DUAL CS-450 DC motor, Power supply, Speed too fast

[jimclark007]

Hi,
I just got a Dual CS450. I collect Duals. Anyway the guy said it didn't come with a power supply. So, I figured, I got enough of those hanging around.
But the speed is wide open, no matter what power supply I try. But, I've read somewhere that this motor requires a 12V/ 20mv??
I tried adjusting the pots on the motor. They are marked L and H. And they go round and round., with no change in speed.
Is it possible to turn those too much and ruin the motor? It looks like someone before me has fooled with this motor.
Are replacement motors available(DC 205-8812 A)?
Jim

 

[Rickster71]

That TT comes in 230V or 120V. Since the power supply is missing, that means someone had it before you, and thought they could change the PS to one that had the voltage they needed. They screwed something up.

Do you have a multi-meter? If so check the pots

 

[TLS Guy]

Hi,
I just got a Dual CS450. I collect Duals. Anyway the guy said it didn't come with a power supply. So, I figured, I got enough of those hanging around.
But the speed is wide open, no matter what power supply I try. But, I've read somewhere that this motor requires a 12V/ 20mv??
I tried adjusting the pots on the motor. They are marked L and H. And they go round and round., with no change in speed.
Is it possible to turn those too much and ruin the motor? It looks like someone before me has fooled with this motor.
Are replacement motors available(DC 205-8812 A)?
Jim

I have been trying without success to find you a service manual. The motor on your turntable is a DC servo motor.

Basically the motor is under PCM control. The shaft angle sensor sends PCM pulses to the controller to tell it the shaft angle. The controller then sends square waves of appropriate duration to move the shaft the appropriate rotation. The pots fine tune the two speeds of the turntable. They will be fine adjustment. If the PCM servo feedback is not working, DC servo motors run wide open.

So your motor is wide open, because you have a power supply that has the wrong PCM unit to detect and or send pulses back to your motor.

If it is the right power supply, then either the motor can not send PCM, or the power supply can not send it, or the square wave generator is broken.

All DC motors for turntable use have to be of this type, as otherwise speed could not be tightly controlled. Older AC motors could be locked to the AC mains frequency.

 

[audiofox]

I have been trying without success to find you a service manual. The motor on your turntable is a DC servo motor.

Basically the motor is under PCM control. The shaft angle sensor sends PCM pulses to the controller to tell it the shaft angle. The controller then sends square waves of appropriate duration to move the shaft the appropriate rotation. The pots fine tune the two speeds of the turntable. They will be fine adjustment. If the PCM servo feedback is not working, DC servo motors run wide open.

So your motor is wide open, because you have a power supply that has the wrong PCM unit to detect and or send pulses back to your motor.

If it is the right power supply, then either the motor can not send PCM, or the power supply can not send it, or the square wave generator is broken.

All DC motors for turntable use have to be of this type, as otherwise speed could not be tightly controlled. Older AC motors could be locked to the AC mains frequency.

Ah, stepper motors-isn't that one of the potential noise sources for direct drive turntables?

 

[TLS Guy]

Ah, stepper motors-isn't that one of the potential noise sources for direct drive turntables?

A stepper motor is a different animal, and would be useless for a turntable. They are used in precision controls. They do have a sevo feedback system to them though. A stepper motor is very "goggy'.