Help with My wiring/Tone Controls !

[thascalus]

Well, here I am, first time poster. I'm relatively new at this guitar stuff, and relatively good at this learning stuff too. But before I even learned to play my second-hand guitar (with three strings missing) I decided it needed a facelift and proper shielding. I followed John @ guitarnuts.com "Quieting the Beast" instructions and enjoyed taking my guitar apart, cleaning it, following the instructions and triple-checking I had everything looking just like this diagram. Sans the 400V capicitor thing that promises to save my life from 'killer amps'.



I'm glad I tested the controls before restringing it, because after reading a lot of internets (including the "read this first" thread on this very forum) and searching fruitlessly for someone else with a problem like mine, I have landed here. Now I am the one gently weeping because I can't figure out why my two tone pots are controlling the volume of my neck and middle pickups. The Volume knob is acting as it should, controlling volume from maximum to muted.

But the tone pots at zero completely silence the neck or middle pickups, and to test this I have a strange sort of set-up. My guitar body has no neck, is plugged into a big 'ol amp, and held up at like thirty-five degrees by a book-bag. Then I position my friends guitar (with strings!) face down and over the top of my guitar's pickups and pluck the strings. And I'm careful not to scratch either one. And the pickups and 5-way switch totally work!

Trying not to be a newbie, I should mention I'm the owner of an '89 Fender Strat/Squier II, and I will take some hi-res digital pictures and maybe make a diagram of my wiring situation in MSpaint. But maybe someone much more experienced than me already knows whats going on and it's an easy fix.

Excelsior!

[newey]

thascalus-

Hello and welcome to GuitarNutz 2!

A few questions you didn't answer. What's the value of C1? Is this the stock cap? Did you resolder C1 as part of your work on this?

Unless you have an LCR meter, there's no way to check the capacitance of the cap. But (as you can probably tell) that's where my suspicions would be directed.

Caps are cheap- if you replace it, get 2 (at least) and use separate caps for each tone pot. Not required, but one of those "best practice" things.

[Yew]

If it is a really high value capacitor, it could be letting al lof the signal through it..

[ashcatlt]

Or if the pot side lead is inadvertently touching something grounded, or if the cap is blown to a short. I suspect it's the accidental grounding thing.

Wanted to mention also that if you've left out the 400V cap, it needs replaced with a wire or something which gets the foil shield to ground.

[thascalus]

EDIT: Fixed the link - I think.

Okay heres my best photograph with some text about that capacitor. Its a huge picture, so I'll post a polite hyperlink.

@ Newey : I hope that text on the capacitor is the value you asked about. And yes I did have to solder both leads. One leads to the star ground, the other to a tone pot.

@ Yew : I'm not sure what that means, but maybe you and Newey are right and I need to replace it with two new ones. Can you point me in the right direction i.e., what capacitors to buy? I've never bought a capacitor ever in my life. (adding two like Newey says sounds like a super idea)

@ Ashcatlt : You could be most right of all. All three of my potentiometers shells have a sort of extension that bends under (or is it over? Depends on which way you look at a pot.) the side and makes contact with the foil. I assume this is grounding them to the shielding. And I assumed that was supposed to be that way.

So, should I try bending those bits backward so they won't ground to the foil shielding? Maybe insulate it with electricians tape instead of bending it? Does the volume pot need to be grounded to the foil?

[ashcatlt]

Your polite hyperlink leads me to a google sign-in page. I think I have a google account, but not sure it'll get me to your pic. I'm having trouble visualizing what you're saying without the photo.

Edit - yeah, no, it takes me to my google dogs account, can't see yours.

[newey]

I do get Thasc's photo, but it doesn't help much.

Stock Fender/Squier cap value is usually .022µf (Also known as 22 nf). The capacitance is the only variable to worry about for tone control purposes- the voltage rating will be well in excess of what guitar pickups can generate in any case.

It is certainly possible that Ash is right, a short to ground. Or, given that you soldered it, you might have burned the cap to a dead short.

When Ash talks about a short to ground, he is not talking about the bent-over tabs on the pots- those are supposed to be grounded to the pot shells. The star grounding instructions tell you to undo those, and run the grounds to the star ground point instead of to the pot shells- but that's not what's causing your problem.

Ash is suggesting that you check the "hot" wire- that's what he means by the "side lead"- coming into the pot from the selector switch to ensure that it is not accidentally contacting a grounded point.

[thascalus]

I didn't think I could kill a cap with heat from the gun. Soldering is not my strong point, but I do have a proper weapon; a variable 100/140 watt gun. Thanks for that info bout the caps I'm sure I can find the right type to buy now. Any tips on how to solder caps to a pot without the heat melting them away?

As for those tabs that were bent over and soldered to the pot shell. I did undo those with my solder gun, but those tabs were different than what I think might be grounded to the foil on the pickguard. I looked carefully at the two hot wires (they are the green wires in my photo) coming from the selector switch to the tone controls and they are not touching foil. I'll snap another picture once the infernal battery is charged and edit it into this post.

[newey]

Any tips on how to solder caps to a pot without the heat melting them away?

Use a heat sink of some sort. I use hemostatic forceps to hold the parts together, placed in between the component and where I'm soldering. But any sort of metal to conduct away heat will do the job.

And, you have to be quick about it. Tin the iron, get it on the joint, hold it just until the solder flows- then get out. Repeat the process if you don't get a solid join the first time- don't hold the iron on the join longer in hopes of making the connection "better".

BTW, if you elect to install individual tone caps, each one is run separately, from the third (grounded ) lug on its respective pot to your star ground point.

[thascalus]

I've taken a multimeter to those two green wires attached to my tone pots (you can see them in my first picture) assuming those were the "hot" leads Newey and Ashcatlt are mentioning. They are connected through that 5 way switch to the neck and middle pickups (via a wiper in the middle). Electrical continuity is good through the switch, and through the wire to the "low" tabs on the potentiometers.
If I put one lead of my multimeter on a "low" tab or even the terminal on the switch, and one lead anywhere on the foil backing, it's also electrically continuous. Is this grounding out? Should there be a lead from the switch to the star-ground?
The switch is screwed into the pickguard and contacting all that shiny foil, should I isolate it from the foil with non-conductive tape?

Edit: More multimeter tests done trying to figure why those hot leads are grounding to my foil shield. I found I can make continuity from the metal plate/cover on the output jack to the foil shield, and both leads of the output jack cable. Not being an expert, I can only ponder whether this is some sort of short caused by my aggressive application of conductive copper tape. I shielded that output jack cavity since I had everything taken apart, and that copper tape shield is touching the inside of that plate/cover. Remove just the tape touching the plate? Or.... all of it?

[newey]

You shouldn't need to ground the switch frame. Nor should you need to isolate it.

If I put one lead of my multimeter on a "low" tab or even the terminal on the switch, and one lead anywhere on the foil backing, it's also electrically continuous.

I'm not entirely clear on what you mean here.

On the output jack, I'd take the shielding tape out of the jack cavity completely. We've debated the need to shield that area before, and the consensus seems to be it's not going to be a huge deal as far as noise-generation.

I've had difficulty shielding that cavity in the past due to the jack tip shorting to the shield. The clearances are pretty tight in there.

Also, if you followed the shielding instructions exactly, it calls for the use of a shielded cable to the output jack, making shielding there superfluous anyway.

However, I'm wondering about your readings here, since you indicated that everything was working (based upon your testing) except the tone controls. What, exactly, are you reading on your meter when you indicate there is continuity between the various components?

[thascalus]

I have it set to measure ohms at 20k. All I know about that setting is that ohms is a measure of resistance, and if I touch two leads of the tester together it makes like a circuit. Im trying to find this mystery short. And now I'm thinking its either from the tape in the output jack cavity or the switch.
My switch doesn't look like anything alike the guitarnuts.com examples. So its likely here I've made an error in my wiring. Looking at Johns rendering of a shielded strat circuit, R1 has a wire that connects to the 5-way switch. And I don't know what exactly that wire is for or why its twisted through his diagram like a snake connecting two leads.
But if I look at my wiring, that wire is soldered from the volume pot to the middle of my 5-way switch on a terminal that connects to the wiper. God I hope that makes sense. And I hope even more that someone identifies that as a problem so I can stop hitting my head against the wall and re-solder that wire... to... something else?

Edit: I found a guy with the same headache as me. He has the exact same switch as me. But reading the "helpful" reply from Tready my headache only gets worse. What is that guy talking about? Could he be any less clear? Maybe sprinkle some punctuation in there?

[ashcatlt]

If I'm reading you correctly, that wire that snakes across the switch is connecting the two common lugs of a more standard 5-way switch. Yours has these connected internally, and only presents one actual lug to the outside world. That wire that you're questioning is provided for you, and I think you've got your switch wired correctly.

You said you put your meter on the 20K setting, and that's good. You did not tell us what actual numbers you got for readings in your tests, so there's some question there. You may already be aware, but I'll just throw it out there anyway. This circuit has a number of paths to ground from just about anywhere you'd want to test - through the volume pot and whichever pickup(s) is(are) selected. You're likely to read something very close to the resistance of the pickup(s) just about anywhere you test from hot to ground. You want to look for readings very close to 0, which might indicate a problem.

Seems the problem I have with your link is that Google recognizes my iphone as a mobile device and re-routes me off somewhere. From a PC/laptop I can see it just fine. The wonders of modern technology!

It looks like you do have one of the lugs on the mid pickup’s Tone bent over the wrong way and possibly contacting the foil. That is not a good thing, and could cause the problem you’re describing. I’d only expect it to go to silence when the neck pickup is selected (by itself or in the N+M position) and then only when the mid tone is at 10 and the neck tone is turned to 0. With the neck at 10 and the mid at 0, or when only the mid is selected, this shouldn’t happen. Unless, of course, that same lug on the neck tone is accidentally hitting ground somewhere, like perhaps the foil on the “wall” of the control cavity, it looks like it might be kind of close oriented the way you’ve got it.

I'm a little concerned about that tone cap. The lead which is soldered to the pot is sticking out there pretty long and bare. It's at least possible that when it's installed in the guitar it is somehow getting pushed or bent to contact something it shouldn't. I'd try to fix that pot lug first.

I hope some of this helps.

[thascalus]

Thanks Ashcatlt, I guess some of those readings on my multimeter of about 8 must have been the pickups. So zero is a number that could indicate a short.

That tone pot's lug was very close to the foil. Maybe it was touching the foil shielding. I made sure it can't by putting a band of electrical tape around the inside of the control cavity. Now if anything is touching the sides, it hitting some non-conductive tape. I've got some confidence in the tone capacitor not touching anything, because its very in-flexible, and nothing gets very close to it at all.

And while typing this, I put it together with a few screws, plugged into the amp, and the tone controls work! Thank you thank you thank you!I even cranked the gain up till I could barely hear the hum, then plugged into a different guitar (the one I used for testing). A cheap stratocaster style guitar from a brand called Austin with a really loud hum compared to mine! ;D

Is it really worth it to buy two new caps for the pots? Also, I didn't have any shielded cable laying around to use for the output jack, so its just the stock wire. Is shielding that wire through to the output jack cavity really going to make a big difference? I could probably "shield" that cable by wrapping it in copper tape.

[newey]

I only suggested using the dual tone caps in the event you were forced to replace the one you have. If it's together and working, I'd leave well enough alone.

Same thing with the shielded cable to the out jack- if things are quiet now, I'd leave well enough alone. We've debated the need to use a shielded cable to the jack, and the consensus seems to be that it will make only a small contribution to noise, if any.