Garrard Motor Speed

[majex45]

Does anyone know the speed (in RPM) of a Garrard Synchro-Lab motor?
This is all the information on it:
On the motor laminations - 234
On the cover plate: GARRARD Series II Synchro-Lab Synchronous Speed Patents Pending
On the centre bearing cover: 220-240/110-120V 50/60 Hz .065/.12A
95 over 02
I want to run it on 50Hz.
I believe it is and idler drive motor as it turned counter-clockwise when I bought it but if you turn the inner parts upside down it runs clockwise.

[WullieD20]

Garrard motors run at the a predetermined speed and the 50/60Hz aspect is determined by changing the capstan pulley that fits on to the motor spindle. (held by a small grub screw).

Search Vinyl Engine for details of Garrard 301 / 401 (or others) user manual. (https://www.vinylengine.com/library.shtml).

[majex45]

Thanks for the reply. This is a synchronous motor where speed depends on the mains frequency.
It is not the motor for hte 401 which is cast iron. Mine is all pressed steel and has 3 suspension spigots.

P1010075.jpgP1010074.jpg

[WullieD20]

Thanks for the reply. This is a synchronous motor where speed depends on the mains frequency.
It is not the motor for the 401 which is cast iron. Mine is all pressed steel and has 3 suspension spigots.

Appreciated, but the same applies to other Garrard motors in different models of turntables. What TT do you have?

As you say, the motor speed is dependent on mains frequency so will rotate at two different speeds - @50Hz or @60Hz. However, the transfer of that speed from the motor, through the idler and on to the platter is determined by the diameters of the 'transfer' diameter of the pulley that is in contact with the idler. ie: a different diameter will determine a different speed. Subsequently, if you research the user manuals for whatever turntable (motor) you have, you will see that there was (is) two different pulleys that may be fitted, depending in which frequency you apply.

UK mains runs at 50Hz, but other countries that run on 110V will run at 60Hz, so Garrard supplied different pulleys to operate the same turntable by a simple change of the pulley, which has three stepped diameters to run 33/45/78.

I hope that clarifies things.

[majex45]

Hi and thanks for the help. I have obviously not made myself clear, my faut entirely.
I don't have a turntable at present I am hoping to use this motor to make my own turntable which I intend to be belt drive as this seems easier to implement than idler drive.
The existing pulley is: 0.232, 0.313, 0.538 inches in diameter.
I believe that for a 12 inch platter driving on the periphery the diamter of the pulley is given by:
circumference of pulley x motor speed = circumference of platter x platter speed. The circumference is Pi x D and the Pi s cancel out.
Therefore: Diameter = 12 x 33.33333/1500
Which is 0.2666666
Is this correct of have I gone wildly wrong?

[WullieD20]

Peter, I've PM'd you.

[Barry]

Hi and thanks for the help. I have obviously not made myself clear, my faut entirely.
I don't have a turntable at present I am hoping to use this motor to make my own turntable which I intend to be belt drive as this seems easier to implement than idler drive.
The existing pulley is: 0.232, 0.313, 0.538 inches in diameter.
I believe that for a 12 inch platter driving on the periphery the diamter of the pulley is given by:
circumference of pulley x motor speed = circumference of platter x platter speed. The circumference is Pi x D and the Pi s cancel out.
Therefore: Diameter = 12 x 33.33333/1500
Which is 0.2666666
Is this correct of have I gone wildly wrong?

The idler wheel drives the inside rim of the platter. This will be less than 12" in diameter. Thus the diameter of the idler wheel will be less than the 0.267" you calculate, and most likely to be the 0.232" you quote.

[majex45]

The idler wheel drives the inside rim of the platter. This will be less than 12" in diameter. Thus the diameter of the idler wheel will be less than the 0.267" you calculate, and most likely to be the 0.232" you quote.

Hi Barry,
That makes perfect sense. I'll think about this some more.
Unfortunately other things are taking precedence for a few days, but I will come back to this.