Sharp AL-840 (serv.man3) Service Manual ▷ View online
(3) Major parts
a. Photoconductor section
No.
Parts
Note
Name
Type
Function/operation
1
OPC drum
OPC
Forms latent electrostatic images.
2
OPC drum earth electrode
Connects the OPC drum aluminum layer and
the earth (high voltage PWB).
the earth (high voltage PWB).
3
Main charger electrode
Connects the main charger output (high
voltage PWB) and the main charger brush.
voltage PWB) and the main charger brush.
4
Discharge brush
Discharges (lower the potential of) the OPC
drum surface.
drum surface.
Japan only
5
Main charger brush
Charges the OPC drum.
6
Toner seal
Shield to prevent toner from leaking outside
the OPC drum unit.
the OPC drum unit.
1)
2)
5)
3)
6)
5)
4)
1)
1 – 16
b. Development section
No.
Parts
Note
Name
Type
Function/operation
1
Developing roller
Attaches toner to the latent electrostatic
images on the OPC drum to convert it into
a visible image.
images on the OPC drum to convert it into
a visible image.
2
Developing doctor
Controls toner quantity on the developing
roller and charges toner.
roller and charges toner.
3
Developing bias
electrode
electrode
Connects the developing roller and the bias
voltage output (high voltage PWB).
voltage output (high voltage PWB).
4
Potential control
electrode
electrode
Connects the developing roller and the bias
voltage output (high voltage PWB).
voltage output (high voltage PWB).
5
Toner stirring roller
Lead toner to the developing roller and
charges toner.
charges toner.
6
Zenor diode
Maintains the potential between the
developing roller and the toner stirring roller
at a constant level.
developing roller and the toner stirring roller
at a constant level.
7
Toner seal
Shields toner from leaking outside the
developing unit.
developing unit.
8
Potential control sheet
Maintains the developing roller potential at
a constant level.
a constant level.
1)
5)
3)
4)
1)
5)
3)
5)
1)
8)
6)
4)
8)
7)
2)
1 – 17
c. Transfer/separation section
No.
Parts
Note
Name
Function/operation
1
Transfer roller
Transfers toner images on the OPC drum onto the paper.
2
Transfer roller
electrode
electrode
Connects the transfer roller and the transfer voltage output (high voltage PWB).
3
Pressure spring
Applies pressure to the transfer roller, paper, and the OPC drum to improve
transfer efficiency.
transfer efficiency.
4
Separation electrode
Reduces paper charging potential to facilitate separation of paper.
5
Earth electrode
Connects the separation electrode and the earth (high voltage PWB).
1)
3)
2)
5)
4)
1)
4)
3)
1 – 18
(4) System diagram
(5) Operation
a. Wiring diagram
DC-200V
DC-310V
DC+500V
DC-850V
AC600V(P-P)
AC600V(P-P)
DC +3.5KV
AC600V(P-P)
AC600V(P-P)
DC
–
850V
DC +200V
DC
–
310V
–
310V/+200V
selection
MCU PWB
Scanning mirror
Laser
beam
Laser unit
No. 1 - 4 mirror
Main
charger
brush
Discharge
brush
Separation
electrode
electrode
Photoconductor drum
Transfer
charger
roller
Developing
roller
Toner
Paper
Image data
High voltage power PWB
TC
Q804
+24VP
Q807
MCON
MC
TC/Bias ON
DC
Bias
Bias
100V
DRUM
EARTH
EARTH
CB
+24VP
Q806
Q803
Q808
PWNSIN
CPU
(IC5)
(IC5)
ASIC
(IC8)
GND
3
TSIN
2
1
1
CN6
+5V
TSIN
MCU(PCU) PWB
Toner sensor
High voltage power PWB
Driver I
C801
T801
transformer
T802
transformer
Charger brush
Discharge brush
OPC drum
Separation electrode
Transfer charger roller
Supply roller
Developing roller
Earth sheet
1 – 19
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