C4170-90959
Engine Control System
81
Fusing Assembly Control
The fusing assembly’s film contains a heater. The Engine Controller Assembly controls the
fusing heater during the following temperature modes. See “Sequence of Operation”
(page 70) for more information on print period descriptions.
•Initial
•Print
• Between-Page
• Postprint
The Engine Controller Assembly maintains a temperature of about 195 degrees Celsius
(383 degrees Fahrenheit) during print temperature mode. If the fusing system overheats
(about 220 degrees Celsius; 428 degrees Fahrenheit), a relay (RL301) opens the power
circuit to the fusing heater, causing a Fuser Error message. If the fusing system exceeds
about 230 degrees Celsius (446 degrees Fahrenheit), the thermal fuse (FU1131) melts,
cutting off power to the fuser assembly. The Engine Controller Assembly monitors the fusing
heater temperature via a thermistor (TH701).
Power Supply and Control
• AC power is supplied to the low-voltage power supply circuit when the power switch is
turned on. This circuit supplies DC voltage (+24V, +5V, +3.3V) to the Main Motor, Laser
Scanner Unit, Interlock Switch, Video Controller, Solenoids, Paper Feeder, High-Voltage
Power Supply, and Formatter.
• Opening the top cover interrupts the DC voltage supplied to the high-voltage power
supply circuit.
• The low-voltage power supply circuit contains an overcurrent/overvoltage protection
circuit that automatically turns off the output voltage when an overcurrent condition
occurs because of a short or abnormal voltage on the load side.
• The protection circuit automatically resets after the input power is turned off then on.
The low-voltage power supply circuit also contains a fuse that shuts off the power supply
to the circuit when overcurrent conditions occur. See “Engine Control System” (page 79)
for more information.
In response to the Engine Controller Assembly, the high-voltage power supply circuit (see
figure 5-5) supplies DC and AC voltage to the various parts of the Image Formation System.
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