Will it work? Wiring Content

[tonyv77]

The Facts:

I have an S-Type guitar, sheilded pickguard and cavities. I have made a wiring diagram based on these:

http://www.guitarnuts.com/wiring/shielding/innards.php

and

http://www.seymourduncan.com/support...vol_1tone_5way

.....to make the attached diagram.

The ground wires are all soldered together on the ring looking thing, then it's insulated. The ground wire from the trem claw is attached attached to a screw that is screw down into the sheilding tape just under the bridge pickup.

So will it work? I sure hope so.

[waparker4]

Correct me if I'm wrong as I'm new to this as well, but it's not going to work.

You need to connect the cold lug of the volume pot to the star grounding ring terminal. In your diagram the negative leads of the pickups are not reaching the ground lug of the output jack.

Also the guitarnuts shielding method calls for a .33 uF 400V capacitor to isolate the metal things you touch on the face of the guitar (bridge, strings, metal knobs if you use them) from the signal ground to protect you from DC failure from the amp. That would go between a washer around the pot shaft, which comes in contact with the shielding, and the ground ring terminal. The bridge ground wire is then connected to the shielding somewhere.

Be sure you test your components with a multimeter before soldering wires to them. The volume pot or switch you get might not actually correspond to the lugs on your diagram. For example, since I think of my diagrams from above the face of the guitar, I draw my pot connections the other way around. You don't want to end up with your bridge and neck switch positions reversed, or for your volume to be all the way "up" when your knob is all the way "down", that would be annoying.

[tonyv77]

Originally Posted by waparker4

Correct me if I'm wrong as I'm new to this as well, but it's not going to work.

You need to connect the cold lug of the volume pot to the star grounding ring terminal. In your diagram the negative leads of the pickups are not reaching the ground lug of the output jack.

Also the guitarnuts shielding method calls for a .33 uF 400V capacitor to isolate the metal things you touch on the face of the guitar (bridge, strings, metal knobs if you use them) from the signal ground to protect you from DC failure from the amp. That would go between a washer around the pot shaft, which comes in contact with the shielding, and the ground ring terminal. The bridge ground wire is then connected to the shielding somewhere.

Be sure you test your components with a multimeter before soldering wires to them. The volume pot or switch you get might not actually correspond to the lugs on your diagram. For example, since I think of my diagrams from above the face of the guitar, I draw my pot connections the other way around. You don't want to end up with your bridge and neck switch positions reversed, or for your volume to be all the way "up" when your knob is all the way "down", that would be annoying.

Hmmm. Thats what is wierd about the guitarnuts diagram/instructions. There is no connection between the pickup grounds and the output.

I knew I forgot something. The big shock saver cap. Not a big deal I'll add it in later.

I have a different switch (import style) but Premier Guitar has a good article on transfering over wiring diagrams for different switches.

[tonyv77]

Wait! Missed a bit of the Guitarnuts diagrams. There IS a wire form the cold lug of the volume to the "star grounding ring" thing. So will it work then?

[jefrs]

I'm not sure what the 330nF cap is doing, it will be connected between the signal cold and the tone pot can, which is not connected to anything, and so that cap does nothing at all. Besides it is not needed, and should it charge itself up (they do) it will give you a nasty surprise. What is happening with that diagram is that the pot cans are now not shielded and one of them is connected to the back end of a 330nF 400VDC capacitor. Sorry but whoever dreamt this one up hasn't much of a clue.
http://www.guitarnuts.com/wiring/shielding/innards.php


You, on your own diagram, are however missing the cold signal connection to the vol pot (the vertical grey wire by the word "insulate"). You also need to connect all the pot cans to your star-earth to keep them shielded. I should quietly forget about that big shocking capacitor - it is actually quite dangerous (apprentices used to leave things like this charged up loose on the bench so the next cove to touch them got a fright).

[waparker4]

Yeah, there is a wire on guitarnuts diagrams from the vol. pot to the star grounding. With that added the diagram should work. As I understand it the 400V cap is not necessary for the shielding to work; it's only there to protect you from a tube amp failure.

Last switch I installed was an open style and I could see all the connections, but I still used a multimeter to test them. Import styles are usually closed kinds and the connections can be weird, but 10 minutes with a multimeter and some aspirin and you should be able to map out what's what. The premier resource is excellent reading but due to the closed nature of the switch you're not going to really know until you test it.

[waparker4]

Originally Posted by jefrs

I'm not sure what the 330nF cap is doing, it will be connected between the signal cold and the tone pot can, which is not connected to anything, and so that cap does nothing at all. Besides it is not needed, and should it charge itself up (they do) it will give you a nasty surprise. What is happening with that diagram is that the pot cans are now not shielded and one of them is connected to the back end of a 330nF 400VDC capacitor. Sorry but whoever dreamt this one up hasn't much of a clue.
http://www.guitarnuts.com/wiring/shielding/innards.php


You, on your own diagram, are however missing the cold signal connection to the vol pot (the vertical grey wire by the word "insulate"). You also need to connect all the pot cans to your star-earth to keep them shielded. I should quietly forget about that big shocking capacitor - it is actually quite dangerous (apprentices used to leave things like this charged up loose on the bench so the next cove to touch them got a fright).

The cap is meant to isolate the metal parts of the guitar you touch from a DC failure from your amp, quote: "I've had a few people ask why I specify a 400V capacitor when guitar circuits usually only have a few millivolts on them. The reason is simple, that capacitor is what stands between you (via the grounded strings) and your amplifier. Some vintage tube amps could fail such that they put a potentially lethal DC voltage on the "ground" side of the jack. This type of failure is extremely rare, but why take the chance?"

Two questions, Is it really going to charge up enough to shock you given the tiny currents running around in the guitar and the fact that you're hands are usually on the strings anyway? and Is this kind of failure ever going to happen with newer tube amps?

The pot cans should all be grounded already through the shielding on the back of the pickguard. Another thing to test with the multimeter.

[Phostenix]

Here's donh's explanation of the safety wiring:

http://www.audiosys.com/safety-circuit.html

[waparker4]

Originally Posted by Phostenix

Here's donh's explanation of the safety wiring:

http://www.audiosys.com/safety-circuit.html

Do you not have to have a 300+ V rated capacitor with this setup? Seems one is for DC shocks and the other for AC shocks, right?

[tonyv77]

I don't run a tube amp. Only solid state. And I won't be purchasing anything but new tube amps in the future if I go the tube route. So I won't worry too much about the big 400V cap.

[rolling56]

Anyone have any statistics on guitar player deaths from playing their guitars?

[jefrs]

Originally Posted by Phostenix

Here's donh's explanation of the safety wiring:

http://www.audiosys.com/safety-circuit.html

No not safe!
Actually rather dangerous and illegal as hell in the UK too.

... "The 'Electricity at Work Regulations 1989' in Regulations 4(1) and 4(2) lay down the requirement to ensure that an electrical installation should be designed, installed, constructed and maintained in a safe manner at all times. The basis for periodic inspection and testing is derived from Guidance Note 3 of the 'IEE Wiring Regulations BS7671:2008'. "

A guitar (certainly if used professionally) is subject to statutory Portable Appliance Testing (PAT)

Earth Bond Test
Readings should show less than 0.1+R Ohms (where R is the resistance of the lead)
Tested at a current of 1.5 times the rating of the fuse and no greater than 25A for a period of between 5 and 20 seconds ...

That bridge string "ground" is not at earth by 220k and a big storage cap. Eek!
- it failed, Oops!

1) That capacitor can store a charge between true earth and the guitar hardware, certainly enough to give you a nasty fright if a fault develops

2) if a fault develops on set and the guitar touches a live connection, then rather than dumping down the earth strap as intended (and tripping the RCD), you get to be the earth conductor and get a trip in the ambulance.