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SME 3012 series 1 ground problem

Discussion in 'classic' started by wieringen, Aug 27, 2017.

  1. wieringen

    wieringen New Member

    I found a SME 3012 series 1 tonearm in my dads attic which he forgot he had. Its was stored very well and besides not being used over 40 years it is in very good shape. However when I touch the arm I hear a humming noise in my speakers so it seems the parts after the knife bearing aren't probably grounded. Which my multimeter confirmed. The base and parts below the knife bearing are properly grounded as I measured this as well.

    I took the whole thing apart and I can't figure out for the life of me what is wrong. Can anybody give me some tips or pointers? :confused:
  2. Tony L

    Tony L Administrator

    The Series I is a very good, rare and valuable tonearm. I've never actually used one so I'm not sure how the earthing is implemented. Any chance of posting some pics of the arm-base and the arm-cable connection as I'm pretty sure it is not the same as a Series II (which I know well).

    PS Image posting assistance can be found in the FAQ beneath the site logo.
  3. wieringen

    wieringen New Member

    Sure I can do that! Click for high resolution.






  4. Tony L

    Tony L Administrator

    Ok, looks very like a Series II:


    But it looks like you are missing one wire, the black one. I've never fully taken a 3009 apart, but IIRC the black earth wire goes to a tag inside the arm tube that is attached to one of the two screws that holds the knife-edge bearing in place. This then connects to the armbase as pictured and finds its way to the arm cable via the connector around the bolt on the left of my pic.

    PS Here's a good Series II strip-down at TheAnalogueDept.
  5. wieringen

    wieringen New Member

    Ahh ok so if I understand you correctly I need to run a wire form the connector to the knife-edge bearing and connect to one of the 2 screws on top which are visible in the first picture. Do you know of some webshop that sells the official wire with tag?
  6. Tony L

    Tony L Administrator

    Yes, that is how I understand it. By the fact your arm still has part of the black wire connected to the armbase makes me think it was like the Series II originally. SME themselves are the obvious place for advice and parts if they have them, they are a great company and very helpful on the phone or via email IME.
  7. Take5

    Take5 pfm Member

  8. wieringen

    wieringen New Member

    I'm still trying to solve this puzzle... I emailed SME no response yet.
    However I do have a picture now of the part i'm missing. But I still am puzzled how this should be attached even after reading the resources you guys provided. There doesn't seem to be any room or space. Whats more the series 2 tag is totally different If somebody has a clear picture. I would really appreciate it!

  9. Tony L

    Tony L Administrator

    Have a good read of TheAnalogueDept link I posted upthread. Step 7 is the relevant one and has a picture (click on the thumbnail to get a proper look). My bet is your original tag is still flapping about in the armtube somewhere, and that the black wire has just broken off it. If, when you removed the knife-edge both screws were present and had something to bite on it pretty much had to be there assuming the S1 is constructed similarly to the other 30xx arms.

    PS Have you continuity-tested the leads that are present in your arm through to the headshell pins as colour-wise they do not correspond to normal wiring? It may be the case that the black wire that is present is the earth wire and one of the signal wires is missing! You will notice my 3009 is standard red, white, blue, green, and then black for the arm earth.
  10. 337alant

    337alant Negatively Biased

    I rewired my SME 3009 mk2 and getting that ground wire back in place is really fiddly
    The tag is just a thin slither of brass with a threaded hole in it and the ground wire soldered to it.
    The site that Tony linked to is what I used for reference as well

  11. ergman

    ergman New Member

    Hi wieringen,
    I would say that tony and 337alant are correct, but the original documentation does throw up some controversy as to where and how it was terminated.
    if you look at the image of the arm base from the original manual jpg you can definitely see from the picture that the arm had 5 wires. But two seem to terminate at pin 3 on the connector.

    http://i335.photobucket.com/albums/... 1 info/SME 3012 Series 1 original manual.jpg

    Unfortunately the original manual wiring diagram does not show the earth, but does show that your earth tag is to be connected to your motor (turntable) see jpg.

    http://i335.photobucket.com/albums/... info/SME 3012 series 1 original manual 1.jpg

    But the original dealers flyer from back in the day (see jpg) does show the arm wires terminated differently with 5 wires (non terminated together), no color given for the earth wire in this flyer. But in the second flyer (see jpg) it clearly states two black wires but one having a yellow spot.

    http://i335.photobucket.com/albums/...3009-3012 Series 1 original dealers flyer.jpg

    http://i335.photobucket.com/albums/...riginal dealers flyer two black arm wires.jpg

    I also have a SME 3012 Series 1 that i am currently working on, mine has been incorrectly re terminated with rca's (with the original wiring) it has had the armbase earthed across to one of the signal negatives.

    Luckily inside the box it came in there is still the original screening can / terminals / arm lead and what looks like the same earth ring that you have shown a picture off (see my jpg). I did call SME today and spoke with Mr Laker, he is reasonably sure that the earth tag does fasten within the tube underneath the knife edge bearing. (as has already been stated).

    http://i335.photobucket.com/albums/m448/jubal100/SME 3012 series 1 info/SME earth tag.jpg

    If you decide to do a complete re wire i would be very interested to speak to you regarding some question i have about the arm tube and how the headshell socket fixes to the arm tube.

    Also i would be very interested to know if the fibre wood damping is still present inside the arm tube.

    I would also say looking at your pictures, your base collar is from a MK2

    Not sure if my jpg url's will work i'm not very good at this sort of stuff

  12. audio grail

    audio grail pfm Member

    Speak to J7 at Audio Origami, he has rewired 6 our our series 1s and a heap of other peoples

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