Read Sharp AL-840 (serv.man3) Service Manual online
SERVICE MANUAL
CODE: 00ZAL840//B1E
BASIC MANUAL
DIGITAL COPIER
MODEL
AL-800/840
SHARP CORPORATION
Parts marked with "
!
" is important for maintaining the safety of the set. Be sure to replace these parts with specified
ones for maintaining the safety and performance of the set.
[ 1 ] OPERATING PRINCIPLE
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1. Block diagram
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
2. Outline of operations
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
A. Paper path and imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
B. Image process and data flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
3. Operations of each section
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
A. Paper feed, paper transport section . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
B. Scanner (reading) section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
C. Scanner (writing) section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-12
D. Image process section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14
E. Fusing/paper exit section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-25
F.
Drive section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-27
G. Electrical section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-28
CONTENTS
[1
]
OPERATING PRINCIPLE
1. Block diagram
CCD
CPU
ASIC
MEMORY
MEMORY
ICU PWB
ASIC
HOST(PC)
KEY
AC POWER
Control signal, detection signal,
drive signal, control data line
drive signal, control data line
Image data signal line
Image (light)
Power line
Paper path line
OPERATION PWB
LAMP (LED)
MAIN MOTOR
PRINT PWB
SCANNER HOME
POSITION
SENSOR
COPY LAMP
LIGHT QUANTITY
SENSOR
MIRROR
DOCUMENT
LENS
SCANNER (READING) SECTION
SCANNER
MOTOR
COPY LAMP
CONTROL PWB
FAN MOTOR
A/D
ONVERTOR
MCU (PCU) PWB
PARALLEL
I/F
MOTOR
DRIVER
DRIVER
HIGH VOLTAGE POWER PWB
FUSING/PAPER EXIT SECTION
TEMPERATURE
SENSOR
HEATER LAMP
PAPER
EXIT
ROLLER
PAPER
EXIT
ROLLER
HEAT
ROLLER
PAPER EXIT
DETECTOR
TEMPERATURE
FUSE
POWER PWB
IMAGE PROCESS SECTION
MAIN
CHARGER
SEPARATION
ELECTRODE
ELECTRODE
PHOTOCONDUCTOR
TRANSFER
ROLLER
DEVELOPING
ROLLER
PAPER FEED
ROLLER
CLUTCH
CLUTCH
PAPER WIDTH
DETECTOR
PAPER EMPTY
DETECTOR
PAPER ENTRY
DETECTOR
PAPER
FEED
ROLLER
PAPER FEED SECTION
PAPER
TRAY
PAPER
PRESSURE
ROLLER
SCANNER
MOTOR
LENS
MIRROR
LASER
DIODO
DIODO
LASER BEAM
SENSER
SCANNER (WRITE) SECTION
POLYGON
MIRROR
1 – 1
Scanner (read) section
In this section, the copy lamp (cathode ray tube, Xenon lamp)
radiates light onto a document, and the reflected light is detected by
the image sensor (CCD element) to convert into electrical signals
(analog signals), which are sent to the MCU PWB.
radiates light onto a document, and the reflected light is detected by
the image sensor (CCD element) to convert into electrical signals
(analog signals), which are sent to the MCU PWB.
MCU (ICU) PWB
The image data from the scanner (reading) section are converted into
digital signals and subject to image process (correction, etc.), and
converted into dot image data and outputted to the scanner (writing)
section.
digital signals and subject to image process (correction, etc.), and
converted into dot image data and outputted to the scanner (writing)
section.
During printing, the dot image data from the ICU PWB are outputted
to the scanner (writing) section directly. The engine status data are
outputted to the ICU PWB.
to the scanner (writing) section directly. The engine status data are
outputted to the ICU PWB.
The loads (motor, solenoid, etc.) are controlled according to the sen-
sor/detector signal.
sor/detector signal.
The above operation is performed by the CPU, ASIC, and memory.
ICU PWB
Print data (compressed data) sent from the host are developed and
converted into dot image data and outputted to the scanner (writing)
section. The engine status data sent from the MCU (PCU) PWB are
outputted to the host (PC).
converted into dot image data and outputted to the scanner (writing)
section. The engine status data sent from the MCU (PCU) PWB are
outputted to the host (PC).
Scanner (writing) section
In this section, the dot image data sent from the MCU PWB are
converted into laser beams (ON/OFF), which is scanned to form
latent electrostatic images on the OPC drum.
converted into laser beams (ON/OFF), which is scanned to form
latent electrostatic images on the OPC drum.
Paper feed section
The paper feed roller feeds paper to the transfer section.
The paper feed operation is controlled by the paper fed roller clutch
and the paper feed roller clutch solenoid.
and the paper feed roller clutch solenoid.
Image process
This section is composed of the photoconductor section, the develop-
ing section, and the transfer/separation section. The images formed
by laser beams in the scanner (writing) section are formed into latent
electrostatic images on the photoconductor and converted into visible
images by toner development.
ing section, and the transfer/separation section. The images formed
by laser beams in the scanner (writing) section are formed into latent
electrostatic images on the photoconductor and converted into visible
images by toner development.
The operations of this section are composed of five processes; ex-
posure, development, transfer, separation, and discharge.
posure, development, transfer, separation, and discharge.
The OPC drum is used as the photoconductor drum, and one-com-
ponent toner is employed.
ponent toner is employed.
For charging, the rotation brush is employed. For transfer, the roller is
employed to eliminate ozone generation. In addition, t is compact.
employed to eliminate ozone generation. In addition, t is compact.
The high voltage required in this section is supplied by the high
voltage PWB.
voltage PWB.
Fusing/paper exit section
Toner is fused to the paper in the fusing/paper exit section using heat
and pressure.
and pressure.
The heat roller surface temperature is detected by the fusing
temperature sensor to maintain the constant fusing temperature (155
˚C).
temperature sensor to maintain the constant fusing temperature (155
˚C).
The heater lamp is driven by the power PWB unit.
Operation PWB
The operation PWB displays various information and supplied the key
operation signals to the MCU (PCU) PWB.
operation signals to the MCU (PCU) PWB.
High voltage power PWB
The high voltage power PWB outputs the high voltage for the main
charger, the developing bias, and the transfer charger. In addition,
the main motor drive circuit is built into the PWB.
charger, the developing bias, and the transfer charger. In addition,
the main motor drive circuit is built into the PWB.
Main motor.
The main motor drives the paper feed section, the transport section,
the image process section, and the fusing section.
the image process section, and the fusing section.
The main motor drive circuit is built into the high voltage power PWB.
Copy lamp control PWB
The copy lamp light quantity is controlled to provide necessary light
quantity even though the conditions of the scanner (reading) section
are changed.
quantity even though the conditions of the scanner (reading) section
are changed.
The copy lamp drive voltage is controlled by the output level of the
light quantity sensor in the scanner (reading) section.
light quantity sensor in the scanner (reading) section.
Power PWB
The power PWB outputs the DC power voltages (+24V, +5V, +3.3V,
+12V), and drives the heater lamp.
+12V), and drives the heater lamp.
Scanner (reading) section
Fusing/paper exit section
Scanner (writing) section
Paper feed section
Image process section
1 – 2
2. Outline of operations
A. Paper path and imaging
Paper is fed, transported, and discharged through the path indicated
with the arrow in the figure below.
with the arrow in the figure below.
1) Paper feed (Paper on the paper tray is fed to the transfer section
by the paper feed roller.)
2) Image transfer (The toner image on the photoconductor is trans-
ferred onto the paper by the transfer roller.)
3) Fusing (The toner image on the paper is fused by the heat roller
and the pressure roller.)
4) Paper exit (The paper is discharged to the paper exit tray by the
paper exit roller.)
B. Image process and data flow
(1) Copy mode
C1)
Images scanned by the image sensor (CCD element) is con-
verted into electrical signals (analog signals) and outputted to
the MCU PWB. (CCD unit)
verted into electrical signals (analog signals) and outputted to
the MCU PWB. (CCD unit)
C2)
Image data outputted from the scanner (reading) section are
converted into digital signals. (CCDD0-7)
converted into digital signals. (CCDD0-7)
C3)
Image process (area separation, filter process, gamma correc-
tion, resolution conversion, zooming) is performed by the ASIC
and the line memory (SRAM). The dot image data, the resolu-
tion of which is converted from 400dpi to 600dpi, are sent to
the data select section. (Image data (LD))
tion, resolution conversion, zooming) is performed by the ASIC
and the line memory (SRAM). The dot image data, the resolu-
tion of which is converted from 400dpi to 600dpi, are sent to
the data select section. (Image data (LD))
C4)
The data are passed through the data select section to the
scanner (writing) section. (Image data (V DATA))
scanner (writing) section. (Image data (V DATA))
In the multi copy mode, image data of one sheet are stored in
the DRAM. (Sharp version only)
the DRAM. (Sharp version only)
1
2
3
4
1 – 3
