fini Posted November 21, 2004 Share Posted November 21, 2004 No, I'm not high, I just have some sort of problem. I just reconnected my KD-500 turntable (SME 3009 arm, Shure V15 type IV cart) to my MAC 1900 receiver. Everything seems fine, except for a loud buzz when I touch (of all things) the "lift handle" on the headshell! I experimented with touching other parts of the arm, and got a slight sound when I touched the counter-weight. Sound like a grounding problem? I have the arm and the table grounded to the receiver, but possibly something came a bit loose at the arm-to-cord connection? I have some suspicion as to the worthiness of this particular cartridge, as it has been involved in a tragic accident in the past (I bumped into the table in such a way as to cause it to slip off the credenza, landing upside-down, snapping the Infinity Black Widow arm previously installed. Miraculously, the Shure seemed unscathed. Maybe it had internal injuries?). I get no buzzing once my grubby hands are off the equipment. Ideas? Quote Link to comment Share on other sites More sharing options...
garymd Posted November 21, 2004 Share Posted November 21, 2004 I have the exact same issue with my Thorens/Shure V15V. It's very minimal however and I just ignore it. It has to be a grounding problem but I don't use that table enough to justify looking in to fixing the problem. Like you said though, goes away once you let go. Quote Link to comment Share on other sites More sharing options...
fini Posted November 21, 2004 Author Share Posted November 21, 2004 I'd like to see someone come up with a better grounding solution, connector-wise. I have three wires (one from the table, two from the arm) that need to be attached to a ground screw. They all have these 2-prong spade lugs that don't fit around the ground screw, because it's diameter is too big! I know some folks ground wires to some chassis screw, but I can't see any that are convenient. Maybe I will run a ground wire from a good screw to a small bolt & nut holding these lugs together. Gold plated? Yeah, right... Quote Link to comment Share on other sites More sharing options...
djk Posted November 21, 2004 Share Posted November 21, 2004 There is a little silver ground strap on most Shure cartridges between the cartridge body and the green pin. Slide it straight back and off using an exacto knife. Try it again for hum. Leave it which ever way is quieter. Quote Link to comment Share on other sites More sharing options...
fini Posted November 21, 2004 Author Share Posted November 21, 2004 Well, I pulled the little (that's an understatement!) ground tab, and no difference. No hum or buzz unless I'm touching the tonearm lift handle, then it's loud. Quote Link to comment Share on other sites More sharing options...
fini Posted November 22, 2004 Author Share Posted November 22, 2004 Monday bump... Quote Link to comment Share on other sites More sharing options...
hwatkins Posted November 22, 2004 Share Posted November 22, 2004 Well Greg - welcome to turntable heck. It does sound like a grounding issue. The irritating part is that the lack of continuity may not be anywhere near where you are most noticing the problem. The only good way to solve is to trace all grounding circuits in the table - unfortunately that is usually a bench project. You can still do some checking on the common areas as others have mentioned. One of the common areas not mentioned yet is the sheating on the L/R output cables - they tend to be the culprit more often than reason indicates. I have found this to be true on two tables - both had the cables directly connected on the TT side and were resolved by simply reheating the solder on the connects. Go figure... Quote Link to comment Share on other sites More sharing options...
JBryan Posted November 22, 2004 Share Posted November 22, 2004 Definitely a grounding problem. You can also try running a ground wire to the TT's bearing. Try it with and without the ground to the tonearm. Also, test the ground of your preamp/receiver and the outlet. Hope it helps - Bryan Quote Link to comment Share on other sites More sharing options...
fini Posted November 22, 2004 Author Share Posted November 22, 2004 There's no ground plug on the receiver, so I guess "ground" is relative to the system, not true, "Earth" ground, right? I will have some time later this AM to try and research and troubleshoot. I may post a few pictures, too. Speaking of ground, do folks ever run a wire to ground on these "2-prong" pieces, or is the AC neutral good enough? The mysteries of the electron... Quote Link to comment Share on other sites More sharing options...
hwatkins Posted November 22, 2004 Share Posted November 22, 2004 AC nuetral is generally a reasonable ground - there are some folks that run power conditioning that gives you a source for earth ground. While this is a good alternative and goes further to isolate any noise issues, you should still be able to quieten that tone arm with a good 'system' ground. I would think that the problem will exist even if you isolated the ground to earth. Quote Link to comment Share on other sites More sharing options...
fini Posted November 22, 2004 Author Share Posted November 22, 2004 I think Henry's correct. I grounded the two arm lead grounds and the table ground together at a binding post box. The green lead (12 ga. solid copper) runs to the ground screw on the back of the Mac 1900. Virtually no hum when I am not touching the lift handle, but the same ol' buzz is there when I touch it. I am now thinking touching the lift handle is creating a second ground route (is this a ground loop?). I'm considering insulating the lift handle, maybe with a rubberized paint? I don't know, any suggestions? Another thing I've noticed, somehow I lost the semi-circular rubber pad for the tonearm lift. No wonder the arm wants to return to the cradle when I cue it up! Quote Link to comment Share on other sites More sharing options...
fini Posted November 22, 2004 Author Share Posted November 22, 2004 Today I sprayed shellac on the lift arm, thinking it'd insulate it. Didn't help. I picked up some of that "Dip-It" plastic tool handle paint stuff. I'm thinking of using that on the arm, but I suspect that won't help either. This is turning into a pain in the a$$. Oh, bought some rubber gasket material, and a jar of rubber cement, too. I think I'll start sniffing after dinner. Quote Link to comment Share on other sites More sharing options...
nicholtl Posted November 22, 2004 Share Posted November 22, 2004 Ooh, what are those sexy bright blue analog cables you got there? Quote Link to comment Share on other sites More sharing options...
garymd Posted November 22, 2004 Share Posted November 22, 2004 If it's any consolation Fini, you take very nice pictures. Quote Link to comment Share on other sites More sharing options...
fini Posted November 22, 2004 Author Share Posted November 22, 2004 ---------------- On 11/22/2004 9:12:16 PM nicholtl wrote: Ooh, what are those sexy bright blue analog cables you got there? ---------------- I will tell you if you fix my hummmmmmmmm... Actually, they were extremely cheap, like $5/pair for 3' lengths. I posted links to the site a year ago. Looks like they only have the 6" versions now... EDIT: I went ahead and ordered a few of them short suckers! I need a few to replace those, uh, bent nail jumpers... Quote Link to comment Share on other sites More sharing options...
Allan Songer Posted November 23, 2004 Share Posted November 23, 2004 I run THREE separate grounds on my rig! The phono cable has a ground and then I ground the tonearm and the turntable chassis each DIRECTLY to earth. No hum. Ever. Even with the volume up ALL THE WAY. I can send you some pictures tomorrow. And you should also consider a better cartridge when funds allow. The Shure you are using is about as wrong a cartridge as you could imagine with the vintage SME 3009 "improved" I sold you. I mean REALLLLLLY wrong! The only thing worse would be a Grado . . . . Quote Link to comment Share on other sites More sharing options...
maxg Posted November 23, 2004 Share Posted November 23, 2004 " think Henry's correct. I grounded the two arm lead grounds and the table ground together at a binding post box. The green lead (12 ga. solid copper) runs to the ground screw on the back of the Mac 1900" I am no expert here, as you know Gregg, but I dont think you should have done that. Peering at the bottom of my own arm and cartridge I have 4 wires coming from the cartridge and a separate ground that is actually anchored to the arm and not to the cartridge. I assume that as the cartridge is screwed into the arm via metal screws the grounded arm provides the earth for the cartridge as well. Coming out of the arm at the back I have 3 wires - Positive and negative RCAs and an earth connection which is screwed into the earth terminal on the back of my phono stage. That is it. In all reason that should be sufficient for any setup. If it is not then I would guess one of the cables from the cart is coming into contact, or into near contact, with the grounded arm at some point. How old is the arm? Could the insultation on the wires inside the arm have come away somewhere? It could be that when you grab the arm, and doubtless move it slightly you are pushing the exposed connection against the arm and making the circuit. This would explain why, however shielded you are and the handle is and, however good the ground the buzz increases. If, for example, inside the arm the wiring has become exposed at the point where it leaves the arm and turns a right angle down through the pivot any movement may well bring it into contact. This is probably not what you wanted to hear - sorry. Could well need a full re-wire of the arm. On a more positive note I dont know anything so I am probably wrong. Lets hope so. Quote Link to comment Share on other sites More sharing options...
fini Posted November 23, 2004 Author Share Posted November 23, 2004 Thanks for ending on a cheery note, Max. I guess the wiring could be a culprit. I will check out Allan's suggestions. Allan, do you suggest an actual Earth ground (i.e. a ground rod driven into the ground)? I could certainly do that if it's required. I am thinking that ground should be tied to the ground rod for the entire house electrical system. Don't want two grounds, eh? I'd best confer with Marksdad (an electrician, of course). Also, I am happy to entertain suggestions for more appropriate cartridges. Quote Link to comment Share on other sites More sharing options...
bkrop Posted November 23, 2004 Share Posted November 23, 2004 fini, YOU'RE not grounded! Take a ten penny nail and drive it through your toe and into the floor, viola, problem solved! (You could also try one of those "self-help" books...) Quote Link to comment Share on other sites More sharing options...
Allan Songer Posted November 23, 2004 Share Posted November 23, 2004 I will shoot some good pics tonight and email them to you tomorrow morning. Are you running a ground from the arm as well as using the ground wire on the phono cable? Quote Link to comment Share on other sites More sharing options...
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