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Help with jazz bass wiring!


HORSE

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  • Members
Posted

I've just finished shielding and rewiring my jazz and it sounds EXCELLENT! I can't hear any hum at all (I'm sure I'll get some 60 cycle stuff here and there). However, I'm having two difficulties with the electronics:

 

1. The tone knob is acting as a volume knob (sort of). When I roll it all the way down, I get a very muted, extremely quiet sound.

 

2. When one pickup is on full, the other volume knob does not act as a volume, but merely like an on/off switch. What I mean is: if I have the neck pickup on full and I start blending in the bridge pickup, I hear no difference in sound until the very end of the rotation of the knob. Then the bridge pickup sound comes fully on.

 

 

I bought this wiring kit from basspartsresource.com (I've had excellent results) and the parts are all high quality (CTS, Switchcraft) so I'm assuming the problem lies with my assembly.

 

Does anyone know off the top of their head what could be causing these problems? I can post my wiring diagram and pictures if necessary, but I'm hoping these are easily diagnosed, common problems....

 

Thanks in advance!

  • Members
Posted

 

1. The tone knob is acting as a volume knob (sort of). When I roll it all the way down, I get a very muted, extremely quiet sound.

 

 

What size capacitor do you have in there? If it's larger, it may act like a quasi volume control because it's bleeding off frequencies that are well within the range of the bass guitar.

 

 

2. When one pickup is on full, the other volume knob does not act as a volume, but merely like an on/off switch. What I mean is: if I have the neck pickup on full and I start blending in the bridge pickup, I hear no difference in sound until the very end of the rotation of the knob. Then the bridge pickup sound comes fully on.

 

 

Did you wire the pickups in series? That would probably do it. You can only have one volume control when pickups are in series because there is only one path to connect the entire circuit. With two volumes, either knob can open the circuit.

  • Moderators
Posted

 

I've just finished shielding and rewiring my jazz and it sounds EXCELLENT! I can't hear any hum at all (I'm sure I'll get some 60 cycle stuff here and there). However, I'm having two difficulties with the electronics:


1. The tone knob is acting as a volume knob (sort of). When I roll it all the way down, I get a very muted, extremely quiet sound.


2. When one pickup is on full, the other volume knob does not act as a volume, but merely like an on/off switch. What I mean is: if I have the neck pickup on full and I start blending in the bridge pickup, I hear no difference in sound until the very end of the rotation of the knob. Then the bridge pickup sound comes fully on.



I bought this wiring kit from basspartsresource.com (I've had excellent results) and the parts are all high quality (CTS, Switchcraft) so I'm assuming the problem lies with my assembly.


Does anyone know off the top of their head what could be causing these problems? I can post my wiring diagram and pictures if necessary, but I'm hoping these are easily diagnosed, common problems....


Thanks in advance!

 

 

If you post pictures, I'll take a look.

  • Members
Posted

Thanks for the thoughts and willingness to help! I have to head out to work, I'll post some pics and a diagram of what I did tonight. I combined a bunch of different ideas for shielding and wiring, so I probably screwed up somewhere along the way.

 

Btw, the cap is a .047mfd Orange Drop.

  • Members
Posted

i had the exact same issues with my j-bass. the fix is actually pretty easy-

 

take it to a repair shop!

 

i tried fixing it myself, and after replacing the pots and jack and all that, it still wasnt right. taking it to the shop might cost more than fixing it yourself, but at least it gets done right.

  • Members
Posted

Ok, as promised, here's the wiring diagram. I can take pics if necessary, but everything is wired up like the diagram. All the shielding and grounding checks out on the multi-meter, so the connections there are good. I'm not an electronics wiz, so I probably have overlooked something or mis-thought something. Thanks in advance!

 

jwiring.jpg

  • Members
Posted

where did you find that wiring scheme? that looks a little... weird. the grounds/black wires going from the pots to the jack and connecting to the same post as the capacitor might be the problem. if the pups are grounded to the shielded control cavity, i dont think grounds on the pots are necessary, but im also mondering why you are grounding the pups to the control cavity.

 

im just used to standard wiring, so if this is some sort of common way to redo the wiring, dont mind me...:thu:

  • Members
Posted

where did you find that wiring scheme? that looks a little... weird. the grounds/black wires going from the pots to the jack and connecting to the same post as the capacitor might be the problem. if the pups are grounded to the shielded control cavity, i dont think grounds on the pots are necessary, but im also mondering why you are grounding the pups to the control cavity.


im just used to standard wiring, so if this is some sort of common way to redo the wiring, dont mind me...
:thu:

 

It's actually a scheme I came up to address my specific needs. It is based on a few different diagrams. It's sort of a modified star grounding system with all the pickup and pickup cavity ground leads going to the control cavity shielding and the grounds on the pots going straight to the output jack. This system works well for only have the signal leads attached to the jack plate (easy access) and there is also no need to solder anything to the back of the pots. Based on my limited knowledge of electronics, it should be working fine. I'm going to swap out the capacitor tomorrow because it might be giving me the tone knob problems. Also, I'm wondering if the pickup volume issue is just me not being used to these type of audio taper pots (I was using an EMG j-set in this bass previously).

  • Members
Posted

maybe the cap needs to go from the post to the back of the tone pot in order to work as a tone control?

 

i just switched to a .1 cap after using a .05 for a long time (i looked around for a .05 and all i could find were .047, and finally got frustrated enough to get a .1 .... :thu:) and it was weird, but ill get used to it. did you check to make sure its a .047? maybe the wrong one came in the kit?

 

there isnt a whole lot of tone difference between the pups in my j (well, there is, but i guess the basic tone is the same), so i also get the "on/off" volume thing. in my case, its just the tone colors of the bridge pup dont really come through until the volume is almost all the way up, so that might be normal. the overall volume gets thicker, but not necessarily louder.

  • Moderators
Posted

Do you have the outer legs reversed? The diagram you have shows you how it would look if you had x-ray vision and were looking at the wiring with everything installed. Make sense?

  • Members
Posted

 

Do you have the outer legs reversed? The diagram you have shows you how it would look if you had x-ray vision and were looking at the wiring with everything installed. Make sense?

 

 

I'm not sure I follow. The diagram I drew shows how the back of the jackplate looks with everything installed. As if you took off the jackplate and turned it over. It's the same layout Fender uses (for instance: http://www.fender.com/support/diagrams/pdf_temp1/basses/0131800A/SD0131800APg2.pdf)

 

If I had the outer legs reversed, wouldn't my volume knobs operate in reverse?

  • Moderators
Posted

 

If I had the outer legs reversed, wouldn't my volume knobs operate in reverse?

 

 

Yes. It was too late for me to be posting...

 

I don't know what the problem is.

  • Members
Posted

 

Yes. It was too late for me to be posting...


I don't know what the problem is.

 

 

 

 

I figured it out. Apparently it was too late for me too...

I had a wire in the wrong spot. I must have looked over it 20 times and not noticed. Sheesh....

  • Moderators
Posted

I figured it out. Apparently it was too late for me too...

I had a wire in the wrong spot. I must have looked over it 20 times and not noticed. Sheesh....

 

I know the feeling. :)

 

I was confused because the schematic looked fine.

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