Tone change after a ground wire is re-soldered?

BillMason · #1 03-09-2009, 07:26 AM

Can someone please explain this to me?

I bought an '08 Fender P Bass last March, just about a year ago. I used round wounds for quite a while, and at one band practice shortly afterwards, the bass fell of the stand with a clang. I checked it out, and no apparent damage, continued on.

Shortly after that I replaced those strings with flatwounds - unused to flats, I found I had to dial the tone control up all the way, and honestly didn't hear a whole lot of difference. I've been playing it that way for several months, and noticed that I was getting a 60 cycle hum whenever we played at my drummer's place, or at my place, and I attributed it to electronic noise interference, and bought a noise filter, which did nothing.

So this weekend, I took off the pickguard, and took a look, and noticed that the bridge ground wire was completely unattached. The pickup ground was soldered to the volume pot, so I soldered the bridge ground there too, and plugged it in. Suddenly I had all this high end, with flats! I was really amazed, but more confused about why soldering the ground to the Volume pot would have an effect on tone, when I didn't touch the tone pot.

Sorry for the ramble, but if anyone can explain this, I'd much appreciate it!

dlb1001 · #2 03-09-2009, 07:50 AM

From looking at a wiring diagram, it appears that the tone cap was floating when the bridge wasn't grounded.

BillMason · #3 03-09-2009, 09:05 AM

Thanks. What's also interesting is that mine is not wired as per the wiring diagram here:

http://www.fender.com/support/diagra...200_02APg2.pdf

I have a third wire (also black) coming from the pickup and soldered to the back of the Volume pot, so there are two black wires soldered to the back of the volume pot. It looked somewhat obvious that the black ground wire from under the bridge had been attached here also, as there was a little bit of broken wire sticking up from the solder blob, so that's where I reattached it. The diagram at the Fender site shows a different grounding circuit. My bass does not have a ground wire attached to the jack at all.

What differences are there between these two?

dlb1001 · #4 03-09-2009, 01:36 PM

Yes, the third black wire should be grounded to the pots. All of the pot bodies need to be grounded; otherwise, they will be floating. From the Fender schematic, it looks like they added a grounding lug to the shielding paint to make sure that it is grounded, too.