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Grounding question

F

fiveoffour

Mar 21, 2013
81
81
#1
Hello there all. I just got a new preamp. I have everything wired in the way it's supposed to be, but I need to attach the pickup leads to a ground. The instructions say to solder it to the ground wire, or to the case of the blend pot. I cannot for the life of my get it to stick to the pot, and the ground wire is too far away.
My question is, can I solder a piece of wire to the existing wire and then solder that to the pickup leads?
Forgive me if this is an absurd question. I've never done this before, and am quite ignorant.
Thanks!
 
#3
fiveoffour said:
I cannot for the life of my get it to stick to the pot, and the ground wire is too far away.
My question is, can I solder a piece of wire to the existing wire and then solder that to the pickup leads?
Forgive me if this is an absurd question. I've never done this before, and am quite ignorant.
Thanks!
Click to expand...

A couple of ideas:

- pot casings are often covered by a protective varnish that requires abundant heat to liquify with a soldering device. I would suggest scratching the surface (knife/small sand paper) to uncover the metal and try again.

- to answer your question about elongating the wire, the answer is yes. As long there is conductivity between point A and B the current (and parasite electric signals) will travel through and get to the ground

I hope this helps
 
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#4
Holy cow, I'm glad I play and am not a tech. I finally got it onto the pot, but something isn't right.
I plugged it in, and when I move the pots back and forth, there is a qualitative change in the "hiss", but no volume comes out. Anyone have an idea what I did incorrectly? By the way, this is a Noll 2083 going into a Warwick Corvette Std.
 
#5
Update. I took them off the blend pot. I plugged it in, TONS of noise. When I connect the leads to the ground wire with another wire, all the noise goes away, but still no sound. So confused. Hoping someone has the obvious solution.
 
#6
MAYBE we can help you if you post a clear, in-focus picture of your bass' control cavity.

You mentioned a blend pot, so obviously you have two pickups, is it a Jazz bass (or "j type")? Stock pickups? Is the power to the preamp wired in properly?

Do you own a multi-meter?
 
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#8
Here we are.
 

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#9
I hope those are clear enough. Let me know if you need to see something more clearly.
Also, the preamp was prewired. All I had to do was solder the hot leads to the bots and ground them. Power is getting to everything. If I pull the passive/active pot, there is an absolute change in "hiss". Gets much quieter.
The bass is a Warwick Corvette Std. Two J style pickups.
 

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#10
Soldering a connection to a potentiometer case can be bad juju if you are not experienced. You may have damaged the pot by overheating it, and this is usually caused, oddly enough, by using an undersize soldering tool. Another thing not clear to me is: is the pot case actually connected to ground (i.e. the sleeve terminal of the guitar cable jack)? Through the years I’ve seen many ground wires connected to a metal piece that, itself, is not grounded.
 
#11
Gee I hope you I didn't...instructions told me to attach to a ground (which it would not reach) or to the case of the pot.
Also, I took them off, and took another wire and attached them to the ground wire. Still nothing.
 
#13
So when I say "hiss", I don't mean some unbearable hissing sound. I just mean the sound of a live instrument. I get zero sound when I hit a string. If I pull the passive/active pot out, most of the hiss leaves. If I move mids up and highs up, the hiss gets a little louder, like it would on any bass. But the sound of the strings does not get amplified.
 
#14
Are the wires coming from the pickups coaxial? Sometimes there are two (or more) wires, separately hot and ground. But sometimes it’s one fat wire that contains an outer braid that needs to be grounded, and an inner wire that is the hot connection.

You didn’t photo the factory wiring, before disassembling it, by any chance?
 
#15
Try some good ol' fashioned troubleshooting.
Solder (or alligator clip) a wire from the output jack tip and ring. Starting from the where the pickups connect to the blend, follow the signal path with the two wires, one on ground and the other on signal.
This will help you narrow down where the issue is.
 
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#18
thewildest said:
A couple of ideas:

- pot casings are often covered by a protective varnish that requires abundant heat to liquify with a soldering device. I would suggest scratching the surface (knife/small sand paper) to uncover the metal and try again.

- to answer your question about elongating the wire, the answer is yes. As long there is conductivity between point A and B the current (and parasite electric signals) will travel through and get to the ground

I hope this helps
Click to expand...
The basic problem with lengthening a wire is every joint adds resistance, especially if you use mechanical connectors or gob on the solder. Sctochbrite the back of your pot, clean and tin your iron and get a small curved metal pick. Tin the pot and wires, then hold them to the pot with your iron. As soon as the solder flows put the pick down next to the iron and take the iron away. You’ll see the solder cool when it loses it’s shine, then you can quit holding the wires down.
 
#19
Picture 1: It appears those pickup wires are shielded, and that you've only connected the pickups' hot wires and not their grounds. This is consistent with the symptoms you describe. Take a look here:

Not sure how to solder this particular wire


Also pic 1:
I wouldn't try to solder to the back of an MEC pot. MECs are built differently than "old school" controls so soldering on the back isn't feasible. MEC helpfully provides an extra solder tab on the back for ground connections, so use that instead of trying to solder to the back of the pot.

[Invalid or Expired Link Removed]
 
#20
So, I tried taking the leads off. I tinned them. I scratched up the back of the pot. All noise goes away if I connect them to the back of the pot, or use another wire to "extend" the ground wire. But nothing comes out from me playing. Did I cook my pot?
 

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