Canon PC300 Service Manual page 34

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i. Main Motor Control Circuit
i. Outline
Figure 3-7 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 (con-
stant)
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 cir-
cuit controls the speed of the motor with ref-
erence to these clock pulses.
OPERATIONS AND TIMING
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.
Drive circuit
Speed control circuit
Microprocessor (Q101)
2
°
Main motor drive
!-4 command (MMD) (-)
es eee
Motor rotation|detection PCB
Main motor clock pulse|
1 signal (MMCLK)
DC controller/DC power supply PCB |
Figure 3-7
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CANON PC300'320/325, FC210/230 REV.O JULY 1994 PRINTED IN JAPAN (IMPRIME AU JAPON) 3-7