Agh! Botched pickup and wiring installation. Help!

ishouldbeking · #1 11-23-2007, 07:23 PM

Ok, so I bought a whole bunch of upgrades for my SX p-bass and today was the big day... I put in a wiring harness purchased from Butch at Bayou Cables, a new Nordstrand NP4 p bass pickup, and a new Gotoh 201 bridge. I threw a new set of strings on there and went to tune up... bam. No signal. Nada.

I'm sure I just made a simple mistake, but I have no idea how to troubleshoot. I don't own a mulitmeter. I double checked all the wiring against the wiring diagram and it all seems right (white pickup wire to the white pickup lead off of the volume pot, black pickup wire to the green pickup lead off of the volume pot, ground wire stripped 3/8" and screwed into place in contact with the bridge). Yes, I turned both pots to make sure it wasn't just a matter of having the volume turned down. I should mention that the pickup wires are temporarily connected with wire nuts (my soldering iron arrives in the mail on monday), but I made sure that there's a solid mechanical connection before i connected the nuts.

Is there anything I should check or try? I have half a mind to admit defeat and bring it in to the shop tomorrow and have them clean up my mess. It's gonna get a pro setup anyway, and I was gonna have a tech fabricate a new nut as I don't trust myself to do that on my own, but the thought of dropping another $50-$75 to fix my wiring just rubs me the wrong way. Any suggestions?

ldervish · #2 11-23-2007, 07:55 PM

Sounds like the pup is not grounded. Usually one lead goes to the vol pot and the other is grounded. You might compare it with this diagram from the Stew-Mac site, or just contact Butch - I'm sure he'd be able to help if you can't figure it out otherwise.

ishouldbeking · #3 11-23-2007, 09:28 PM

Quote:

Originally Posted by ldervish

Sounds like the pup is not grounded. Usually one lead goes to the vol pot and the other is grounded. You might compare it with this diagram from the Stew-Mac site, or just contact Butch - I'm sure he'd be able to help if you can't figure it out otherwise.

Well... it looks like it should in the diagram. If i understand correctly the black wire is grounded to the back of the volume pot, and then a ground wire runs over to the bridge, which is screwed down on top of the exposed wire, right? Chances are that I've got some kind of bad connection somewhere... should I worry that I might have a faulty component? Maybe a bad pup or pot? It's sad how little I know about electronics... I was hoping this would be my big leap into the electronics world paving the way for future success, but so far it's been more of a headache than anything else.

atrapp · #4 11-23-2007, 10:09 PM

You should have two leads coming off the pup - one white one black. The black should be the ground and soldered to the back of a pot, the white wire should be soldered to the center tab of the volume pot.

Take a look at the link ldervish posted - follow the instructions.

ishouldbeking · #5 11-23-2007, 10:48 PM

Yup, that's what I did. Only difference is that Butch's pre-soldered harness has lead wires coming off the pot which I attached to the pickup wires with wire nuts. My plan was to wire it up with wire nuts for the next few days, then when I get my soldering iron I'll make the connections more permanent. Having gone over all the connections again I still can't tell what I did wrong.

ishouldbeking · #6 11-23-2007, 11:00 PM

one more question: I used springs underneath the screws on my pickup, and it holds the pickup casing in place at the proper height, but the actual pickup is separating from the pickup casing and dropping down into the pickup cavity. how do i prevent that?

ishouldbeking · #7 11-24-2007, 12:13 AM

Well... I double then triple checked my wiring, reconnected each connection, took off the bridge to make sure I had a solid ground and still nothing. For the heck of it I even tried swapping the wires (on the off chance the white and black wires were switched or something), but that didn't help either. So unless I'm blatantly missing something, it looks like I have a bad component.

What are the odds that I got a bad Nordstrand pickup or a messed up CTS pot?

GlennW · #8 11-24-2007, 01:10 AM

If you don have a DMM and want to check the pickup, run it directly to the jack with nothing else in between or connected. White to hot, black to ground (though it won't matter). You don't have to solder, just strip the insulation off the ends of the pickup wires and twist them together with the ends of the wires coming from the jack, and see if you get any sound. If not, it's probably a dead pickup (assuming the amp and cord work).

Nighttrain1127 · #9 11-24-2007, 02:54 AM

It could be a dead pickup if you take the covers off the pickups look where the leads attache to the plastic of the pickup base and see if there is a Very thin wire connected there if it is not there or not connected then you probably have a dead pickup. That you can do without a meter.

GlennW · #10 11-24-2007, 07:43 AM

An easier way to test your pickup than I suggested before is to disconnect your pickup and then aligator clip the leads to one end of the cord, plug the other end into your amp and tap the poles lightly with something metal - if it works you'll get a popping sound from your amp. You can leave the pickup in the bass and all the other stuff alone this way.

Busker · #11 11-24-2007, 07:58 AM

The ground wire leading to the bridge shouldn't have anything to do with your problem. The pickups and controls should work whether the bridge/strings are grounded or not.

The odds you got a bad pickup or pot are not good. They are most likely fine. Try checking the pickups by temporarily wiring them direct to a guitar cord, like the poster above says. If they are good (and your guitar cord is good), your problem almost has to be in the way you wired or grounded the pots.

And by the way, all pots have to be grounded, so make sure you have a ground wire running from back to back on the pots. In the old days, a lot of companies would simply run a bare wire from pot back to pot back to insure all the pots were grounded. That may or may not be necessary if the pots are mounted on a metal control plate.

ldervish · #12 11-24-2007, 08:01 AM

Quote:

Originally Posted by ishouldbeking

one more question: I used springs underneath the screws on my pickup, and it holds the pickup casing in place at the proper height, but the actual pickup is separating from the pickup casing and dropping down into the pickup cavity. how do i prevent that?

Put the spring beneath the pickup, not between the pickup body and cap. The spring end should be bigger than the screw hole, if not you need a different spring.

GlennW's test is a good one to isolate the trouble to either the pickup or the harness. If it is difficult to connect to the output jack without soldering, you could also test the pups by holding the leads directly to your cable's guitar plug (one wire to shaft, one to tip) and tapping the pup with something like a coin or small screwdriver.

EDIT: I see Glenn just covered this. Great minds..., and all that.

I think you're on the right track.

Busker · #13 11-24-2007, 09:09 AM

I just realized its a P-bass, with the controls mounted on plastic. Any chance that you forgot to ground the tone pot? That will make it flat out not work, I think (see above post).

ishouldbeking · #14 11-24-2007, 02:31 PM

SUCCESS! I took all of your advice to heart and managed to get my SX in rip-roaring shape and it now sounds amazing!

First off I tested the pickup by touching the leads directly to the guitar cable, and I was able to strum the strings and get signal through my amp. That was the biggest relief, knowing I hadn't dropped some serious cash on a bum pickup.

My girlfriend had been watching me get frustrated all yesterday so she decided to sit in and help out this morning. I'm not ashamed to admit that she was the one who solved my grounding problem. I explained to her the difference between the hot wires and the ground, and where they were supposed to go... and she noticed that I had accidentally screwed the tone pot down with one of the white wires breaking the connection between the "spiky ring" (don't know it's real name) and the metal foil on the back of the pickguard. In my haste I hadn't noticed it, so all i did was detach the pots from the pickguard and pull that wire free. I replaced everything, making sure to keep good contact with the pickguard foil, and voila! Sweet, sweet tone coming through my lil practice amp.

I still need to replace the springs under my pickup (they're tiny!), then solder the pickup connections in place making them permanent (the wire nuts don't seem very solid), and I'm definitely gonna get a pro setup to get this beast in tip-top shape... but now that I've got it all working I can already hear a huge difference in tone... it's probably a combination of better electronics, solid bridge (the old one gave off horrible ringing overtones), and the Nordstrands, but it's sounding pretty fine.

Thanks for all of your help guys -- you saved my @$$!

bassmanrocke · #15 11-24-2007, 02:51 PM

A good way to keep the pickup and cover from separating is to put foam rubber under the center of the pickup. The springs are not really effective unless the pickup is mounted in the cover with epoxy, and since you've dished out serious dough on the nordies I don't think you want to do this. Just cut a piece of foam small enough to fit between the mounting screws of both parts of the pickup. If the foam is thick enough it will hold up the pickups high enough, but also allow enough compression to tighten them down low enough. (PS-This is how Fender mounts their P-Bass and J-Bass pickups) Most pickups are packaged with foam that works well for this, check your box.

ldervish · #16 11-24-2007, 03:04 PM

Congratulations, glad you found the problem.

I have to say that I don't much like the idea of using the foil as the grounding connection though. It is there to shield the electronics from outside hum sources and needs to be connected to ground to do that, but if it were mine I would physically connect each of the pots, output jack and bridge (as shown in the diagram). As it is, if the foil is torn by the lock washer (the "spikey ring") you are back to square one.

A second thought: It occurred to me that Butch surely must have a grounding wire connecting the parts in his harness, which then connect ground to the shield via the lock washer. So what might have happened in your case is that the lock washer perhaps made a small cut through the white insulation, contacted the wire inside and grounded the signal. In that case what you have already done will be sufficient.

ishouldbeking · #17 11-24-2007, 05:21 PM

Quote:

Originally Posted by ldervish

So what might have happened in your case is that the lock washer perhaps made a small cut through the white insulation, contacted the wire inside and grounded the signal. In that case what you have already done will be sufficient.

Thinking back on it, this seems to be what happened. I had the nut twisted on there pretty tight and the white wire was really clamped down underneath it. When I take my bass to get a setup and new nut I'm gonna have the tech look thru my wiring just to be on the safe side... can't really afford a mid-gig failure! Again, thanks guys for all your help.