Jazz Bass Pickup Rewind

Hello everyone, today I am going to do a walk through for rewinding a set of Fender 60s Jazz Bass pickups. The neck pickup has stopped working so the customer opted to do a custom rewind instead of trying a repair. Both pickups bobbins looked to be in good shape, but the lead wire connections have become brittle and fell off. These pickups are a good candidate for a Sullivan Music Equipment Jazz Bass Pickup Custom Rewind. As you can see in the image below the leads are loose from the bobbin and have wax flakes around the pickup. Our goal with this set of pickups is to darken the tone of the bass since it will be used primarily for blues and some heavy rock music. The customer has chosen to rewind with vintage 42 AWG  Formvar wire and to over wind the pickups to 10,000 turns on the neck and 10,500 on the bridge.  This will be around a 10%  to 15%  over wind from the stock Fender 60s jazz bass pickups.  It should be noted that the bass guitar is very bright sounding to start with and the customer is trying remove some of the harshness of the bright tones. The original pickups measure 7.6K Ohms on the neck pickup and 7.9K Ohms on the bridge.

Jazz Bass pickup

Here are the original set of Jazz Bass pickups for rewind

Jazz Bass Pickup Rewind: When repairing a pickup I like to use a cutting board as a work surface and a large magnifying glass with a bright light. I also use an assortment of hand tools you will see as we walk through the repair. Above the work area you can see some of our test instruments.

Cutting Board

This image shows the cutting board and the first set of tools used to remove the coil wire.

Jazz Bass Pickup Rewind: First I remove the wire leads from the bobbins and make a cut in the coil wire at the center of the bobbin, then I pull the coil wire off in layers. When pickups are wax potted like this set it makes removing the coil much easier. You have to be very careful  when cutting the coil wires or you can scar the bobbins and create a jagged surface that can break the new wire as it is being wound.

Cutting the coil wire

Here is where I make the cut to separate the coil wire from the bobbin

Jazz Bass Pickup Rewind: An hobby knife is the best for cutting the coil wires as it is thin enough to reach inside the bobbin, box cutter type razor knife have a blade that is to wide and they do not fit into the bobbin.

Jazz Bass coil removed

Here is an inside shot of a bobbin where you can see the wax and coil wire together. Notice the wax buildup between the magnet post. These pickups are wound very tight so the wax could not escape when removed from the hot wax pot.

Remove the coil wire from the eyelet

This image shows the removal of the coil wire from the bobbin eyelets. The wires are very thin so I use tweezers to remove the wires.

Cleaning pickup with a software brush.

Here I am cleaning the pickup bobbin with a soft brush to remove all the wax.

Jazz Bass Pickup Rewind:  It is important to clean the bobbin to a like new condition, not only because it make the pickups look better, but it assures the success of a cleaner and tighter coil.

Formvar wire

The customer wanted to custom wind the pickups with 42 Formvar wire, here you can see the difference in color. 42 Plain Enamel is thinner than 42 Formvar so the it will create a thicker bobbin using the same number of turns. These bobbins will be over wound to bring out more bass and mids on a bass that is very bright in tone.

Jazz Bass Pickup Rewind:  Fender mainly used two different type of coil wire in the early years ( Formvar and Plain Enamel) mainly because of availability and cost. Well it turns out that those types of wires can add to the tone of the pickups as they age and this why so many people request them in the pickups.

Winding the pickup

Here you can see the pickup being wound, Jazz Bass pickups are RWRP for hum cancelling when used together. The pickup is secured to the winder so that it does not fall off and there are guides to make sure the coil wire stays on the bobbin.

Jazz Bass Pickup Rewind:  Hand winding the pickups is also known as “Scatter Winding” the coil. Machine wound pickups can sound dull and lifeless because they introduce capacitance coupling within the inter coil due to the wire being wound so perfectly close together and in parallel lines. Scatter wound pickups eliminate this capacitance coupling by using a winding pattern that randomly overlaps the coil wire and reduces the parallel lines with in the bobbin. There is a lot of information on the internet about this subject for those who would like to read more about it.

Hand winding the pickup

Here you can see the how I use my fingers and small piece of a shop paper towel to guide the wire and to adjust tension to the coil wire while it is being wound. The specs for this set of pickups are for 10,000 turns Neck and 10,500 turns on the Bridge.

Jazz Bass Pickup Rewind:  When winding a pickup we have found that keeping the winder at about 600 RPMs produces a tighter coil with less wire bulge from the centrifugal force. It also allow you to apply more tension on the wire without stretching the wire and making it thinner or breaking the wire, of course it does slow down the process, but the end results are worth it.

After the pickup is wound

After winding the pickup the leads are attached and the pickup is ready for wax potting.

Jazz Bass Pickup Rewind:  Here you can see the final assembly of the pickup, if you look closely you can see the coil wires overlapping each other and if you look at the ends of the pickup you can see how the shape is not completely parallel to the magnet poles. The contour of the coil shows that there are many overlaps as it was wound. Note: Pickups that have coils contours that are too parallel to the magnets or that are uneven on both sides shows a lack of attention to detail form the winder. Below are good examples of how a pickups should look after winding.

Wax Potting the Jazz Bass Pickups

Here you can see the pickups as they have just been placed in the hot wax. We keep the wax at 155 degrees. When first inserted the pickups are colder than the wax and the wax hardens around the magnet poles until they heat up.

Finished Jazz Bass rewound Pickups

And here is the pickup after cleaning all the excess wax off of the bobbin. The pickups were test after cooling to make sure their specs met the customers expectations. With 10,000 turns on the neck pickups we measured 8.5 Ohms and with 10,500 on the bridge pickup we measured 9.4 Ohms. Since the idea was to darken the tone of the bass we should have achieve our goal.

Jazz Bass Pickup Rewind

Ready for installing

I will post sound clips of the bass as soon as possible.

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