A. Heat roller
A teflon roller is used for the upper heat roller and a silicone rubber
roller is used for the lower heat roller for better toner fusing perfor-
mance and paper separation.
Simple raising of the fuser compartment accessing lever separates
the upper heat roller from the lower heat roller for easier misfed paper
removal.
B. Separator pawl
Three separator pawls are used on the upper heat roller. The
separator pawls are teflon coated to reduce friction with the roller and
prevent a smear on the paper caused by the separator pawl.
C. Thermal control
1
The heater lamp, thermistor, main PWB, DC power supply PWB,
and triac within the power supply unit are used to control the
temperature in the fuser unit.
To prevent against abnormally high temperature in the fuser unit,
a thermal breaker and thermal fuse are used for safety purposes.
2
The surface temperature of the upper heat roller is set to 185
∼
165°C. The surface temperature during the power save mode is
set to 120°C.
3
The self-check function comes active when one of the following
malfunctions occurs, and an "H" is displayed on the multicopy
window.
a. When the heat roller surface temperature rises above 240°C.
b. When the heat roller surface temperature drops below 140°C
during the copy cycle.
c. Open thermistor
d. Open thermal fuse
e. When the temperature does not reach 185°C within 27 sec
after supplying the power.
D. Fusing resistor
Fusing resistor
This model is provided with a fusing resistor in the fusing section to
improve transfer efficiency.
General descriptions are made in the following.
General descriptions
Since the upper heat roller is conductive when copy paper is highly
moistured and the distance between the transfer unit and the fusing
unit is short, the transfer current leaks through the copy paper, the
upper heat roller and the discharging brush as shown in the figure
below.
Without fusing resistor
With fusing resistor
Safety device
(thermal breaker, thermal
fuse)
Triac (in the
power supply unit)
Heated by the
heater lamp.
(950W)
The surface temperature
of the upper heat roller
is sensed by the thermistor.
Level of the thermistor is
controlled by the main PWB.
With the signal from the
main PWB, the triac is
controlled on and off.
(power supply PWB)
Discharging
current
Fusing frame
Discharging brush
Upper heat roller
Lower heat roller
Leak transfer current
(Large)
Transfer unit
Transfer charger
Copy paper
OPC drum
Discharging
current
Fusing frame
Discharging brush
Upper heat roller
Fusing resistance
Lower heat roller
Lead transfer current
(small)
Transfer unit
Transfer charger
OPC drum
Copy paper
7 – 4
www.freeservicemanuals.info
1/11/16
Published in Heiloo, Holland.
