CANON GP215
Manual de Servicio

3. OPERATIONS AND TIMING

4. Detecting Overheating on the Fixing Heater End
The rear end of the fixing heater is equipped with a sub thermistor (TH2) to check for overheating. This is to prevent overheating and consequent damage to the fixing film which could occur when continuous copying is performed using copy of B4 or smaller in size. (Overheating tends to occur where the drum is not in contact with paper.) When the output of THE2 exceeds 250°C, the machine increases the sheet-to-sheet distance to accelerate heat discharge of the fixing heater, thereby preventing overheating. Copying operation is continued with the increased sheet-to-sheet distance even after the output of TH2 falls below 250°C. If overheating continues after increasing the sheet-to-sheet distance and the temperature exceeds 260°C, the on-going copying operation will be stopped and the power will be turned OFF. (E001 will be registered.)

5. Protection Mechanisms
The machine is equipped with the following protection mechanisms to prevent malfunction of the fixing heater: a. Thermistor (TH1, tH2) 1. The microprocessor on the DC controller monitors the voltage of the thermistor (TH1, TH2); if it detects overheating of the heater or error low temperature, it stops the power to the heater and turns off the power. (E000 through E003 will be registered.) 2. If the error temperature detection circuit finds that the output of TH1 is 250°C or more or that of TH2 is 260°C for 0.2 sec or more, the heater error detection signal (HTNG) will be issued to turn off the relay, stopping the power to the fixing hater and turning off the power. b. Thermal Fuse (FU1) When the temperature around the thermal fuse reaches 226 °C and the condition remains for a specific period of time, the thermal fuse will melt to stop the power to the fixing heater. c. Heater ON Detection Circuit (200V model only) The period of time during which the fixing heater drive signal (HTRD) remains OFF is monitored; if an error is detected, the power is turned OFF. (E004 will be registered.)

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COPYRIGHT © 1996 CANON INC.

CANON GP215/200 REV.0 JULY 1996 PRINTED IN JAPAN (IMPRIME AU JAPON)