Converting AC power for my TT

[Malcolm]

Wow! Over a month and still no solution?

FWIW the motor is
what the manufacturer calls a "double synchronous" motor. Synchronous
motors are AC and their speed is a function of line frequency. Power line frequency in any country with a power grid that connects generating plants is extremely stable because the plants have to stay in sync. In the USA, it is rock solid, so it is an excellent reference for a turntable, clock, etc.. I
haven't heard the term "double synchronous" before this. But I have
heard of doubly-fed induction motors. The key feature of such devices
is that they can be sped up above the normal synchronous speed, or
slowed down below it. If they are fed in
phase, the motor runs at normal synchronous speed. If you simply replace the power supply with one that will work
on 120V 60Hz, the motor will run exactly 20% faster than on 50Hz. That $1000 box the
manufacturer wants to sell you is likely a slightly modified version of one of the speed controls listed on
their site. The ones on the site are listed as being able to change the speed up to 5% or 10%. You need more, but it wouldn't be difficult to modify one of the existing models to do that and run on 120V. It works by changing the frequency of one of the
feeds. I
don't know if running on 60Hz will damage the motor. I suspect it will not if
the fix that the manufacturer is suggesting is a speed control. As long as you don't burn the insulation with the additional heat, you will be fine, just running 20% fast. If the motor is happy with 18V 60Hz, I would just have a new pully machined and installed, and of course, get a new wall wart that will give me 18V out with 120V in.

[greg928gts]

Wow! Over a month and still no solution?

FWIW the motor is what the manufacturer calls a "double synchronous" motor. Synchronous motors are AC and their speed is a function of line frequency. Power line frequency in any country with a power grid that connects generating plants is extremely stable because the plants have to stay in sync. In the USA, it is rock solid, so it is an excellent reference for a turntable, clock, etc.. I haven't heard the term "double synchronous" before this. But I have heard of doubly-fed induction motors. The key feature of such devices is that they can be sped up above the normal synchronous speed, or slowed down below it. If they are fed in phase, the motor runs at normal synchronous speed. If you simply replace the power supply with one that will work on 120V 60Hz, the motor will run exactly 20% faster than on 50Hz. That $1000 box the manufacturer wants to sell you is likely a slightly modified version of one of the speed controls listed on their site. The ones on the site are listed as being able to change the speed up to 5% or 10%. You need more, but it wouldn't be difficult to modify one of the existing models to do that and run on 120V. It works by changing the frequency of one of the feeds. I don't know if running on 60Hz will damage the motor. I suspect it will not if the fix that the manufacturer is suggesting is a speed control. As long as you don't burn the insulation with the additional heat, you will be fine, just running 20% fast. If the motor is happy with 18V 60Hz, I would just have a new pully machined and installed, and of course, get a new wall wart that will give me 18V out with 120V in.

Jaime from Axiss sent me an email and apologized for dropping the ball and forgetting my email. That's why the delay.

If I had a pulley machined, I would still probably have to have a speed control, because I doubt I could count on the speed being perfect. The pulley might not be the perfect size based on what the calculations should be, and calculating the new pulley size based on the two different power inputs may not be exact because of slight differences between the power inputs.

A wall wart will likely have two wires, but the motor has six.

Greg

[LarryC]

Hmm, so Transrotor doesn't have a US 60 Hz pulley? You're right, Transrotor should manufacture the pulley. How do they do it in US models? Only by power supply?

[BEC]

Greg,

How about one of these to start with using a 12 volt battery.

http://www.voltageconverters.com/itemdesc.asp?ic=ERP400-12

If that works well, you can then use a small battery charger (117VAC to 12VDC) to power this rig.

Bob Crites

[Malcolm]

If the turnatable doesn't need a speed control when run on 230V/50Hz it won't need one if the pulley is changed and it is run on 120V/60Hz. There is no question about the speed being a little off because of the different power inputs. This is a sychronous motor. It will run exactly 20% faster at 60Hz than it will at 50Hz. That means the circumference, and therefore the diameter, of the pulley needs to be 16 2/3% smaller when run at 60Hz. A decent machine shop can produce a pulley to the same tolerances as the original.

Anyway, I hope you find a solution that works for you. I am sure you are anxious to see how the turntable sounds.

[Malcolm]

Might be better to use an inverter with true sine wave output than one with modified sine wave output. But it will be more expensive.