Fender Jaguar star grounding

[jedikuff]

Hey all! I'm new to this this forum and glad to be a part of it.

I've star grounded a strat using the instructions at the original GuitarNuts site and it works great. I love it. It works so great in fact that a friend of mine recently asked me to star ground her jaguar. It's kind of tough though. There's two different circuits involved so to have the ground wires meet up in the same place would require very long cable runs. I was thinking of coating the whole cavity with copper foil tape and running a single ground wire through all of the compartments. Each compartments ground wire would ground onto this one wire. I guess the end of that wire would ground to a terminal that comes into contact with the copper foil, and then the output jack would be grounded to that terminal as well?

Would that work the same as a star ground?

I'm still a DIY newbie and have lot's to learn. Any pointers would be greatly appreciated.

Much thanks
Chris

[newey]

Hi Jed!

I've personally never looked inside a Jaguar, so I'm a bit unclear on your difficulties here. Someone around here undoubtedly has done this so more specific help is probably on the way. But for starters:

There's two different circuits involved

Unless it's wired for stereo, there's only one circuit. I assume what you mean is that the neck pickup cavity doesn't physically connect to the bridge pickup cavity, except for where the wires run. If that's why you're having difficulty, remember that the whole principle is just that there needs to be electrical continuity across all your shielding, wherever it lies.

You should be able to achieve this. If you're using metal tape for your shielding, you will be shielding the underside of the pickguard. The shielding in your cavitie(s) should run up over the edge, onto the face of the guitar underneath where the guard lays. Make sure the foil contacts several of the guard screws. Then, when you screw the guard back on, the neck cavity shielding will have continuity, via the shielding under the guard, with the rest of the shield. Then star-ground as usual.

If that's not what you mean as to your difficulty, more explanation is needed.

[jedikuff]

Thanks for your help man. I guess that was a little vague.

What i meant was there's a DPDT switch that switches between two volume and tone controls so that one can be set up for rhythm and one for lead. This is a pretty hip idea, but the controls are at opposite ends of the instrument, so the two tone caps (amongst other things) are being grounded to different points very far from each other. It seems silly to me to extend a capacitor lead by a foot so that it grounds to the same place as another.

In a strat it's all right there in that cavity. In the jag there's 4 cavities that all have grounding needs. The underside of the pickguard came with aluminum foil shielding, so i'm going to line each cavity with copper, insure connectivity, and have it hang over the face of the instrument and make contact with the aluminum. Then i was thinking of making a ground wire that passes through each cavity, picking up grounds as it goes and eventually depositing them in a star ground in one cavity. Does that negate the purpose of the star ground?

[newey]

Aha, Jed, now I see what you mean. I agree, running a long grounding wire doesn't seem to make a lot of sense. I might be tempted to leave the grounding on that cap "as is" and see if you get any noise issues first, before trying anything else. Most noise issues will be from the pickups and associated wiring anyway. You would (probably) be leaving a ground loop in place but it might not audibly matter.

But, again, someone has probably already done this to a Jag and will weigh in soon with a definitive method..

Oh, and:

star ground her jaguar

If she plays a Jag, I'd say she's a keeper!

[sumgai]

jeki,

Hi, and welcome to the NutzHouse! ;D


The standard running joke around here is that whenever a Jaguar or a Jazzmaster is mentioned, I invariably pop up with "ship it to me, I'll fix it for you, and send it back in about 5 years." ;D In this case, though, I'll forego the usual prank, and instead offer to accept the shipment of the Jaguar and owner for the period of time needed to fix it/them up! ;D

Your idea of using a long wire to connect the cavities is sound, for all the obvious reasons. This won't "harm" the star-grounding concept at all, if you pay attention to letting components that need ground find it only on this one long wire. The end near the jack is where you'll tie into the capacitor, and the other cap lead can mount directly to the output jack's ground tab.

I'd actually use different pieces of wire from one point to the next, only so as to keep as much insulation in place as possible. A bare wire that came in contact with the cavity shielding would negate the desired protective effect!

Also, if you're gonna use copper tape/foil to line the cavities, I'd remove that aluminum from the pickguard, and cover it with copper too. However, I've seen in the recent past that many of those aluminum covers are stuck down with such a strong glue that it'd take a stick of dynamite to get the stuff off! Just cover the whole thing with a sheet of copper foil, don't let any of the existing aluminum show, and you're all set. The reasons are two-fold: Copper is a better shielding material, and copper-aluminum contact is not electrically perfect, there's a bit of resistance along the contact point. Best to eliminate it while you're in there, and be sure you're getting the best performance for your efforts.

HTH



sumgai

[jedikuff]

sumgai, you have totally helped out in a big way, and i appreciate being welcomed to the nutzhouse! i have a few further questions about some of the grounds, and then i think that myself and the jag should no longer need fixing.

The end near the jack is where you'll tie into the capacitor, and the other cap lead can mount directly to the output jack's ground tab.

Are we talking about the .01 cap or the 33/400V cap? I was thinking of leaving the latter out of the equation. If so then i think that i would run the wire throughout the body and let it end at the output jacks ground, and also connect the other end of the .01 cap to the output jack ground?

Also, aren't pot tabs grounded to their own shells a ground loop? The volume pot has this, so do i need to take it apart and ground that tab to the big ground wire?

Lastly, do have any advice on shielding jag pickups or can you link me to a thread that might?

You rock
Chris

[sumgai]

jedi,

The end near the jack is where you'll tie into the capacitor, and the other cap lead can mount directly to the output jack's ground tab.

Are we talking about the .01 cap or the 33/400V cap?

The 0.33µf/400vDC cap is the one we speak about for protection against certain tube amplifer faults. The 0.01µf cap is your tone capacitor. (And IMO, that value is a bit low, but that's just me, your mileage is probably varying. )

I was thinking of leaving the latter out of the equation.

Many of us leave it out, myself included.

If so then i think that i would run the wire throughout the body and let it end at the output jacks ground, and also connect the other end of the .01 cap to the output jack ground?

The main purpose of installing a star ground system is to reduce the humming and buzzing. This is done by eliminating as many separate ground paths as possible. Now if you're looking at what I'd call a special case (Jaguars and Jazzmasters), I'd say that you can bend the rules, in the name of sanity - who needs a boatload of separate foot-long ground wires running to one spot? Answer: no one.

That said, I'd run the single wire from the jack to the farthest point, and hook up the various items along the way. Also, I'd hook up the shielding at only one point, probably at the jack itself, as it mounts into the pickguard-with-shielding (Jazzmaster) or the metal plate (Jaguar). You get a good compromise, IMO, between star and regular wiring practices.

But that 0.01µf cap..... You don't want to mess with that in this context, we'll deal with it in the next section.

Also, aren't pot tabs grounded to their own shells a ground loop? The volume pot has this, so do i need to take it apart and ground that tab to the big ground wire?

Yes, pot tabs are usually just bent over and soldered to the shells, which goes against the grain of star grounding. To be complete, you should separate them from the shells, and run wires from the appropriate lugs to the ground "buss" wire you're installing. Small effort, to be sure. Perhaps only a small gain, perhaps a large enough one to be audible, only you'll be able to tell for certain. You'd absolutely do this, if you were installing the protection capacitor, though.

Does that include the tone capacitor's lead that goes to the pot shell? Yes indeedy, it surely does. If I were going all out for a star ground, I'd separate the cap lead from the shell, and run it to the "buss" wire. For that reason, you'll want to shape the "buss" wire to come near this cap, so that you aren't going through extra contortions just to make this particular hook-up.

Lastly, do have any advice on shielding jag pickups or can you link me to a thread that might?

No, sadly I don't. Jag pups are supposed to be well shielded as they come from Fender. HAH! The problem being, the plastic shells are tight up against the coil, making it deucely difficult to wiggle any shielding material in there without screwing up the works. There are other Fender forums that specialize in the Jaguar and Jazzmaster, perhaps they have more on this? Have you tried Offset Waist Guitars Forums, they're pretty deep into this kind of thing... or at least some of them were, last time I checked.

You rock

No, at my age, I only roll around a little bit, but thanks anyway!

HTH


sumgai

[jedikuff]

wow. look at you go man. awesome.

i'll be getting to work now. thanks.

chris

[jedikuff]

alright, i know i'm getting to the point of being annoying, but this is quick...

the grounding tabs on the back of the switches touch the underside of the control plate, which i assume needs to be coated in copper. could i just put a shim between them?

this project is so much more daunting then the strat. dear lord.

[sumgai]

jedi,

Your switch plate is metal, which means that it's already the best possible material for shielding - it doesn't need any additional treatment.

If you're not using the special cap (0.33µf/400vDC), then you don't need to worry about the isolation of anything, just continue to use the current mounting method for the switches, and the current grounding method for the whole assembly. If perchance the metal plate is not currently grounded, then make it so.

HTH


sumgai

[jedikuff]

wow. so i just finished assembling this thing that i've been working on for a few days on and off.

there's absolutely no improvement. really loud 60 cycle. it gets louder if i touch the plastic on a switch but quiter if i touch metal, strings or guard. rhythm circuit still doesn't work when switched on.

my soldering isn't bad. there must still be a ground loop.

[pete12345]

Perhaps you reversed the wires to the jack when you were assembling it. That would basically turn it into an antenna for hum. Touching the strings or any other metal would ground the guitar through you, making it quieter. Try swapping the jack wires around.

Pete