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Section 4 – Troubleshooting Guide
Problem
Faulty motor
Faulty tachometer
Faulty transducer
SECTION 4 – TROUBLESHOOTING GUIDE
1. Remove the mixing cup from the motor.
2. Place the AUTO/MANUAL switch in Manual.
3. Push the VAR button in.
4. Rotate VARIABLE SPEED control counterclockwise.
5. Turn the MASTER switch to ON. Motor should not
be turning or should turn at a very low speed (<100
rpm). Motor speed should increase to 16,000 rpm
when knob is in full clockwise position.
Some apparent malfunctions of the tachometer may be
caused by other components:
1. The tachometer indication is zero and the mixer is
running properly.
2. The tachometer reads zero and the mixer is running at
very high speed (greater than 12,000 rpm).
3. The tachometer reads zero or is erratic and the mixer
speed oscillates over a wide range (greater than +/- 200
rpm).
If these symptoms are present, the cause of the problem
will most likely be found in the speed transducer circuit.
1. To verify that the tachometer is working properly,
connect a 6000 Hz 0.5 vdc square wave signal to the pins
of the transducer cable connector. The tachometer
should read 1000 rpm. If reading does not indicate the
correct value, the tachometer should be repaired or
replaced.
With the motor running, the tachometer will indicate the
RPM of the motor. If the tachometer is known to be
functioning properly but indicates zero RPM when the
motor is turning, the transducer may be faulty or in need
of adjustment. Most common symptoms of a faulty or
misadjusted transducer are:
1. A zero RPM indication
2. The motor runs at very high speed (usually greater
than 12,000 RPM).
3. The Control Enclosure cannot control the speed of the
motor.
4. To verify the transducer is faulty, disconnect the
transducer cable from the Control Enclosure. Measure
the voltage at the two pins on the connector at the end of
Solution
4-1
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