I just did a rewiring job for a friend on a Gibson RD Custom. The guitar had all sorts of active electronics with treble boost and a printed circuit board, etc. He was dissatisfied with the sound the way it was before. We basically gutted the guitar and put in decent Seymour Duncan pickups and I replaced all the potentiometers with 500k following basic diagram for 2-humbucker 2-volume 2-tone w/series-split-parallel on bridge pickup.
When wiring the guitar, I noticed that this instrument has no wire coming from the bridge to ground the instrument. When I got done with the wiring job, and tried out the instrument, it is not buzzing or making any extreme interference-indicating signs, BUT if I touch the metal knobs of the potentiometers (or anything else that is electrically "ground") the (very) small amount of noise that is present gets quieter. I am thinking that this might have to do with there not being a wire from the bridge.
Do you have any thoughts on this, or are there any workarounds without adding holes to the instrument? Do you even think that this is the problem?
I have grounded ALL of the pots and switches, and I do it without wiring the grounds into a full loop - i.e. the input jack is grounded to the 3-way. that's grounded to a tone control, which goes to a volume, to the other volume, to the other tone, to the on-on-on switch.
One other comment, and I haven't tried this with other instruments so I am not sure if this is just "normal". If I touch anything inside the guitar that is in the signal path, it causes a lot of feedback. Maybe that's the way it always is, I can't remember.