I have an Ibanez RG220H (IBZ neck pickup, Seymour Duncan bridge pickup) that I've been trying to de-hum, and have run out of ideas/internet searches. The guitar is currently wired with a humbucker pickup connected directly to the output jack, in attempt to rule out all other components. Even with that basic setup, the guitar continues to produce a loud hum.
I've tried grounding the bridge/strings to the output jack shield, have replaced the output jack, and swapped the output jack leads, but still nothing, the guitar continues to hum.
If I connect the bridge pickup, I get the same hum as the neck pickup (maybe slightly louder), but I've noticed that the hum gets much quieter if I rotate the guitar to face a certain direction. When trying this same trick with the neck pickup, the hum doesn't get any quieter.
If I connect a different (and nicer) guitar to my exact same setup, everything is dead silent.
Am I running into a shielding issue? Maybe a busted pickup?
UPDATE: I've since rewired and shielded the heck out of the guitar (all pickup, electrical, and bridge cavities), and I'm now only getting that awful hum from the bridge pickup (neck still has slight grounding hum, but is manageable). The hum goes away if I rotate the guitar about the neck axis. At this point, I'm thinking the issue is an error in the wiring diagram. This is the official diagram from Ibanez, but apparently the VLX91 switch is problematic...