Pickup Rewinds

[big_teee]

I have mine more min/nom like this.
T

[kayakerca]

Hi Jim:
That is a fine looking 73 Jazz.
I redid a few in the 74 range, and they were all warped and mangled.
I like to keep the neck pickups wound on the lower side.
7500 ohms or less, in the 8500 turns range.
I show this screen shot in the ball park.

What ohms/1000ft. are you using in that calc Terry? I'm having difficulty replicating the results with the online version of the coil estimator.

[big_teee]

I agree on the wire size.
PE can be all over the place on ohms per foot, and wire size.
The 74s I rewound were dipped in some dark looking varnish.
They were all corroded and broke where they touched the magnets.
A set is RWRP, and I can't remember for sure without looking at my shop notes which is which.
I went back without the varnish, and wax potted them.
GL,
T

[kayakerca]

Hi Jim:
That is a fine looking 73 Jazz.
I redid a few in the 74 range, and they were all warped and mangled.
I like to keep the neck pickups wound on the lower side.
7500 ohms or less, in the 8500 turns range.
I show this screen shot in the ball park.

Thanks Terry. Yes, from the pictures the guitar tech sent me, the physical pickup looks very "clean". I did check the coil estimator, but am never sure about the wire size listed for particular pickup, so I thought I'd ask the question. It will be interesting to see which way the client wants to go re: output range. When I looked at the SD FAQ, it had the old at 9,000 turns and the new versions at 8,000 turns. Your 8,500 looks pretty safe.

Thanks again Terry.

[kayakerca]

#42 PE, about 7,800-8,000 turns for stock neck. I usually wind them to about 8,500, sometimes more.
The early 70's J bass pickups are pretty weak sounding.

Thanks Stratz. The specs I can find for the early 70's seem to be running in the 6.6kΩ - 6.8kΩ on the necks, but apparently the current Fender reissue version is ~ 8.3kΩ. The client will have to decide where he wants it to land.

Thanks again.

[big_teee]

Hi Jim:
That is a fine looking 73 Jazz.
I redid a few in the 74 range, and they were all warped and mangled.
I like to keep the neck pickups wound on the lower side.
7500 ohms or less, in the 8500 turns range.
I show this screen shot in the ball park.

[Stratz]

#42 PE, about 7,800-8,000 turns for stock neck. I usually wind them to about 8,500, sometimes more.
The early 70's J bass pickups are pretty weak sounding.

[kayakerca]

Had a request from a local guitar tech to rewind a dead '73 Jazz Bass neck pickup for one of his customers. 42 PE?



Thanks in advance.

[Jim Darr]

Rewind from Heck! Gibson "Tarbacks" Not recommended!!

Okay maybe I shouldn't even post this at all because they were such a pain, but I have lately done two of these and although it is possible to rewind these it is not very economical. At least I can offer from my experiences advice to any others that are dumb enough to try this some ideas that might help. Back in the late 70's and early 80's Gibson brought in Bill Lawrence, aka Wili Stitch to do some pickup design work. He liked to use ceramic magnets and hide everything inside epoxy potting. One result was the "tarback" pickups. These have some half decent sounds but are not at all amenable to being rewound and they do fail. But there is a demand for them as vintage pups and they do have some value for collectors. Most rewinders won't touch them at all because of the full epoxy potting. I got in one to rewind in a batch of several other kinds from one of my best customers and I decided to give it a try because it was for such a good customer and the pickup does have substantial original value for the original guitar it came in. Then I made the mistake of posting a note about that particular rewind on my shop's facebook page and immediately got in another one to rewind, and it was for an even more valuable guitar. So like a dummy, I reluctantly agreed to do the second one. The first thing I ran into on the first rewind was trying to figure out how to get the pickup apart. After many attempts at various techniques I discovered that the epoxy can be softened with enough heat and the best technique was to use a very hot soldering iron as a chisel to soften and slowly scrape away layers of the epoxy around the edges. Then at the appropriate time a sharp wood chisel can help cut into areas that are needed to be freed. It helps to have lots of padding on the bench and something substantial to push against. Otherwise you might dent the cover. On the first one, I quickly burned out the heating element in my very nice soldering station by running it too hot for too long. That cost me about $12 to replace but I had a spare. So on the second one I went out and got a couple of the cheapest $4.00 Harbour Freight 30 watt soldering irons to use as hot chisels so that I could afford to waste them again if needed. That has seemed to work so far. The big problem is that it takes a tremendous amount of time and patience to slowly chisel away the tough epoxy filling, not to mention the fumes and the messy crud that ends up all over your bench, in your nose, and on everything around. But it does work in the end.

This design does not use a baseplate it is instead just a brass strip held in by the epoxy. The cover is used as a mold to hold the assembly together. There is not a regular keeper with holes for the screw terminals, instead there is a keeper for the slug side that is a solid piece of key stock. The magnet is a thicker than usual ceramic type that touches the screw poles. So if you can get the screws out, and save the magnet without breaking it, and save the brass strip and the metal keeper, you can toss the bobbins, which are after all just regular 49.2 mm T-tops, and the slugs that are normal Gibson style slugs, and replace them with modern parts and then re-use the rest of the original parts, and it will be very close to original.

Here is how I got the pickups apart. I tediously removed epoxy all around the edges with the very hot soldering iron a little at a time until I could get down to maybe half the depth all around the perimiter. I also unsoldered the connection between the cover and the brass strip and worked the soldering iron along the edges of the strip until I got it free. I also removed all the polescrews. Then I used a heat gun to heat the cover and used repeated percussion taps to knock out the "blob". This included using a dowel to tap through the holes through where the screw poles were. It would have been more difficult on one of the solid cover versions but both of mine had screw poles. At first with the repeated tapping, first the magnet came free then the keeper and then the "blob" which consisted of both bobbins and the slugs. In both cases I had to use a sharp wood chisel to get the rest of the "blob" free. Then I cleaned out the cover and used the wood chisel to expose some of the coil wire which I then miked for the rewind. Both the pickups that I rewound were open so I had to go on published ohms data to calculate the rewinds. I used new bobbins and slugs and a new lead wire, but the rest were the original parts. I rewound the bobbins to about 4800 turns each with #42 spn which is the same as the originals had. (Not all of the originals were like these: some were wound colder or hotter and some had #44 wire etc. Bill L. wasn't consistent at all on these, it depended on the guitar model.) I then used a layer of double sticky tape put inside the cover and trimmed with an xacto knife to attach the screw side bobbin to the cover so the potting wouldn't leak out. This is similar to the precut foam double sided tape that Gibson used, you can see it in some of the photos. In my case, I opted to use a thin layer of hard black bankers wax to pot in the new coil assembly and after that set I finished it up with black epoxy as the originals had. I used some very slow curing epoxy that I dyed with black pigment to fill it in. Here are some photos of the second rewind. I don't really recommend rewinding these to anyone, but here are some pics and my notes.

Sonny,

Great post...thanks for the detailed account.

[SonnyW]

You're right Teee, Bill L. did save having to make the drilled keeper and the nickel silver baseplate, so it was cheaper to make. Another change was the ceramic magnet. That was probably cheaper then but now would be the hardest part to replace if you ever broke the magnet doing a rewind. If I could find the magnet or cut one down from a bigger one I could make a reproduction tarback easily enough. As far as what's up next, I will have to wait and see. This same customer that had the last tarback told me he has four broken DeArmond pickups that he is going to send me to look at, so maybe there is another gem or two in there. I think he said he had a Rythm Chief 1100 model so it would be another Monkey on a stick, but I don't know if it is one of the four that are coming. He's a jazz player and a bit of a collector so whatever they are ought to be interesting. Then I have a different customer that has been inquiring about rewinding one of the Gibson "The Original" pickups with the circuit board on the bottom. I gave him a quote, but haven't seen anything back. I also have another regular customer that sends me vintage pickups to rewind all the time. They deal in vintage guitars and that's where most of the old ones I see come from, including the first tarback that I rewound, and also the first Monkey one I did long time ago. We will just have to see what shows up in the mailbox. If there is something out of the ordinary I'll post it.

[big_teee]

It sounds like Wili Stitch, was just trying to come up with a cheaper way to make a paf type pickup?
Not a better pickup, a so-so pickup, which is what he apparently got, but at the cost of a Non-maintenance type pickup.
That is where the Vintage mindset, out-ways all practicality!
My hat goes off to MR. Sonny!
Anyone that can rewind the infamous Monkey on a Stick, we expect no less than he be able to perform miracles on a Gibson Tar-Back!
Good Job!
Who's next on the rewind table?
T

[SonnyW]

Thanks Pepe, I'm probably no Saint, but you have shown great knowledge about the difficulty of this. I'm likely more of a dummy than a saint to try it but both of the examples did come back to life okay. Not so sure I'd want to do this for a living though.

[LtKojak]

Oh, man, Sonny... I'll be sending a request to the Vatican to beatify you.

You have made a certified miracle by doing something only a saint would do.

Sonny Walton, SANTO SUBITO!

[SonnyW]

Rewind from Heck! Gibson "Tarbacks" Not recommended!!

Okay maybe I shouldn't even post this at all because they were such a pain, but I have lately done two of these and although it is possible to rewind these it is not very economical. At least I can offer from my experiences advice to any others that are dumb enough to try this some ideas that might help. Back in the late 70's and early 80's Gibson brought in Bill Lawrence, aka Wili Stitch to do some pickup design work. He liked to use ceramic magnets and hide everything inside epoxy potting. One result was the "tarback" pickups. These have some half decent sounds but are not at all amenable to being rewound and they do fail. But there is a demand for them as vintage pups and they do have some value for collectors. Most rewinders won't touch them at all because of the full epoxy potting. I got in one to rewind in a batch of several other kinds from one of my best customers and I decided to give it a try because it was for such a good customer and the pickup does have substantial original value for the original guitar it came in. Then I made the mistake of posting a note about that particular rewind on my shop's facebook page and immediately got in another one to rewind, and it was for an even more valuable guitar. So like a dummy, I reluctantly agreed to do the second one. The first thing I ran into on the first rewind was trying to figure out how to get the pickup apart. After many attempts at various techniques I discovered that the epoxy can be softened with enough heat and the best technique was to use a very hot soldering iron as a chisel to soften and slowly scrape away layers of the epoxy around the edges. Then at the appropriate time a sharp wood chisel can help cut into areas that are needed to be freed. It helps to have lots of padding on the bench and something substantial to push against. Otherwise you might dent the cover. On the first one, I quickly burned out the heating element in my very nice soldering station by running it too hot for too long. That cost me about $12 to replace but I had a spare. So on the second one I went out and got a couple of the cheapest $4.00 Harbour Freight 30 watt soldering irons to use as hot chisels so that I could afford to waste them again if needed. That has seemed to work so far. The big problem is that it takes a tremendous amount of time and patience to slowly chisel away the tough epoxy filling, not to mention the fumes and the messy crud that ends up all over your bench, in your nose, and on everything around. But it does work in the end.

This design does not use a baseplate it is instead just a brass strip held in by the epoxy. The cover is used as a mold to hold the assembly together. There is not a regular keeper with holes for the screw terminals, instead there is a keeper for the slug side that is a solid piece of key stock. The magnet is a thicker than usual ceramic type that touches the screw poles. So if you can get the screws out, and save the magnet without breaking it, and save the brass strip and the metal keeper, you can toss the bobbins, which are after all just regular 49.2 mm T-tops, and the slugs that are normal Gibson style slugs, and replace them with modern parts and then re-use the rest of the original parts, and it will be very close to original.

Here is how I got the pickups apart. I tediously removed epoxy all around the edges with the very hot soldering iron a little at a time until I could get down to maybe half the depth all around the perimiter. I also unsoldered the connection between the cover and the brass strip and worked the soldering iron along the edges of the strip until I got it free. I also removed all the polescrews. Then I used a heat gun to heat the cover and used repeated percussion taps to knock out the "blob". This included using a dowel to tap through the holes through where the screw poles were. It would have been more difficult on one of the solid cover versions but both of mine had screw poles. At first with the repeated tapping, first the magnet came free then the keeper and then the "blob" which consisted of both bobbins and the slugs. In both cases I had to use a sharp wood chisel to get the rest of the "blob" free. Then I cleaned out the cover and used the wood chisel to expose some of the coil wire which I then miked for the rewind. Both the pickups that I rewound were open so I had to go on published ohms data to calculate the rewinds. I used new bobbins and slugs and a new lead wire, but the rest were the original parts. I rewound the bobbins to about 4800 turns each with #42 spn which is the same as the originals had. (Not all of the originals were like these: some were wound colder or hotter and some had #44 wire etc. Bill L. wasn't consistent at all on these, it depended on the guitar model.) I then used a layer of double sticky tape put inside the cover and trimmed with an xacto knife to attach the screw side bobbin to the cover so the potting wouldn't leak out. This is similar to the precut foam double sided tape that Gibson used, you can see it in some of the photos. In my case, I opted to use a thin layer of hard black bankers wax to pot in the new coil assembly and after that set I finished it up with black epoxy as the originals had. I used some very slow curing epoxy that I dyed with black pigment to fill it in. Here are some photos of the second rewind. I don't really recommend rewinding these to anyone, but here are some pics and my notes.

[big_teee]

Here's the pics I took Saturday of the Tele pickup.
Before, during, and after.
I always make mine with .630" A5 magnets.
These were made with .688" magnets, and they had some sticking out the top and bottom.
When I redid it, I needed a flat surface to mount it, so I stuck all the extra out the bottom.
My PE is Nom/Max, and it filled up fast.
I had to quit before I got to the winding turns target.
I will get them returned today.
T
**Edit
Diagram, is viewed from the top of the pickup looking down.