Canon CP660 Service Manual page 218

CHAPTER 6 FIXING SYSTEM
2. Fixing Heater Safety Circuit (on the power supply circuit; E808)
The fixing heater safety circuit is found in the power supply assembly, and serves to
check the upper and lower fixing heaters for a fault.
a. When the fixing heater safety circuit finds a fault in the upper fixing heater,
If the fixing temperature increases abnormally, the power from the power supply
assembly to the upper/lower heater will be cut off.
Fixing assembly
THU
Upper thermistor
Upper Upper fixing
roller
thermal
switch
Lower
thermal
switch
Lower
fixing roller
THL
Lower
thermistor
JP2
6-6
COPYRIGHT © 1999 CANON INC.
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Power supply
RL101
T101
+5V
IC102
9
10
13
8
11
Fixing assembly
error detection
circuit
Q111
5
12 10
Fixing heater
14
safety circuit
6 2 15
FXTHL
FXTHU
Figure 6-202
+24V
Q101
Fixing heater
drive circuit
IC102
14
+5V
Q112
10
13
IC101 11
9
14
+5V
8
JP1
FXENB
CANON 660/2100 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
DC control PCB
30
D-CPU
C2
IC201
FXSTS
60
M-CPU
IC202
30
31
FXUON
+5V
FXUONS
+5V
Q203
Q204
BUS
FXSEL
Expansion
I/O
21
22
FXLON
23
FXLONS
24
FXRON
20
18
FXTYP
96
IC203
97 19
+5V
+5V
+5V
Q237
ACTYP
Q20