Comment

Comment by Terry Carmack on September 23, 2009 at 3:12pm

Hey Kevin, Josh both had great ideas but still got the damn noise. Ive tried everything you guys suggested, If I take the pot out of the equation the noise goes away. I know...dont use a pot but I really want this to work. but I am at my wits end. Im sure Im doin sumptin wrong I just cant seem to put my finger on it.

Comment by Kevin Lawton on September 23, 2009 at 11:31am

Josh, well thanks very much for rubbishing my reply Terry in such a way as to prove that you either didnlt really read it or didnt understand it. You appear to have assumed that I said the exact opposite of what I actually did put. To be honest with you, I cannot see any kind of 'ground loop' on the diagram, as all of the earth connections appear to be in a 'star' formation centered around the back of the pot. Where do you see a loop ? As regards the need for someind of screening, do remember that Terry is using a piezo pickup and thus the circuit is very high impedance. Under the 'right' conditions, at that impedance, just a few inches of unscreened wire can pick up hum and noise.

Comment by Terry Carmack on September 23, 2009 at 7:13am

Thanks Josh, Ive tryed re soldering still the same, I kinda think I might be over heating the pot, so will look into that tonight and the shielding tape or paint. Thanks for the help from everyone. You guys are awsum..

Comment by Josh Gayou (SmokehouseGuitars) on September 23, 2009 at 5:13am

Actually, given his current drawing, doing this will create a ground loop in his circuit.

If you want to shield your circuitry, all of the circuitry must be encased in the shielding medium. Whether you're using foil or paint, you would need to line the entire inside of the box with the stuff for it to have any effect. Also, you don't want to use self adhesive tape unless it's specifically made for shielding work. The regular self adhesive stuff you get at the hardware store will not conduct through the adhesive. You can use this hardware store stuff if you get creative with how you fold it, making sure that all joints in the tape are metal to metal and not adhesive to metal, but this is a pain and it's just better to get the real stuff. Conductive paint is by far the easiest to use.

Even so, I don't think shielding is going to get you that much of a noticeable difference. A piezo disk is not an antenna like a mag pup, so you don't really need to worry about mains hum and, assuming everything is properly grounded and all your joints are good, you shouldn't really be getting any hum when you touch your components (shouldn't be getting hum when you're not touching them either). Coaxial wire is good, but you really only need it for a long run (say from a neck pickup all the way to a set of control pots on a full sized solid body. I've wired up more guitars than I can remember just using standard hookup wire without any hum or noise issues. Honestly, I think you just need to double check all of your joints and maybe try re-soldering.

One other thing to think of: too much heat will damage a pot, so you really want to minimize the amount of time you're taking to heat the case of your volume pot. What I do is first scratch the hell out of the back of the pot with my pliers or something, melt a big wad of solder onto the tip of my iron, and then touch it down to the pot (the solder and not actually the iron). I wait for the solder to wick to the pot, spread it flat a little with the iron, and then pull away and allow the pot to cool completely before trying to connect anything else to it.

"Yeah, the wirin drawing seems okay to me - though it might have been better ha you used screen (coaxial) wire instead of hookup wire. A bit of shielding might well help but first carefully check that the connection between the jack 'outer', the end of the pot track, the pot casing and the piezo are all good. A quick way to achieve a it of screening is to get some of that aluminium self-adhesive tape. Unscrew pot and jack and run a band of tape over the inside of the two holes where they mount and as to close the piezo as you can get. make holes in the tape for the pot and jack and screw them back in place so they both make contact with it. Might help - certainly won't do any harm."

Comment by Kevin Lawton on September 23, 2009 at 12:54am

Yeah, the wirin drawing seems okay to me - though it might have been better ha you used screen (coaxial) wire instead of hookup wire. A bit of shielding might well help but first carefully check that the connection between the jack 'outer', the end of the pot track, the pot casing and the piezo are all good. A quick way to achieve a it of screening is to get some of that aluminium self-adhesive tape. Unscrew pot and jack and run a band of tape over the inside of the two holes where they mount and as to close the piezo as you can get. make holes in the tape for the pot and jack and screw them back in place so they both make contact with it. Might help - certainly won't do any harm.

Comment by Ted Crocker on September 22, 2009 at 7:12am

To embed a pic in a discussion you click the little camera icon in the message box and upload it following the link

Comment by Josh Gayou (SmokehouseGuitars) on September 22, 2009 at 6:43am

Drawing looks right to me. Maybe a cold joint?

Comment by Terry Carmack on September 22, 2009 at 6:36am

by the way how do I post a pic directly to the group page.

Comment by Terry Carmack on September 22, 2009 at 6:36am

http://www.cigarboxnation.com/photo/pick-up?context=user I think this is how Im wirin it, I have a detaled pic I down loaded on line on the bench. I did this real quick with paint. Im pretty sure I have a ground issue to but cant figut out why

Comment by Ted Crocker on September 22, 2009 at 5:29am

Terry, have you grounded the back of the volume pot to the ground lug of the jack?

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