Sunday, 14 April 2013

SME Conversion shown on a rare 3009 MK1 tonearm

This assembly guideline is written by SKFong on his experience using the kit. The basic kit set comprises: 

1. Tone arm wand and extension for counterweights. 
2. Balsa wood for damping the arm wand 
3. Two M2 screws and one nut (earth wire) for fixing the saddle
4. a steel saddle 
5. One 60mm long M3 screw and silicon damped extension tube
6. Extension cap 

The basic kit might have been customized with:
7. Main counterweights either 220g or 160g and a end cap to fix the wayrod and to position the
8. Rider weight
9. You will need tone arm wires with the correct length for a 12 inch tone arm (42 cm). You will also need a ground wire of the same length if you do not use the ground connector from the 3009. You will need to colour code the wires with different coloured markers or heat shrink sleeves.

The kit upgrades the SME 3009 models up to the 3009 Improved to function as SME 3012 with the heavy arm wand and counterweight system of SME 3012 Mk1.

Shown is a conversion with a rare 3009 MK1 to a 3012 MK1

Dis-assembling the 3009 tone arm

You will need all the components from the 3009 tone arm, except for the arm wand, the extension, and the counterweights. Unsolder the internal tone arm wires and ground wire from the tone arm out put. Remove the 2 screws securing the yoke head and remove the yoke head. The 3009 arm wand may now be removed. Pull the 5 wires out through the pillar carefully if you intend to keep the tone arm wires. Now remove the cartridge socket, saddle and the ground wire connector from the arm wand. You may now want to clean all the parts from the 3009 tone arm. 

Assembling the 3012 tone arm

Step 1: Internal tone arm wires  
This part is written assuming that you will not want to use the ground wire connector. If your new tone arm wires are not colour coded you may want to attach suitable coloured  fine heat shrink sleeves at both ends of the 4 wires, or in the case of silk insulated wires, use coloured markers. However this is not mandatory as you can identify the correct wires using a meter and head shell with SME convention cartridge leads during final assembly. Lay the 4 tone arm and ground wires in the channel cut in the balsa wood and press in the two small pieces of wood to hold the wires in the channel. Estimate the length of the wires that need to protrude from the balsa wood to reach the cartridge socket. You can tie the 5 wires in a knot approximately 50 mm from the cartridge socket. Tie the wires at both ends with thread.

Push the balsa wood damping with axial turns into the straight end of the tonearm wand. When it is completely pushed in, use a pencil of small diameter with its blunt end to push the wood till the first whole for the bridge (image). Make sure that all wires will not get damaged and when finished try if they can be moved forward and backward.

If you use colour coded wires make sure you identify the coloured wire to the correct pin. (lower drawing)

Caution: Mount a fully cabled head shell to act as a heat sink during soldering. Use a soldering iron of low wattage (7 watts recommended) and do not solder for longer than 3 seconds for each pin.

After soldering, slide the plastic sleeves over each pin. Now strip off about 10 mm of insulation of the ground wire. Align the screw holes of the cartridge socket and the arm wand. Hold the exposed end of the ground wire on the body of the cartridge socket as you push it into the arm wand so that the wire is press fitted between the cartridge socket and arm tube. Secure the cartridge socket with the screw.  At the other end of the arm wand, thread the 5 wires through the large hole beneath where the saddle will be mounted. Take the rubber grommet from the 3009, thread the 5 wires through it and insert the grommet onto the hole. You may want to tape the 5 wires onto the arm tube body as you carry on the assembly.

Check the bearing and polish the marks if neccessary

Step 2: Mounting the saddle  
It is assumed that you are not using the ground wire connector. It might be helpful at this stage to tape or bind the arm wand on to a piece of wood, and clamp the wood on a table so that the arm wand is not easily moved. The holes to insert the saddle screws should face up. Take the saddle from the 3009 and place it on the arm wand. Align the 2 holes on the saddle with the corresponding 2 holes on the arm wand. Grip the M2 nut with a pair of tweezers through open end of the arm wand and hold it beneath the hole nearer the cartridge end. Turn the M2 screw into the nut. A few attempts may be needed before you succeed to secure the screw. Useful tip: Tie the saddle in position with a rubber band or adhesive tape, and to hold the tweezers closed with rubber band/tape. You can then concentrate on holding the nut in position. The step is similar if you are using the ground connector from the 3009. Grip it with tweezers and hold it beneath the hole nearer the cartridge end. Insert the original SME saddle screw (thread size is not M2 metrical) and secure it. Thread the ground wire through the grommet and set the rubber grommet into the hole. (In this case of course you need not have a ground wire press fitted with the cartridge socket.)  

Step 3: Fitting the arm wand extension   
Turn the M3 X 60 screw until its end is roughly in line with the end of the extension tube. Further insertion of the screw too far beyond this point makes it difficult to insert the silicon rubber into the arm wand as the silicon core becomes harder to compress.  The extension is attached to the arm wand with a disc. The disc has an M3 screw hole in the centre and an M2 screw hole on its circumference. Take a long M3 screw (30 mm or so) and turn it into the M3 hole on the disc. Insert the disc into he arm wand and align the M2 screw hole with the second hole of the saddle. Secure the saddle and disc with the M2 screw. Turn the M2 screw till it contacts the M3, then loosen the M2 screw a little. 
It might be helpfull to use a lttle bit of highly concentrated liquid soap to to push the silicon rubber damping sandwich into the extension tube. Stop when the rubber will end out of the extension tube at a lenght of 12mm. Take the long M3 screw and turn it from thr open end side into the rubber. Stop at 75% of its lenght. Hold the extension tube, use again a bit of soap and push the silicon rubber into the arm wand. Stop when a ring of silicon rubber between 0.5 and 1 mm wide separates the arm wand from the extension. Now turn the M3 screw until it engages the thread in the ring. You might wait till the liquid soap has dried out and you might use a drop of cyclanat glue to fix the silicon rubber to the extension tube. Cap the open end of the extension. Make sure you press the cap in fully.

Step 5: Fitting the tone arm  
Re-assemble the pillar, control bracket, base and base assembly of the tone arm. Also fit the cueing bridge below the saddle. Push the 4 tone arm and ground wires into the hole at the centre of the pillar. When the wires emerge from the bottom, gently pull the wires as you seat the saddle knife edge on the yoke. Place the yoke head over the knife edge and yoke, and secure it with the two screws. Identify the correct tone arm wires for Left, Left earth, Right and Right earth and solder them to the respective output (upper drawing). Finally solder the ground wire to the ground lug. Slide on the screen can. You may now install the tone arm onto your turntable. After mounting the tone arm, fit the counterweights. You need to use the wayrod from the 3009.

SME 3009 MK1 has been succesfully converted into 12'' version

I have to mention that a conversion from 3009 MK1 might have a problem, the original headshell socket of the earliest type does not fit the new tonearm wand without modification. If you want to do such a conversion, be prepared to adapt a difference of 0.5mm in diameter to clamp the too small socket

No comments:

Post a Comment