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Post by guitarnerdswe on Apr 28, 2024 8:46:41 GMT -5
No problem with copper foil - just spot solder all the pieces together, and solder to a ground lead Even easier is to buy the copper foil with the conductive adhesive. It's more expensive but not unreasonably so, and it works well. I've used it for years. You just overlap the pieces and it all has continuity. No soldering necessary. Oh, that sounds like a sweet deal.
The reason I leaned more towards painting my cavity than using copper tape was the concern that the solder joints might touch something on the circuit board, since it's so crowded in the cavity and the clearance is minimal. It's at best 1.5 mm between the cavity wall that the pots and switch go through, and the components on that side of the circuit board. It might be even less.
I will have to consider that kind of copper foil though. |
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Post by mikecg on Apr 28, 2024 15:17:16 GMT -5
I do think I get the gist of what you're saying, and it makes sense. I assume you mean that the dummy coil is acting like the tuning coil in this scenario, and both the guitar cable and backplate act like antennas, with the cable providing the necessary impedance for picking up the interference? Sort of - perhaps a graphic way to think about the properties of a Faraday cage is to imagine yourself on a golf course during a thunderstorm, holding a golf club aloft. That situation is rather like your circuit board in its non-conducting control cavity, with a conducting back-plate in close proximity. If you get struck by lightning - you will certainly feel it. But if you take cover inside the conducting shell of a vehicle (golf-cart?) and lightning strikes - you may not feel a thing, as you will be inside a Faraday cage, and the current in the lightening bolt will flow only through the shell of the vehicle, and not through you, as the electric field inside the shell will be close to zero. |
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Post by unreg on Apr 28, 2024 19:46:49 GMT -5
So I'm going to apply some myself. I read the thread where you had to redo it 4 times to get it working. What was the issue? Just want to make sure I do it right  I do understand you are going to try the sticky copper tape, but just want to answer your question. The issue was my external ground loop. Remember? I had plugged my guitar pedals into a separate outlet in my room from the outlet my amp was plugged into. That setup caused a sometimes-noisy ground loop to affect guitar sounds coming from my amp. You know, it was the loop of (ground wires from both outlets through my walls connected at my home’s electrical box + my equipment, touching those ground wires, connected together to accept audio from my guitar) ; that situation isn’t good. 👍 That external ground loop situation lasted for me throughout that thread, I stopped painting just because of frets’ recommendation. If you find my initial post, to you, on page1 of this thread, you can follow the link to my external ground loop solution. It’s quite helpful, for me, at least. |
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Post by guitarnerdswe on Apr 29, 2024 2:43:58 GMT -5
So I'm going to apply some myself. I read the thread where you had to redo it 4 times to get it working. What was the issue? Just want to make sure I do it right I do understand you are going to try the sticky copper tape, but just want to answer your question. The issue was my external ground loop. Remember? I had plugged my guitar pedals into a separate outlet in my room from the outlet my amp was plugged into. That setup caused a sometimes-noisy ground loop to affect guitar sounds coming from my amp. You know, it was the loop of (ground wires from both outlets through my walls connected at my home’s electrical box + my equipment, touching those ground wires, connected together to accept audio from my guitar) ; that situation isn’t good. 👍 That external ground loop situation lasted for me throughout that thread, I stopped painting just because of frets’ recommendation. If you find my initial post, to you, on page1 of this thread, you can follow the link to my external ground loop solution. It’s quite helpful, for me, at least. I actually haven't decided yet (still weighing the pros and cons of each method), so your input is not in vain!  I should have specified a bit more: When you did the painting, did you ever figure out why your initial readings were so high? Was is the need for more stirring, more graphite, or was it the acrylic paint you used? |
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Post by guitarnerdswe on Apr 29, 2024 2:54:37 GMT -5
I do think I get the gist of what you're saying, and it makes sense. I assume you mean that the dummy coil is acting like the tuning coil in this scenario, and both the guitar cable and backplate act like antennas, with the cable providing the necessary impedance for picking up the interference? Sort of - perhaps a graphic way to think about the properties of a Faraday cage is to imagine yourself on a golf course during a thunderstorm, holding a golf club aloft. That situation is rather like your circuit board in its non-conducting control cavity, with a conducting back-plate in close proximity. If you get struck by lightning - you will certainly feel it. But if you take cover inside the conducting shell of a vehicle (golf-cart?) and lightning strikes - you may not feel a thing, as you will be inside a Faraday cage, and the current in the lightening bolt will flow only through the shell of the vehicle, and not through you, as the electric field inside the shell will be close to zero. I might be overthinking it, combined with not fully grasping the physics behind my particular setup: Like if the buffered output would make the circuit board less susceptible to noise, to the point that this shouldn't be happing? Also what effect the grounding wire has in my situation? I do feel I understand the basic principle about the Faraday cage though. I'm just trying to rule out the circuit board being at fault |
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Post by unreg on Apr 29, 2024 18:11:10 GMT -5
I actually haven't decided yet (still weighing the pros and cons of each method), so your input is not in vain! I should have specified a bit more: When you did the painting, did you ever figure out why your initial readings were so high? Was is the need for more stirring, more graphite, or was it the acrylic paint you used? Hmmm… I believe after stirring the mixture a lot; that helped the graphite to mix well with Anita’s water based acrylic craft paint; because without the massive stirring, the AGS graphite powder stayed at the bottom of the mixture. I just spent time attempting to measure resistance of my conductive paint. After much time wasted, I was able to receive a reading of around 284Ω after I pressed the wires hard against the paint. But, as frets said, there’s enough graphite in there to do its job after my 4 coats. Maybe use a different acrylic paint? If you do decide to use frets’ recipe, 3 teaspoons does equal 1 tablespoon, so feel free to use a tablespoon if you can’t find a good teaspoon. And frets usually receives a resistance of about 9Ω when she follows her recipe. So my 284Ω is insanely too high. Maybe it’s my meter? I easily receive around 6Ω when touching the two wires, each wire to a different pot case, to my 2 pots; there’s a ground wire soldered between them. Though, 6Ω is quite high there. EDIT: After 4 coats my entire electronics cavity, including the potentiometer holes in my guitar’s body, was completely covered; I believe I missed some spots during the first coat, so be thorough. |
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Post by newey on Apr 29, 2024 19:02:32 GMT -5
So my 284Ω is insanely too high. Maybe it’s my meter Those two things may be related if you pushed the probe through the paint layers a bit. |
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Post by unreg on Apr 29, 2024 20:38:52 GMT -5
Off-topic, sry. Those two things may be related if you pushed the probe through the paint layers a bit. Ah but I wasn’t using the probes; I connected its alligator claw to each probe, then had each alligator claw grab a small stripped wire end; I was using those other stripped ends of the wires to resistance test; as you instructed me in that thread, newey. |
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Post by mikecg on Apr 30, 2024 19:20:23 GMT -5
I do feel I understand the basic principle about the Faraday cage though. I'm just trying to rule out the circuit board being at fault Hello again, guitarnerdswe, I'm guessing that testing and repairing printed circuit boards (PCBs) is not something you do for a living - so that being the case - if the PCB is faulty, your best course of action may be to return the guitar to MM and ask them to quote you for a repair. As I think I mentioned, a while back, I did a search on the MM forum, and noticed quite a few posts related to noise problems, and this one caught my attention: forums.ernieball.com/threads/music-man-luke-3-hh-hum-issues.73348/The upshot seems to have been that the OP had swapped the pups, and had installed the new ones out of phase (OoP), resulting in excessive noise in the split positions, and I was just wondering if you might have done something similar? Long shot - I know! |
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