Jazz Bass pickup specs and some questions

[fidule]

Hello

Someone gave me a JB pickups for rewinding.
It's a 1972 neck pickup
Here the specs:
*top and bottom bobin: 1,65 x 8,85 cm
*magnets: 0,49 mm diameter x 2 cm
out of the top: 0,15 cm
out of the bottom: 0,05 cm

there is a tape wrapping the magnets
the pickup was potted in a resin: shellac? i will do some tests to know which resin was used

i don't known if the bobin is made of Forbon, it is greenish (top: 0,2 cm and bottom: 1,9 cm for the thickness)

the magnet wire is black. Could it be Plain Enamel?
the wire seems to be thiner than 41 AWG. Could it be 44 AWG?

the winding direction seems to be clockwise, like the bridge pickup. For the magnets i will check it if it's north or south.

What could be the resistance? around 7kOhms? i couldn't mesure the restistance of the bridge pickup

For the "potting": should i directly potted it in the resin or should i use a brush for aplly the resin during the winding?

Thank you for your answers

(sorry for my awfull english)

[Sam Lee Guy]

Hi, the resin used for potting is nitrocellulose which in time degrades and gives off gasses which cause the enamel to fail. The black wire is plain enamel. The original wind would have been 7,800 turns, around 6.8K for a neck pickup. Bridge pickup is longer, so longer turns, so higher DC resistance. For rewinding, don't use nitrocellulose, but shellac, the orange brown stuff, not the clear or white which will never dry properly. Apply with a small brush and keep applying till it doesn't soak in. Neck pickup usually north up, bridge pickup south up.

[fidule]

Thank you Sam Lee Guy

Does the black color of the wire come from its degradation by nitrate vapours?

Should i potted or used a brush with the resin?

[GlennW]

Scarlet, does your pickup have the vapors again?

[David Schwab]

the wire seems to be thiner than 41 AWG. Could it be 44 AWG?

It should be 42AWG.

[Sam Lee Guy]

yes, 42 and black from new, not discoloured.

[David Schwab]

Hi, the resin used for potting is nitrocellulose which in time degrades and gives off gasses which cause the enamel to fail. The black wire is plain enamel. The original wind would have been 7,800 turns, around 6.8K for a neck pickup. Bridge pickup is longer, so longer turns, so higher DC resistance. For rewinding, don't use nitrocellulose, but shellac, the orange brown stuff, not the clear or white which will never dry properly. Apply with a small brush and keep applying till it doesn't soak in. Neck pickup usually north up, bridge pickup south up.

Sure sounds like Seymour to me...

I know... wishful thinking...

[Stan H]

Sure sounds like Seymour to me...

I know... wishful thinking...

Dollar to a doughnut

[Zhangliqun]

Am pondering getting into bass pu's myself. Would plain ol' parafin/beeswax (PB) properly de-squeal a J-bass pu or do bass pu's require something heavier? I guess not since guitar players are getting roughly the same SPL's standing next to the bass player at a gig and the ol' PB seems to hold up fine.

So maybe I answered my own question. But in case I didn't, bass pu gurus chime in...

[Stan H]

I use the plain ol' parafin/beeswax. Never had a problem.

[David Schwab]

Am pondering getting into bass pu's myself. Would plain ol' parafin/beeswax (PB) properly de-squeal a J-bass pu or do bass pu's require something heavier? I guess not since guitar players are getting roughly the same SPL's standing next to the bass player at a gig and the ol' PB seems to hold up fine.

So maybe I answered my own question. But in case I didn't, bass pu gurus chime in...

The pickups in my own personal bass aren't potted at all. Only once did I have a pickup squeal, and that's because I was leaning right against the speaker cab.

The pickups I sell (and eventually in my own basses.. once I stop tinkering with them) are potted in polyurethane, and then epoxy.

[fidule]

Thank you guys for your answers

If i pott in shellac, could i make a superficial potting like with parrafin/beewax potting?

[GlennW]

I'm just a hobbyist and I pot the way shown in SK's site. He had a picture, but that's gone. I got some and the label reads:

Sherwin Williams
Wood Classics
Interior Wood
FASTDRY Sanding Sealer
Clear
6403-15891

Other stuff will probably work, but I didn't want to risk it.

[Sam Lee Guy]

Yes, you can apply a thick coat, let dry, then apply a couple more coats. It won't go in too far, especially if you use tape under the coil.

[fidule]

thank you

i rewound it, and the shellac seems to be a good potted

i would like to wrap with tape, what tape do you use ?

thank you