Technics SL-1200 DC Power Supply

[niekos]

I have a 1210 from August 1999, are there any differences between 1200/1210 except for the color?

 

[peppennino]

Yes, 1210 has a voltage selector (110/230V) under the platter, so it has a different transformer (two primaires in series for 230V). Yoi can use the same values as mine, posted in this thread some pages ago.

 

[peppennino]

For 230V use blue and brown as primaries and tie black and white together.

 

[peppennino]

I just measured the stock transformer with the Quasimodo jig to get a proper snubbing network to replace that 220nF cap.



The values are

Cx: 10nF
Cs: 150nF
Rs: 270R

This is for a primary wired for 230V.
Sorry no measurements yet for 110V, but with something like 250R you should be close enough for a first evaluation.

And here are some scope captures

With just the 10nF cap attached. Quasimodo ringing the bell full strength.



And here is what's left of the ringing with the values above.

Here for Quasimodo results

Thanks Dimkasta

 

[niekos]

Thanks Dimkasta and peppennino! And for the bleeder resistor: what did you use? Value between 1-5k? How many watts?

 

[peppennino]

I used 2k2 2W

 

[peppennino]

 

[niekos]

Here for Quasimodo results

Thanks Dimkasta

Do I understand it correctly if this means that the values will be like this as in the attachment? I just want to make sure I do not mess up

 

[niekos]

Nice X-mas music 🙂 Are your feet also DIY?

 

[peppennino]

Do I understand it correctly if this means that the values will be like this as in the attachment? I just want to make sure I do not mess up

Nope. Simply substitute the 0,22uF snubbed cap with this circuit:

And let all the rest exactly as it is.
Feet are Isonoe M6 dampers.

 

[peppennino]

This way

 

[niekos]

wow, thanks! Was just doing the same in powerpoint 🙂

 

[peppennino]

Nice X-mas music 🙂 Are your feet also DIY?

Isonoe feet

 

[niekos]

I received all the parts I need, including some of the voltage regulators. These can be adjusted to the voltage desired. Since I do not want to damage the the mainboard of course I want to adjust these before installing them. Can this be done withut any load connected? The output should be 21V, is that correct?
Also, can you safely turn on the turntable without the platter installed? And also, is it safe to press start/stop without the platter?

 

[6L6]

Do not run table with platter removed.

...I don't even plug it into the mains when platter is removed.


As for voltage, where are you connecting the PSU to the SL-1200 PCB?

 

[niekos]

thanks, that is clear advice 🙂

 

[niekos]

This way

Question about the 270 Ω resistor in the snubber circuit: does it matter what wattage this resistor is?

 

[peppennino]

I used 0,25W

 

[niekos]

Finally found some time to spend some time to work on the external power supply (after recapping the mainboard), and decided to test the voltage regulator first. Very easy upgrade using one of the boards I ordered, see pictures.
All that is needed is to add a ground wire to the board and connect J1 (in) and J3 (out) and adjust to 21V (display shows 20.9 since it was 20.98 measured).
Maybe useful for someone else as well? See pictures, I think it is self explanatory?

 

[peppennino]

Any improvement over stock stabilizer? Why you didn't remove the transistor and disconnect J2?