Download Sharp AR-168S Service manual

A. General description
2) The surface temperature of the upper heat roller is set to 165 190°C. The surface temperature during the power save mode is
set to 100°C.
General block diagram (cross section)
Thermal fuse
Separator pawl
PPD2
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 100°C during
the copy cycle.
c. Open thermistor
d. Open thermal fuse
e. When the heat roller temperature does not reach 190°C within 27
second after supplying the power.
Thermistor
Pressure roller
(4) Fusing resistor
Fusing resistor
Heat roller
This model is provided with a fusing resistor in the fusing section to
improve transfer efficiency.
Since the upper heat roller is conductive, when using copy paper that
contains moisture and the distance between the transfer unit and the
fusing unit is short, the transfer current may find a path to ground via
the copy paper, the upper heat roller and the discharging brush.
Paper guide
Top view
Heat roller
Thermal fuse
Thermistor
Heater lamp
5. Paper feed section and paper transport
section
A. Paper transport path and general operations
4
3
5
Separator pawl
2
1
(1) Heat roller
A Teflon 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.
6
7
8
9
10
(2) 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.
14 13 12
11
(3) 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.
Heated by the heater
lamp. (800W)
Safety device
(thermal breaker, thermal
fuse)
Triac (in the
power supply unit)
The surface temperature
of the upper heat roller is
sensed by the thermistor.
1
Scanner unit
8
Drum
2
Copy lamp
9
Transfer unit
3
LSU (Laser unit)
10 Pickup roller
4
Paper exit roller
11 Manual paper feed tray
5
Main charger
12 Manual paper feed roller
6
Heat roller
13 PS roller unit
7
Pressure roller
14 Paper feed roller
Paper feed is made in two ways; the tray paper feed and the manual
paper feed. The tray is of universal-type, and has the capacity of 250
sheets.
The front loading system allows you to install or remove the tray from
the front cabinet.
The general descriptions on the tray paper feed and the manual paper
feed operation are given below.
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-168S/168D OPERATIONAL DESCRIPTIONS 7 - 4