New Technics SP10 motor controller specification

[Nanook]

thanks for the information. I was commenting that if you were starting to dismantle a good working PS, and SP10, then it could be construed as sacrilege.

Good luck with your project. Pictures when you can (please).

stew

[Shaun]

Nanook

I understood what you meant. My two SP10's are troublesome and they're not mint, being ex-ex-SABC. They also do not have original power supplies. My main gripe with the SP10's is that they are not 9- or 10-inch arm-friendly, forcing one to mount these arms at odd positions. Considering all of the above, I think I'll be forgiven for my intentions.

[rich121]

Originally posted by 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.

Would this be something you would sell to others that are intersted, that is, when you have finalised the prototype?

If so, would you also be able to adjust performance for different platter weights? I am planning on having a brass/aluminium platter built for one of my SP-10's, it will weigh around 28 lbs.

I would also like to seperate the electronics modules that are currentlly below the platter to a seperate box via some sort of "umbilical cable"... anyone thought about this?

On more thing, I have the "HI-FI World Supplement, Novemeber 1997, D.I.Y. Letters" printed off the net from a couple years ago. I have tried to find the site again, but no longer have the Web address, and "searchs" have turned up nothing.
Does anyone have the web address to this?

Thanks...

Rick

[Shaun]

The project will be published for all to build. I'm not too sure how one would go about accommodating platters of differing mass. Perhaps it will turn out to be a simple setting. It seems the umbilical connection is a given.

I did stumble upon some articles once. IIRC, one suggested upgrading the regulators, and the other one recommended removing the rubber damping piece in the motor assembly. To be honest, I did not think much of those suggestions... but, as always, I could be wrong.

[Steerpike]

The project will be published for all to build. I'm not too sure how one would go about accommodating platters of differing mass. Perhaps it will turn out to be a simple setting.

I'm happy to give away freely anything information-wise I discover; but I wouldn't sell ready-made PC boards etc.

With a microprocessor driving it, adjusting the servo parameters for different masses would be a simple matter of pressing a few buttons and dialing in the number, shown on an LCD display. A display is a nice thing to have - can show the speed error, controller parameter setting etc.

I have one of the SABC "Mark3" turntables - without its motor;

my real fantasy was to get the SP10 motor into that, but at the same time not harming the Mark3 in any way - i.e., maybe a few under-platter holes drilled, but NO serious cutting of any metalwork.
The platter bearing puts the SP10 to shame!

[Nanook]

went to hit the link...dead ended at vinyl engine...

but did a little searching for steerpike and found them.... why not drive the SABC with an idler being driven by an SP10 motor if possible?

[Steerpike]

went to hit the link...dead ended at vinyl engine...

Is it? Works for me every time even if I'm not logged into the VE - maybe VE's finding a cookie.

but did a little searching for steerpike and found them.... why not drive the SABC with an idler being driven by an SP10 motor if possible?

I doubt it would work - the Mark3 needs a FAST motor. Maybe I should keep the SP10 motor for a project on its own; the other plan was to put a PLL-controlled ReVox reel motor into the Mark3. The Mark3 has 3 idlers, one for each speed. It's quite severe on the motor bearings - there are no springs for the idlers, and no 'give' in the linkages, each selected idler is pulled hard against the motor pulley with a solenoid.

[rich121]

I am very intersted in this, and hope that you guys are serious, as I would love to build 2 of these.. only problem, I can solder, but I can't design

Have a great day!


Rick

[Steerpike]

I can solder, but I can't design

That should make you perfectly qualified for a senior position in the design department of some of the 'hi-fi' manufactureres whose products now adorn our retailers shelves.
I will excercise much control and not mention any brand names!

[Steerpike]

I'm in two minds about using a microprocessor in this project. The uP makes hardware things easier & simpler, but it does make it more of a niche project, since maybe not everyone has the tools and hardware to get the software into the chip.

If the software (HEX dump) is free on the WWW, would most (all?) readers have some access to a PIC or EEPROM programmer?

THEN what happens in 10 years when the particular microconroller chosen is obsolete?