JMJM shielding/grounding guide

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metsam
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JMJM shielding/grounding guide

Post by metsam » Wed Oct 21, 2020 10:10 am

Getting ready to shield and ground a JMJM squier. Any thorough guides out there, especially for the vibrato/bridge grounding? Most guides I find are very general, I need one that shows exactly what I need to do.
Thank you!!

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HarlowTheFish
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Re: JMJM shielding/grounding guide

Post by HarlowTheFish » Wed Oct 21, 2020 12:25 pm

As far as shielding, Mike Adams (Puisheen on Youtube) has a guide on shielding cavities with copper tape, and I think Phil McKnight has a couple somewhere about using shielding paint. For the grounding, you need a tiny hole from your main cavity to the trem cavity to run a ground wire, then find a spot along the outside of the rout that's covered by the trem baseplate, press the wire in (if you have a soft finish - the JMJM is poly and might need you to scratch a tiny channel in the finish to get it to stay). Put the ground wire in the hole, put the trem back on and make sure it's holding the wire but isn't being pushed up anywhere, and attach that to the rest of your wiring as a ground.

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Re: JMJM shielding/grounding guide

Post by alexpigment » Wed Oct 21, 2020 7:03 pm

Was this guitar previously stripped? The guitar already has shielding paint in all cavities and the bridge is already grounded. Unless there's an issue with the guitar, I would not waste your time and enjoy the fact that the work has already been done for you :)

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Re: JMJM shielding/grounding guide

Post by mackerelmint » Wed Oct 21, 2020 7:11 pm

Don't forget the back of the pickguard, and be sure it connects to the rest of the shielding. This is why I kinda lean toward using copper foil tape because it's easy to just create a spot where you can be sure the guard meets the body and has shielding on both parts making contact.

And a great trick to help keep the noise down is to twist your pickup leads together into a long rope, like what you'd see inside of an amplifier. They build amps this way because twisting the wires like that helps reject interference. I did it with that in mind, because I didn't have any thing handy to cut the wire with and thought it was worth a shot because if nothing else, my leads would be shorter. It turned out to work really really well, that JM is crazy quiet.
This is an excellent rectangle

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Larry Mal
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Re: JMJM shielding/grounding guide

Post by Larry Mal » Wed Oct 21, 2020 7:37 pm

Fender's shielding paint is barely applied, you need a few coats to build up enough thickness to really get any benefits from that cheap carbon based paint they use. And they don't... they don't do a good job with it.

I would place no faith in that... in fact, I don't, I put copper tape right the hell over that stuff.
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Re: JMJM shielding/grounding guide

Post by jvin248 » Thu Oct 22, 2020 2:23 am

.

Aluminum works better than copper foil (research with cell phones and computers is out there if you need data) plus it's only $7/roll for Nashua Aluminum Flashing tape that will shield two dozen guitars, fold over/wrinkle the strips/add a small bridge strip and verify continuity with an ohm meter. Certainly the copper foil looks fancy for Instagram shots but no one ever looks inside the guitar later and only cares about the noise through the amps at the gig. Run a strip up over the top face of the guitar at a pickguard screw hole to connect the pickguard as a lid over the cavity for a complete Faraday cage.

Replace the two wires to the jack with shielded cable. Most important on Strats and Teles that have wires going outside the Faraday cage of a shielded cavity but good practice on offsets with contained jacks too. Scrounge up an old audio RCA patch cable to repurpose. Twisting wires into a rope looks nice but does nothing at guitar frequencies and voltages. If the industry believed twisted cables worked they would sell us twisted pair cables to use from the guitar to the amp, but we don't, we need shielded cables to ensure low noise.

.

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Re: JMJM shielding/grounding guide

Post by soggy mittens » Thu Oct 22, 2020 2:36 am

I do star grounds through a 1.0uF 450V capacitor, can go as low as 200v tho. Also remember that they're single coils and can buzz when using just one and you can't always control interference in every room you're in. Do everything you can and remember it won't always be perfect. xD
If OSG has tort me anything...

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Re: JMJM shielding/grounding guide

Post by metsam » Thu Oct 22, 2020 6:39 am

Hey guys,

Thanks a lot for the tips!

Will try to locate Puisheen's video. This is what I need, to see it documented, in a step by step guide!

Cheers!

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Re: JMJM shielding/grounding guide

Post by MKR » Thu Oct 22, 2020 8:40 am

Are you using the stock adonized gold pickguard? If so, I don't recommend additional shielding. ALuminum pickguards are excellent shielding and make the guitar much quieter than something with a regular plastic pickguard. I had a JMJM and it was very nice and quiet stock. I swapped the pickguard to a mint green one and the guitar was way noisier as a result. put the stock one back on and it was quiet again.

If you are using an aftermarket plastic pickguard, then yes additional shielding would be good, if it's stock leave it alone. you're not going to see much improvement.

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Re: JMJM shielding/grounding guide

Post by alexpigment » Thu Oct 22, 2020 2:45 pm

MKR wrote:
Thu Oct 22, 2020 8:40 am
Are you using the stock adonized gold pickguard? If so, I don't recommend additional shielding. ALuminum pickguards are excellent shielding and make the guitar much quieter than something with a regular plastic pickguard. I had a JMJM and it was very nice and quiet stock. I swapped the pickguard to a mint green one and the guitar was way noisier as a result. put the stock one back on and it was quiet again.

If you are using an aftermarket plastic pickguard, then yes additional shielding would be good, if it's stock leave it alone. you're not going to see much improvement.
Don't forget you can get those metal pickguard shields for 3rd party guards. Sure, it costs slightly more money than copper tape, but they're quicker and easier to use imho.

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Re: JMJM shielding/grounding guide

Post by mackerelmint » Thu Oct 22, 2020 3:05 pm

Tape is a bit more work, for sure. The advantage is that you can get creative, and the various scraps that inevitably accumulate can be put to use as vias from one cavity to another and across to the back of the guard with no fussiness required.
This is an excellent rectangle

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Re: JMJM shielding/grounding guide

Post by alexpigment » Thu Oct 22, 2020 4:45 pm

That's true - and I totally get it. I just don't know if many modern players know about the metal shields. I have one on every JM I own and you can swap them around with different pickguards rather than taping up each individual pickguard.

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Re: JMJM shielding/grounding guide

Post by mackerelmint » Thu Oct 22, 2020 4:53 pm

alexpigment wrote:
Thu Oct 22, 2020 4:45 pm
That's true - and I totally get it. I just don't know if many modern players know about the metal shields. I have one on every JM I own and you can swap them around with different pickguards rather than taping up each individual pickguard.
Oh! I was thinking of the peel n stick kind that are preshaped. But I know what you're talking about. I'd forgotten about those, they're awesome! Good call.
This is an excellent rectangle

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Re: JMJM shielding/grounding guide

Post by Larry Mal » Thu Oct 22, 2020 4:54 pm

Good point... I love anodized pickguards.

I still shield the guitars, though.
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Re: JMJM shielding/grounding guide

Post by Johnnytheboy72 » Sun Oct 25, 2020 5:34 am

I've been modifying most of my guitars for the past 10 years or so, and have always used stick on aluminum tape, as it's cheap and readily available and can look very neat. I always test with a multimeter on continuity testing setting, to make sure all's good after fitting. Have always covered underside of pickguards as well. I guess the copper looks the dogs danglies, but I agree with what jvin248 advises 👍 you certainly won't see it.

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