Canon PC920, Service Manual

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COPYRIGHT © 1999 CANON INC. CANON PC800s/900s REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
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The following rules apply throughout this Service Manual:
1. Each chapter contains sections explaining the purpose of specific functions and the
relationship between electrical and mechanical systems with reference to the timing
of operation.
In the diagrams,
represents the path of mechanical drive—where a signal name
accompanies the symbol , the arrow indicates the direction of the electric sig-
nal.
The expression “turn on the power” means flipping on the power switch, closing the
front door, and closing the delivery unit door, which results in supplying the machine
with power.
2. In the digital circuits, ‘1’ is used to indicate that the voltage level of a given signal is
“High,” while ‘0’ is used to indicate “Low.” (The voltage value, however, differs from
circuit to circuit.)
In practically all cases, the internal mechanisms of a microprocessor cannot be checked
in the field. Therefore, the operations of the microprocessors used in the machines
are not discussed: they are explained in terms of from sensors to the input of the DC
controller PCB and from the output of the DC controller PCB to the loads.
The descriptions in this Service Manual are subject to change without notice for
product improvement or other reasons, and major changes will be communicated in the
form of Service Information bulletins.
All service persons are expected to have a good understanding of the contents of this
Service Manual and all relevant Service Information bulletins and be able to identify and
isolate faults in the machine.