Post by funkykikuchiyo on Jun 3, 2020 9:11:16 GMT -5
The key here is that the noise is remaining when touching a ground, albeit reduced. I'd check through all the components and see if there is one wherein you touch it and the noise increases instead of decreases. In that case, that part is not properly grounded. If this is an old one, a lot of the shields are metal boxes with solder joints that can become brittle, so be sure to go through everything. It is also possible the varitone circuit has gone funky, as those chokes can sometimes get funny.
If it does require shielding then doing the pickup cavities won't do much. Gibson pickups are already shielded all around, so adding some copper foil doesn't do much. The control cavity could help, but if this is an old one, it is more likely some other issue than just shielding. But, pop it open and take a look. They did it a variety of ways over the years, so I could be wrong.
I would also want to verify that all the controls are working as intended to further troubleshoot bad components or bad solder joints.
On the face of it, with its covered humbucking pickups and shielded wiring, an EB3 should have far lower inherent levels of hum / buzz than a regular Fender. Is that not the case, what are the details of the instruments you are comparing it to? I would check the resistance of the pickups as early in the chain as possible, eg at the switch. Then plug a cable into the instrument and at the other end plug, check for anomalies in the resistance from the shield to all connected metalwork, and between tip and shield in each switch position, with the controls up full. I‘m thinking that the issue may just be due to an old jack / switch / pot, whose contact surface has worn or otherwise become degraded?
Post by funkykikuchiyo on Jul 27, 2020 9:46:31 GMT -5
I'm also remembering having issues with the varitone in these things from time to time. I'm not sure if all EB3s had the varitone or not. Or, if it was called a "varitone" when on a bass. Basically the same idea.