Unwinding a pickup

[eclecticsynergy]

I have a P90 which is way hotter than I need, since I have a spot for it in neck position. Started a thread about possible mods but it was pointed out that the problem is just too much wire.

So I'd like to take some wire off the coil. I've done a fair number of mag swaps but have zero experience handling coil wire.

So I have questions.

First of all, how practical is it to attempt this without experience? Doesn't sound especially complicated - still, I'm not sure it's quite as simple as it seems.

Second, how to go about this physically? Can I leave the bobbin on the baseplate? Do I need to rig something to actually rotate the pickup, or should I mount it somehow to let it spin freely by itself as I gently pull the wire, or can it just be unspooled manually without turning the bobbin at all?

Next (assuming the wire is 42 AWG, which I'm pretty sure it is) about how many turns do I need to take off to bring a P90 coil from 9.9K down to about 7.5K? I know the outermost layers are a bit longer and I'll check the DCR with a meter once in a while of course. But it'd be a lot easier if I had an approximate target figure in mind beforehand.

Can you still toast the insulation off coil wire with a match?

Is there anything special I need to know about reattaching the end wire to the leads when I'm finished?
I can leave the start wire attached to the baseplate, yes? Best not to disturb that unless necessary, I think.

Finally, what else do I need to know about this that I haven't thought of yet?

Advice would be welcome.

 

[DavidRavenMoon]

Re: Unwinding a pickup

This is how I got started winding pickups. I had a P-90 from an SG, and wanted to put it in the neck position on a LP copy. It was about 9k. I had a mid 60s ES-330 with P-90s that read about 8k and wanted that tone.

So I unwound about 1,000 turns of wire off the pickup. I periodically checked my progress by quickly passing a lighter past the wire, then I had a small folder piece of aluminum foil I’d fold over that spot and take a reading with my meter. This was around 1978 so I had an analog Radio Shack meter.

I used to use a lighter to burn the insulation off, but these days I just wrap the magnet wire around the lead and solder it. Hold the iron on for a bit. I have my iron set at 400°C. That’s enough to melt the insulation.

I also unwound a DiMarzio Super Distortion for a guy that wanted it less hot. That was before the Super II and stuff.


Sent from my iPhone using Tapatalk

 

[Clint 55]

Re: Unwinding a pickup

So you used your soldering iron on low to melt the wax?

 

[beaubrummels]

Re: Unwinding a pickup

So you used your soldering iron on low to melt the wax?

To melt the insulation. You need bare wire to test when you are getting to your target DCR.

 

[Clint 55]

Re: Unwinding a pickup

I see. A potted coil won't unwind though without breaking the wire.

 

[eclecticsynergy]

Re: Unwinding a pickup

I see. A potted coil won't unwind though without breaking the wire.

No, what he's talking about is the fact that coil wire itself has insulation on it.
Otherwise the windings would short each other out and the pickup wouldn't work.
To get a reading you have to melt through the insulation to the wire inside it.

But I think you're right that heavy wax potting could make unwinding difficult.

 

[eclecticsynergy]

Re: Unwinding a pickup

So I unwound about 1,000 turns of wire off the pickup. I periodically checked my progress by quickly passing a lighter past the wire, then I had a small folder piece of aluminum foil I’d fold over that spot and take a reading with my meter. This was around 1978 so I had an analog Radio Shack meter.

I used to use a lighter to burn the insulation off, but these days I just wrap the magnet wire around the lead and solder it. Hold the iron on for a bit. I have my iron set at 400°C. That’s enough to melt the insulation.

Did you just unwind it off the bobbin by hand?
And did you leave the inmost end attached to the baseplate?

PS: I still have my old Radio Shack VOM!

 

[AlexR]

Re: Unwinding a pickup

No, what he's talking about is the fact that coil wire itself has insulation on it.
Otherwise the windings would short each other out and the pickup wouldn't work.
To get a reading you have to melt through the insulation to the wire inside it.

But I think you're right that heavy wax potting could make unwinding difficult.

You just use a hairdryer or heat gun on the coil when you're unwinding

 

[hamerfan]

Re: Unwinding a pickup

I did it several times, because i love underwound pickups. If its unpotted its really easy, just lay the bobbin on the ground and pull.
If its potted, you better warm it with a hair blower and unwind it with your hand rotating around the bobbing slowly. I wrap the unwinded wire around my rotating hand. But it becomes easier with every layer, because the wax does not penetrate thru all layers.

Be careful with the bobbin tape, you have to reuse it or buy some of this special paper tape (never use household or electrician tape - its a mess)

 

[eclecticsynergy]

Re: Unwinding a pickup

I did it several times, because i love underwound pickups. If its unpotted its really easy, just lay the bobbin on the ground and pull.
If its potted, you better warm it with a hair blower and unwind it with your hand rotating around the bobbing slowly. I wrap the unwinded wire around my rotating hand. But it becomes easier with every layer, because the wax does not penetrate thru all layers.

Be careful with the bobbin tape, you have to reuse it or buy some of this special paper tape (never use household or electrician tape - its a mess)

Do you think it's practical to unwind while the bobbin is still attached to the baseplate?
I'd rather not disturb the start end of the coil; am a little worried about not having enough slack to reattach.

I already have vintage-type paper pickup tape; got a roll for mag swapping.

 

[hamerfan]

Re: Unwinding a pickup

Never tried that with the backplate on. It might work with unpotted pickups, but with wax in the coil you have to handle it warm and slow and always watching the getting-off-the-coil spot.

 

[eclecticsynergy]

Re: Unwinding a pickup

Never tried that with the backplate on. It might work with unpotted pickups, but with wax in the coil you have to handle it warm and slow and always watching the getting-off-the-coil spot.

Okay. With the bobbin removed from the baseplate, was there enough slack in the inner end of the windings to reattach it easily?

 

[hamerfan]

Re: Unwinding a pickup

You have the black or white hookup wire, which is 2 inches long, everytime i desected a bobbin. Just stop unwinding and let the copper wire hang out, than take paper tape and tape the coil with exception of a small gap where the copper comes over the top. Then solder the copper to the hook up. Then tape the coil with the hookup coming out at the lower flange of the bobbin.
Look for a vid at utube to make sure what you are supposed to do.

 

[eclecticsynergy]

Re: Unwinding a pickup

You have the black or white hookup wire, which is 2 inches long, everytime i desected a bobbin. Just stop unwinding and let the copper wire hang out, than take paper tape and tape the coil with exception of a small gap where the copper comes over the top. Then solder the copper to the hook up. Then tape the coil with the hookup coming out at the lower flange of the bobbin.
Look for a vid at utube to make sure what you are supposed to do.

What I'm more concerned with is the inner end of the wind that goes to ground on the baseplate.
With the outer end, slack isn't a problem - you can always take one more wind off to get a little extra.

 

[jeremy]

Re: Unwinding a pickup

you shouldnt have to do anything with the start of the coil and usually there isnt any slack.

 

[ItsaBass]

Re: Unwinding a pickup

It's pretty easy to do. I would say you don't need to know exactly how to make a pickup in order to do this operation.

I would use a heat gun to melt as much wax as possible off the coil first. You don't need to disassemble the pickup. Just enough to remove the lead from the coil wire.

As far as winds, you just have to check DCR first, and then check it again every now and then. A soldering iron will remove the insulation so you can take a reading. No need to reinsulate with nail polish, as you are removing wire that will get trashed anyhow. if you were adding windings, you'd want to reinsulate each time after checking DCR.

 

[eclecticsynergy]

Re: Unwinding a pickup

Yah, I think I'm going to try it without removing the bobbin from the baseplate.
That way I won't need to worry about reattaching the start end.

 

[GuitarDoc]

Re: Unwinding a pickup

I have my iron set at 400°C. That’s enough to melt the insulation.

I think you meant 400 degrees F. (400 C is over 3600 F!!). Not only will that melt the insulation, it will melt/vaporize the wire.