paulem55
Rookie Solder Flinger
Rickenbacker, Gretsch, Ludwig
Posts: 14
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Post by paulem55 on Sept 1, 2006 8:20:36 GMT -5
I need help! I'm putting together a guitar with 2 humbuckers, one three way-switch, one volume & two tones. It has a floating tailpiece and a fixed adjustable bridge. My problem is a ground problem. I tried grounding to one of the fixed posts of the bridge but it doesn't help. I did not shield the cavity, but after reading an article in GuitarNuts, I think I need to do so. I am following the schematic given by GuitarElectronics.com, but the grounding is vague. The 'star-grounding' sounds like the way to go. Can someone give me some specific directions on this setup? John's directions are for a Strat. I need help in a hurry!
Thanks,
Paul (Rickenbacker lover)
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Post by sumgai on Sept 1, 2006 11:49:50 GMT -5
Paul, Hi, and  to the forums! There are several possible causes of your grounding problem. Presumably, you have done everything right so far, but just for drill, let's go through the form..... The QtB article is generic, John A. simply used a Strat as a common example. What you learned with that set of pictures and directions will apply equally well to any other solid body guitar. (With the exception of an LP, where you can't "shield" the hole between the selector switch and the control cavity - that's where you'd use a length of shielded cable instead.) HTH sumgai |
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paulem55
Rookie Solder Flinger
Rickenbacker, Gretsch, Ludwig
Posts: 14
Likes: 0
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Post by paulem55 on Sept 1, 2006 12:06:15 GMT -5
Thanks for the quick response.
The ground wire to the bridge post which I spoke of, is just stuffed in the hole with the post forced down on it. All connections are soldered well. I tried to tie all grounds together and then ground them to a central point, i.e. the back of the volume pot. That didn't stop the noise either. I'm thinking I need to shield everything.
I have a guestion. What about shielded wire? I used it on another guitar with the same setup and it is almost noise free. But I didn't use it on this one. I used single wires (stranded). This is all trial and error for me, but I'm no novice at soldering. I am a little confused about grounding in general of an electrical instrument. Am I to assume that my body is the actual ground? If so, then shielding the cavity and pickguard seems to be the logical thing to do (as per John's article).
Thanks,
Paul
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Post by ccoleman on Sept 1, 2006 13:19:21 GMT -5
If you are sure the star grounding is done correctly, then I think you found your problem right there: you are using non-shielded hookup wire, in non-shielded control and pickup cavities, and like that the wires can pick up hum from the environment. I would try replacing it with shielded cable and see what happens.
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Post by sumgai on Sept 1, 2006 20:53:37 GMT -5
Paul, Shielding the cavities of your rig is considered superior to shielded cable for the reason that even the terminals on your pots, the leads to any capacitors, the exposed selector switch, all of these things can act as antennae, and conduct hum into the system. Sadly, shielded cable can't protect against that. Shielded cable is the only answer for non-solid body guitars. It's also the best solution to protecting the signal up to and back from the selector switch on LP type guitars. (Where the switch is in the upper bout.) Use shielded wire sparingly, if at all. And of course, if you do have to use it, then be sure it's good quality stuff. Bulk microphone cable from Radio Shabby does not qualify!  Uh oh, how did John get misquoted like that?  No, you aren't the ground, the grounded conductor of the cable from the amp to the quitar is ground (actually, "it is grounded", to be proper about it). Your body is an antenna, it is a focal point for lots of small amounts of hum. When you touch a properly grounded guitar, at least part of this "focused energy" is siphoned away from you, harmlessly passing to ground. For those parts left over (due to resistance and other effects), we need to shield the instrument against the body's residual focused energy field. HTH sumgai |
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paulem55
Rookie Solder Flinger
Rickenbacker, Gretsch, Ludwig
Posts: 14
Likes: 0
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Post by paulem55 on Sept 2, 2006 6:33:15 GMT -5
Sumgai,
Thanks for the tips on grounding and all. I'm sorry I haven't replied sooner but as I told Unk, for some reason my other computer would not bring up the task bar at the top of the screen with the 'member' portion and the 'messages' portion. I could not read any personal message and I could not reply to any posts. I don't know why. I wonder if it has something to do with the pop-up blocker or something?
Have you ever heard of this problem?
At any rate, I wasn't quoting John about my 'body being a ground' but just saying that shielding the cavity and pickguard seems to be the logical thing to do (as described and recommended by John's article). No, he's not the ignorant one, I am.
I do understand now, that the electrical cord is the actual ground (should have known that), so it seems only reasonable to me that the jack is the most important ground area. Right?
I'm sure I will keep asking for help. I need to get this thing resolved. I will continue working on it this afternoon and let you know if it is resolved.
Thanks again,
Paul
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Post by tacobobbo on Sept 7, 2006 15:51:22 GMT -5
Sumgai and everybody else more knowledgeable than me:( pretty much everyone  ) Just out of curiousity........would the audio cable from a computer work, i e: the ones that are used to go from the cd/rom to the sound card? I realize they are maybe a bit on the lite side as far as guage goes, but they DO have wire shielding in them...( at least as far as my ignorance would allow they look like GOOD shielding). Anyway, thanks for the input. Bob |
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Post by sumgai on Sept 8, 2006 0:38:58 GMT -5
Bob, It would work fine..... as long as you don't burn the insulation whilst trying to solder the tiny wires to whichever terminals!  Good re-use of old parts..... +1 for you! sumgai |
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