The Lenco motor is a 4 pole ac motor, which keeps it’s speed synchronized with the power line frequency. There is little or no speed variation with line voltage, which makes it a very good motor for a turntable.
The basic design of the motor has not changed significantly over time, and lenco motors are interchangeable between models.
Two main versions of the motor exist, a 110/220 volt 50 Hertz (Euro) version, and a 110 volt 60 Hz (US) version. For both versions, power consumption is 15 to 19 watts. (Actual currents: 85 ma @ 220V/50 Hz, 140 ma @ 110V/60 Hz)
There is a rare third motor type which is a 110/220 volt, 50/60 Hz motor. The Lenco label for a turntable with this motor shows both line frequencies, not just one as it does in the case of the other two motors.
Apparently, this motor was present in turntables sold in army personnel outlets.
Some Lenco motors of different vintage
The difference between a 50 hertz and 60 hertz motor is in the diameter of the shaft, and in the coils. A 60 Hz motor has a smaller shaft because the motor runs 20% faster on 60 Hz.
The motor has two coils, one on each side of the rotor. These coils can be connected in series or parallel, depending on the desired voltage (110/220 coils). An alternate connection is however only possible for the 110/220 version, the 110 volt version requires the coils in series and can therefore only be used on 110 volt. Please note that on a 110 volt motor, a diagram cast in the housing suggests that it can be wired for 220 volt, but this is not possible. The presence of this diagram can therefore not be used to identify a motor. A motor wired for the incorrect voltage will have no power, or vibrate and hum excessively.
Wiring
Each coil has two wires, red and white for the left coil, and blue and white for the right coil. The normal connection of these coils is in series: The power is applied to the red and blue wires, and the two white ones are connected together.
This is correct for a US and Euro motor in their native environment.
The only exception to this rule is the parallel wiring of a Euro motor wired for 110 volt use. Power is still applied to the red and blue wires, but now the white wires “cross over”. The white wire from the left (“red”) coil goes to the blue wire and the white wire from the right (blue) coils goes to the red wire.
Connections are made in a connector block, early models had a plug block for voltage selection which was eliminated in the later models.
Wiring for a 110/220V 50Hz motor used on 220 volt. The line power goes on the outermost terminals, the switch goes on the two rightmost positions. Note that the red jumper wires connect the two white motor wires together, this is series connection of the coils.
Wiring for a 110/220V 50 Hz motor, used on 110 volt. Note how the red jumper wires connect the coils in parallel. The switch and power connections stay where they are.
Wiring for a 110V/60 Hz motor. Two terminals are not used. The power goes on the outer terminals, (red and blue wires), the switch goes on the middle terminals (white wires). Note that this is series wiring of the coils. The capacitor is mounted on the motor, not on the switch. There are no jumper wires.
Rotor identification:
All shafts are tapered, but with a "step" between 16 and 33 rpm.
50Hz: Shaft diameter is approx. 11.5 mm at the widest point, 5.4 mm at the step.
60Hz: Shaft diameter is approx. 10.5 mm at the widest point, 4.4 mm at the step.
50/60Hz: 10 and 4.5 mm. These measurements are unconfirmed.
Coil identification:
50 Hz coils usually have yellowish tape around them, through which “110/220 volts 50 Hz” may be readable. 60 Hz coils usually have green tape, with no visible writing underneath. The 50/60 motor has the dual voltage coils of the 50 Hz motor.
Because the DC resistance of each coil is approximately 250 Ohm for 50 Hz coils, and 70 ohms for 60 hz coils, we can do a quick identification by measuring the resistance between the pins of the power cord with the turntable switched on:
500 Ohm means 110/220 volt, 50 Hz, wired in series for 220 volt. (520 for older models)
125 Ohm means 110/220 volt, 50 Hz, wired parallel for 110 volt. (130 for older models)
140 Ohm means 110 volt, 60 Hz, wired in series for 110 volt
35 Ohm means 110 volt, 60 Hz, incorrectly wired parallel (this would be for 55 volts…)
Intercontinental issues:
It is possible to use a Euro motor in the US by wiring the coils parallel, but it will run too fast, and so the the speed settings will be out of range. 33 rpm will appear somewhere between the 33 and 16 rpm position, but other than that it will work. It can happen that for 33 rpm, the idler wheel is riding on the edge of the sudden step in diameter of the motor shaft, but that problem can be solved. See also the "speed adjustment" post.
Using a US motor in Europe is also possible. Not only is 33 rpm now close to the 45 rpm setting, but one would also have to reduce the voltage to the motor with a transformer or resistor. 78 rpm can not be obtained under these conditions.
Mounting:
6 springs are used to mount the motor. The longest and shortest two go at the motor (heavy) end, one set on each side. The shortest ones go between the motor and the deck, the longest ones go underneath the motor, carrying the weight. The two leftover springs can be of the same length or not. This is the set for the spindle or nose (light) end. If they are not of the same length, try the shorter one between the motor and the deck first. If the plateau doesn’t turn, switch them around. See also drive system Arrow there.
Text: Sander, Eng, Gatto Murr & Colin
Illustrations: Sander, Eng.
