Protective Mechanism For The Fixing System - Canon GP335 Service Manual

CHAPTER 9 FIXING SYSTEM
D. Protective Mechanism for the Fixing System
To prevent overheating of the fixing heater, the copier is equipped with the protective
mechanisms shown in Table 9-102. The DC-CPU* checks for an error in each assembly; and, upon
detection of an error, it will cut off the relay RL1 and, at the same time, indicate an error code on the
LCD.
If the fax function board is installed, however, the copier will not turn off the main power, since
doing so would erase image data.
To reset the copier in response to any of the following error codes, execute error clear in service
mode (FUNCTION>CLAER>ERROR)
* CPU for the DC controller PCB (on the image processor PCB).
Item
The main thermistor
(TH1) temperature
reading does not
increase.
The main thermistor
(TH1) temperature
dose not increase after
a specific period of
time.
The main thermistor
(TH1) detects
overheating.
The sub thermistor
(TH2) detects
overheating has an
open circuit.
The thermistor (TH1,
TH2) detects an
abnormal drop in
temperature.
The SSR has a short
circuit.
9-10
Error code
E000
E002
E001
E001
E003
E004
Table 9-102 Protective Mechanisms
COPYRIGHT © 1999 CANON INC. CANON 405/335 REV.0 JAN. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
Description
The main thermistor temperature reaching fails to
reach 55°C 45 sec after the main power switch has
been turned on.
The output of the thermistor meets the following:
• 31 sec or more after detection of 40°C to
detection of 75°C.
• 23 sec or more after detection of 75°C to
detection of 100°C.
• 19 sec or more after detection of 100°C to
detection of 120°C.
• 19 sec or more after detection of 120°C to
detection of 140°C.
• 19 sec or more after detection of 140°C to
detection of 160°C.
• 15 sec or more after detection of 160°C to
detection of 170°C.
This error is identified when the output of the main
thermistor exceeds 220°C; in response, the relay
drive signal (RL-D) will be turned off to shut off the
relay (RL1).
This error is identified when the output of the sub
thermistor exceeds 235°C; in response, the relay
drive signal (RL-D) will be turned off to shut off the
relay (RL1). Overheating is detected by the sub
thermistor, and the sub thermistor is checked for an
open circuit.
The thermistor detects a drop below 100•‹C after
the wait period.
This error is detected when any of the following
occurs as a result of a short circuit in the SSR; in
response, the relay drive signal (RL-D) will be
turned off to shut off the relay (RL1):
• The fixing heater continues to remain on.
• The fixing temperature increases abnormally.