Protection Mechanisms - Canon FC220 Service Manual

D.

Protection Mechanisms

The copier is equipped with the following protection mechanisms to prevent
malfunction of the fixing heater.
1. The microprocessor monitors the voltage of TH1, and displays 'E0'
(PC420/430/FC220)/ 'Jam' (PC400/FC200) and turns the power off upon detec-
tion of any of the following conditions:
i. The temperature of the fixing heater does not reach 80°C 2.5 sec. after copying
starts.
ii. The temperature of the fixing heater does not reach 150°C within 7.5 sec. after
copying starts.
iii. The temperature of the fixing heater drops to 135°C or less after it has reached
150°C.
iv. The temperature of the fixing heater rises in excess of 215°C.
v.The maximum power (400 W) is detected for 5 sec. continuously after the temper-
ature of the fixing heater has reached 150°C.
2. TH1 registers 234°C as the temperature of the fixing heater; as a result, the fix-
ing heater error temperature detection circuit causes RELAYD to go '0' and
the relay (RL101) to go OFF, thereby cutting the power to the fixing heater.
3. The thermal fuse (FU2) blows after it has reached 228°C and a specific time
has passed to cut off the power to the fixing heater.
COPYRIGHT © 1998 CANON INC. CANON PC400/420/430,FC200/220 REV.0 JAN.1998 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 6 FIXING SYSTEM
6-5