Canon PC980 Service Manual - Page 220

CHAPTER 8 ADF G. Controlling the Pickup Motor 1. Outline Figure 8-121 is a diagram of the control circuit for the pickup motor (M2). The pickup motor is a DC motor. The CPU (Q1) on the ADF controller PCB sends the motor drive signals PM0 and PM1 to the motor driver (Q5). The pickup motor rotates clockwise or counterclockwise according to the combinations of the states of these two signals. (Table 8-102 shows how the pickup motor rotates for each combination.) The motor driver is equipped with a limiter function, preventing overcurrent from flowing into the motor. When an overcurrent occurs, the limiter function cuts off the motor drive current, thereby preventing damage to the motor. When the limiter function is activated, the pickup motor cannot rotate as controlled, possibly leading to pickup faults. Any pickup fault causes the ADF controller to flash the JAM indicator on the copier and stop the pickup motor at the same time. ADF controller PCB +24V Q1 CPU PM1 PM0 Q5 Motor driver PMRD1 PMRD1* Pickup motor M2 Figure 8-121 Motor drive signal (PM0) '1' '1' '0' '0' Motor drive signal (PM1) '1' '0' '1' '0' Table 8-102 Pickup roller rotation Braked Picking up Delivering At reset (free) 8-14 COPYRIGHT © 1999 CANON INC. CANON PC800s/900s REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)