mains frequency

EMT 930 with a different mains frequency

The motor of the EMT 930 was built for a certain mains frequency, thus terminating the number of revolutions and the platter speed. This is either 50cps or 60cps.

Therefore an EMT 930 made for 50cps but connected to 60cps will run too fast and vice versa (60cps unit connected to 50cps).

With the correct mains frequency the small holes in the auxiliary platter above the stroboscope bulb will show whether the platter rotates too slow, too fast or correct. With the fine tuning brake the correct speed can be adjusted. The stroboscope divisions of the auxiliary platter are of course fix and valid only for one mains frequency (50cps or 60cps).

Even if the platter runs with the correct speed a wrong platter will show a wrong velocity.

How to adopt an EMT 930 to another mains frequency?

1. The best and most correct way is the replacement of the motor and the auxiliary platter:
Motor for EMT 930 50 Hz: 7 930 006
Motor for EMT 930 60 Hz: 7 930 012
Auxiliary platter 50 Hz: 7 930 237
Auxiliary platter 60 Hz: 7 930 398

2. Another way is to supply the turntable not directly with the mains voltage. On the market you will find a lot of frequency converters.
Although it would be technically correct the combination of a sine wave oscillator, power amplifier and reverse used mains transformer can't be recommend as one would work with hazardous voltages which may cause personal injuries.

3. Resourceful people may also offer different solutions like modifying the motor axle. These ways don't lead always to useful results and will cause trouble in case of a repair. Also the motor is used in a frequency range where it was not made for.

It is clearly recommended one of the first two methods. But it is not recommended to adjust the exact speed by means of an artificial mains frequency and to avoid the fine tuning brake. Each deviation of the nominal frequency (50cps or 60cps) leads to a misalignment of the auxiliary phase thus causing hum and warmth.

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