Strat Master Volume Pot Problems!

[guernica2]

Hi guys, this is probably in the wrong thread but I'm really pulling my hair out.
I've replaced the PU switch and pots in my guitar. I've used the standard strat wiring diagram that I found on a site. The switch works fine and the two tone pots are ok but the volume pot just fades in and out. It doesn't give the same readings as the other two Pots either when I test it with my multi-meter! When I take the pot back out of the circuit it is fine!!! Help me please!

[ashcatlt]

Welcome aboard.

This is definitely the wrong forum for this post. We can let you slide just this once. Do expect it to move to Electronics and Wiring as soon as newey or sumgai get a second, though.

I'm a little unsure what you're looking for here. Seems like fading in and out is exactly what a Master Volume is supposed to do. Do you mean that it comes in and out without touching the pot? That would indicate either poor soldering or a faulty pot.

What readings are you getting? How are you measuring the things - like where are you putting the probes? I kind of expect you to get a different DC resistance reading from a Volume pot than what you'd get from a Tone pot if they're all wired into the same circuit.

Finally, what's fine when you take the pot out of the circuit? The circuit, or the pot?

[guernica2]

Yes, sorry about the wrong thread!
I'm going to read some more on your site before getting really stuck in but it is confusing me.

To answer your question, it does just fade in and out without me touching the pot. It's more like an on/off switch with it mostly staying off! When I take the pot out of the circuit and test the outer 'wands' with a multimeter I get a reading of 241 which I assume is correct for a 250k pot.

When I take a reading from the volume pot on contacts 1/2 or 2/3 out of the circuit, I can turn the pot dial and get a smooth increase or decrease in the reading, from 0 - 241.

When I put the volume pot back in and test it in that way I get a reading going from 0 - 40 when I'm halway through the turn, then it goes back to 0 when I complete the turn. Surely this is incorrect and that's why I now think that it may be a wiring problem.

This is the diagram that I followed, and apart from using green and white wires for ground from the pick ups, I'm sure it's indentical! The old wiring to the pick ups didn't use two wires for ground. Is that perhaps something that I missing?



I even took some pics from the old wiring when that was in there and apart from a difference in which tone pot the capacitor was soldered to, it's the same as the diagram!

I've tested all of the connections end to end and the soldering seems good. Slightly off topic, but related, I recently made myself an arcade stick from an xbox joypad. The soldering on that was slightly tricky, but it worked. The massive contacts that I get to work with on the guitar bits seemed like it was going to be easy...

I'll take some pics my wiring and post them! Thanks, Wayne.

[guernica2]

I been looking at the Ge-Fooey 'topic' in the 'Read This First' thread and it kinda baffles me. I feel like I'm going to have to take an electronics degree to solve this, but solve it I will.

I tried the 'brain surgery through the nostril' trick with my multimeter. I wasn't getting any significant results. All pickups except the neck were just returning a value of 3, which I could vary with the tone. When I selected the neck pickup the numbers were going crazy?? Bizarre!

I know it's not the lead or the amp as my friend's guitar was working fine through them.

Here's a couple of pictures of the original wiring.



Here's a couple of my new wiring. Only the selector switch in the old setup seemed to be faulty, but I replaced that and all three pots with 250k pots.

[maxcalibur]

Do you have any spare pots to try? Testing the resistance of the component when in the circuit won't isn't a good way to do it in case parts of the circuit are closed and you'll then be measuring a parallel resistance of them along with the pot.

Does sound like a dodgy pot to me though if it's changing without you touching it.

[maxcalibur]

Is the bit of white wire going onto the volume pot soldered on properly? There's a lot of bare wire wrapped around and if they're not properly connected you'll get an intermittent signal.

Also, too much bare wire might short on other wire when its all compressed into the guitar cavity.

[guernica2]

Yeah, I have taken the volume pot back out of the circuit and it tests fine.

I don't have any white cables going to the volume pot on bottom pictures, they are all going to the switch from the pickups.

The pink cable was a ground loop I made to connect all the grounds from the pickups, etc. I though I was destroying the volume pot before by soldering all the grounds individually.

[maxcalibur]

I had another look at the picture and its actually a wire that splits going from the pickups. What I meant is that the ground wires that go onto the vol pot look like they have a lot of bare wire and might not be fully connected to the pot. Maybe some electrical tape around the bare wire? Or maybe its me just seeing the picture wrong again! Check for anywhere that cables or pots might compress into each other or other contacts when its all squeezed back in, though it looks like you did a neat job.



With regards to testing the resistance of the pickups, you would have to make sure they're switched out of the circuit when you test them, eg, turn on bridge pickup only when testing the resistance of the neck. Otherwise I'd say a complete rewire, not the end of the world but has been known to mysteriously fix problems!

[guernica2]

Thanks Max, I've had other people telling me a may have a short due to bare wire showing.

A complete rewire may be the answer. I've just made an amazing discover though. When I lay it flat on my lap it works fine, if a little crackly. When I pick it up in a playing position it doesn't work. I don't recall installing a tilt switch!!!

[D2o]

Hi guernica2,

Intermittent problems are, by their very nature, difficult to diagnose, but - based on the symptoms you've described - it does sound like max has hopefully nailed it.

Good job, max - I am fairly certain you won't be stuck in the "apprentice shielder" position for long.

[maxcalibur]

Hahah, thanks D2o, this is my first contribution. Thought it was time to stop just leeching and start returning some of the stuff I've picked up.

Sounds like you got the problem there guernica. I think most problems that cause an intermittent signal are going to be caused by a "mechanical" fault. Get yourself a new pot and sounds like you're ready to go.

Let us see the finished result too if you can.

[ashcatlt]

These kinds of things are always annoying. Everything looks fine but... I wish you luck in fixing it.

I did notice that you've put foil on the pickguard, but I'm not seeing anything inside the cavities. This is less than ideal, especially considering that the closest noise source to the guitar is behind the pickguard, and would not be screened out by that bit of foil.

[sumgai]

ash,

Even the cheapest of Fenders come with that small amount of foil. You're correct, lotta good that does, but there you have it - all the goodness that must be good, 'cause it's straight from Fender's own mouth.... right?
</sarcasm>



~!~!~!~!~!~!
guernica,

Hi, and to the NutzHouse!

If you do elect to try re-wiring the whole thing, you should consider stepping down a size (gauge) of wire. The stuff you used is pretty thick, much more so than necessary for good operation, let alone long life and reliability. Refer to other discussions on this Forum about wire sizes, I'm sure you'll get an epiphany.

Good luck!



sumgai



p.s. Me personally? I use 22ga. "bell wire". It's usually solid (not stranded), and is cheap - should be available at your local hardware store, if nowhere else in town.