Fender Custom Shop P-Bass Question

[FuryGuy]

I picked up a set of CS P-bass pickups for my 2001 MIM P-bass. I installed it and had to add a bit of wire to the ground wire to get it to reach under the bridge. I also had to re-solder one of the jack connections. Anyway the bass sounds good but when I touch the magnet on the pickup with my thumb it makes a noticeable buzz/hum. I got a friend to check the ground wires with his ohm meter and they all zeroed out so I think my solders are fine. Is this type of buzz normal with these pickups? Any thoughts would be appreciated.

 

[RobbieK]

Yep, some buzz on one coil's mags is normal, but the other coil should be silent.

If you notice a little buzz when you touch one coil, but a louder buzz on the other coil, then reversing the phase of the pickup should leave you with one coil that buzzes a little, and the other that is silent. This is because the coil that is silent now has its inner windings at earth.

The trick then is to swap the positions of the d/g bobbin with the e/a bobbin and vice versa, so that your thumb only touches the silent bobbin.

This all sounds a bit complex, but really, its very simple, especially since you can solder.

There's three other ways you can overcome this.

you can paint a little clear nail polish or super glue or something on the tops of the magnets.

You can replace the pickup covers with ones that have no holes. You'll have to add shims next to the magnets on the tops of the bobbins so the cover won't distort.

and, thirdly you can earth the magnets. This is usually done with copper tape that has conductive adhesive, underneath if the mags are alnico, or on top if you don't fancy prying off the ceramic mags then replacing them. FWIW, if you earth the magnets on a vintage fender pickup you can often short it and stop it from working. These old pickups often have corroded magnets and the inner windings will be short to them. No biggy though, as a pickup can keep working for many years like this before needing a rewind, so just go with one of the other options.

 

[FuryGuy]

Great information RobbieK, I managed to solder a these few grounds but my $11.99 iron wasn't taking any solder on the tip so it took quite a while and was very frustrating. I think I may be in over my head with what you were suggesting. I have friend that builds amps so this would likely be something I'd get his help with.
I appreciate the info and ideas.

One other question I have is, the CS pickup has a brass plate under the pickup that I believe has grounds soldered to it. Would that be the same thing as doing the copper tape trick?

 

[RobbieK]

If you mean a brass plate that sits on the floor of the route like the 60's and 70's fenders, then no that won't ground the magnets.

I didn't mean to over-complicate the issue. There's a good chance that there's nothing wrong at all.

Plug in your bass and try touching the tops of both coils. You've mentioned that the E/A coil buzzes when you touch it. Well there's a 50/50 chance the D/G coil will be silent when you touch it. If this is the case the only mod you need to do is to remove the pickup, spin it 180 degrees, and put it back in. This way, the silent coil is now in the E/A position so it won't buzz when your thumb touches its top.

OTOH, if the D/G coil actually buzzes more loudly than the E/A coil, you'll have to break out your 12 dollar the soldering iron to swap its hot and cold wires, as well as spin the pickup.