Canon PC400 Service Manual page 4

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,
nal name accompanies the symbol
electric signal.
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.
Note:
The descriptions in this Service Manual are subject to change without notice for
product improvement or other purposes, 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.
ii
COPYRIGHT © 1998 CANON INC.
represents the path of mechanical drive
, the arrow indicates the direction of the
CANON PC400/420/430,FC200/220 REV.0 JAN.1998 PRINTED IN JAPAN (IMPRIME AU JAPON)
where a sig-