Canon PC400 Service Manual - Page 37
D. Main Motor Control Circuit, Outline, Operation, Overcurrent Sensor, D - specifications
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CHAPTER 2 BASIC OPERATION D. Main Motor Control Circuit 1. Outline Figure 2-101D shows the circuit that controls the main motor (M1), and the circuit has the following functions: a. turns the main motor ON and OFF. b. controls the main motor speed (constant) The main motor (M1) is a DC motor and is equipped with a motor rotation sensor (Q901) to serve as a clock pulse generator. Clock pulses (MMCLK) corresponding to the revolution of the motor are generated while the motor is rotating. The speed control circuit controls the speed of the motor with reference to these clock pulses. 2. Operation The drive circuit on the DC controller/DC power supply PCB causes the main motor drive command (MMD) to go '0' in response to instructions from the microprocessor, thereby causing the main motor to rotate at a specific speed. 3. Overcurrent Sensor When the overcurrent sensor circuit detects an overload in the main motor (M1), the speed controller circuit exerts control so that the rotation of the motor is slowed down. If the revolution of the main motor falls below a specific revolution, however, an error associated with 'E2' can occur. Overcurrent detection circuit Microprocessor (Q101) Speed control circuit Drive circuit Q101 +24V J201 -5 (+) Main motor drive -4 command (MMD) (-) M1 Main motor Q901 Motor rotation detection PCB Main motor clock pulse -1 signal (MMCLK) DC controller/DC power supply PCB Figure 2-101D COPYRIGHT © 1998 CANON INC. CANON PC400/420/430,FC200/220 REV.0 JAN.1998 PRINTED IN JAPAN (IMPRIME AU JAPON) 2-5