Rippper Ground Problem

[borgward]

My Ripper has a ground problem. It goes away when I touch the strings. Picks up noise when near neon signs. I bought this mid 70's model from original owner over 20 years ago. Still original. No loose wires. Ground wire to bridge post is completing circuit. It has been doing it for a long time now, but did not use to. I notice that wires from pickups are unshielded. Is this a common problem for Rippers.

Favorite rig for thsi is Peavey Bass 400 head w/ 1820 cabinet (2 tens and 1 eighteen)

[THand]

Sounds like you are on the right track.

The neon lights causing noise could be helped by shielding(that part is not a grounding prob, IMHO).

I believe in star grounding and shielding, but I don't know how much you want to alter the bass.

Since the wires are looking right, you might just heat up the existing solder and that may correct the problem since it wasn't there before.

It could also be the pickups themselves. But lets hope not.

Lots of info here in TB on doing all of that. I usually follow the sticky on silencing a Marcus Miller bass. The main difference with me is, when I join multiple wires together(for star grounding) and solder them to a single wire, I put heat shrink around that joint just for the additional peace of mind.

[lethargytartare]

When you touch the strings, what is actually happening is that the noise your body attracts, like an antenna, is shunted to ground by way of the wire connecting the bridge to the circuit's ground path. When you're not touching the strings, that same noise is getting into some unshielded part of your guitar's signal path.

As THand says, a lot depends on how much you want to tinker with it. But there are some improvements you can make that will help out a lot. The easiest is to fully shield the cavity with copper foil, including the cavity cover (making sure there are places where the foil on the cover makes solid contact with the foil IN the cavity). Then connect that foil to the ground path ground lug on the jack. Then you have all of the signal path in a box, and that box is shunted to ground.

Read up -- there are more things you can do to improve the wiring (I'm also a big fan of star grounding), but cavity shielding is pretty basic and should help a lot. Shielded wires IN the circuit are another option, but that can end up being a bit more work, and you STILL should probably shield the cavity better.

[borgward]

Originally Posted by THand

It could also be the pickups themselves. But lets hope not.

I am thinking pickups. Shielding could help, but the bass did not need it originally. Can you explain how the pickups could be the problem? Is there any way the pots could cause the problem?

[lethargytartare]

Originally Posted by borgward

...Shielding could help, but the bass did not need it originally....

Your bass also didn't have this noise problem originally :-)

Here's the thing -- if touching the strings kills the noise, then it's unlikely to be the pickups. Consider: the strings are between the pickups and any noise sources in the room, and they are properly shunted to ground, so it would be tough for room noise to get to the pickups without being "caught" by the strings.

I'm looking at a pic of ripper electronics -- assuming yours are the same (http://img241.imageshack.us/img241/8259/ripperfz7.jpg) you could test that the foil backing of the pickguard has continuity with the ground lug of the output jack -- to insure that that foil is also shunting to ground properly.

All that said, there do appear to be unshielded wires that are a bit exposed in there, and there's also a component in there I don't recognize (Bill Lawrence designed these basses? I wonder if it's something similar to his q-filter, which is also a passive tone control that looks a bit similar) -- I wonder if that could be a culprit.

Personally, I'd decide if I wanted to keep the bass as close to stock as possible. If so, I'd be investigating every wire and path for continuity, and the ground wires, the current shielding, etc. If not, I'd reshield the whole cavity -- that's been good to me with all of my instruments, so I do it as a matter of course. here's a a pretty minimal thing you could try (a fair amount of labor, but zero changes to the wiring itself): take all the components off the pickguard. Line the entire underside of the pickguard with aluminum foil, making sure it has electrical continuity with the existing patch of foil (copper tape with conductive adhesive would be the best IMHO but I use tin foil on my cheaper guitars). Put all the components back on. What that does is give you a broader wall of protection to all the unshielded pickup wires.

Also, confirm whether the problem exists equally with all of the pickup settings -- neck, bridge, both, etc. If it's only when a specific pickup is engaged, well, maybe that IS the bad guy. They're both humbuckers, so they should each be quiet by themselves. If the noise is the same (or mostly the same) in all positions, then it's likely something in the electronics.

cheers!
ltt

[THand]

To me, it sounds like you may have more than one problem.
The noise around neon lights indicates needing shielding.
The other buzzing indicates a ground problem.

To answer your question, the coils inside the pickup could be corroding, or they may be "loosening" for lack of better terms.
The wires leading to and from the coils may need re-soldering. I'm just naming things since I can't see it.

Yes pots can cause problems like your ground issue if they aren't soldered well, which is why I mentioned just reheating the connections earlier. After 30 years, they could just need heating up to reconnect better. Most pots that I have seen actually going bad became "scratchy" sounding when operated.

If you don't have much experience with this sort of thing, take it in to a tech and tell them what you are having trouble with. It doesn't sound like a major problem(unless it's the pickups) and they should be able to shield and star-ground it without costing too much. I'd hate to see you mess that bass up.

If it were me and it was discovered that the problem is the pickups, I'd look for somebody to rewind them before I'd just replace them.

[borgward]

I recently played my Ripper thru a GK amp. No noise whatsoever. Beginning to think the problem is w/my Peavey Bass 400 Mark III amp.

I posted the problem to the Talk Bass Amps Forum:

Ground Problem

Hope that does not constitute "cross posting"

I was reluctant to Shield the wiring. Stratocaster Guitars are famous for noise, but they loose their tonal qualities if the wires are shielded. So i guessed the same could happen w/the Ripper. The Foil shield under the pickguard does complete a circuit w/the input jack. If not shielding the wires was a problem, the problem would have been exhibited from day one.

[borgward]

No More Ground Problem. It was my amp. I recently unplugged the power cord from the wall, and the ground prong pulled out of the plug staying in the receptacle.

Fixed that, no more problem.

I had shielded the wires inside the bass, but that definitely made an undesirable tone problem. The shielding caused the D and G strings to have a pronounced boingy sound compared to the E and A strings.

I removed said shielding and it now sounds right.

I remember reading in Guitar Player Magazine that shielding the unshielded wires wires in the Fender Stratocaster would ruin that signature Strat sound. (The internal wiring of the Ripper is also unshielded by design)

[SGD Lutherie]

Originally Posted by borgward

I remember reading in Guitar Player Magazine that shielding the unshielded wires wires in the Fender Stratocaster would ruin that signature Strat sound.

Frankly, I think that's nonsense. The only way a shielded cable would alter the tone of a guitar is if the capacitance was very high. In the short lengths of wire found in a guitar, that would never happen.

(The internal wiring of the Ripper is also unshielded by design)

The Ripper has aluminum foil under the pickguard. That's the shielding.

[mongo2]

Originally Posted by lethargytartare

When you touch the strings, what is actually happening is that the noise your body attracts, like an antenna, is shunted to ground by way of the wire connecting the bridge to the circuit's ground path. When you're not touching the strings, that same noise is getting into some unshielded part of your guitar's signal path.

More generally speaking, your body (aka a big bag of water with electrolytes) acts as a shield when you contact a grounded portion of the bass.

[rtslinger]

I agree with the masses you need shielding. But my 70's Ripper came with shielding, so my only thought is someone who was clueless removed it?