Jazz Bass volume doesn’t fully zero, tone partially affects volume

[Arch1medes]

Hello! I’ve lived with this issue for awhile, and I’m taking another crack at fixing it. Hoping for some insights from the community here since I’m a novice at soldering and electrical.

So, with the neck volume solo’d + tone @ 20% i still have a quiet signal, say 10% if I were to estimate.

THEN when I roll the tone up or down, I get modest volume increase/decrease. Same situation with both volume knobs at 0 (or any combination)

Any thought or advice is appreciated!

now, to publicly humiliate myself, please see the pictures of my first soldering job ever:

 

[dwizum]

Are both of the pickup negative leads grounded through that one black wire on the top of the tone pot case?

Ideally you'd have a ground wire running across the backs of all three pots. As is, you're relying on the mechanical connection between the pot cases and the shielding for signal ground. This works sometimes, but other times it can cause all sorts of weird issues. If I were you, I'd add a ground wire.

Otherwise I would suspect a bad solder joint and/or a ruined pot (poor soldering technique can cook pots). Double check your solder work. Clean off all that corrosion and old flux (rubbing alcohol works fine). Get your soldering iron hot, clean the tip, and tin the tip. The tip should be bright and shiny and glossy. If it isn't, clean and tin until it is. Then, touch the tip to each solder point and heat it until the solder reflows. Make sure you're heating the PARTS and not just the solder. The parts need to be hot enough for the solder to bond or else the joint will be bad.

If you try all that and can't figure it out, toss your pots and cap and start over. A Jazz bass is a couple dollars of parts, it's not worth troubleshooting all day.

 

[Arch1medes]

Are both of the pickup negative leads grounded through that one black wire on the top of the tone pot case?

Ideally you'd have a ground wire running across the backs of all three pots. As is, you're relying on the mechanical connection between the pot cases and the shielding for signal ground. This works sometimes, but other times it can cause all sorts of weird issues. If I were you, I'd add a ground wire.

Otherwise I would suspect a bad solder joint and/or a ruined pot (poor soldering technique can cook pots). Double check your solder work. Clean off all that corrosion and old flux (rubbing alcohol works fine). Get your soldering iron hot, clean the tip, and tin the tip. The tip should be bright and shiny and glossy. If it isn't, clean and tin until it is. Then, touch the tip to each solder point and heat it until the solder reflows. Make sure you're heating the PARTS and not just the solder. The parts need to be hot enough for the solder to bond or else the joint will be bad.

If you try all that and can't figure it out, toss your pots and cap and start over. A Jazz bass is a couple dollars of parts, it's not worth troubleshooting all day.

Thank you for the help!

To answer your first question: yes. I believe it’s called a star ground?

couple confessions: I had to rework a few of the solder joints for various reasons. Also there were a couple times the back casing of the pot was almost too hot to touch for more than 2-3 seconds. Probably caused some damage.


Your suggestions seem pretty reasonable. I’ll do that pot-to-pot ground, and redo some iffy joints. If that doesn’t work I’ll put in an Amazon order for some new pots.

 

[dwizum]

A couple of those solder jobs do look highly suspect. But to be fair, a couple of them also look really good for a beginner, so don't beat yourself up too hard. We all learned, and everyone has sloppy work as they're learning.

 

[Arch1medes]

A couple of those solder jobs do look highly suspect. But to be fair, a couple of them also look really good for a beginner, so don't beat yourself up too hard. We all learned, and everyone has sloppy work as they're learning.

thank you. I really enjoyed the process, but found out quickly that 7 YouTube videos, while helpful, are still no substitute for hands on experience lol. For example: setting up a proper work bench instead of a towel on the living room floor was huge!

 

[Arch1medes]

A couple of those solder jobs do look highly suspect. But to be fair, a couple of them also look really good for a beginner, so don't beat yourself up too hard. We all learned, and everyone has sloppy work as they're learning.

I found out the solder joint on the neck volume pot ground lug was bogus. I used a jumper wire between various spots to find this out. After re-flowing the solder on that lug, I soldered a ground wire across each pot chassis like you advised. Everything worked. However I felt compelled to redo the whole job, so I ordered some linear taper pots and gave it a 2nd go.

While I’ll always be a hobbyist, I was pleased with the improvement, and I pulled it off with barely any rework. And maybe it’s in my head, but the signal and tone sounds more articulate. Anyway, here’s to learning from experience!

 

[dwizum]

Well done, that job looks much cleaner!