NOW what did I do ?

[VRICKY63]

Tried to shield the bass and lost tone and volume. Removed the shielding and everything sounds fine except......when I roll both volume controls all the way off I get a huge hum until I touch the strings ?

[songdog]

Check the ground connection to the bridge (and thus to the strings).

[AndyM]

The same thing happened to me when shielding an electric guitar. It only takes one spot in the cavity for you to make contact with one of the pots or the output jacks to short the instrument signal to ground (shielding). One option, although not so pretty, is to wrap electrical tape around the pots and jacks. Ensure there's no connection between those items and the shielding and gorund wire and you should be OK.

[VRICKY63]

Yes. When the shielding was still in the bass I did wrap the vintage tone switch in electrical tape. The tape works well to isolate any ground problem with shielding.

[rictified]

Yes. When the shielding was still in the bass I did wrap the vintage tone switch in electrical tape. The tape works well to isolate any ground problem with shielding.

You must have a short somewhere, it can be tricky in a 4001 cavity, I shielded two 4001's with no problems years ago and they were quiet as a church mouse. I shielded everywhere, the treble pickup cavity, the bass pickup cavity, the little drilled out cavity to the bass pickup, the pick guard, everything, the whole cavity.

[VRICKY63]

I found the ground wire under the tail piece was loose but even after securing it and checking continuity from the tail to the pots and pickups. I still have a bad hum with both volume pots turned off ??????

[rictified]

I found the ground wire under the tail piece was loose but even after securing it and checking continuity from the tail to the pots and pickups. I still have a bad hum with both volume pots turned off ??????

If I were you in that situation, I would take it all apart and start over again. It sounds like you either have the hot wire going to ground somehow or you have a large floating piece of shielding, in other words if a piece of shielding isn't grounded it acts like an antenna and picks up AC hum.

I think I misread it, you took the shielding out? Do you have another Ric bass? If so take it apart and make sure everything matches, if not find an online schematic and make sure your bass matches the schematic.

[VRICKY63]

Going to look at the schematic next. There is still some shielding under the tailpiece to remove.

[cassius987]

There is absolutely no reason to shield the tailpiece because there is no "information" over there that can be exposed to background noise. It's all ground. Just FYI. I doubt shielding there it could harm your signal, either.

[VRICKY63]

Wierd. I pulled the shielding out of the tailpiece cavity and scraped out all the shielding paint that was in the control cavity. No more hum with the volume controls off.

[cassius987]

The paint was likely the culprit; if there is a way for shielding by the tailpiece to affect your sound I am unaware of it. Of course I'm assuming you actually had a continuous ground set up.

My 4001FL -- that I bought as a beater, essentially -- came with the control cavity "slathered" in that carbon shielding paint. It was dangerously close to the ROS jack when I opened the bass up to get it to actually sound like a bass. I removed it from the area just around the jacks so there's no chance they could touch when a plug was inserted. I did other changes as well. In any case the bass actually sounded like a bass after that! When I received it, all it could do was make weird AM radio noises. The wiring harness was redone really half-arsed among other things such as the excessive shielding job.