New Technics SP10 motor controller specification

[Shaun]

I'm jumping in the deep end tackling a BLDC controller circuit to replace the original analogue controller of a Technics SP10 MkII turntable. If it is assumed that I can successfully emulate or even improve (!) upon the stock circuit's performance, what additional features would you deem desirable in such a controller?

It is likely to be (but needs not be) a stand-alone controller that bypasses the on-board switches and replaces the existing power supply.

Your ideas, please...

[Shaun]

Yikes!! No takers?

OK, let's start:

1. Start/stop button (single or separate?)
2. Variable speed dial/slider (variable by what %age?)
3. Four user-presetable speed buttons
4. Reverse function (could be dangerous!)
5. Electronic Brake for stop function
6. Hold/ free platter when stopped.

Questions:

Should the controller (or a version of the controller) use the existing on-board controls or be self-contained?
Should it use own power supply or the existing unit?

[rich121]

Hello Shaun,

Have you started on this project? I know that if you take this to other forums (vinyl asylum for example) you would get much more attention.
I for one would love to be able to have "

1.) a modern power supply

2.) speed control (at least within 0.1% increments, and with knob not slider)

3.) Remote control

4.) Would also like some sort of "umbelical cord" made so that the tables' electronics can be isolated from the plinth, giving it even better performace.

I have 2 SP-10 MKII's both mounted on the factory Obsidian plinths...

Keep in touch!

Rick

[Shaun]

Hi Rick

Finally(!) some interest! I have not really progressed beyond looking at what the options are among the various controller chips. The project is still on, though it is competing with others for available time. Over at VinylEngine there is a(nother) member developing a controller, though I suspect that it will be a commercial product.

Thanks for the encouragement. I'll post some info as soon as there is more movement on this project.

[Steerpike]

Ahh.. interesting.. I was about to do the same thing, since I acquired a NOS SP10 motor for R20.
I figured a pic was the easiest way to do it.

[Shaun]

Hi Steerpike

1. Do you have any ideas to share?

2. What is "a NOS SP10 motor"? Is that the whole motor unit?


Edit: Duh. I'm slow. You meant "PIC", as in microcontroller. Yes, I agree. There are (should be) some code already available.

[Steerpike]

Hey Shaun

The motor I got at a spares shop close down sale - its an unused replacement for the SP10ii - the motor only, no plinth or platter.
One problem is that I dont have an original platter, so the mechanical characteristics of the motor/platter will be different from Technics' intended - hence a 'real' controller wouldn't work optimally anyway.
At some point I need to measure the behaviour of the motor to get all of its parameters!

I wanted to use a PIC (Microchip's all-in-one chip) so I can dial in the platter mass, and then use it with a variety of different ones.

The basic idea is a software PLL, with a software PID contoller - minimal analogue processing because I'm too lazy to do harware replacement of components if I need to adjust controller parameters!

First issue though is to build the three phase drive amplifier. Electrically thats not difficult, but I'd use a few op-amps rather tham all-transistor like the original. Only once I have that can I measure the motor behaviour.

[Shaun]

My eventual goal is to make an acrylic platter and plinth. To retain the quick start/stop characteristics I intend keeping the platter mass as close as possible to the original platter. If you're interested, I'd be willing to let go of my other SP10Mkii enclosure (I have two SP10's). PM me if you're interested.

[Nanook]

if the SP10s were in good operating condition----else go for it....

(oops just read you'r making up via NOS parts....)

stew

[Shaun]

The problem with many SP10's is that their electronics start to misbehave, and can be quite difficult to fault-find. A micro-based controller will be much simpler to troubleshoot, and modern parts should be more readily available.