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Standard Bass Guitar Maintenance And Setup
Changing Strings
Truss Rod Adjustment
Bridge Saddle Height Adjustment
Shimming The Neck
Pickup Height
Intonation
Wiring Diagrams
 
Important: before you attempt to do any of the following procedures, please carefully and thoroughly read the entire page, then read each section as you do that procedure of your set up. For best results, do your set up procedures in the same order that they are found on this page. If you have little or no experience setting up guitars or working with hand tools, I suggest that with exception of changing strings, you first learn do set ups or any other maintenance and modifications on an inexpensive instrument.
 
Changing Strings
If you are new at doing any bass guitar maintenance, it would be best for your instrument that you to change one string at a time to avoid a major change of tension all at once on the neck if all the strings were removed. You will need a pair of diagonal cutters or a string winder that has a string cutter on the end. After unwinding the old string from the tuning peg, straighten it as best you can and then carefully remove the string. You might want to save it as a back up in case you break the new string. I like to bend up the end of the old string at the bridge, so when I start to push it out, the ball end doesn't scratch the end of the bass before I can grab it. Carefully pushing the old string through the bridge holes as you pull from the rear side can help get it out easier. With the string out of the way, it's a convenient time to clean the areas of the neck, body and bridge that are hard to get to when the string in place.
Straighten the lead of the old string after unwinding
Bend up the end up of the old string
When you have the new string ready to install, make a very slight bend in the leading end of the string before you push it through the hole of the bridge. Push the string through the hole with the bend up so you can grab it easier and it doesn't go under the bridge saddles. If your bass is designed so that you can load the string through the back, bending the leading end won't be necessary and just pass the string through the ferrule. In either case, carefully guide the string through the hole and over the bridge saddle. Hold the string, especially the ball end away from the body of the bass so not to tear up the finish. When the string is completely through, cut the leading end approximately 3 inches past the intended tuner post. For best results, the string should neatly wind around the post 2 to 3 times.
Carefully pass the new string through the bridge and over the saddle
Cutting the leading end of the string
With a needle nose pliers, make a 90° bend in the string approximately 1/2 to 3/4 inch from the leading end. Put the bent end of the string in the hole in the in the center of the slot of the tuning post. The string should be wound from the side of the tuning post that makes it look most parallel with it's direction over the fingerboard, which with most bass guitars is usually the side opposite the tuner key. Now hold the leading end down with your thumb and the rest of the string up with your index finger as you wind the tuner key to bring the string to pitch.
Make a 90 degree bend at the lead of the string
Placing the lead of the string in the post hole
Now hold the leading end down with your thumb and the rest of the string up with your index finger as you wind the tuner key with your other hand to bring the string to pitch. You want the first winding of the string to be at the top of the post, the last winding at the bottom of the post. Keep the string from crossing over itself on the post. As the slack of the string is taken up, be certain that the string is positioned in its saddle and nut slot. Before you bring the string up to pitch, position the string under its retainer on the headstock if there is one for it. Do not tighten too quickly, you can break or damage the string if it goes past its normally tuned pitch. Follow the same procedure for the remaining strings.
Hold the string like this while winding it up on the post
The string, properly wound on the post

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Truss Rod Adjustment
Truss rod adjustments are something I advise a player who has had no experience at this, to learn on an inexpensive instrument. Improper adjustments can wind up in a costly trip to a repair shop visit with your nice bass. Most basses have the truss rod adjustment at the head, where you might have to first remove the truss rod cover. Some adjust at the body end of the neck and the neck might have to be removed on some cases, like Fenders made before the 80's. Turning the truss rod adjustment to the right (clockwise) reduces forward bow, no matter which end of the neck the adjustment is made. Turning the truss rod adjustment to the left (counter clockwise) reduces back bow, no matter which end of the neck the adjustment is made. The truss rod adjustment should never exceed more than 1/8 turn at once. It might take two or three days to get your neck to the proper adjustment. Never force the adjustment to turn. If you can't turn it, it may already be at the end of it's traveling distance on the rod. Forcing it can break the truss rod and /or pop the fingerboard off the neck. To tell if your neck needs an adjustment, using the tuned strings as a straight edge, get a guitar capo and capo the strings at the first fret. After putting on the capo, holding the string down at the last fret, you should be able to slide a piece of loose leaf paper between the string and the 9th fret, with the string baredly moving at all. Or you can hold the string down with your first finger on your left hand and hold the string down at the last fret with your other hand. With your pinky on your left hand go to the furthest fret you cab reach with it and tap down on the string. It shouldn't move much, just enough to hear a tiny plink noise. If there was no sound, your neck is too straight or has a back bow and the truss rod adjustment has to be loosened (turned left). If the string has to be pushed down a bit and the plink is loud, the truss rod adjustment has to be tightened (turned to the right). Exactly how much relief the neck of your bass should have, will depend on the strings you use and your playing style. If your strings are buzzing against the first few frets, your neck might need a little more relief
Truss rod adjustments on Rickenbacker 4000, 4001 and 4002 basses need to be performed differently and is covered on the Rickenbacker bass maintenance page. Rickenbacker 4003 and 4004 basses can have their truss rods adjusted as described above. Rickenbacker basses have 2 truss rods in the necks for more accurate adjustments. Some manufacturers will also put two truss rods in the necks of their multistring basses, especially basses with 8 or twelve strings.
The Fender Precision made in Mexico Fender Precision has the adjustment at the head and takes a 3/16" Allen wrench (below, left). The Musicman basses have a very cleverly designed truss rod adjustment wheel. You insert an Allen wrench or thin screwdriver into one of the holes to turn the wheel (below, right).

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Bridge Saddle Height Adjustment
Adjusting the bridge saddles is usually done by turning screws, one on each side of the bridge saddle. The screws are usually adjusted with an allen wrench usually a 1/16" allen wrench is the right size. Many guitar manufacturers will supply a bridge adjustment allen wrench with a new instrument. Turning the screw clockwise raises the bridge saddle, therefore raising the string height. Turning the screw counterclockwise lowers the saddle, therefore lowers the string height. The height of the strings are usually 3/16" from the bottom of the E string to the top of the 12th fret. The first string can be slightly closer to the fret. The overall string height as well as the string to string height on your bass should depend on your style of playing, type of strings used and the radius (curvature) of the fingerboard. After you have changed the string height, you will have to retune the string since lowering the height of a string will loosen it and raising the height of a string will tighten it.

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Shimming the Neck
This step is for bolt on necks only. Shimming the neck is done if all of the above steps are performed correctly and string height is still unsatisfactory. Loosen the strings and remove them from the tuning posts. Loosen and remove the neck mounting screws at the back of the body. Carefully separate the neck from the body. There may already be a shim in place that might have to be added to if the string action is too high or removed if the string action is too low. If you need to add a shim, cut the end of a match book cover approximately 1/4 to 3/8" from the end and place it in the neck pocket. Depending on exactly where you place it in the neck pocket can increase or decrease the desired effect. In the deepest part of the neck pocket, the shim will have a small effect on the neck angle which is most likely all you'll need, but you may need to move it a little closer to the center a bit for more effect on the neck angle. Centering the shim between the front and rear neck mounting screws will give no effect. Placing it towards the front neck mounting screws will change the neck angle the opposite direction and increase string height. If you are having trouble keeping the shim exactly where you need it, a tiny bit of Avery glue stick can help keep it in place until you mount the neck back on the body. When mounting the neck back on the body, and you realize that your bass that does not have a tight neck joint, make sure the neck is lined up well before completely tightening the mounting screws. With the neck mounting screws only slightly snug, use the reinstalled strings with barely any tension of them to judge the neck alignment. When the alignment looks correct, tighten the neck mounting screws. The neck mounting screws are among the few screws on your bass that should be very tight when you are done. Then reinstall your strings on the machine heads and tune them to pitch. Shimming the neck too much can cause the strings to buzz against the upper frets. After shimming the neck you may have to readjust the height of the bridge saddles.

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Pickup Height
It’s best to adjust your pickups with your bass plugged into your amplifier so you can get the output you desire, quicker and easier. Don't have the volume level on your amp too loud as you most likely will make some popping noises during the procedure.
Pickup height is adjusted by the screws on the sides of the pickups. Single coil pickups usually have one screw on each side. Humbucking pickups usually have two screws on each side, but some may have one screw on one side and two on the other side. On most basses, turning the screws to the right (clockwise) lowers the pickup. Turning the screws to the left (counterclockwise) raises the pickup. There are usually springs that on the shaft of the screw between the pickup and the body to hold the pickup to the height that is set by the screw. If you want a reference point, set your pickup height to 5/32" between the top of the pole pieces and the bottoms of the strings. Some pickups, like those made by Bartolini or EMG do not have exposed pole pieces. So set the 5/32" height from the top of the pickup to the bottoms of the strings. Depending on your playing style and music you play and the type of pickup, you might want to lower or raise the pickup slightly to get the sound you want. The closer the pickups are to the strings, the louder the output from your bass will be, but if the pickups are too close, your notes will have less sustain and you can have unwanted distortion and the notes might sound odd, especially on the upper frets.

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Intonation
This step is done last in a set up procedure since all of the previous steps can affect intonation. After changing strings, and your bass seems to not need a set up, you should still check the intonation of the strings, especially if you've changed gauges, brand or construction type. You'll need a dependable tuner, small screwdriver and an instrument cable. Plug your bass into the tuner using an instrument cable. Turn all volume and tone controls to maximum on a bass with passive electronics. If your bass has active electronics, turn the volume to maximum and the tone controls the center (detente) position. Hold your bass in playing position and play the first string open. Make sure the string is perfectly tuned, and then play the first string at the twelfth fret. If the tuner shows that the 12th fret note is sharp when the open note is in tune, You must increase the length on the string by moving the bridge saddle in the direction away from the headstock. First loosen the string, the turn the saddle intonation adjustment screw to the right (clockwise). If the tuner shows that the 12th fret note is flat when the open note is in tune, You must decrease the length of the string by moving the bridge saddle in the direction towards the headstock. First loosen the string, the turn the saddle intonation adjustment screw to the right to correct a sharp 12th fret note or to the left to correct a flat 12th fret note. How much you will have to turn the screw depends on how much adjustment it needs. Approximating will come with experience. Bring the string back up to pitch and check the note at the 12th fret again. It might take several tries to get it perfectly intonated. Repeat the same procedure with the rest of the strings. The picture on the left shows a Fender Precision bridge, the picture on the right, a Musicman StingRay5 bridge.
   

Wiring Diagrams
It is important that you realize that some of the uninsulated (ground) leads in these diagrams were drawn longer than they actually should be, so they would appear clearer in the drawings. When wiring, you should actually keep all the uninsulated wire leads, hot or grounded, to a minimum length for neatness and to avoid having exposed wires touch each other.
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Basic P-Bass Wiring Diagram PDF  
Basic J-Bass Wiring Diagram PDF  
Volume Volume Tone Wiring Diagram PDF
   
   
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