Tone pot problems

[gareth]

The tone pot in a bass I have has never worked and I’ve at last got the time to sort it out

 

Should I just replace the pot itself, or just the capacitor or both?

 

If both don’t need replacing how do I decide whether it’s the pot or the capacitor that is faulty?

 

Thanks

Edited December 26, 2021 by gareth

[Dan Dare]

Caps (unless they are ancient paper in oil types) are most unlikely to fail. Pots are cheap, so buying one to try will not break the bank. Before you do, check the wiring. If it doesn't work at all, as opposed to badly/noisily/intermittently, that would suggest a wiring fault.

Edited December 26, 2021 by Dan Dare

[Supernaut]

Cold solder joints can easily happen but fortunately, easy to fix. 

[mcnach]

Capacitors are so cheap that you could take the opportunity to try several values and see which one gives you the best tone control for your liking.

[Woodinblack]

A simple way of testing out the pot is to put a bit of wire wrapping the pins that the capacitor connects to together, and then if it works as another volume control (going to completely quiet), the capacitor is wrong, and if it doesn't, the pot is broken.

Or, more likely, something is not connected correctly, and when it comes to guitar wiring, 9 times out of 10 it is that the wire that connects the tone to earth is missing or not connected properly

[Grangur]

If the tone pot hasn't ever worked then the issues can be different to those where is has stopped working.  Is this an active bass or a simple passive circuit?

If it's an active circuit, as @Supernautsays it could be a dry joint, so simply re-soldering the joints may solve it. Don't forget to also check the connections at the other components too. 

It may also be a bad capacitor or pot. Check the pot by taking it out of circuit and use a multimeter.

Edited December 28, 2021 by Grangur

[Chienmortbb]

On 26/12/2021 at 20:42, Supernaut said:

Cold solder joints can easily happen but fortunately, easy to fix. 

The correct term  is dry joints. Cold joints is common amongst YouTubers but is wrong as the joint can be poor no matter how hot you get the solder. 

[Chienmortbb]

On 26/12/2021 at 21:24, mcnach said:

Capacitors are so cheap that you could take the opportunity to try several values and see which one gives you the best tone control for your liking.

I was never happy with either the volume or tone control on my Aerodyne. When I put a set of DiMarzios in it, I contacted them for advice. The result was a revelation. I wired my Peavey P Bass the same way and again the ranges were much more flexible even with the fitted Peavey pickup. Also don't worry about fancy capacitors. Orange drop and oil filled paper are very old designs that were OK at the time but there was no magic. Modern polymer or mylar caps are fine and much cheaper.

[mybass]

6 minutes ago, Chienmortbb said:

I was never happy with either the volume or tone control on my Aerodyne. When I put a set of DiMarzios in it, I contacted them for advice. The result was a revelation. I wired my Peavey P Bass the same way and again the ranges were much more flexible even with the fitted Peavey pickup. Also don't worry about fancy capacitors. Orange drop and oil filled paper are very old designs that were OK at the time but there was no magic. Modern polymer or mylar caps are fine and much cheaper.

Could you explain what the ‘revelation’ was and was the DiMarzio company contacted in the U.K. or USA. ? Cheers

[Chienmortbb]

The relevation was that there was useful control over the whole range of both volume and tone pots. From memory they recommend Log* pots rather than Linear. Many wiring diagrams suggest linear are best but for me the DiMarzio wiring diagrams plus log pots really worked. They show custom** law pots on the diagrams below but I was recommended normal Log pots. The wiring diagrams I used are linked below.

 

When I asked DiMarzio about pots, saying that many suggest Linear are best they said "We do not feel linear pots are effective with passive, high-impedance pickups. This is subjective, and you may come to a different conclusion." I came to the conclusion that they were right.

 

*Log is known as Audio Taper in the USA.

**DiMarzio sell custom taper pots but they are hard to find over here in the UK.

DiMarzio Model P Wiring Diagram_1.pdfDiMarzio Model P & J Wiring Diagram_1.pdf

 

 

[mybass]

9 hours ago, Chienmortbb said:

The relevation was that there was useful control over the whole range of both volume and tone pots. From memory they recommend Log* pots rather than Linear. Many wiring diagrams suggest linear are best but for me the DiMarzio wiring diagrams plus log pots really worked. They show custom** law pots on the diagrams below but I was recommended normal Log pots. The wiring diagrams I used are linked below.

 

When I asked DiMarzio about pots, saying that many suggest Linear are best they said "We do not feel linear pots are effective with passive, high-impedance pickups. This is subjective, and you may come to a different conclusion." I came to the conclusion that they were right.

 

*Log is known as Audio Taper in the USA.

**DiMarzio sell custom taper pots but they are hard to find over here in the UK.

DiMarzio Model P Wiring Diagram_1.pdf 197.1 kB · 2 downloads DiMarzio Model P & J Wiring Diagram_1.pdf 149.93 kB · 2 downloads

 

 

Many thanks for updating and yes…..the Log appears to be an ‘okay’ pot for volume and tone from other source as well.

I’ve recently installed some new CTS pots and I’m not so sure they are the real deal, with so many copies of stuff on the market I’ve run into a few problems lately with pots which is why I was interested in this post. Cheers for adding the schematics too.