P-90 wiring buzz

[TellyBelly24]

I am finising up assembly of my first guitar build, Thinline Tele, with a Seymour Duncan P-90 neck pickup and a SD Jerry Donahue single coil bridge pickup. The wiring harness is a four way switch, that has a volume pot plus push pull phase switch tone control pot that allows for treble "bleed" (Hoagland Bros. "all the toys" harness). I think therein lies the problem..should have gone with a simple 3 way switch, as this seems to be more complicated than I thought. The single coil works and sounds great, no hum whatsoever.

The P-90 hums and buzzes, and only picks up the string vibration in one switch position (#4) and only when the phase switch is depressed - the pick up doesnt work at all when the phase switch is pulled out. The P-90 has a single lead from the pickup, having a steel braided jacket, which I understand is the ground, and an inner core wire, which is the hot lead. I have tried jumping the wires here and there but nothing seems to get the pickup to work in the other switch position, nor get rid of the loud buzz.

Any suggestions out there?

 

[Funkfingers]

Re: P-90 wiring buzz

Welcome to the forum.

The single conductor + braided shield wiring from the P90 pickup, combined with a phase reversal switch, is never going to work correctly.

At best, you will eliminate the shielding from circuit. Usually, using the braided screen cable as the hot output conductor turns all of the metal screening parts of the pickup into a radio aerial.

Lifting the ground connection from the pickup interrupts the circuit, effectively silencing it.

Sound familiar?

The solution would be to make the Tele Bridge PU the one that reverses phase. This will involve cutting the jumper wire between the baseplate and the soldering eye of the black conductor and then adding a third discreet conductor just for the baseplate.