EB-0 wiring help

[Pilgrim]

Usually, the mystery wire exits out of the top of the control cavity.  The other end is supposed to be wedged between the lower bridge insert and the body.  If it isn't making good contact, that might be your problem.  Run a temporary jumper from the jack to the bridge to see if that helps.

<Mr. Burns mode: ON>

Excellent!  (Rubs hands)

<MB mode: off>

[Pilgrim]

SORRY to drag this out, but........................................

I have done more testing and simplified things.  

Let's consider my EB-0 to have only one pickup, the Gibson mudbucker in the neck position (the other pickup is completely disconnected.)  Perhaps that will help me figure out what's going on.

Here's the situation.....

- The mudbucker pickup is wired to 500K ohm pot.  
- Grounds run to the jack shield connection,
- The live wire runs to the jack tip connection.  
- The ground/shield wire from the mudbucker is also wired to the metal pickup cover to assure that it's grounded.

When I connect the bass to an amp, I get little or no hum when I touch the strings...but when I prop my thumb on the pickup cover to pluck, I get loud hum.

I tried connecting a ground wire from the bass's internal bridge ground wire and the ground side of the jack around to the bridge.

- This results in hum all the time.  
- When I touch the strings, the hum is silenced.
- When I prop my thumb on the pickup cover with my fingers on the strings, the hum gets louder but not too bad.  
- If I touch the pickup cover without putting my fingers on the strings, the hum is quite loud.

Could it be a problem with the way the pickup is wired?  It has the original leads including shield for about 2 inches, then the leads were cut.  I've had to graft extension wires on at that point.

There is clearly something going on with the grounding, but logic fails me in my attempt to understand what.  Can someone help me reason this out?

[exiledarchangel]

Try this: connect the mudbucker directly to the jack (no pot) and also connect a ground wire from the pickup to the strings (with an alligator clip) and check again. If the problem dissapears, then its the bass' ground that has some problem. If the problem persists, your mudbucker is sick.

[Pilgrim]

Definitely worth a try!

[Pilgrim]

Latest report with pickup wired direct to output jack, no pot in between:

• No finger contact with strings: slight hum.
• No finger contact with strings AND touch the metal pickup cover: loud hum.
• Touch strings with finger: no hum.
• Touch strings with finger AND touch metal pickup cover: moderate hum.
• Adding a ground wire between the ground side of the output jack and the bridge has no effect - does not reduce hum.

Any ideas on what to try now?

I think that to make the bass functional for the time being, I'll connect the Dimarzio Model one and just leave the mudbucker out of the circuit entirely.

[Highlander]

That don't sound healthy...

Do you have a multimeter...?

[Daniel_J]

Try taking off the metal cover completely and see what happens. And after that, try wiring the metal cover to the ground side of the output jack instead of wiring to the shield/ground of the pickup.

[Dave W]

Try taking off the metal cover completely and see what happens. And after that, try wiring the metal cover to the ground side of the output jack instead of wiring to the shield/ground of the pickup.

+1

The cover is contacting something it shouldn't.

[chromium]

On my old EB-0, I had run a ground from the mudbucker's metal frame/enclosure to one of the mounting screws on the cover.  Prior to doing that, it hummed more than Jenna Jameson when I touched the cover as you describe.

My EB-3 does the exact same thing, and I still need to add a ground there.  I like to use the mud's cover as a thumbrest, but as it stands now I avoid it because it starts to become an instrument of its own!

Not sure if this is the same grounding problem you are running into, but its something to check...

[exiledarchangel]

Prior to doing that, it hummed more than Jenna Jameson when I touched the cover as you describe.

[outpost mode=on] Maybe your fingering was too intense? [outpost mode=off]

Definately worth a try, if it doesn't work then try to isolate the mud cover from the rest of the pickup, with duct tape or something.

[Pilgrim]

Try taking off the metal cover completely and see what happens. And after that, try wiring the metal cover to the ground side of the output jack instead of wiring to the shield/ground of the pickup.

Can do!

On my old EB-0, I had run a ground from the mudbucker's metal frame/enclosure to one of the mounting screws on the cover.  Prior to doing that, it hummed more than Jenna Jameson when I touched the cover as you describe.

A rather delightful simile! I have a wire from the shield side of the pickup's output to the cover, but it's not doing the job.  I'll try the connection suggested at the top of this reply next....or maybe I should just call Jenna.  I suppose I can always ask my wife if she has any ideas.

You guys are INCREDIBLY patient!  I appreciate your ongoing help.  And BTW, yes, I have a number of multimeters, digital and analog.

[Highlander]

Check everything to ground, including covers... ensure that all metalwork not part of the circuit is common with the ground, ie as close to zero ohms as possible...

[Pilgrim]

All of you have had a piece of it - I got back in there and removed the cover - hum still present.

Then I tried running a ground wire from the body of the pickup to the ground on the output jack - hum still present.

Then I thought it over....and tried reversing the leads from the pickup.  Something that someone wrote in the last few posts this thread sparked the idea.

HUM GONE.

Maybe I saw things wrong when installing the pickup - maybe the wiring was somewhat deceptive, as this pickup has been through other sets of hands - but reversing the leads solved the problem.  No hum with or without pickup cover present.  How can you get more basic than that???

Now I'll try to re-connect both pickups (I have have the wiring totally screwed around by this point) and see what happens.  But if nothing else, I now have a functional Gibson pickup, so I can at least play it the way it was designed...with one pickup.  Adding the second one will just add options!

EDIT...............................

I now have both pickups working!  The Model One is a lot brighter than the Gibson, and in alternating volume, I find it's not nearly as loud..but it's quite usable.  Also, if I have both volume puts wide open there is a bit of signal cancellation at the max settings.  So far, I like the sound best with either the mudbucker up full and the Dimarzio off, or the Dimarzio down a tad at about 7 of 10.  It adds just a hint of brightness at that setting.

Darn thing is finally playable! Hot-ta, hot-ta damn!

[Daniel_J]

Yup! That is what I was going to suggest next, after testing without the cover. Because it would mean that the cover was acting like the lead and by touching it you would be sending the noise fpicked up from your body to the system.

So, by reversing the leads you mean you connected the shield/ground from the pickup wire to the lead of the jack? Or you had it all wrong from start and now you correctly wired the shield/ground to the ground of the jack? Or is it that the wired from the pickup is not the shielded type?

[Dave W]

Yay!