Problem with pickup/wiring/output

danishbacon

Neck works fine. Switch in middle position works fine (though presumably only neck is outputting). Tone knob for neck works in middle position, bridge tone does nothing. Bridge position volume works, tone can't tell, and there is some garbled output.

Any ideas on what I can check?

Thanks

mart

danishbacon said:

Neck works fine. Switch in middle position works fine (though presumably only neck is outputting). ..

This, at least, is easy to check: select the middle position and tap the neck pickup with a screwdriver. You should hear a loud tap through the amp. Do the same on the bridge pickup and you should be able to tell if that’s coming throug st similar volume, reduced volume, or not at all.

danishbacon

I was getting the tapping through on bridge, albeit at a reduced volume.

I decided to pop out the switch and cleaned the contacts a bit, now working fine. I didn't test the guitar with the switch out, pre-cleaning, so it could be that there was some contact with a wire somewhere shorting?

Still curious to know what causes this particular distorted low output sound.

Funkfingers

Poor contact between the sprung leaves of a Switchcraft style three-way selector switch can do that. 

Dirt, moisture, corrosion, oil and physical obstruction can all contribute. 

ICBM

Yes, that does sound like a switch issue. Sometimes a very thin layer of corrosion (which is non-conductive) on one of the surfaces can act like a primitive 'crystal diode' and actually produce distortion! As well as introducing a lot of resistance which reduces the volume.

danishbacon

Thanks @Funkfingers and @ICBM. Strangely, after taking switch out and messing around with the sprung leafs a bit, or running a bit of sandpaper on the contacts, it works, but within 24hs it's back to the distorted sound. Is it worth trying anything else or is it new switch time

ICBM

If you're sure you've cleaned it well, it could be the bridge volume pot instead.

Funkfingers

danishbacon said:

... after taking switch out ...

When you first persuaded the selector switch out to inspect it, was the distortion effect still present? 

I cannot help noticing that your bridge/Treble pickup tone control does not seem to do very much. It is possible that you have a dry solder joint or a component problem there. 

danishbacon

@ICBM I'm not entirely convinced I have to be honest, pulling it out and scratching the contacts a bit made it function, albeit temporarily.

@funkfingers, I didn't notice the first time around, but second time yes, distortion and low output when pulling switch out. I will try it again and report back.

Funkfingers

danishbacon said:

second time, yes, distortion and low output when pulling switch out.

The thought behind my question was that something could be coming into physical contact with the metal parts of the selector switch.

It might be worth checking how firmly the sprung leaf contacts push together.

While the switch is accessible, it might be worth refreshing the solder joints. 

ICBM

Funkfingers said:

While the switch is accessible, it might be worth refreshing the solder joints.

Not unless they look likely to be the cause. In general it’s bad practice to just ‘reflow’ solder joints if there’s no evidence of a problem - it’s possible to cause one, especially on heavier metal terminals where there is a risk of causing a cold joint.

danishbacon

Well that was confusing. Earlier in the day, lunchtime, I plugged it in quickly and got the distortion sound at bridge. Now this evening I did not. No changes done at all.

@funkfingers, the contact with extraneous wire was my first thought, but have pretty much ruled out as it all looks pretty tidy and well wired. One of the times I pulled the switch off, I realized that there was  poor tension on on of the leafs, causing the middle position to engage/disengage bridge at the tiniest touch. I pushed the offending leaves a bit closer together.

@icbm, solder joints look good. With respect to cleaning, I had a hard time getting into the contact area to clean. I've since found some high grit sandpaper paper which I managed to fold on itself an turned into a tiny skinny file, thin enough to fit within the two leaves, and ran it back and forth a few times, saw dark streaks on the paper and put the switch back in. Hope this may have now solved it for good.

Thanks for the help both. 

danishbacon

Ok, back to the default issue and now can't get the switch to function properly on bridge at all. Taking to tech as I don't want to muck anything up. Will mention potential bridge vol pot @ICBM ;