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Passive Jazz Bass. Why is this happening?

G

GoneFission

Dec 2, 2012
176
199
Pennsylvania
#1
I have an older Squire Jazz that i had pickups installed in several years ago. Never noticed this problem when i got it back and have since just had it in the case and haven't been playing it much.
Started playing it again and i am noticing weird volume issues. For one, when i solo the bridge pickup the tone pot is severely reducing the volume of that pickup. It is fine on the the neck pickup however.

What could be going on here my friends? I'm clueless and would like to get this sorted out as i also just installed a fretless neck i had laying around on it today as well. Sounds great with all full volume but having this issue. Something else is odd too with the volume that i can't put my finger on(jack?). Seems like there is either a pot issue or wiring issues. Totally ignorant in that regard and reaching out to any knowledgeable gurus here. Anything?

Just seems SO odd that the tone is effecting the rear pickup volume now. Have had many jazz basses and none acted like this.
 
#2
You can put your bass on a bench or table, Use a small mat under the body and use a neck support like a paper towel roll or TP roll and set up a small amp. maybe on a chair under the table. plug it in, hang a cable from it, and set the volume low.

Remove the ctrl plate, set aside screws, carefully plug in to the jack with the cable wire itself anchored down with a weight or something so it doesn't fall and pull on the wires.
Now, doing your best to not pull excessively on those wires, carefully wiggle or tap each solder joint on the 3 lugs of the middle pot with something like a dowel or a chopshick. Feel for the one that can make the signal go in and out. You're looking for loose broken or disconnected wire or possibly just a crappy connection that needs to be reflowed. Unless the tech didn't copy the original connections, it's likely not a wiring problem like you had mentioned.

Thats the first thing i'd check.
Otherwise, send us a clear pic of those soldering connections.
 
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#4
BassCajon said:
You can put your bass on a bench or table, Use a small mat under the body and use a neck support like a paper towel roll or TP roll and set up a small amp. maybe on a chair under the table. plug it in, hang a cable from it, and set the volume low.

Remove the ctrl plate, set aside screws, carefully plug in to the jack with the cable wire itself anchored down with a weight or something so it doesn't fall and pull on the wires.
Now, doing your best to not pull excessively on those wires, carefully wiggle or tap each solder joint on the 3 lugs of the middle pot with something like a dowel or a chopshick. Feel for the one that can make the signal go in and out. You're looking for loose broken or disconnected wire or possibly just a crappy connection that needs to be reflowed. Unless the tech didn't copy the original connections, it's likely not a wiring problem like you had mentioned.

Thats the first thing i'd check.
Otherwise, send us a clear pic of those soldering connections.
Click to expand...

thanks, I’ll check that out!
 
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#5
GoneFission said:
I have an older Squire Jazz that i had pickups installed in several years ago. Never noticed this problem when i got it back and have since just had it in the case and haven't been playing it much.
Started playing it again and i am noticing weird volume issues. For one, when i solo the bridge pickup the tone pot is severely reducing the volume of that pickup. It is fine on the the neck pickup however.

What could be going on here my friends? I'm clueless and would like to get this sorted out as i also just installed a fretless neck i had laying around on it today as well. Sounds great with all full volume but having this issue. Something else is odd too with the volume that i can't put my finger on(jack?). Seems like there is either a pot issue or wiring issues. Totally ignorant in that regard and reaching out to any knowledgeable gurus here. Anything?

Just seems SO odd that the tone is effecting the rear pickup volume now. Have had many jazz basses and none acted like this.
Click to expand...
The two problems could be related.
Can you expand more on the second problem with the volume control. Just describe what's happening without trying to analyze?
 
Last edited:
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#6
Old Garage-Bander said:
The two problems could be related.
Can you expand more on the second problem with the volume control. Just describe what's happening without trying to analyze?
Click to expand...
Yeah...i noticed when i tapped on the bridge pickup pot it would reduce the volume sometimes and tap it again it would become louder. Same with the jack. Move the cable in the jack and the volume may reduce. Not a scratchy sound but just a reduction in volume. Then went to lower the neck pickup and the volume reduced again but that could be me just moving something internally by placing it flat.

My guess is wiring but plead ignorance. Also noticed my bridge ground wire floating freely and unattached to anything? I was like..."great". That being said i am having no noise issues to speak of. Guess that could change in a bad room somewhere though. Didn't think a loose ground wire should be causing this eh?
So there is no ground wire connected to the jack. Just one wire. Like i said i plead ignorance and that certainly seemed strange that there was just one wire to the one lead at the jack soldering points. The one has nothing.
 
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#7
BassCajon said:
You can put your bass on a bench or table, Use a small mat under the body and use a neck support like a paper towel roll or TP roll and set up a small amp. maybe on a chair under the table. plug it in, hang a cable from it, and set the volume low.

Remove the ctrl plate, set aside screws, carefully plug in to the jack with the cable wire itself anchored down with a weight or something so it doesn't fall and pull on the wires.
Now, doing your best to not pull excessively on those wires, carefully wiggle or tap each solder joint on the 3 lugs of the middle pot with something like a dowel or a chopshick. Feel for the one that can make the signal go in and out. You're looking for loose broken or disconnected wire or possibly just a crappy connection that needs to be reflowed. Unless the tech didn't copy the original connections, it's likely not a wiring problem like you had mentioned.

Thats the first thing i'd check.
Otherwise, send us a clear pic of those soldering connections.
Click to expand...
Thanks for that! Will be doing this
 
#9
A cheap Jazz that I fixed up had the tone pot miswired by somebody. It behaved as you describe with tone knob cutting both tone and volume.

Thankfully, Jazz basses are easy to get at the wiring. Download a standard Jazz bass wiring diagram, and clean things up. Sounds like your jack may be getting loose. Clean gunk off the tabs and bend the tip tab in a little bit to tighten it up.
 
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#11
I had this happen before. Turned out that the tone cap leads were shorted out to places it should not have been. I don’t remember the specifics but that might be worth checking. When you take it apart, the problem may go away if it’s the cramped cavity pushing things together.
 
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#12
GoneFission said:
Yeah...i noticed when i tapped on the bridge pickup pot it would reduce the volume sometimes and tap it again it would become louder. Same with the jack. Move the cable in the jack and the volume may reduce. Not a scratchy sound but just a reduction in volume. Then went to lower the neck pickup and the volume reduced again but that could be me just moving something internally by placing it flat.

My guess is wiring but plead ignorance. Also noticed my bridge ground wire floating freely and unattached to anything? I was like..."great". That being said i am having no noise issues to speak of. Guess that could change in a bad room somewhere though. Didn't think a loose ground wire should be causing this eh?
So there is no ground wire connected to the jack. Just one wire. Like i said i plead ignorance and that certainly seemed strange that there was just one wire to the one lead at the jack soldering points. The one has nothing.
Click to expand...
I would not expect an unattached ground wire to the bridge to cause what you are experiencing.

For the grounding on the jack... If you have a metallic (or otherwise conductive) control plate, that could be how your jack is eventually grounded. Remember, nothing is grounded until your instrument cable is plugged in at both ends.

If you have wires that are soldered to the back of at least one pot, it's likely that the pot being bolted to the control plate is also connected to the jack ground which is bolted to the control plate. Then when you plug in your instrument cable to your bass, the ground side of the cable, which is the plug/jack shield carries ground to the rest of your bass. Sans the bridge in your case, which should be corrected.

In the above case, having a wire on the ground lug of the jack is not necessarily, necessary. Exceptions might be if using a jack who's ground is isolated from the rest of the control panel. Then the wire is a must have.
 
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#13
weird.... I have the exact opposite problem.

I've got tone knobs (VVTT) that sound like I have a .033 uf (or less) when I put .1 uf on each pot. I wanted more than enough. It does some shaping.... just nothing near what you would expect from a .1 uf.
 
#15
Appreciate the input everyone! Not good with uploading photos. Will have to find a good wiring diagram and see if mine has been done correctly. If not then get my soldering chops back and get to work. Hate to take it to a tech if i don't have to. Seems like it is a bad connection somewhere so i will fiddle around when i have more time. Thanks again!
 

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