First post - found you via Google. I see some good info here, so I thought I'd give it a shot before I find a tech.
I finally set up all my tube audio equip. About 20 yrs. ago, I bought a NIB (sealed) Technics SP-15 complete w/base, d.c. and EPA-250 from a studio which never used it. I'll skip listing all the stuff I have because it's not relevant, but the two (other) pieces which are relevant are the Acoustic Research (ARC) SP-11 Pre-amp and the ARC VT-100 P.A.
My friend put the SP-15 together and mounted the (six) carts (all Shure -- V-15 MR-V MR; Me95ed, etc.) because he's done it many times in the past and I didn't want to mess it up because I've never done it.
Everything works great, except I get an intermittent hum when I either am changing the bayonetted headshells or if I happen to touch the tonearm itself. It doesn't happen all the time. It seems as if it's happening randomly, but everything happens for a reason and I just can't find it (yet). When it does happen, once I break contact with the headshell (or tonearm), the hum stops.
Both the T.T. grounding wire and the tonearm grounding wire are attached to the grounding post on the back of the ARC SP-11. The hum doesn't happen when I touch the T.T. base or any other piece of equipment (tape decks, CD, tuner, etc.) -- just what I mentioned above -- sometimes.
He mentioned he had the same problem and fixed it by running the grounds (w/extensions) to a cold water pipe.
Could the problem be that you're not supposed to attach both the T.T. grounding wire and the tonearm grounding wire together to the grounding post on the SP-11?
Or could it be the (possible) lack of self threading plastic slip on nuts when mounting the carts (which prevent electrical grounding of the cartridge body to the headshell)?
Or could it be the proximity of the T.T. to the power amp? Everything I have are on these specially constructed racks with non-conductive shelves (no metal!) The T.T. is on the top of a 6-shelf rack and is approx. 4 ft.+ above the p.a., which is on the bottom shelf because I was trying to avoid any electro-magnetic interference.
Or, could it be something else of which I'm not aware? (I also have an anti-stat mat on top of the stock mat, which eliminated the static electricity I was getting when I would change the record, so it's not that).
Also, as an aside question. I didn't have any SFW 010 spindle oil (my fault -- I didn't realize you needed it at the time), but my friend used a couple of drops of 3-in-1 oil instead (and said there would be no problem). The first time I tried it, it ran too slowly and with a warble (as if you were starting a car on a cold winter day). After about 2-3 mins. of running it, turning it off, then on again and trying it again, it's had no problems whatsoever. So the question is, will there be any problems (in the long run) with using 3-in-1 oil?
Thanks in advance for any help you can give. If you need more specific info, please ask...
I'm unclear whether this is a problem only while you are changing headshells or while you are touching the tonearm for cueing purposes. Or whether this problem exists with all six cartridges or just a few.
Ground problems are a "suck it and see" solution. Most of your questions are related to things you can try yourself, so try them. You can easily disconnect the grounding wires from the table and the tonearm, so try it. Eventually you'll find the answer. Sorry to be so "uninformed" but ground problems are solved on site and usually not on a forum.
Your cartridge should be grounded to the tonearm even with plastic nuts since the cartridge body (which would be what the screws and nuts touch) is touching the tonearm. If your buddy placed something between the cartridge body and the headshell, this could be the problem. Separately grounding a lead out of the cartridge's ground pins might solve your problem. You'll have to try some combinations to solve this issue. Always keep the volume level down when changing any ground connection as the resulting 60Hz hum can ruin a low frequency driver.
It's unlikely your problem is in the location of the gear since the problem only occurs when you touch the tonearm. Touching the base of the table shouldn't have any effect on ground problems as it is normally only the cartridge/tonearm combination that is grounded. Try different grounding schemes to find which is best. Begin with no ground connection and put each earthing wire to ground while you experiment.
The center screw on your AC outlet should be the same as a dedicated earth ground unless you have AC problems at your house but most tonearms want to be grounded to the pre amp and not the earth ground. If you are running the pre amp and the table off different AC outlets, combine then to one outlet. If you are running any sort of surge protector or AC conditioner, take these out of the system temporarily.
The bearing oil is a bit light and will do but is not what most manufacturers would recommend. The oil had to run up the bearing and eventually fill the shaft before it gave its full lubrication. I prefer a Teflon based lubricant for most turntable bearings.
As you can tell by the times of these posts, I work some mighty strange hours, but since you were nice enough to respond, I wanted to do so in kind even though I hadn't had a chance to completely check everything yet. [Actually, I didn't expect a response so soon.]
It'll take me a day or two to check out and experiment with everything to answer your questions fully, but in the meantime...
"I'm unclear whether this is a problem only while you are changing headshells or while you are touching the tonearm for cueing purposes. Or whether this problem exists with all six cartridges or just a few."
>> So far, this seems to be random, but that's one of the things I will test completely in the next couple of days.
"...but ground problems are solved on site and usually not on a forum."
>> I (mostly) agree, but since I don't have a tech over here, I thought I'd give this a shot. Hopefully, you may be able to help me somewhat.
"You can easily disconnect the grounding wires from the table and the tonearm, so try it."
>> Which I will do, but wouldn't it be easier (and with the same result) if I just disconnect the table and tonearm ground wires from the grounding post on the back of the SP-11 (or is that what you meant)?
That brings me back to one question which I asked above: "Could the problem be that you're not supposed to attach both the T.T. grounding wire and the tonearm grounding wire together to the grounding post on the SP-11?"
"If your buddy placed something between the cartridge body and the headshell, this could be the problem."
>> On that subject, I can say definitively that he didn't. I was only wondering if the (possible) lack of the self threading plastic slip on nuts could be the source of the hum. Some carts came with them and some didn't. However, that's another thing I will also thoroughly check in the next day or two.
"Separately grounding a lead out of the cartridge's ground pins might solve your problem."
>> How do you do that? Sorry for the 'newbie' question, but if I recall, there are LG and RG pins on the cart. Would I run a small wire from one (or both) of them? And if so, where would the other end terminate?
"Touching the base of the table shouldn't have any effect on ground problems as it is normally only the cartridge/tonearm combination that is grounded."
>> That's correct -- it doesn't produce a hum when touching the base. I know what the tonearm grounding wire grounds (obviously), but what part of the t.t. does the t.t. grounding wire (which comes out from underneath the center of the t.t. on the bottom) ground? I thought it grounded the base, but I'm inferring from what you said, that it doesn't.
"...unless you have AC problems at your house..."
>> No problems there.
"...but most tonearms want to be grounded to the pre amp and not the earth ground."
>> So I guess grounding it to a cold water pipe is out?
"If you are running the pre amp and the table off different AC outlets, combine then to one outlet."
>> All my equipment's AC cords are plugged into a Furman PL-PLUS SERIES II Power Conditioner, which is plugged into one outlet.
"If you are running any sort of surge protector or AC conditioner..."
>> I'll take the T.T. and the Pre-amp and plug them directly into the same 4-receptacle outlet, into which I plug the Furman.
"The oil had to run up the bearing and eventually fill the shaft before it gave its full lubrication."
>> Ah - that would explain the 2-3 mins. of speed fluctuations. You sure know your stuff. Now that I know about the SFW 010, I would have preferred to use that, but unfortunately it's too late, so it'll just have to do and hope it works out in the long run.
That should be enough for now. As I mentioned, I'll get back to you in a day or two with more complete answers to the above, but in the meantime, if you had a minute and could let me know about my above-mentioned questions, that would be a help and would be much appreciated.
It doesn't matter where you break the connection for the ground wires. The point is merely to try only one wire at a time for proper operation.
*
"Separately grounding a lead out of the cartridge's ground pins might solve your problem."
"How do you do that?"
The simplest way would be to break out the VOM or some sort of continuity tester and determine whether the tonearm might happen to share a ground with the cartridge leads. Touch the probe to a bare spot of metal on the arm and to the ground ring (outer ring) on the phono (RCA) plugs that go into the pre amplifier. Since you have a separate ground lead for the arm, I doubt there are any shared grounding connections. If not, temporarily connect a wire from the phono ground lug to one of the cartridge leads at the cartridge and check for any improvement in your grounding problem. I'm not really expecting any change with the Shure cartridges but this can sometimes be the solution to grounding problems that occur when the arm is handled.
*
" ... what part of the t.t. does the t.t. grounding wire (which comes out from underneath the center of the t.t. on the bottom) ground?"
Probably a separate ground lead for the motor itself. My first guess is disconnecting this lead will solve the problem.
*
"...but most tonearms want to be grounded to the pre amp and not the earth ground."
"So I guess grounding it to a cold water pipe is out?"
No, you can try a cold water pipe ground, if that is what you use for electrical ground in your home. Most current codes have done away with water pipe grounds for safety reasons. You will run the risk of having too many locations for the earth ground but you can certainly try this connection.
*
You can clean the bearing and shaft with a lint free Qtip and then replace the lubricant with whatever you please.
I've had a really bad (hectic) week, so unfortunately (for me), I won't be able to check out all the headshells (and the rest), which I mentioned way above until the weekend.
However, if you happen to see this before then, I wanted to check a few things with you, so I could incorporate them into all the things I'm going to try this w/e.
"The simplest way would be to break out the VOM..."
>> I have a multimeter, so which voltage setting would I put it on and then after I "Touch the probe to a bare spot of metal on the arm and to the ground ring (outer ring) on the phono (RCA) plugs that go into the pre amplifier.", what number would I be looking for and what would that number signify? In other words, what's good and what's bad?
The other thing was you mentioned, "most tonearms want to be grounded to the pre amp and not the earth ground," but you also mentioned, "you can try a cold water pipe ground."
>> That sounds contradictory to me (unless I'm reading it incorrectly). Or should I just try both and see which one works better? (Right now, it's grounded to the pre-amp.)
Lastly, you mentioned, "My first guess is disconnecting this (the separate ground lead for the motor itself) will solve the problem."
>> Is that one of those 'try it out and see kind of things?' Only reason I'm asking about that is that I thought (and the manual said) to ground them both.
Thanks and when I hear back, I'll try everything all at once this w/e and let you know what's up. I like getting back to people that help me out because I sort of do tech support on a PC site when I have time (I'm a programmer), so if/when I help somebody out, I'm always curious to make sure it worked...
Your meter should have a continuity tester. It is typically at the end of the switch positions and will create a beep when the two probes are contacting one another either directly or through a continuous connection.
*
Try both ground connections. You might find some benefit to grounding your pre amp to the pipe also. As I said, these problems are only solved on site so I can only guess at what might make the best ground connection for you. The problem always becomes having too many potential grounding locations which will cause even more hum. Remember, your center screw on any AC outlet should represent an earth connection which should be the equivalent of a pipe connection and will most likely be a better connection than a water pipe if any of the pipes have been replaced with a PVC section.
*
I would guess the motor doesn't require grounding in a consumer application. It's been ages since I sold Technics but the motor should only require a ground in situations where hum occurs without the connection. Typically this would be for DJ's who do set ups in various locations on a constantly rotating basis. Earth ground is not always available in those situations and so the motor might hum if it doesn't share a ground with the tonearm. In your case, the reverse is probably true.
I'm back. Sorry for the very long delay, but I had a personal thing with a hospital visit (and the rest is not important or relevant and nobody cares anyway...)
If you still are in the mood to help out, I'd appreciate it, although I would understand if you didn't after all this time.
In case you want to help though, I can bring you 'up to date' and tell you what I have done and what I eliminated (I won't repeat all the stuff above, because it would just be easier and quicker if you scrolled up to reference it yourself).
First thing is it turns out the (six) carts. have nothing to do with the hum. When I mentioned above ("I get an intermittent hum when I either am changing the bayonetted headshells or if I happen to touch the tonearm itself."), I originally thought it had something to do with some (or all) of the carts. It doesn't. The relevant part of that sentence was, when I was changing the headshells, I was touching the tonearm.
I detached the separate grounding wires from the tonearm and the table from the grounding lug on the back of the SP-11. Just for the heck of it (and as an aside, in case the info helps), when they were both detached, I touched them together in mid-air and the hum got much louder (referencing my point in a previous post above, wondering if the both of them should be grounded together on the SP-11's grounding lug).
Then I grounded the table ground to the center screw on the AC outlet where the Power Conditioner is plugged into. Then I reattached the tonearm ground back onto the grounding lug of the SP-11.
[I tried a bunch of other things, but since they didn't work, I won't waste time mentioning them.]
Basically, nothing changed, but here's when it produces a hum and when it doesn't.
The only time a hum is produced is when I touch the tonearm itself.
It does not hum at any other time or if I touch any other piece of equipment, including touching the metal t.t. platter and surrounding base. When it's playing a record, there's no hum.
So, when I'm touching just the tonearm itself with one hand (to produce the hum), what's interesting is to get rid of the hum, I -either- put one finger of my free hand on the grounding lug in the back of the SP-11 (where the tonearm grounding wire is attached) -or- if I put my free hand under the turntable base and touch the piece where the interconnect wires (and the other end of the tonearm grounding plug) go into. In other words, I'm acting as the ground -- one hand on the tonearm and the other hand on either end of the tonearm grounding wire.
I almost feel as if I took a piece of wire, wrapped it around the tonearm and ran it to the grounding plug on the back of the SP-11, that would stop the hum (the wire would be acting as me, when I do that manually). But isn't that exactly what the tonearm grounding wire is supposed to do?!
Does the above sound anything like you've run into before and if so, would you have a suggestion?
One other quick question. When I bought the SP-11 (used), I noticed the grounding plug was loose, so I tightened the screw which holds it to the chassis and then it was alright. Is there any circuitry attached to that grounding plug on the inside of the SP-11 or does it simply terminate right at the chassis?
If you see this, I'd love to hear what you think or what I could try and then I (we) could take it from there.
Let me start by asking a question that seems relevant to me. If the hum is only produced when you touch the tonearm, why worry? You don't touch the tonearm when you're playing a record, so, no hum; yes? No?
"You don't touch the tonearm when you're playing a record, so, no hum; yes? No?"
>> You're correct. I only get the hum when I actually touch the tonearm.
What is very odd to me is when I described above what happens [i.e. one hand touching the tonearm and the other hand touching either terminus (grounding lug on the SP-11 or the connection point under the turntable base) of the tonearm ground wire, the hum disappears -- as if my body were acting as a ground).
Would you have any idea why I'm acting as the ground, but the tonearm grounding wire isn't (and would there be any 'fix' for that)? If it's not fixable, then I guess I'll have to live with it, but if there is, I'd sure like to find it!
Thanks again,
Mike____
P.S. Btw, not that this is important, but I just noticed in my first post that I said I had an 'Acoustic Research' pre and p.a. Obviously I meant 'Audio Research'. I must have been thinking of the speaker line when I wrote that -- brain lock, I guess...]
The ground lug on the pre amp is simply attached to the chassis with no intervening circuitry.
It sounds as if the ground wire has broken inside the tonearm. Since rewiring a tonearm is a bit of a hassle, you can either leave it as is or have it repaired depending on how much this bothers you. If the hum only occurs when you touch the arm, you might simply insulate the armlift so you do not provide the ground plane for the arm when you touch it. Try a bit of electrican's tape or some shrink tubing on the lift. Be sure to re-balance the arm for the additional mass.
["The ground lug on the pre amp is simply attached to the chassis with no intervening circuitry." >> Good -- saves me the trouble of removing the top. Thanks.]
A couple more questions and then I'll be out of your hair:
"It sounds as if the ground wire has broken inside the tonearm."
>> That sounds like it makes perfect sense, since my body is doing what the tonearm grounding wire is not.
What I don't understand is this whole unit (SP-15, base, d.c., EPA-250 t.a.) came from a radio studio to my house 15 years ago and it was completely sealed (not re-sealed). They had two extra (complete) units leftover (when they changed to digital) and I bought both (one for myself and one for a friend). He put mine together for me as I previously mentioned and I was right there and I didn't see him break or fumble with anything (but anything is possible of course).
Is there a way I could check to see if that ground wire (inside the t.a.) is broken, using the multimeter I have? (As I'm not an ET, please let me know which setting to use and then what readout to look for -- and of course, where to place the red and black leads).
If it is broken (depending on the above readout), is there anybody you (personally) would recommend to fix it?
Re: what you mentioned about insulating the armlift. (I know, I know -- I'm going to sound dumb here, but...), where exactly would I put that tape (i.e. Where is the armlift? On the outside, where I could get at it or would I have to uninstall the tonearm from the base?)
"Is there a way I could check to see if that ground wire (inside the t.a.) is broken, using the multimeter I have? (As I'm not an ET, please let me know which setting to use and then what readout to look for -- and of course, where to place the red and black leads)."
Well, I'm not exactly certain since I am not all that familiar with the specific table you own. I don't know where the tonearm ground is connected inside the arm. It is probably at the base of the tonearm and you could access this by removing the bottom cover of the table. (If the table has any automatic functions, the ground wire might run through a muting circuit which could also be causing the problem.) However, the ground connection could also be made at the headshell area. Look for a small screw around the front of the arm that doesn't appear to have any wire attached to it, the connection would be inside the arm and not easily visible. Ultimately, the tonearm ground wire "grounds" the tonearm. Sounds simple, huh? In theory you should be able to touch any part of the tonearm that causes the hum when you physically touch it and then make a continuity test between that point and the ground lug of the tonearm/table. The arm is probably just grounded to one location but I don't know which on this table. It is most likely the same ground lug that would appear to ground the cartridge and is unlikely to be the grounding point for the motor.
You will need a multimeter or a simple continuity tester. With a c.t. you merely touch the two probes to the opposite ends of the "circuit" you are checking. So, you place one probe on the tonearm where your finger causes a hum and the other probe on the ground lug. If you don't have an indication of continuity, you've found your problem - in all likelyhood.
If you have a multimeter, you place the switch on "continuity". The meter will tell you what selection this is, but most modern digital meters have a "beep" sound when you touch the probes together on this setting. Analog meters swing the stylus to one side to show continuity. Check that you have the meter set to the correct selection and then test between the two points on the tonearm and the ground lug. It doesn't matter which probe, red or black, goes where for a continuity check. Beep - continuity. No beep - no continuity.
"If it is broken (depending on the above readout), is there anybody you (personally) would recommend to fix it?"
Not in New York. But you should be able to find someone who could do the repair. Call a few shops and they can probably direct you to the appropriate person. Feel comfortable this person understands your table. Pro sound shops are probably going to be your best bet since Technics tables are still used by DJ's.
However, re-wiring a tonearm is labor intensive and the cost might not be worth the result.
It is possible the ground wire connection has merely oxidized at some point in the arm. This would only require a good cleaning. Oxidation is certainly possible after fifteen years time. Once again, the fix is probably labor intensive and not that dissimilar in cost to a complete re-wire. If there is a muting circuit involved, there could be a small capacitor that has dried out and needs to be replaced.
"what you mentioned about insulating the armlift. (I know, I know -- I'm going to sound dumb here, but...), where exactly would I put that tape (i.e. Where is the armlift?"
The armlift is the small metal piece that protrudes from the front/outboard side of the headshell that allows you to manually move the arm without touching the headshell itself. Almost every arm has a lift and you have probably been touching it whenever you move the arm to play a record. To test whether insulating this lift would take care of the problem, just wrap a piece of tape around the metal protrusion (or put on a latex glove and touch the arm) and listen for the hum while moving the arm by holding this device. If this solves the problem, I don't believe I would go any further since touching the arm is the only time the hum is apparent. (You should have the pre amplifier powered down when swapping cartridges.) My guess would be a cost of at least $100 to re-wire the arm and probably more if a cable harness needs to be replaced. More than one tonearm manufacturer made do with a small piece of shrink tubing on the arm lift to eliminate this very problem.
Yes I'm back. [Same (continuing) medical problem I mentioned in my 6/6 post. Nothing I can do about it except what I'm doing.] I also had the displeasure of finding my 45 year audio tape collection will not play on my Teac X-2000R Reel-to-Reel and I might have to 'bake' all of these tapes and at the same time, my ancient cassette deck went completely south, so I'm not a real happy camper overall. After all the work I did and money I spent to finally get the stuff I want, it appears I'm not finished yet. I'm having more fun than I legally have a right to have...
I know your social life has ground to a complete halt waiting for me and for that I apologize. (Yes, I'm kidding...)
I did some things in the last few days, which I won't mention to save some time, so I'll just get right to what you said in your last post...
"I don't know where the tonearm ground is connected inside the arm."
>> It's at the base of the tonearm, but I don't have to remove the bottom cover of the table (because there is none). There's a small 'box' protusion sticking out below the base where the Left/Right/Ground connector (all one cable harness, which splits off in three places at both ends -- gold tipped, as are the connections at the bottom of the base). I completely DeoxIt every connection I have (using their regular -and- Gold)
"If the table has any automatic functions..."
>> The table has no auto functions, so that eliminates the muting circuit you mentioned above.
"...the ground connection could also be made at the headshell area. Look for a small screw around the front of the arm..."
>> Unless I'm misunderstanding what you're saying, then it's grounded where I just mentioned in the previous pp. There are two tiny screws on the t.a., right by the knob which tightens the cart. to the t.a. (bayonet), but I don't think that's what you were referring to.
"It is most likely the same ground lug that would appear to ground the cartridge and is unlikely to be the grounding point for the motor."
>> Correct -- which I mentioned way above. There are two separate grounds. I grounded the motor ground wire to the center screw on my AC outlet after you suggested way above that I do that.
"If you have a multimeter, you place the switch on "continuity"."
>> I have a multimeter, but don't have a continuity tester. Here's where I need a little more 'guidance,' if you will.
There is no 'continuity' setting. However, reading the guide which came with the M.M., it says to put it on the appropriate Ohms setting (depending what you're checking). [Remember - I'm not an ET!] I have a digital M.M. and the Ohm settings are 200, 2000, 20k, 200k and 2000k.
"Check that you have the meter set to the correct selection"
>> For my M.M., which one would be the "correct selection?"
"Beep - continuity. No beep - no continuity."
>> Since mine doesn't 'beep,' what would the equivalent reading be for 'continuity.' "1" Ohm? "0" Ohms? Something else?
As I mentioned above I did make a few tests and got all kinds of (fluctuating) readings depending on where I placed the probes, but since I didn't know which setting was correct -and- which reading was correct (for any setting), I stopped and figured I'd ask you first or I'd just be wasting my time. (The M.M. guide doesn't have anything referencing what I'm trying to do.)
Re: "rewiring....oxidation....My guess would be a cost of at least $100 to re-wire the arm..."
>> I did find one place on the Net, which is pretty far from me (but closer than anywhere else). I don't have any problem spending the $100 if need be (and I don't mean to sound flip as if I'm Bill Gates or somebody, but after all the time, trouble, effort and money put into all this stuff, $100 is no big thing. It's just getting it there -- or more likely, having someone come out to where I am).
Re: "armlift"
>> I must have been really tired when I asked you that -- or had a severe case of 'brainlock'! I know what the armlift is, but I must have been thinking of something else when I was asking that -- sorry. And yes, that's how I move the arm to start the t.a. and return it to its rest position. The latex glove is the only thing I haven't tried yet, so I'll get a pair at the hardware store. Since rubber is not a conductor, I would think that would work.
One other thing (which I don't know if it's normal or not), but when I remove the cart., the tonearm has 4 pins (all cleaned with DeoxIt, as are all the cart. pins). When I touch one of the probes of the M.M. to either of the top two pins (Left Pos. - White or Right Pos. - Red), it produces a big hum. When I touch one of the probes to either of the bottom two pins (Left Gnd. - Blue or Right Gnd. - Green), I don't get any hum (or any sound, for that matter). Is that normal?
Anyway, if you could let me know about the correct setting(s) on my M.M. which is equivalent to the 'continuity' setting on a c.t. and what readings I'm looking for after I have it set to the correct setting(s), that would help a lot.
[Btw, I liked the way you got rid of that Eric guy, who completely killed my CD post and that other nitwit in the Speaker section. I talked to Art via e-mail and we were both going to leave scathing posts, but decided against it. Especially me, since I'm a newbie to this forum and I save my arguing for forums where I've been around forever, so I'm glad you did it ::thumbs up icon:: !]
Hi again, Mike. The ohms setting on your meter should be at 200. If your meter has a diode check(can't draw diode) that is the function with the beep, touch the leads together to check. When you touch the lead to the tonearm connector, with the power on the TT, you are introducing the voltage from the battery in the meter to the table. Checking for voltage is fine, but the ohm function uses battery power, it is assumed that ohms are checked on a dead, open circuit.
As Nuck suggests testing for continuity with the meter set to "Ohms" will not give the results you desire. The meter will fluctuate but you won't have any idea what to look for. Use the diode check function or buy a simple continutiy checker for a few dollars at a home improvement store. Touching the probes to the hot connections inside the tonearm will produce the results you've described.
I believe you've probably done all you can at this point to solve the problem other than insulating the armlift. The next step will have to be done by a technician willing to tear the table down.
I hope Eric sees the light, though I'm not placing any bets.
Sorry to hear aout your health and that of your tape equipment. Getting old only beats the alternative.
Thanks guys. At the risk of alienating you totally, I'm still a little confused (which seems to be a semi-permanent condition now). So, while I know you're going to roll your eyes, as I said a long time ago, I'd rather ask too many questions than not enough, because I'm trying to learn what you guys have probably known for decades and it comes as easily to you as breathing. {God, some days I wish I was a tech}.
Nuck,
I understood part of your post and part I didn't.
"If your meter has a diode check(can't draw diode) that is the function with the beep, touch the leads together to check."
>> I do have a diode check function on my M.M., but when I touch the probes together, I don't get a beep.
But, regardless of that, in the sentence before, you mentioned: "The ohms setting on your meter should be at 200." (seemingly implying, unless I misunderstood again, that it should be set to 200 Ohms). Which setting is correct and what numerical reading am I looking for (since I don't get a beep)?
The pp. starting, "When you touch the lead..." I read about 3-4x and while I understand the English words(!), I'm afraid I missed the point of what you were saying - sorry...
Jan,
You mentioned, "Use the diode check function..." (and not the Ohms setting). As I said to Nuck, since my diode check setting does not produce a beep when the probes are touched to each other, what numerical reading would I be looking for? (Or would it just be easier to buy a continuity tester?)
"Touching the probes to the hot connections inside the tonearm will produce the results you've described."
>> Ahh - so getting the hum I described by touching the probe to those two hot connections is normal? (i.e. I would get that regardless of whether or not I had that hum problem - correct?)
"Sorry to hear aout your health and that of your tape equipment." >> Thank you
Buying the cheapo ct will be best but try this; set the meter to diode check. Just touch and hold the red and black probe's tips together and observe the reading on the meter. That's what you want to see when you have continuity. Break the connection between the two probes. That's what you'll see when the circuit is open.
Well the results are in boys and girls and here's what I've got. I have my own 'suspicions,' but I thought I'd ask you for yours, since you've been helping me all along and I don't think it would be right to not let you know what happened after all this!
[Btw, in case I didn't mention it before, I have a Technics EPA-250 t.a., which was part of the 'package' that came with the SP-15 (along with the base and the dust cover).]
"Set the meter to diode check. Just touch and hold the red and black probe's tips together and observe the reading on the meter. That's what you want to see when you have continuity. Break the connection between the two probes. That's what you'll see when the circuit is open."
[and from above]: "If you don't have an indication of continuity, you've found your problem..."
1.) Set the M.M. to diode check.
Held the black and red probes together - reading was 000 (i.e. continuity)
Broke the connection between the two probes - reading was 1 (i.e. no continuity)
2.) Touched one probe to the tonearm and one to the ground lug on the back of the pre-amp where the t.a. ground wire is attached. Reading was 1 (i.e. no continuity)
3.) Remember I said above, "There's a small 'box' protusion sticking out below the base where the Left/Right/Ground connector (all one cable harness, which splits off in three places at both ends [gets inserted])"
a.) Touched one probe to the tonearm and one probe to the ground connector at that point (the 'box'). Reading was 1 (i.e. no continuity). b.) Touched one probe to the ground connector at that point (the 'box') and one probe to the ground lug on the back of the pre-amp. Reading was 000 (i.e. continuity)!
Which means tome that the tone arm ground wire is FINE (please correct me if I'm wrong).
4.) I did a few more tests. Remember I said above, "There are two tiny screws on the t.a., maybe a 1/2 inch to the rear of the knob ('locking sleeve') which tightens the cart. to the t.a. (They are on the bottom of the t.a., so you have to look from underneath to see them, preferably with a magnifying glass.)"
a.) I touched one probe to one of the screws and one probe to the ground lug on the back of the pre-amp. Reading was 000 (i.e. continuity). b.) I touched one probe to one of the screws and one probe to the ground connector going into that box at the bottom of the turntable. Reading was 000 (i.e. continuity). c.) I did the same two tests [a.) and b.)] with the other screw and the readings both times were 000 (i.e. continuity). d.) The last test I did was to touch one probe to one of those screws and one probe to the other screw and the reading was 000 (i.e. continuity).
All this tells me that the ground wire itself is fine and those two tiny screws play some role in grounding the tonearm. I don't know what's inside of the tonearm on the other side of the screws, but I'm guessing with my limited knowledge that since every other connection is o.k., that something(?) on the other side of those screws is not grounding the body of the t.a. correctly.
Does all that sound right (or am I way off base here)? If that does sound right, does that mean what you said above re: the t.a. might need an internal rewiring or possibly just a cleaning to get rid of the oxidation (if there is any)?
Hope all the above helped. If you want me to make another test that I may have left out, please let me know.
You are not there yet. If I follow the route laid out above correctly, you have not touched the probe to one of the screws and the other probe to the "tonearm". The screw is touching the bare metal of the tonearm at some point, internally at lest where there is no plating. However, the outside of the tonearm might be insulated by the plating that has been applied to its surface. Touching two points on the outside surface of the tonearm might not result in continuity. Unlikely, but you need to check this before you make a final decision. Just make contact with one of the screws and touch the tonearm in various locations with the other probe. If you have continuity there, you have a problem with the tonearm wire inside the arm. Whether the problem is a broken wire internal to the arm or mere oxidation of the connection, you will have to decide on a course of action from that point. The screw very likely holds a very small lug connection to which the grounding wire is crimped. If you wish to disassemble the arm's front end to do further inspection, remember, this is not really a job for half century old eyes.
Did what you said (and a couple of other tests)...
"However, the outside of the tonearm might be insulated by the plating that has been applied to its surface."
>> True - it is.
"Touching two points on the outside surface of the tonearm might not result in continuity."
>> True -- it doesn't (i.e. no continuity).
"Just make contact with one of the screws and touch the tonearm in various locations with the other probe."
>> I did (with each screw, one a time). Reading was (for each screw), 1 (i.e. no continuity).
You said, "If you have continuity there, you have a problem with the tonearm wire inside the arm." Since I didn't get continuity, I don't know what that's supposed to signify -- that I have no problem with the tonearm wire inside the arm?
However, you said something in your post from Thursday, June 07, 2007 - 06:28 pm: "You place one probe on the tonearm where your finger causes a hum and the other probe on the ground lug. If you don't have an indication of continuity, you've found your problem."
That seems contradictory to me (unless I'm misunderstanding something again).
In the first instance I mentioned in this post, you said havingcontinuity would be a problem: ("If you have continuity there, you have a problem with the tonearm wire inside the arm.")
In the second instance I mentioned in this post, you said nothavingcontinuity would be a problem: ("If you don't have an indication of continuity, you've found your problem.")
So I guess the two obvious questions stated above are:
1.) Which of the above two statements is right? 2.) And then, depending upon the answer to #1 -- Is continuity (or lack thereof) good or bad?
[Btw, before I forget, I removed the cart. from the t.a. and I touched one probe to one of the screws and the other probe to either of the bottom two pins (Left Gnd. - Blue or Right Gnd. - Green) in the t.a. head and the reading was 000 (i.e. continuity). Both screws - both ground pins - same result.]
"If you wish to disassemble the arm's front end to do further inspection, remember, this is not really a job for half century old eyes."
>> Only thing I could 'disassemble' would be unscrewing those two screws. Everything else, back to the base (except for the locking sleeve) is one piece. Hey - to paraphrase you -- better a half century (plus) than the 'alternative'!
"1.) Which of the above two statements is right? 2.) And then, depending upon the answer to #1 -- Is continuity (or lack thereof) good or bad?"
To be honest, I don't know any longer. Tracking this sort of problem is a matter of elimination by process. And I've become lost in a process I'm not conducting. I've tried to follow what you've told me, Mike, but it's very difficult to do this over a forum.
In the first case, you seem to be wanting to solve a problem the hard way. To my knowledge this is somewhat of a non-problem since it only occurs when you touch the tonearm. I've given you a route to resolve the issue by insulating the finger lift. Once again to be honest that is the route I would have taken quite a while ago.
(As a possible solution, there should be a small rubber washer that fits between the tonearm and the headhsell. It usually stays on the bayonet [male] portion of the headshell when it is removed. If this is missing, this could be the source of the problem.)
I really don't know your table and where the wires should have continuity and where they should not. I'm trying to follow what you've told me, but without being there to say, "if A then B", and doing this over days at a time I have become lost. Sorry. I seriously doubt rereading all the posts in this thread will help me find my way either. At this point I have to go with my last post as that is the logic I've followed and any other assumption I might have made would have been based upon something you told me that possibly wasn't actually true or has now changed with further testing.
If I have it straight, here's what I would do now. Connect a wire to your pre amp's ground lug. Then touch the other end of the wire to both of the small screws on the tonearm - one at a time - as this is very likely the spot where the ground wire is attached. With the wires touching the screws touch the finger lift. If the hum is removed, you have a clue as to where the problem can be fixed. If the hum stays, you will have to resort to other methods to repair the table.
This really is the best I can do at this point, Mike, short of coming over to your house to try to figure this out in person. Good luck.
"I've tried to follow what you've told me, Mike, but it's very difficult to do this over a forum."
>> I completely understand.
The only reason I answered you was because you said I needed to do one more step ("Just make contact with one of the screws and touch the tonearm in various locations with the other probe."), which I did -- and reported back to you with what I found.
"...you told me that possibly wasn't actually true..."
>> Trustme! Everything I told you was true! (Why would I lie?!) I have enough problems without misleading you. I tried to give as much (maybe too much) accurate info as possible, believe me.
"This really is the best I can do at this point, Mike, short of coming over to your house to try to figure this out in person."
>> Anytime! If I could afford your flight and hotel, I'd take you up on it!
Anyway, I'll do your last suggestion and take it from there. Don't worry about it any more. If someday, I find what/where it was, I'll post back and let you know, so, on the one in a million chance that someone else has the same problem in the future, you can refer back to this thread without having to go through the whole thing again.
In the meantime, I wanted to thank you for all your time and trouble, etc., etc. - I really appreciate(d) it.
I said I'd be back if I ever found the problem, so I could let you know what it was.
Well, I'm back -- and I finally found the problem (myself).
Remember I said in my first post that my friend set this up because he had done it many times before?
Then I said above, "I completely DeoxIt every connection I have (using their regular -and- Gold)."
And I also said above (in reference to your grounding location question), "There's a small 'box' protusion sticking out below the base where the Left/Right/Ground connector (all one cable harness, which splits off in three places at both ends -- gold tipped, as are the connections at the bottom of the base)."
First I did the remaining tests you mentioned and also double-checked to make sure there were the 'small rubber washers' on each cart (there were).
Everything was checking out and I was ready to give up and live with it and then I remembered... I have 11 components and I treated every single connector (whether the component was old or brand new with DeoxIT). I also treated every IC terminal with DeoxIT (whether it needed it or not).
BUT I didn't treat the SP-15's cable harness -or- the insertion points on the box below the t.t. because when my friend got to the house that day, we opened up all the sealed boxes and I was busy installing tubes in my pre-amp and p.a. while he was putting the t.t. and t.a. and carts, etc. together. I never cleaned those connections.
Just on a hunch (because there was nothing left to do), I lifted the t.t. and pulled out the harness connections (no easy task for one set of hands). Then I DeoxIT each connection (male and female) and inserted the harness back into the 'box' (and made an even tighter connection than my friend had done).
VOILA - no more hum -- ANYWHERE. Touched the t.a., the carts, the armlift, the screws, the grounding plug, the base, etc., etc., etc. -- NOTHING.
EITHER he hadn't installed the harness tightly enough -OR- one connector or another had gotten slightly oxidized (even though it didn't look like it was) after being sealed in the boxes for 15+ years --OR-- possibly both. One or the other or both -- I don't care -- I found it and fixed it.
So again, thanks for all your advice above (which I followed and helped narrow down everything). Like you said, it's really tough to do this when you're not there in person, but I did learn a heck of a lot, which I appreciate.
I felt I at least owed it to you to write back if I found the problem, so on the remote chance anybody ever asks you something similar again and you've gone through all the other steps, you can add this to your 'knowledge base' and maybe it'll help out the next guy...
Actually Jim, I much prefer jabbing #2 pencils into my eyes!
"Really, you will find another bugaboo to chase next."
>> Oh don't worry about that! I'm sure I will. I've taken care of most of them, but I still have two left. Hopefully one of them will disappear when that Nak. Dragon C.D. gets here today or tomorrow to replace the non-working, crappy, 35 y/o Akai I have now. I'm just hoping everything works alright (as ::cough:: advertised). So far, I've been lucky. If not, I'll have to find somebody who services Naks.
[Btw, I reread my prev. sarcastic post and I should have said, "God, I miss HAVING that hum."!]
"Any chance you are quietly spinning a mono recording, Mike?"
Nah Jim - that's too new-fangled for me. I was in the middle of playing my old cylinders and watching the player piano, when Al Bell and Tommy Edison called me. They wanted to come over and show me some cool new things like electricity, wireless and telephony. I told them they were both nuts and then we sat around drinking JWB and had a big laugh over it. Since we didn't finish the bottle, I figured J.V. might want some...
