individually. To check the intonation of a specific string, play the string open and then its octave at the 12th fret. If the octave is flat, move the bridge segment (with a screwdriver) toward the butt of the guitar. If it is sharp, bring the bridge in toward the neck.
- On a guitar without individual saddles, the bridge will often have two rotating rods going into the guitar. You can rotate the circular piece to raise or lower each side of the bridge. This gives you less flexibility for each individual string. Your goal here is to center the octave exactly at the 12th fret or to make the distance between the nut and the 12th fret equal to the distance between the 12th fret and the bridge. You might at first try doing one string at a time because cranking six saddles all at once will throw the pressure balance off, nullifying your efforts. Note: Perfect intonation is not possible, so just try to get it good enough for playability.
- Fret buzz: This can be caused by a warped neck, a worn out fret or excessively low action. If you experience fret buzzing with only a single note, chances are it's either a fret that needs to be replaced or a neck warping issue. If it is a group of notes, try increasing the action a little bit. As a semi-permanent fix, you can put a small bit of thick paper (like an index card) under the string in the nut to provide just enough height to eliminate the buzz.
A note on replacing guitar strings: If you get a different gauge set of strings than you did before, the guitar will react in an adverse way. Make sure you get the same strings, or if you get a heavier gauge, you might need to increase the action.