Protection System - Canon 1130 Service Manual

C. Protection System
The fuse on the DC fuse PCB is designed to melt if an overcurrent occurs in any of the loads.
Or, the overcurrent protection circuit on the DC power supply PCB will turn on to stop the output
of the DC power supply.
If the overcurrent protection circuit 1 on the DC power supply PCB detects overcurrent, it will
stop output 1 and output 2; output 1 is used to drive the logic system so that its suspension will help
prevent malfunction of the copier. If the overcurrent protection circuit 2 detects overcurrent in the
drive system, on the other hand, the copier will stop output 2 only.
DC power supply PCB
Converter
circuit 1
3.3V/5V/-8V
+8V/+8VU
12V/15V
24V-F
Conversion
circuit 2
24V/38V
Sequence control
circuit
Stops output 2.
Stops outputs 1 and 2.
Figure 9-502 Block Diagram of the Protection System
Detection by
Overcurrent protection circuit 1
Overcurrent protection circuit 2
COPYRIGHT © 2002 CANON INC.
CHAPTER 9 EXTERNALS / AUXILIARY MECHANISMS
Output 1
3.3V,-8V,+8V,+8VU,12V,24V-F
Over-
current
detection
5V
circuit 1
15V
Output 2
38V
Over-
current
detection
circuit 2 24V
A
B
DC power cut
relay (RL3)
Copier operation
Stops outputs 1 and 2
from the DC power
supply PCB.
Stops output 2 from the
DC power supply PCB.
Table 9-505 Protective Functions
CANON CLC1100/1130/1150/1160/1180 REV.1 FEB. 2002 PRINTED IN JAPAN (IMPRIME AU JAPON)
DC fuse PCB
A
FU901-FU906
FU940-FU941
B
FU921-FU925
C
FU931-FU939
15V,38V
C
Cover switch
(SW3, SW4, SW5)
Turn off the power switch, and remove
the cause; then, wait for about 3 min,
and turn on the power switch.
PCBs
Resetting
9-11