This came in for a rewind a couple of weeks ago and while I keep saying I don't really wanna rewind a lot of pickups, I also say if it's something weird and wonderful and you can't just buy a drop in replacement, I'll help out if I can.
This pickup had seen some action and measured short from the 2 lead wires so the next step is to remove the cover and measure each coil to see what's causing the trouble.
I'm not sure if this cover had been removed or the solder holding it in on had just cracked over time but I hit it with a hot soldering iron just to be sure and removed the cover.
This exposed the 2 big fat cols that look VERY similar to the guitar WRHB bobbins. The CuNiFe threaded poles are assembled the same way (only 4 per coil instead of 6) and these coils are held in with giant metal bolts the same thread as the poles that run through the base plate and into the threaded bobbins. There's A LOT of metal in these pickups and they are very heavy.
It was pretty obvious on first inspection that at least one coil was damaged. The tape that had been used to protect the coil from the cover was ripped and worn away, leaving exposed coil wire. I measured both coils and one was good at about 12.8K while the other, with the damaged tape, was short.
As I've mentioned in many of my pickup repair/rewind blogs, I always start but trying to unwind the damaged coil in case it can be salvaged with the original wire. With this many winds you can conceivably unwind a few hundred winds and not really affect the tone of the pick up.
I got the bobbin out of the assembly, got the tape off, cleaned it up and worked out which way to go from the broken coil to unwind the coil. I started by "unwinding" the wire to the end to remove the wire from the break to the end where it solders on the lug. With this gone I measured the wire from the end I had to the start of the coil. Nothing.
So I started unwinding the wire from there. I got about 30 winds in and found another break under the original break so took that wire off and measured again. Nothing.
So I unwound a little more thinking I was going to have to cut this coil off and rewind when I came across a damaged looking section under the original break. I broke this off and measured the coil again. BAM. 12.9K.
This coil was OK and in fact slightly higher (depending on temperature etc) than the other coil. The amount of wire taken off probably only made up .1 or .2 of a K anyway. Maybe 80-100 turns?
So, with the coil reading again I just had to clean and solder the wire back onto the lug on the bobbin, wrap it in tape and solder and screw it all back together. These have 2 acrylic off-cuts sitting on top of the coils to space the bobbins in the cover to make the base plate line up with the bottom of the cover.
This is delicate work and all of this still took well over an hour to do but it was nice to save the original coil and it cost the customer less than I originally quoted. Sometimes this kind of work takes as long as just stripping the wire off and rewinding it but like I say, it's kinda nice to keep that original wire as technically, this pickup hasn't been rewound.
All back together and measuring a staggering 25.something K and back to it's owner (or tech doing the work) to pummel some bass frequencies into submission.