AMT Datasouth Accel-7350 Service Manual page 85

Drive method
Data control signals from gate array consist of speed control and phase signals. The speed
control signal is set at a certain voltage level by transistors QA11, QA12 and resistor R180,
R182 and R183, and is supplied to U23. This voltage level determines how U23 controls the
current, which flows to the motor.
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