Canon 1000 Service Manual page 193

b. Paper Deck Motor Control Circuit
The paper deck motor control circuit is found on the DC controller PCB. See Figure 3-619 for a block
diagram.
The combination circuit in the figure consists of various logic circuits, and they combine the output
signals from various sensors and the control signals from the microprocessor to generate the lifter up/down
signals (STMUP/STMDN).
The two signals are used to activate the motor drive IC to rotate the paper deck motor clockwise or
counterclockwise.
An overcurrent detection circuit is provided to force off the paper deck motor if a short-circuit or the like
allows an overcurrent to flow into the motor. When the circuit has activated, the copier may be reset by
removing the cause and turning off and on the power switch.
Moving the Lifter Up
• The paper deck cover must be closed, i.e., the cover open signal (STDO) is '0'.
• The light-blocking plate must not be over the lifter position sensor and, in addition, the lifter upper limit
switch must be off and the lifter position signal (LTP) must be '0'.
• The lifter up/down control signal from the CPU is '0'.
• The motor ON control signal from the CPU is '1'.
As a result of the above conditions, the output signals from the combination circuit will be as follows:
• The lifter up signal (STMUP) will be '1'.
• The lifter down signal (STMDN) will be '0'.
whereupon the lifter starts to move up.
COPYRIGHT © 2001 CANON INC. CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)
3. OPERATION AND TIMING
3-149