So... the tone on the new (to me) vintage Fender MB-4 is awesome. Except that I have an annoying A/C signal hum. Not really noticeable when jamming along, but it's certainly there when I want to be silent.
Checked everything out - it's not pedals or cable or amp or any intervening device - the noise is coming from the bass. I went and found Seymour Duncan has a wiring diagram for P/J pickups with a blend knob, and their schematic shows a bunch of grounds going to the master volume pot. However in the MB-4 it appears there has been some wiring work done, and the majority of grounds have ended up on the volume pot (see below).
Now, J.A.S. my friendly tech friend, says that should not be a problem although any loose ground will act just like an antenna for AC or other frequency hum. Ha, advice from Sick Rick was "I don't mess around with other people's work anymore, I just buy a new assembly."
I went on eBay looking around and found this dude KellingSound88 who makes all sorts of pot assemblies, 5,767 reviews since 2002... 100% positive! And I found a P/J with blend assembly.
Per KellingSound88: P/J Bass Harness with Bridge pickup blend pot, this wiring is perfect for the P/J setup this allows you to blend in the bridge pickup a little or all the way with the Neck pickup, but it doesn't give the bridge by itself. The blend pot is A500k and is no load so when its all the way up its out of the circuit giving a fuller sound. The Volume is A250k with a treble bleed circuit. The tone pot is A500k with a .082 Vitamin Q paper in oil capacitor this gives a smooth taper adding a little treble cut but will give dark tone when all the way down than a .047 giving a wider range of tone options.
And the piece arrived with a nice handwritten note of where to wire the pickups and grounds.
I am looking to install sometime before our next Dismalhead jam and I am really looking forward to it. The assembly is total craftsmanship down to cloth-wrapped wires and rubber-covered connections for the jack. Ha, however it is funny for once I want something that IS a buzz kill.
