What are some things to check why a pickup doesn’t work?

There are many things that can cause a pickup to be inoperative. Pickups don’t always have to be used and abused for them to fail. Here are some things to check.
? Broken magnet wire from the beginning eyelet or pigtail*: On Fender style pickups the beginning magnet wire is connected to one of the eyelets. The beginning of the coil is wound from the inside and finishes on the outside. It can be difficult to repair the beginning wire if it is broken next to the coil. If the magnet wire is broken near the eyelet, there is a chance the magnet wire can be extended by soldering an extra length of conductor and connecting it to the eyelet. Becareful soldering it to the eyelet and remove excess soldering flux. Extreme care needs to be done when repairing all types of single coil pickps. On early Gibson style single coil and humbucking pickups, the lead wire begins inside the bobbin and extends through an exit hole to be hooked up. It will be difficult to repair if the problem exists with the pigtail inside the beginning of the coil. At times there can be a cold solder joint or break at the beginning of the coil where the magnet wire and lead wire are pigtailed. The coil will have to be completely unwound, repaired and rewound again. Don’t distroy the original wire to do this. It can be re used.
? Broken magnet wire from the finish eyelet or pigtail*: On Fender style pickups the finish wire connects to the other eyelet. If the magnet wire is broken at the eyelet or outer part of the coil, repairing can be made easier. I carefully use a heat gun to soften or remove hardened wax on the outer turns of the coil. I can unwrap as many turns needed to find the break and then reconnect it to the finish eyelet. If the pickup still doesn’t work, then more turns need to be removed to see if there is an external break. I use a fine tooth brush to loosen the break in a coil. At times I use a chemical solvent to remove the outer layers of magnet wire on Fender style pickups. Chemical solvents such as lacquer thinners should be used with extreme care always use a protective eye covering used when soldering or using chemicals. If there is no break visible after examining the coil then the pickup could have ICPC which is listed below. Heat guns and chemical solvents should not be used on plastic Gibson style bobbins. The heat and chemicals can distort and dissolve the bobbin material. If you need to remove old tape that is gummy or sticky, I use lighter fluid as a cutting agent. Use sparingly and wipe off excess fluid.
? *Pigtails: The connection between the insulated magnet wire and hookup wire. I use between 28 & 30 gauge stranded hookup wire for most connections in humbuckers. They are usually the black and white wires used for connecting two bobbins in a humbucker in series or used with single or 4 conductor shielded cable. When connecting the hookup wire, I find it best to sand the magnet wire with 600 grit sand paper to remove the insulation on the magnet wire so soldering (pigtail) is made easier.
? ICPC- Inner coil pole corrosion: Most often on Fender single coil pickups, moisture and condensation can occur inside the bobbin. Playing in hot sweaty nightclubs with moisture at times soaking the pickups can cause major problems down the road. The moisture can cause the magnets to rust and particles of oxidation begin to break down the insulation on the magnet wire. When there is insulation breakdown on the magnet wire, the non insulated copper wire can oxidize and deteriorate. On Fender style pickups, the coil is normally wound directly around the magnets. When the magnets rust it promotes breakdown of the magnet wire. Moisture can be absorbed in the lining of the guitar case and when exposed to high heat or sunlight, condensation can take place within the case.
? Guitar string snag under the lip of the pickup: When playing hard your high E or low E string can snag the edges of the bobbin when there are no covers to protect the coils. I see this often especially on Telecaster rhythm pickups when players remove the covers. This leaves an exposed coil which is subject to string or pick damage. During the 60’s Jeff Beck started the fad of removing covers from his Gibson humbuckers. Soon after that many players started using lighter strings which have less tension and bend easier. The lighter strings, tension and exposed humbuckers contributed to the strings getting snagged under the outer edges of the bobbins. This happens more and more with guitars equipped with tremolo’s that can drastically loosen the strings. The loose plucked string is more likely to get snagged under the outer edges of the pickup so extreme care while playing needs to be used. If you desire not to use covers make sure you don’t damage the coils. Breaking one turn of magnet wire will make the pickup non functional.
? Bent contacts on switches: The 3 & 5 lever switches used on the majority of Fenders have contacts where many pickup and circuit connections are made. On the early Centralab 1452 lever switches the contacts are connected to the phenolic wafers by small brass eyelet’s. The contacts are precisely bent so the wiper blade inside the switch makes proper contact. At times when working on your pickups the contacts or solder connections can get bend making the pickup selection non functional. The contacts need to be carefully inspected and realigned for proper contact. It is best to used a Volt-Ohm meter to check continuity. I use small round needle nose pliers to re-shape the contacts. On Gibson style toggle switches the contacts can be easily aliened for proper connections
? Worn or oxidized contacts on switches: The constant movement of switches can wear thin the contacts and replacement may be necessary. If switches are not used an extended period of time, oxidation can build up on the contacts from extreme moisture in the instrument case or high humidity. A special contact cleaner for switches should be used to remove, clean and lubricate the contacts. Check with your local electrical supply or Radio Shack for proper solvents for cleaning contacts. Always be careful not to overspray and get the solvents on the finish of the instrument. Properly cover and mask off the instrument. Be careful using certain adhesive tapes as the adhesive can react with the finish of the instrument. Check with your local tape dealer for specific tape recommendations.
? Grinding pole pieces: I remember during the 60’s many players were trying to level the pole pieces on their newer Telecasters to simulate the flat poles of early Fender Broadcasters, Esquires and Telecasters. I’ve received many pickups in for rewinding because the coils stopped working. I found that the grinding of the magnets caused the pole piece to get so hot that it cooked the insulation on the magnet wire. In time the exposed copper wire would oxidize and the DC resistance would change then stop working. Remember that the magnet wire on most single coil pickups are wound tightly in contact with the rod magnet pole pieces. Grinding the magnets can also degauss or weaken the particular pole you are grinding. Also grinding magnets can leave small particles of magnet dust that can eventually vibrate and may cause pickup to be microphonic in extreme cases.
? Movement of the cast magnet rod pole pieces on single coil pickups: Earlier rod magnets in Fenders are sand cast and have pits and rough sides. Most all Fender style single coil pickups have the magnet wire wound directly in contact with the rod magnets. Moving the magnet will snag and break the tightly wound coil especially on the early Fender pickups. Moving the magnets to change the height of the polepieces on newer Fender style pickups is possible but I wouldn’t recommend this be done. I never move the outer pole pieces because there is maximum pressure at both ends and is where the bobbin supports most of the coil tension. There are some nylon and plastic molded bobbins which allow the movement or rearrangement of the rod pole piece. I never change the pole height on Fender Telecaster style pickups that have a ferrous bottom plate. You can’t press the extended pole pieces down on those type of pickups with the ferrous elevator plate in place. Applying extreme pressure on magnet can cause them to crack. I wouldn’t try moving pole pieces without the proper tools as extreme damage can result. Never insert magnets into bobbins as it will likely break the exposed coil inside and if you use older Fender magnets, be careful as they may be a larger diameter.
? Magnetic field re-oriented: You need to be careful not to have your pickups near any AC sources that could change the orientation or domains within your magnet. The magnetic field on a rod pole piece is normally South on one end and North magnetic polarity on the opposite end. Depending on the outside source such as motors, solenoids or other AC current sources can change the alignment of magnetic orientation. On bar magnets such as the ones used on Gibson style humbuckers the magnets measure on average 2.5”(L) x .5”(W) x .125”(T). The magnet is magnetized across the .5”(Width). One side is North and the other is South. Most bar magnets used in humbuckers are Anistropic or having a preferred direction of magnetization. If a magnet is reversed in one pickup and used with another, it could be magnetically out of phase. The thin bottomless sound makes you think you have a bad pickup. This can be easily solved by reversing the magnet or reversing the electrical phase then check to see if you have a full round sound when two or more pickups are used.
? Magnetic phasing per pole: I’ve seen rewinds come into me where the customer decided to flip flop magnets in their single coil pickups. I had a pickup come to me where the top magnet polarity was (S) (N) (S) (N) (S) (N) and the pickup was completely out of phase with itself and from string to string when using a combination of pickups. Another pickup had the top polarity (S) (S) (S) (N) (N) (N) with the player thinking it would make it humbucking. You need to use either all (S) or all (N) magnetic polarity in single coil pickup where one coil is used.
? Magnetic field improper phasing: Another big problem is when you combine pickups from different manufacturers. You need to get proper phasing both electrically with coil direction or magnetic phasing with magnetic orientation. When using a combination of pickups test’s need to be made and discussed in a future article on how to determine the phasing of each pickup. I will show you how to test magnetic polarity and electrical phasing using your volt-ohm meter. You can use phase switches or have all the pickups in phase using proper hookup with various magnetic polarities.
? Magnets degaussed: Having a magnet that is degaussed will make your pickup have less output and sound warmer. It can be caused by extreme heat, shock, alternating currents and other environmental conditions. The size and shape of a magnet will determine how stable a magnetic field will be and recharging a magnet in a pickup if desired will often make the pickup sound brighter and have more output.
? Low DC resistance in pickup: At times there’s internal breakdown inside the coil because of insulation fatigue that causes shorting of several layers of magnet wire. This breakdown can reduce the DC resistance of a pickup. I’ve seen this happen with resin potted pickups and four conductor pickups where the wires can short out with each other during final hookup. Make sure you measure pickups one at a time and not in combination with others. If a pickup is used in combination with other pickups or circuit there will be inaccurate DC readings per single pickup. It’s best to use high quality materials and especially insulation’s on magnet wire. Thicker insulation’s will have better reliability than thinner insulation’s and less likely to fatique.
? Pickup sounds thin with no bottom: When a single pickup sounds thin with no bottom is usually a sign that the pickup has a broken coil. If you get little signal and turn your tone control to zero and you get so sound, this is usually an indication that the coil is bad. Also check to see that the components such as switch, capacitors and circuit are all hooked up properly. The coil will have to be inspected to see what the problem is and if it can be repaired without rewinding.
? Humbucking pickup sounds thin when used by itself: This can be a sign that there is a damaged coil or even the wiring inside the pickup is not correct. If the wiring inside the pickup rewired you can have a phase problem. Normally the two finish wire of a humbucker are hooked together. The beginning adjustable coil is grounded and the beginning stud coil is positive. The adjustable side of the humbucker is normally South magnetic field and the stud side is North. The actual coil direction of each bobbin must be determined to make sure the coils are hooked up for proper wiring. If you look at the top of typical Gibson bobbins, the coil is wound counter-clockwise around the bobbin.
? Potentiometers-effects of wrong value: Make sure the potentiometers are of proper value and working correctly. Make sure they are clean and oxidation free. Make sure the capacitor is hooked up properly and of the proper value. Fender Telecasters and Stratocaster normally use a 250 K audio taper potentiometer. Gibson originally used 500 K audio taper potentiometers for both volume and tone. Since the 70’s Gibson used 300 K audio taper volume controls. If you use a 100 K audio or 50 K audio the high end on the pickup will be drastically reduced. If your using a 250 K audio taper and need a slightly brighter sound, try using a 500 K audio or a 1 Meg audio taper potentiometer. To retain the clarity in your pickups when turning the volume down, you can use a .001 mfd. capacitor between the # 2 & 3 lug of your volume potentiometer. You can also put a 150 k resistor in parallel with the .001 mfd. capacitor. Normally the # 1 lug is grounded to the chassis of the potentiometer.
? Removing covers: During the 60’s and 70’s the fad was to remove the covers from your humbuckers. Many wanted to see if they had those famous double cream Patent Applied For humbuckers designed by Seth E. Lover for Gibson during the mid 50’s. Jeff Beck removed them so he could get more output and height adjustment from the pickups. He also told me that he removed the cover so he would have less microphonic feedback when playing at higher volumes. Many players and repairman had problems getting the cover with jagged solder joints off the pickups without destroying the coils. The solder residue from the covers snagged many coils and caused complete failure in the pickup. I was upset to see so many pickups badly rewound because of just one broken wire on outer turns of the coil. The whole coil doesn’t need to be rewound but carefully repaired. You need to remove a few turns to find the broken wire and rejoin a new section, rewind a few turns, insulate and hook back up. A solder wick should be used to absorb the excess solder holding the cover onto the bottom plate. Keep the old covers in a drawer for future use when removing it. Removing old covers from Stratocaster pickups should be done with care as moisture and grime over the years can cause the cover to stick to the coils. Damage can result if trying to pull the covers off. I’d leave the covers on unless there was an extreme need for them to be removed. Pickups are fragile and should be handled carefully. Covers should always be kept on pickups with exposed coils.
? Careless handling: Over the years many working pickups were removed from instruments and thrown in boxes or tossed in a drawer. Bottom plates or misc. pickup parts could hit the coils breaking the exposed windings or cracking bobbins. When pickups are removed from an instrument they should be carefully wrapped in tissue and even aluminum foil to further protect them. They should be labeled and put in a safe place for further use. Remember the pickups of today will be the vintage of tomorrow.
? Improper hookup: If you work on your pickups or have other do custom work for you, make sure they are qualified and are careful with your pickups. The pickup is the heart of the instrument and if the pickup is damaged in any way the performance of the instrument will be diminished. Each time you work on your instrument, make a drawing and keep the wiring available. The worst thing when working on your guitar is to have it all apart and then you get that phone call. When you get back you’ve forgotten where the wires went. I get calls all the time from players and repairman trying to rewire guitar. Make sure all the wires are connected and soldered correctly and leave enough wire for connections to the jack and other hardware. Don’t pull and stretch wire and it can bend the delicate contacts on switches and also bend them where they could short out with each other.
? Environmental conditions: Don’t leave your instrument unattended where someone else can get a hold of it or knock it over. Keep it away from little kids, cats and dogs and out of direct sunlight. Never leave an instrument lying next to a heater or window where some passerby might like to borrow it! Don’t keep the instrument in extreme cold or inside your car truck that can get very hot. Never use steel wool to clean your frets as the fibers will be attracted to your pickups. It’s a mess to remove the fiber’s and can cause other problems when your playing. You can get steel wool stuck in your fingers which can cause awful irritation.
? Soldering insulation’s: Insulation’s on magnet wire come in various thermal temperatures. Some take moderate heat to melt and some take much higher temperatures. Using to high of a temperature and actually anneal the copper magnet wire that can cause it to fatigue at a later date. I like sanding the insulation’s first as it reduces excessive heat that could damage other pickup components. Sand the wire before inserting the beginning wire into the eyelet on Fender rewinds to reduce the cooking effect it has on the surrounding vulcanized fibre. Always use proper ventilation and eye protection. Wipe off excess flux with alcohol or flux cleaner and dry.
? Faulty conductor inside insulated hookup wire: I have seen insulated hookup wire with invisible breaks inside. You should always use an ohm meter and check at various points in the pickup connections or contacts. Always check both ends in a hookup wire. I once had a pickup that worked at the eyelet’s but when I hooked it up to the switch it didn’t work. Another time I remember checking the two soldered eyelet’s on a Stratocaster pickup with my ohm meter and the pickup showed a complete short. I almost thought the pickup was shorting inside when I noticed the ends of the cloth braid hookup wire were accidentally touching each other. Always double check any possible connections before deciding the pickup may need repair or rewinding.
? Color coding of various pickups: When putting pickups in your instrument, make sure you are using the proper color code for the particular manufacturer of the pickups. Many companies have their own way of hooking up pickups and if you use the same color code that was previously in the instrument, it may not work. That’s why it’s important to have work done by a reputable dealer or repairman as they will have all the necessary technical information to make your instrument work properly.
? Cold solder joints: The majority of pickup failures that I’ve seen have been cold solder joints. This is usually caused when there is high production in manufacturing pickups and not enough time is taken for proper soldering. Heating and cooling of solder joints can cause them to expand and contract. The coil may work at first as the heat melts the insulation on the magnet wire. After time if there are pits and voids in the solder joint the bare copper can oxidize and eventually not make a proper contact or the copper magnet wire can break. Usually reheating the joint with proper temperature the time duration will help solve the problem and restore the pickup to proper operation. If you use too high of a temperature, the solder can boil and leave minute air bubbles that can eventually oxidize or corrode. Take your time and always use a rosin core solder not acid core that is used for plumbing.
? Faulty volume control: The hookup wires from the various switches eventually go to the volume potentiometer to adjust the output voltage of the instrument. Many times when soldering hookup wires to the contacts can cause the solder to travel down the lug and short out with another lug. Normally the # 1 lug on the volume control is soldered to the outside chassis of the volume control. Soldering to the outside chassis of the potentiometer can cause extreme heat to travel through the elements inside the pot. The extreme heat can cook the resistance element causing it not to work properly. Extreme use and oxidation on the sweeper contacts can cause the pickup to cut in and out. Worn resistive elements need to be replaced when volume is no longer working properly.
? Potting solutions: Potting is embedding a pickup in a resin or hot wax solution to help eliminate vibration or eddy currents in a pickup that can cause microphonic feedback. Potting resins have been known to shrink and breaks the magnet wire or some element in the circuit inside the pickup. Most potting resins have a thicker viscosity to saturate or permeate a wound coil and are often used to encapsulate the circuit and components of a pickup to avoid tampering. Resin potted pickups allow not further modification or rewinding. When pickups potted in a resin or epoxy and stop working, pickup replacement is needed. Warming the resin potting solution helps thin the viscosity. There needs to be a relationship to temperature and time duration when wax potting a pickup. If you leave a plastic humbucking pickup to long in hot wax, the pressure from the wound coil can distort the pole spacing, bobbin shape and cause the pickup to fail. If you wax pot a Fender style pickup too long or at to high a temperature the wax can seep back out still leaving the pickup still microphonic.
? Incorrect wiring of circuit: Make sure you have all the wires connected to the proper contacts and everything is grounded properly. Follow the procedures or schematics for the particular instrument or pickups. Check for proper solder joints, connections to switches and grounds. Make sure the wires on the connections don’t have strands accidentally touching other wires or shorting out. When wiring in new pickups, use the proper procedures recommended by that manufacture. Double check any custom schematics and wiring diagrams for accuracy. If in doubt, call the manufacturer or custom shop.
? Mounting screws shorting out wiring circuits: Be careful when screwing in pickguard or mounting ring screws that are to long. They could be screwed into a cavity or channel where the hookup wire goes through and short out a component. I’ve seen pickups work before being installed in an instrument and stop working after all the assembly hardware is put in place. The humbucking mounting ring screw shorted out the pickup cable.
? Faulty Jacks: Most jacks are nickel or even gold plated. If the plating wears off the jack from constant use it leaves the inside unplated. The unplated brass can oxidize from moisture and outside elements causing improper connections between the shaft and inside wall of the jack. This can cause the guitar to be intermittent and one might think failure in the pickups. Double check the jack and clean or replace if necessary.
? Faulty Ground: On several Fender instruments the jack is grounded to a thin aluminum shield underneath the pickguard. I’ve seen oxidation so extreme that the connection between the lock washer between the jack and aluminum shield made improper contact causing the instrument to fail. You couldn’t get a proper reading and the jack assembly had to be removed cleaned with a contact cleaner using a fine brass wire brush and reassembled. Make sure there are proper ground connections between the potentiometers, switches and pickups.
? Bad guitar cord: I’ve had guitars sent to me that worked fine to find out that the musician had a bad guitar cord. Do routine checks of your guitar cords, connections on your foot pedals and accessories. Always keep extra cords around too as there seems to be somebody always tripping over them.
Amplifier not working: This is another important one to check. This may sound funny but make sure your amp is plugged in and have power. Make sure someone didn’t borrow your fuse holder and your standby is working condition. I had a bass player use my amp at a practice and blew out the speaker without me knowing it. I played my guitar and thought my pickups went bad till I checked it with another amp. Probably my number one rule is don’t let anybody use your equipment. I’ve had band members borrow my tubes, speakers and even borrow a volume potentiometer.