Humbucker Cover Issues

[iamdavidmorris]

I'm trying to install nickel pickup covers on a set of Seymour Duncan P-Rails.  I thought I had it all figured out, but the covers came in the mail today, and as it turns out, they won't reach the baseplate of the pickup when pressed down all the way.  And yes, I tried removing the "tape" around the pickup coils.  It's back on there now, as it seems to make no difference either way.  The pickups are just too tall.

The issue of whether or not pickup covers must be grounded seems to be rather controversial, but I'm concerned.  I really want to use nickel covers if I can make them work, but I think these P-Rails are just too tall.  Poor planning on my part, but I think there's a solution.  I feel confident in using a simple adhesive like silicone caulk (or something - I'm open to suggestions) to hold them on.  As for the grounding issue, I'm considering running a very small piece of wire from the cover to the baseplate on each side.  I realize it's sort of a cheeseball solution compared to properly soldering the cover to the baseplate, like you're supposed to do, but the idea seems sound to my ignorant mind.

What do you think?

 

[TroubledTreble]

Yes, absolutely ground the covers. The ground will "drain" any outside emf and keep the noise to a minimum.

Whatever method you use to attach these just be sure the cover wont vibrate against the top of the pickups especialy the pole screws. A piece of masking tape can work. I can't see the top of the cover to see if there are pole/screw holes.

Good luck!

 

[dNA]

what Ken said. As long as they're grounded and don't physically rattle or move you should be good.

 

[iamdavidmorris]

They're a pretty tight fit.  I performed this modification over the weekend, and I don't know if it worked or not.  I definitely messed up somewhere.  Just not sure where.

These covers have no holes in the top.  The SD P-Rails pickups (for anyone not familiar) consist of a P-90 and a rail pickup pushed together like a humbucker.  It occurs to me that the cover is touching the poles for the P-90 and for the rail, and I'm trying to figure out if that's the case with a normal humbucker cover.  I think it is, but I wonder if I'd have been better off if I just put some tape between the cover and the pickup to break the connection between them.

Generally speaking, I need some help.  I think I got in a little over my head on this one, but it's a good learning exercise, and I'm committed to seeing it through.  If anyone's willing to help me, let me lay out what I've discovered so far.  For reference purposes, here's my wiring diagram:

http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=2_prails_1v_1t_tspp

It's exactly like that, except I'm using a 3-way blade switch instead of a toggle.  I used this diagram:

http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=3ws_trans

I used a 40w soldering iron with a chisel tip and 60/40 solder I got at Home Depot.  I used a Warmoth wiring kit, and I used red, black, and white wires interchangably.  (I didn't know why the colors mattered, though the red and black looked like copper, and the white looked like nickel or something.)  I used the heavily insulated wire for the longer connections to the jack and bridge.

I have not installed the wired pickguard in a guitar yet.  However, I plugged a cable into the jack and quickly got a mess of buzz.  I had a bridge on hand, and I touched my ground wire to it in several places.  It seemed to make no difference.  If anything, it made it worse.  I found that if I turned the volume up all the way, the buzz generally stopped, until I shook a couple of wires leading to the jack, and it started again.  Shake it again after that, and...it stops.  If I turn the volume to less than 100%, it buzzes.  As I turn the volume down, the volume of the buzz decreases, but doesn't completely go away unless I turn it back to 100%.  I've tried touching the back of the pole pieces with a screwdriver to see if the switching works, but it's pretty unreliable.  I think the switching is working, but I'm usually hearing taps on those pole pieces no matter where the switch is set.

I should also add that with every connection, I threaded the wire through the little hole in the terminal, bent it back, and soldered it in place.  Where I thought there was even a chance a bit of exposed wire might brush another terminal, I wrapped it in electrical tape.

My first inclination is that I've got a serious ground problem, and the best solution is to order some solder lugs.  But I'm wondering if I might have fried my volume pot too.  The pickups seem fine.  I was very careful with them, and never even directly touched them with the soldering iron.  I can't imagine I would have fried the switch, right?  It was a tele-style blade switch.  It seemed pretty sturdy.  I got the jack sort of hot, but I didn't think there was much of a risk there.  And I tried to be very, very careful not to overheat those pots, but I'm pretty green at this, so who knows?

One more thing.  This made sense to me, but maybe it was crazy.  Rather than solder the capacitor directly to the tone pot, I ran wires from each end of it to the tone pot, and taped it to the back of the pickguard.  (I'd like to put in a varitone at some point, so that made sense to me.)

That's a lot of information.  If you've read this far, and have any thoughts, I'd love to hear them.  I'm ordering solder lugs.  Do you think I should also order one/two new pot(s)?  New switch?  New jack?  New...?  If pictures would help, I'd be glad to take some.

Thank you in advance,
David

 

[Cagey]

Touching a ground wire from a loose pickguard to a loose bridge isn't going to do anything, so no surprise there.

You may have your output jack wired backwards.

It's unlikely you fried the switch or jack, but pots burn pretty easily. Still, I wouldn't expect that to hum. More likely, you'd be at full-tilt boogie all the time because it's opened internally.

Past that, more pictures might be helpful, if you've got a real camera. Cell phone pics are generally useless. Use lotsa angles.

If you don't have one, you may want to buy/borrow a multimeter.

 

[iamdavidmorris]

Thanks Cagey.  I'll try and get some good pictures tonight.  I could buy a multimeter, but I'm not sure what to do with it.  I know you can test pots with them, but does it work if they're wired up?  And if not, it might be cheaper just to order new pots than to buy a multimeter.  Could I somehow use it to isolate the problem?

 

[Cagey]

Usually, you don't need a multimeter to solve these kinds of problems. But, there's a very real possibility you've shorted or opened a coil wire inside or lead wire coming out of the pickup, and while that can be obvious, sometimes it's not. So, instrumentation helps. You don't need a benchtop lab-grade Norton unit traceable to NIST; a $10 Radio Shack one will do.

But, perhaps just as handy might be a set of test leads...

They're real handy, and real cheap. A set of 10 leads at the link above is $7. You can temporarily wire things up a number of different ways, test different caps or pots, jumper suspicious parts out, on and on. Gotta have 'em. Just be aware that they're not shielded or anything like that, so any temporary wiring you do with them is gonna be noisier than hell. Once you have a set you'll wonder how you lived without them.

Also, a tuning fork is a Good Thing. Tapping on pickups is a crude way at best of testing to see whether pickups are wired, or wired properly. Get a little tuning fork like one of these...

and you just bang it on something handy, then hold it over the pickup. You'll be able to tell exactly which coils are hot and whether or not your switches/volume/tone controls work. Plus, you'll have a frequency standard. $6 at Amazon.

 

[Cagey]

Just to be clear, with those two items above and your pots/switches/pickups/etc., you won't need a multimeter. You could wire a single coil from your P-Rails to an output jack using nothing but clip leads, and plug it into an amp to see if it works. Do the same for the other coil. Wire them in series to see if they humbuck. Add a pot to make sure you know how to wire that in, using nothing but clip leads. Add a tone pot the same way. Switches, etc. No heat, no power, very few tools and nothing dangerous. It's an erector set for guitar electronics! <grin>

 

[iamdavidmorris]

Ok.  I'm gonna do just as you suggest.  Sure hope I didn't short out a pickup.  Those wouldn't be cheap to replace, and I was very careful.  Guess I'll have to unwire everything and start over, huh?

 

[Cagey]

Ok.  I'm gonna do just as you suggest.  Sure hope I didn't short out a pickup.  Those wouldn't be cheap to replace, and I was very careful.  Guess I'll have to unwire everything and start over, huh?

For some tests, yeah. You'll have to have a way to hook up the pickup to your amp without any of your existing wiring involved. So, you'd remove the pickup wires from whatever you've tied them to and tie them directly to the output jack using the test leads. It'll be noisy, but you'll be able to tell if it works or not. Assuming it does, then you'd slowly add parts back in until you find either a bad part or some bad wiring.

 

[iamdavidmorris]

Cagey, that was a brilliant solution.  Today I unwired everything so I could start over and take it step by step.  I'm tempted to say everyone should do it this way, so they can learn what things do, rather than just follow diagrams.  My clip wires haven't come in yet, but I wanted to test my pickups.  So I just twisted wires to the jack, tested each coil individually, and am relieved to say the pickups seem to be working fine.  I heard the tuning fork clearly through my system.  Good feelings abound.

After that I wired the entire bridge pickup through a Home Depot off/on button switch I picked up for kicks (works great as a kill switch).  Everything still works just as before.  Here's a picture:

I'm wondering if I can effectively get rid of the buzz at this point, so I can determine if my pickup covers are properly grounded.  The buzz I'm hearing is similar to the buzz I hear when I just hold the end of the guitar cable in my hand.  I'm running through a Line 6 Pod X3 Live hooked up to the computer modelling a Marshall amp with the drive turned up, so I expect a bit of buzz anyway.  But is there a good way to effectively shield/ground what I've built so I can test more accurately?

Thanks,
David

 

[Cagey]

You need any signal cables to be shielded, with the shields tied to ground, in order to minimize the hum. But, it's never going to go away with the single coils, pickup cover or not. I also wouldn't expect the cover to do much, if anything, grounded or not. The two paths to noise-free operation are either low-impedance pickups (such as EMG makes) or common-mode rejection ("humbucking" configurations).

 

[iamdavidmorris]

Well, I figured out one thing I did wrong today.  The wiring diagram I had for my 3 way blade switch was wrong, at least as it relates to the switch I bought from StewMac.  Behold!

I post this not to shame the wonderful company that made the diagram on the left, but in the hope that it may help someone else at some point that makes the same mistake.  I would have never gotten it right by just following diagrams.  I had to look at the switch, figure out how it worked, and test it with the alligator clips.  Love those little alligator clips.

 

[Cagey]

I have little use for wiring diagrams for that very reason. A schematic is the only thing worth anything, but good luck ever finding one. Everybody who provides such diagrams figures their users wouldn't know how to read a schematic, so they use wiring diagrams instead thinking they will be useful in that they don't require any circuit knowledge. The problem is a wiring diagram depends heavily on the user using the parts depicted, which isn't always the case. Without a schematic, you're lost unless you know exactly which parts and manufacturers it's based on. You can look at a wiring diagram all day long the the most prescient of engineers won't be able to tell you if it'll work, or how to troubleshoot it. But, with a schematic, you can know immediately if something makes sense or not.

In any event, I'm glad that's all working out for you. Aren't those test leads great? Beats the snot out of soldering/desoldering joints a bajillion times to experiment if you're lost.

 

[iamdavidmorris]

Well Cagey, I can't thank you enough.  After playing around for several hours over a few days, I now know exactly how all my parts work.  Test leads and a tuning fork are the way to do it.  I'm pretty sure I could draw my own wiring diagrams at this point, with a little reference help regarding things like series/parallel, phase/out-of-phase, etc.  Now, as soon as my push back wire comes in the mail, I'm going to start the wiring process all over again, testing each connection as I go.

I'm going to be wiring two humbucking pickups (P-Rails) through a three-way blade switch with two push-pull pots, a kill switch, and a 6-position rotary varitone in tandem with the tone, which I realize will suck a little level out, but I'm prepared to deal with that.  It's a moderately complicated wiring system, but now I know what I'm doing (though my soldering skills are admittedly still sub-par).  

One more question (for now).  I know I should be using shielded cable for all my long (over 2"-3"?) leads, and I've read it's critical to use shielded wire for the output jack's ground wire, but is there anyplace else I should be concerned with using shielded wire?

Thanks again,
David

 

[Cagey]

You're more than welcome. It's what most of us are here for - to relax the slopes on learning curves we've already navigated and make it easier and faster to have fun <grin>

One more question (for now).  I know I should be using shielded cable for all my long (over 2"-3"?) leads, and I've read it's critical to use shielded wire for the output jack's ground wire, but is there anyplace else I should be concerned with using shielded wire?

You've gotten bad information. You never need to shield ground wires. In fact, the shields themselves are often the ground wires (also sometimes called the "return path"). And as long as we're talking terminology, you'll also read/hear "ground", "neutral" and "common" used interchangeably, and while there are subtle differences depending on the kind of circuit we're talking about, when we're talking about guitars they're all equal and mean the same thing. Another term you'll hear in association with grounds is "ground loops". As soon as you see that, go back to Google and keep searching. The author is a poser. There are as many ground loops in guitars as there are three-legged polar bears in space playing Donkey Kong for high stakes.

Signal wires are a whole different thing, though. In guitars, they're the part of a high-impedance circuit that carries the actual "sound" signal. It's a very small signal, so the circuit is sensitive to the slightest interference. Most of the interference they pick up is well outside the frequency response range of human hearing, so we don't care about it. Radio, TV, cell phones, microwaves, boogeymen, Star Trek communicators, etc. - none of that matters. We can't hear it, and the amplifier can't amplify it. But, lower frequency signals such as power lines and anything that operates off them are well within our range, and drives us batshit when made audible through the magic of Marshall Stacks and Ampeg SVTs.

What a shield does is intercept that interference and conduct it to ground before the signal wire ever sees it. If the signal wire never sees it, neither does the amp, and life is good. And fair.

So, you want to shield signal wires. Be aware that a shield is not a shield unless it's tied to ground. Also, be aware that shields are conductors, so anything that touches them gets sent to the never-never land of ground hell, too. With guitars, it's sometimes not practical to shield every signal wire, so what you want to do is keep the lines as short as possible. No 2" - 3" stuff. Long runs like pickup to control, or control to output jack can be long, but they'll be shielded. You can get away with murder with a shielded cable. Look at that 20' cord running to your amp. Only reason it works at all is because the signal line is in the center of a shield. Which is grounded. Which is the return path. All circuits begin and end, that's why they call them "circuits". It's circular. Electrons in, electrons out. Gotta balance, or it's an open circuit, and nothing happens.

 

[iamdavidmorris]

Does that mean when I have a braided shielded wire I need to string the braids to another wire that goes to ground?  Also, if I just shield every cavity with tape/paint/foil, won't it create something like a "Faraday cage" making the whole issue of grounding a non-issue?

 

[AutoBat]

i lol'd when reading the above post, and whilst making this.

 

[Cagey]

Does that mean when I have a braided shielded wire I need to string the braids to another wire that goes to ground?  

Yes. Most emphatically, yes. If there's no path to ground, there is no shield. You could wrap the signal wires in precious unobtanium, and it would do no good unless the garbage it picks up has someplace to be flushed to.

Also, if I just shield every cavity with tape/paint/foil, won't it create something like a "Faraday cage" making the whole issue of grounding a non-issue?

Well, it would be "something like" a Faraday cage, but it'd have gaping holes in it with antennae (also known as "pickups") sticking out. It's a waste of time, unless you just like the aesthetics of a copper- or aluminum-lined cavity. Since they're generally hidden from view, I question the value of the whole thing. It doesn't hurt anything, but it doesn't help, either. You'll notice Gibson, Fender and PRS don't line their cavities, even though they'd be strongly motivated to do so if it worked, and they charge a bajillion dollars for their guitars. If anyone could afford it, they could. Why do you suppose they don't do it? Do you think they're just trying to piss people off? They don't sell aftermarket kits for it, so it's not like they're trying to hose you after the fact. They just know better.

 

[Cagey]

i lol'd when reading the above post, and whilst making this.

Very funny. I should probably print it out, frame it, and tack it to the wall above my monitor <grin>