AR-161 (serv.man8). AR161 Service Manual-Operational Descriptions - Sharp Copying Equipment Service Manual (repair manual). Page 10

1

Before-fusing
paper guide

Guides the paper transported from
the process section to the fusing unit.

2

Upper heat roller

Applies heat and pressure to the
paper to fuse.

3

Thermistor

Detects the surface temperature of
the upper heat roller.

4

Thermostat

Stops power supply to the heat roller
in case of an abnormally high
temperature of the heat roller.

5

Separation pawl

Separates the print paper from the
upper heat roller.

6

POD1

Detects that the paper has been
transported from the fusing section.

7

Heater lamp

Heats the heat roller.

8

Lower heat roller

Applies a pressure to the paper
together with the upper heat roller.

A pressure roller is used for the heat roller and a silicone rubber roller
is used for the lower heat roller for better toner fusing performance
and paper separation.

Four 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.

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 thermostat is used for safety pur-
poses.

2) The surface temperature of the upper heat roller is set to 180˚C ~

195˚C. The surface temperature during the power save mode is
set to 100˚C.

3) The self-check function comes active when one of the following

malfunctions occurs, and an "H" is displayed on the copy quantity
display.

Fusing temperature error value

H4 (Low temperature error)

•

During machine operation
The case where the fusing temperature (thermistor output
value) does not reach 155˚C within 55 sec from lighting of the
heater lamp. (If the toner motor rotates for 10 sec or more
continuously when starting the machine, the case where the
fusing temperature does not reach 155˚C within 60 sec.)

•

During printing
When the fusing temperature (thermistor output value) falls
below 145˚C. 

H3 (High temperature error)

Fusing temperature (thermistor output value) of about 220 to
240˚C (varies depending on the resistance.)

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.
To prevent against this, a resistor of 150MOhm is provided between
the frame and the discharge brush to minimize leak current and
improve transfer efficiency.

Safety device

(thermal breaker, thermal

fuse)

Triac (in the
power supply unit)

Heated  by the

heater  lamp.

(950W )

The surface temperature

of the  upper hea t 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 )

AR-160/161 FM/E [6] OPERATIONAL DESCRIPTIONS 11/27/1998

AR-161

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