Dual CS505-1

On Tue, 29 Aug 2006 21:14:32 +0100, "Nick" put finger to keyboard and composed:

How does the pitch control work? Just curious.

- Franc Zabkar

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Please remove one 'i' from my address when replying by email.

**The pitch control for the 505 is an expanding pulley. Quite nifty. The pulley comprises of a bunch of 'fingers' with a dome, which is pushed up through the centre, thus expanding or contracting the diameter of the pulley. It is barely possible that there is enough range in the adjustment to cope with 50Hz, but I doubt it. It is possible that 50Hz pulleys may still be available. The 505 is worth fixing, unless it has massive problems, since it is an excellent turntable.

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Trevor Wilson
www.rageaudio.com.au

**Probably by connecting the windings in series, but I am not certain about that. **Very likely, yes.

I suspect the answer to

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Trevor Wilson
www.rageaudio.com.au

On Wed, 30 Aug 2006 12:18:21 +1000, "Trevor Wilson" put finger to keyboard and composed:

The specs allow only +/- 6%.

Would it make sense to machine your own fixed pulley and dispense with the pitch control?

- Franc Zabkar

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Please remove one 'i' from my address when replying by email.

**Possible, but difficult. It would make more sense to do one of the following, IMO:

• Locate an original 50Hz pulley.

• Find cheap, small power amp, feed it with a stable 60Hz sine wave into a reverse connected power transformer. No need to adjust for 240 VAC and no need to adjust for 50Hz. Power requirements for the 505 is probably less than 10VA.

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Trevor Wilson
www.rageaudio.com.au

If the windinga are parallel connected now, you'll be be able to connect them in series.

yeah, the "pulley bit" on the end of the shaft will have to be replaced with one that's 20% larger, these may ba available as a spare part or you may have to get one made (someone with a lathe, maybe a mechanical engineer)

otoh maybe you could just hook both motors up in series :)

Bye. Jasen

Can't source this so far. Found scrap TTs on eBay, but that rather defeats the object, since this is already a "scrap" TT!

Trevor, spookily I thought about that yesterday. I understand that sync motors don't like anything other than a nice sinusoidal input, so a conventional inverter is out.

The label on the back of the TT says 110v at 50mA so only 5.5VA required. With a linear amp a 10W design might just do it. I have an old Mullard one with Germanium transistors that is rated at 10W so will try that first.

Thought about 3 types of 60Hz sources;

- xtal controlled with divider then low pass filter;

- xtal controlled with divider then counter and simple DAC to generate stepped sine wave;

- free running analogue oscillator using and op amp.

I am inclined towards the last option. It's simple and there's no nasty edges to get rid of.

Nick

**At least it would be a cheap and easy experiment. Personally, I would look for something a little more (ahem) robust than an old Germanium amp, though. Still, if you don't mind sacrificing it......

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Trevor Wilson
www.rageaudio.com.au

Hi Trevor, would it be feasible to place a resistance in series with the motor to achieve the design current flow through the motor? Is there any nasties to be aware of with respect to doing this that would make it a no-no? I ask because I also have a 110-120v turntable motor (Fujiya Audio IM-275-12B,

50Hz 110v 1500rpm 7.5w) that I purchased with the view to using off 240v 50Hz. Best Regards.

"APR" >> defeats the object, since this is already a "scrap" TT!

**That should work. I've done it a few times, quite successfully. Measure the resistance of the motor and choose a resistor of the same value or slightly larger (TT motors should work fine with reduced Voltage, down to as little as 50% supply). Be careful with resistor choice and location, since it will have mains Voltage on it. If you want to get really tricky, you can use a capacitor. Make sure the cap is a mains rated type!

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Trevor Wilson
www.rageaudio.com.au

Thanks Trevor, I shall experiment one day and see what I can come up with.

Thanks to all who posted to this thread.

I now have the wiring details for 230v but am unable to source a 50Hz pulley.

Building a 60Hz synchronous PSU for it.

Nick