Technics 1210 internal regulation mods

[Paul Hynes]

This has been a while coming but I wanted to be sure the instructions were clear and accurate before posting the upgrade information.

I have revised the upgrade application instructions after feedback from Martin T and Anthony TD who have both applied the upgrade to SL1210 decks. Thanks for the feedback and suggestions. I have upgraded another SL1210 this last week, using these instructions, to verify that they are correct. If you decide to apply this upgrade yourself it is your responsibility to follow the instructions carefully. If you have any questions that need clarification, ask for this on this forum thread, so the information may benefit others. If you doubt your ability to apply this upgrade correctly, and safely, find a technically capable person to do it for you. I am looking into the possibility of appointing technically competent agents in key areas of this country, and overseas to provide a fitting service for those who require it.

PHTAP3
Paul Hynes Technics SL1200/SL1210 Application Note 3 (PHTAP3).
Modification of internal power supply regulation.

Modification procedure.

TAP3.1 to TAP3.11 are photographs showing the modification procedure.

http://i700.photobucket.com/albums/w...ynes/TAP31.jpg
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Remove the Technics mains transformer and power supply board. (TAP3.1) These are now redundant.
Remove the Motor board. (TAP3.1)
Install TDR21 dual regulator board using the transformer mounting screws. (TAP3.2)

Remove the motor board
Remove the following components from the motor board :-

Resistors
R1 – 5K6
R2 – 6K8
R3 – 2K7
R4 – 470R
R5 – 470R
R304 – 560R

Transistors
Q1 – 2SD1265
Q2 – 2SD637
Q3 – 2SD637

Capacitors
C1 – 1,000uf 50V
C2 – 33uf 25V
C5 – 0.022uf
C6 – 0.022uf

Diodes
D1 – Bridge rectifier
D3 – 5v1 Zener diode
D301 – 5V1 Zener diode

Cut pcb track to separate the motor control electronics from the motor drive electronics. (TAP3.3)

Cut pcb track to pin 9 of IC301 (AN 6682). This disconnects IC301 from the 9v4 supply generated by IC201 (AN 6680). (TAP3.5)

Drill a 1mm hole in the now isolated pad next to pin 9 of IC301. (TAP3.5)

Drill a 1mm hole in the pad between IC301 pin 5 and test point G

Drill a 1mm hole in the pad between the junction of C108, C110 and R7. This pad is also connected to pins 19 and 20 of IC101 (AN6675) via a track on the PCB.

TDR21 terminals 1 to 6 are marked on the TDR21 PCB, Z1705, and S1709v4 pin outs are marked on the boards. TDR21 has two 21v regulators on board. The first 21v regulator nearest the 27v input side feeds the control circuitry 21v rail and the two regulators Z1705 and S1709v4. The second 21v regulator furthest away from the 27v input side feeds the motor drive circuitry.

If using Fine Silver wire or annealed copper wire with Teflon insulation it helps to cut and prepare the leads first. The modification requires 1.3 metres of wire if the external power supply lead is wired into the deck or 1.5 metres of wire if a DC inlet connector is fitted to the inlet flange. Fitting a coloured coded rubber sleeve over each end of the Teflon insulation will help with wire identification during assembly. Use red sleeves for positive and black sleeves for 0v wires.

Prepare 2 x 65mm wires for connecting the Z1705 regulator to the motor board in place of D301 zener diode as shown in (TAP3.10). Fit the wires to the motor board and solder.

Prepare 2 x 75mm wires for connecting the S1709v4 regulator to the motor board as shown in (TAP3.9). Fit the wires to the motor board and solder.

Prepare 1 x 240mm wire for 0v and 1 z 300mm wire for +21v to feed the motor drive circuitry as shown in (TAP3.7). Fit the wires to the motor board and solder.

The motor board can now be replaced in the Deck chassis and the various connectors can be refitted.

Fit 12mm stand-offs to Z1705 and S1709v4 and mount them as shown in (TAP3.10) Solder the wires from the motor board as shown in ((TAP3.10).

21v outputs from the first regulator from terminal 4 on TDR21 regulator module. Prepare 1 x 150mm wire for connection to the jumper wire (Marked J on the motor board next to C3), 1 x 140mm wire for connection to Z1705 and 1 x 190mm wire for connection to S1709v4. Solder these wires to the motor board jumper, Z1705 and S1709v4 as shown in ((TAP3.10). Twist the three wires and fit to terminal 4 on TDR21.

21v outputs from the second regulator from terminals 5 and 6 on TDR21 regulator module. The 240mm and 300mm wires that feed the motor drive section are connected to TDR21 with the 240mm 0v wire to terminal 5 and the 300mm 21v wire to terminal 6.

Connect the external 27v power supply to TDR21 input terminals either directly from the power supply DC lead or via an input connector as shown in ((TAP3.11). The DC input 0v wire should be fitted to terminal 2 and the +27v wire to terminal 1.

Thoroughly check all wiring before refitting the platter and applying power to the external power supply.