Volume pot problem

AustrianJohn

After I rewired my David Gilmour Strat clone it had an intermittent electrical fault. I originally built it with a push-push pot (tone 2) to switch the neck pickup on, but then decided to change it to a microswitch (like the original). Having checked all of the wiring (everything checks out fine) I eventually realised that the volume pot now only works with a setting of 4, 5 or 6 - everything else is silent.

As the volume pot wasn't involved in the rewiring I'm confused about why it should have failed at this time (coincidence?).

Should I just shrug my shoulders and replace the volume pot?

Nomad

If it works on some settings, doesn't that suggest that the pot is okay? Or do you mean it only works in the middle of the range?

AustrianJohn

Yes, it only works in the middle range - if I turn the pot from 1 to 10, the guitar is silent until the volume hits 4, gets louder up to 6, then goes silent again.

GuitarMonkey

There's clearly something wrong with the way you have wired things. Check against a diagram or maybe post a photo here?

ICBM

GuitarMonkey said:

There's clearly something wrong with the way you have wired things. Check against a diagram or maybe post a photo here?

I agree, that has to be wrong wiring - there's no way it could do that if it was a faulty pot. It sounds like you have the top and bottom connections of the pot both grounded and both the signal hot and output connected to the middle… but quite how, I'm not sure!

AustrianJohn

Thanks for your suggestions. I'll check it out in the next few days and - if not too embarrassed by a wiring cock up - I'll post a picture.

ICBM

AustrianJohn said:

Thanks for your suggestions. I'll check it out in the next few days and - if not too embarrassed by a wiring cock up - I'll post a picture.

Don't be embarrassed, I've done some great ones .

The best was failing to check the orientation of the contacts on a replacement mains switch of a different type, meaning that as soon as the amp was turned on it produced a direct live to neutral short, melted the switch which then burst into flames and blew the fuse in the plug along with tripping the entire workshop off. If I'd been any closer to it I would have looked like Wile E. Coyote when something goes bang in his face.

Familiarity, contempt and all that .

Danny1969

I was repairing a Peavey PA mixer head, was distracted by a phone call  and soldered in 2 of the 6800uf electrolytic caps the wrong way round.... turned it on, smoke everywhere, caps ruined and neigh on killed the toroidal transformer as well 

It happens 

AustrianJohn

I took the strings and scratch plate off (yet again) and checked the wiring against the wiring diagram. Everything seemed ok. In desperation I squirted some WD40 into the pot - which now works fine. Half the world seems to say not to use WD40, while the rest says it works well. I guess I'm in the "works well" camp - at least for now.

For what it's worth, here is the volume pot wiring.



1st lug (in) connects to the switch and whatever pickup is/are selected (including the neck if selected by the mini-switch)
2nd lug (out) connects to the jack socket
3rd lug is soldered to the base, earth from other pots and earth to the jack socket
red wire is the earth connection to the bridge

Thanks again for advice - sometimes it's good to know you're not alone!

ICBM

Sounds like there might have been a fragment of solder or something in there that was causing a short, which the WD-40 has washed out. Despite constant advice not to, I've been using WD-40 (sparingly) on electronics for 30 years and never had a problem with it. I find it works well as a last resort fixer when 'proper' methods have failed. Don't use it on Line6 (and probably other) rotary encoder pots though, it's on good authority that it buggers them! Not that you ever usually need to clean them anyway...