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Dry/Cold solder joint?

wraub

wraub

Apr 9, 2004
7,761
10,630
ennui, az
#1
Greetings. My '84 Jazz bass has a problem.

Whenever the neck polepieces are touched, there's a buzzing sound. Only on the neck PU, not there if not touched, and the rest of the electronics are dead silent, touched or not.

Hasn't really bothered me, but between trying some different picking styles and doing more recording of late, I think it's time for a fix.

My guess is there's probably a bad joint somewhere.
Suggestions?

Thanks!

wraub
 
#4
Fender pole pieces are never grounded, and that's the problem. When you touch the pole pieces you get hum induced into the signal.

The cure is to try and ground the pole pieces with some copper foil tape on the bottom of the pickup. You need the tape with conductive adhesive. You have to press it against the magnets and burnish it with a lead pencil or something to get good contact. Also, some pickups have been dipped in lacquer, so you need to get that off the magnets. Then solder a ground wire to the copper foil and the noise should be gone.
 
#7
wraub said:
Both PUs have copper plates in the bottom of the PU routes.
Also, it only happens with the neck PU, the bridge PU doesn't have the same issue.

wraub
Click to expand...

The brass plates have nothing to do with grounding the magnets. You need to physically ground the magnets.

This is nothing new. Even though Fender doesn't see fit to do it, companies like Nordstrand do:

732_b-dcplastic_02.jpg
 
#9
Thanks again to all for the replies.
David, some interesting stuff on your website.

I decided to start the easier way, and open the bass up, looking for potential potentiometer wiring swaps ala narud.
Imagine my surprise when I discovered the wiring was not, apparently, done correctly in the first place,. At least according to Fender specs...
So, I'll be starting there.

More to come, probably. :)

Thanks again,

wraub
 
#10
OK, after a while swapping wires, I realized that the wiring diagrams for both the 62 ri and the 75 bass (Geddy Lee) do not apply to this bass, apparently.

Now recovering from burning lead fumes, will re-attempt tomorrow.

Thanks,

wraub
 
#11
Was able to unground and then reground the bridge PU, but the neck PU remains the same as before.

The PU routes have metal plates at the bottoms, and these have additional wires not covered in the wiring diagrams mentioned above. Attempts at wiring without these additional wires achieved the same results as before.

I am at the point of considering shooting the damn bass with a large caliber handgun.
Since I do not have one at the moment, I guess I have to try again.

Will do so tomorrow.

wraub
 
#12
wraub said:
Was able to unground and then reground the bridge PU, but the neck PU remains the same as before.

The PU routes have metal plates at the bottoms, and these have additional wires not covered in the wiring diagrams mentioned above. Attempts at wiring without these additional wires achieved the same results as before.

I am at the point of considering shooting the damn bass with a large caliber handgun.
Since I do not have one at the moment, I guess I have to try again.

Will do so tomorrow.

wraub
Click to expand...

post some pics if you can. an 84 jazz shouldnt be that different than anything else. my own 78 serial number jazz is actually an 80 and looks slightly different with a ground point screwed into the cavity wall but still wires up the same as any other jazz. all you should have to do is connect the hot to ground and the ground to hot on both pickups.
 
#14
OK, having photobucket issues.

Here's the current status:

Neck PU: White to hot, black twisted with black from neck PU rout brass plate and soldered to back of neck PU pot:

Bridge PU: White to hot, black twisted with black from bridge PU rout brass plate and soldered to back of bridge PU pot:

Brass grounding strip from brass plate under bridge PU and running under bridge.

Brass plate in control cavity has a wire soldered to it, not currently attached to anything.

Have tried attaching this wire to various places with no difference in result.

Bridge PU is dead quiet, neck PU has same issue (noise when touching polepieces, which stops when touching any other metal on bass.)


Anyone have advice for my fragile little mind?

Thanks...

wraub
 
#15
Update:

Actually, the above wiring scheme is a vast improvement over the original layout of all black wires soldered to the back of the volume pot.

Sound is now clearer and more distinct, pickups individually now have more of the typical J bass tones, and overall it just "sings" more.

Additionally, the polepieces on the neck PU do not buzz when touched if I am, say, touching the strings at the same time.

I guess I'll call it a minor success.

Thanks again to you guys.

wraub
 
#16
OK, what'd I do?

I did the above mentioned mod to the wiring, and this bass is just silly!

Each of the knobs (V,V,T) now have control over the full throw of the pot, and each of the J PUs are silent with the other PU at 0.

What have I done? :) Any ideas? Hard to believe something so simple would make such a difference...

wraub

p.s. it really sounds great...
 
#18
wow, even though i'm a complete amateur, i've been swapping pickups for years and never encountered this problem nor heard of this solution (i also thought that the magnets aren't supposed to be part of the circuit).

I will make a mental note and subscribe to this thread. Thanks.
 

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