Brother International HL-2400C Service Manual - Page 89

(3) Control of the Fusing Temperature Each roller of the fusing unit is controlled to maintain the appropriate temperature so that toner will be fixed correctly onto the print paper. FLS: Thyristor to switch the power supply to the heat lamp. TFU1/TFU2 Temperature fuse to shut down the circuit for safety when the : temperature becomes too hot within the fixing unit. TH: Temperature sensor to detect the surface temperature of the heat roller (HR). RY: Relay to prevent further heating when it becomes hotter than the set temperature within the fixing unit. GA/CPU: Process circuit to control the temperature signal (micro computer). CM1: Sensor circuit for temperature signal (for ACOFF signal). CM2: Sensor circuit for temperature signal (for HON signal). CM3: Sensor circuit for temperature signal (for processing). Q: Sensor circuit for shut-down by the thermistor (for THERR signal). HR: Heat lamp for the heat roller. BR: Heat lamp for the back-up roller. < Signal Functions > HON-N To turn on/off the heater inside the fuser roller. ACOFF To turn off the relay RY1 if overheat occurs. THERR To detect the shut-down by the thermistor. AD To convert the temperature sensing signal to AD. Temperature TPS TA 150 C TS ( C) Time IV-40