Brother 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.
<Basic Structure of Temperature Control (Fig.4-35)>
FLS:
TFU1/TFU2
:
TH:
RY:
GA/CPU:
CM1:
CM2:
CM3:
Q:
HR:
BR:
< Signal Functions >
HON-N
ACOFF
THERR
AD
<Controlled Temperature and Safety>
( )
C
Thyristor to switch the power supply to the heat lamp.
Temperature fuse to shut down the circuit for safety when the
temperature becomes too hot within the fixing unit.
Temperature sensor to detect the surface temperature of the
heat roller (HR).
Relay to prevent further heating when it becomes hotter than
the set temperature within the fixing unit.
Process circuit to control the temperature signal (micro
computer).
Sensor circuit for temperature signal (for ACOFF signal).
Sensor circuit for temperature signal (for HON signal).
Sensor circuit for temperature signal (for processing).
Sensor circuit for shut-down by the thermistor (for THERR
signal).
Heat lamp for the heat roller.
Heat lamp for the back-up roller.
To turn on/off the heater inside the fuser roller.
To turn off the relay RY1 if overheat occurs.
To detect the shut-down by the thermistor.
To convert the temperature sensing signal to AD.
Time
IV-40
TPS
TA
150 C TS