Doping (protecting) coil tails

[Jim Shine]

Most Fender coils that need repair are not due to the lead wire interface failing, but 99% of the time it's the magnet-vs-wire corrosion/interaction causing shorts or breaks.

That has been my experience. The ones that "just die" not due to being screwed with will have a one or magnets corroding inside that causes the problem.

[big_teee]

That has been my experience. The ones that "just die" not due to being screwed with will have a one or magnets corroding inside that causes the problem.

I agree.
I think it is the night club sweat and beer running down the magnets on the inside.
Modern day taping the magnets should cure that!
T

[David Schwab]

We all know Fender pickups die because of inner wire corrosion. I'm sure Bruce knows that too. I think what he was saying is why build them that way at all? Fender got some flack for using plastic bobbins and all, but I think that was mostly in people's heads, and also because they couldn't have implemented that better. The wax was Leo's way to try and stop moisture from getting int he coil. It doesn't work. If your pickup is wax potted, then sealed in epoxy, it's not going to corrode. Plus get the wire off the magnets/poles. It will then last for a very long time.

I used to wind my pickups directly around a steel blade (insulated with tape). But I would get the occasional short. So then I went to a plastic bobbin so the wire never touches the blade. That places a small space between the blade and the wire. When A/Bing the pickups I don't hear any difference worth worrying about. Now I have pickups that won't fail because of that problem.

My feeling is I want to find better ways of doing things, that make the pickups easier to build, and like Brad says, I have no legacy. But I plan on extending that to legacy designs. I like when I see a humbucker with a circuit board on the bottom. Think about how much smarter that is. No futzing with pigtail wires, etc. And that's not new. Bartolini and Bill Lawrence have done it since the 70s.

Then you ave the dumb two point humbucker mounting. I was just watching a video on Premier Guitar showing Soundgarden's gear. Chris Cornell had duct take on the ends of most of his humbuckers to stop them from tilting. Is resorting to duct tape better than giving people a 3 or 4 screw mount?

Many of us are stuck with these legacy designs for no good reason except tradition. String on Tele pickups? Let's wear Leo's plaid pants while we are at it. I know the argument; "my customers want that." If your customer's REALLY want that, and they aren't restoring a vintage guitar, look for new customers. There are a lot of people using more modern designs. I see them all the time when I'm installing pickups and doing setups, etc. I see more hum canceling Strat and Tele pickups than single coils. Lots of DiMarzio and Duncan blade pickups.

So my point is don't get stuck doing things the old way just because you think there isn't a better way. Try some new things. If you get a more reliable and great sounding pickup, then you have something. And that's in the spirit of Leo Fender too. He always looked for an easier/cheaper and better way to do things.

OK that's my rant.

(oh and congratulations to our own Jason Lollar for having his pickups in Chris Cornell's signature Gibson guitars! )

[Bruce Johnson]

Oh yeah, I agree. There's no question that internal corrosion is the biggest cause of failures of old pickups, by far. Preventing future corrosion is a major factor in how I design and build my pickups. That's why I like the full encapsulation in hard epoxy. My whole pickup should be completely water-tight. Even the magnets aren't exposed to the air. That's also why I like the CPES epoxy for the coil-potting; to fill up all the space inside, so there's no air or water trapped in there.

The reason that I've obsessed a bit on the termination points, is because that is the specific reason why the Ampeg AMB-1 pickups are failing. They are epoxy encapsulated, but they did a poor job on the terminations. They soldered the lead wires to some kind of weak terminals deep down inside, and then cast it in epoxy. So the mechanical strain relief is the epoxy holding on to the insulation of the lead wire. Not good. Over the years, the insulation of the wire shrank, and the strain relief was lost. Someone opens up the bass, nudges the wires a bit, and something snaps off deep down in the pickup. It goes dead and can't practically be fixed. So far, I know of about 5 out of 500 built that this has happened to, but there are probably many more. Many of the AMB-1's around today have been routed out for P-bass pickups, and a dead original pickup was probably the reason this mod was made on most of them. So, since I'm building my AMB-2 Scroll Basses (which are close replicas of the Ampeg AMB-1's), I'm just a bit sensitive about flimsy terminations. That's not going to happen to my basses!

And, of course, that's what Sheldon asked about in his original post!

I believe that encapsulating the pickup in epoxy is the way to go for long term durability. The technology is well proven in the electronics industry and aerospace. But, you've got to do it right and pay attention to details. There are ways to screw it up, as Ampeg did.

Historical question: Ampeg started epoxy encapsulating their pickups on the AMB-1 and SSB models in mid 1967. The 1966 AEB-1 models used pickups that were cast into a block of epoxy, but it was more to provide a mounting method, rather than fully seal it. Were any other manufacturers epoxy encapsulating their pickups before that? I can't think of any offhand, but I haven't researched it.