Sharp AR-M550 (serv.man12) Service Manual ▷ View online
AR-M550/M620 DETAILS OF EACH SECTION 6 - 75
C. Operational descriptions
The OPC drum surface is negatively charged by the main charger. The
laser beam images are radiated to the OPC drum surface by the laser
unit to form latent electrostatic images.
laser beam images are radiated to the OPC drum surface by the laser
unit to form latent electrostatic images.
1) The OPC drum surface is negatively charged by the main charger.
The main charger grid is provided with the screen grid. The OPC
drum is charged at a voltage virtually same as the voltage applied
to the screen grid.
drum is charged at a voltage virtually same as the voltage applied
to the screen grid.
2) LED lights are radiated to the OPC drum surface by the laser unit
to form latent electrostatic images.
When LED lights are radiated to the OPC drum CGL, negative and
positive charges are generated.
positive charges are generated.
Positive charges generated in CGL are attracted to the negative
charges on the OPC drum surface. On the other hand, negative
charges are attracted to the positive charges in the OPC drum alu-
minum layer.
charges on the OPC drum surface. On the other hand, negative
charges are attracted to the positive charges in the OPC drum alu-
minum layer.
Therefore, positive charges and negative charges are balanced
out on the OPC drum and in the aluminum layer, reducing positive
and negative charges to decrease the OPC drum surface voltage.
out on the OPC drum and in the aluminum layer, reducing positive
and negative charges to decrease the OPC drum surface voltage.
Electric charges remain at a position where LED lights are not radi-
ated.
ated.
As a result, latent electrostatic images are formed on the OPC
drum surface.
drum surface.
3) After transfer operation, remaining toner is removed by the clean-
ing blade.
Toner removed from the OPC drum surface is transported to the
waste toner section in the toner cartridge by the waste toner trans-
port screw.
waste toner section in the toner cartridge by the waste toner trans-
port screw.
4) The whole surface of the OPC drum is discharged.
By radiating the discharge lamp light to the discharge lens, light is
radiated through the lens to the OPC drum surface.
radiated through the lens to the OPC drum surface.
When the discharge lamp light is radiated to the OPC drum CGL,
positive and negative charges are generated.
positive and negative charges are generated.
Positive charges generated in CGL are attracted to the negative
charges on the OPC drum surface. On the other hand, negative
charges are attracted to positive charges in the aluminum layer of
the OPC drum.
charges on the OPC drum surface. On the other hand, negative
charges are attracted to positive charges in the aluminum layer of
the OPC drum.
Therefore, positive and negative charges are balanced out on the
OPC drum surface and in the aluminum layer, reducing positive
and negative charged to decrease the surface voltage of the OPC
drum.
OPC drum surface and in the aluminum layer, reducing positive
and negative charged to decrease the surface voltage of the OPC
drum.
Aluminum
layer
OPC drum
CTL
CGL
High voltage unit
Main corona unit
Screen grid
OPC drum
LED lights
Aluminum
layer
OPC drum
CGL
CTL
Drum
Lamp
CLT
CGL
Auminum
layer
Auminum
layer
CLT
CGL
Drum
AR-M550/M620 DETAILS OF EACH SECTION 6 - 76
D. Maintenance and parts replacement
(1) Maintenance list
✕
: Check (Clean, replace, or adjust as necessary.)
❍
: Clean
▲
: Replace
∆
: Adjust
✩
: Lubricate
❏
: Shift position
AR-M550U/M550N (PM: 250K)
When
calling
250K 500K 750K 1000K 1250K 1500K 1750K 2000K
Remark
AR-620U/M620N (PM: 300k)
300K 600K 900K 1200K 1500K 1800K 2100K 2400K
Unit name
No.
Part name
Drum
peripheral
section
peripheral
section
1
Drum
✕
▲
▲
▲
▲
▲
▲
▲
▲
2
Cleaning blade
✕
▲
▲
▲
▲
▲
▲
▲
▲
3
Toner reception seal
✕
▲
▲
▲
▲
▲
▲
▲
▲
4
Side seal F/R
▲
▲
▲
▲
▲
▲
▲
▲
5
Drum separation pawl
✕
▲
▲
▲
▲
▲
▲
▲
▲
6
Discharge lamp
✕
❍
❍
❍
❍
❍
❍
❍
❍
7
Image density sensor
✕
❍
❍
❍
❍
❍
❍
❍
❍
8
OPC drum marking sensor
✕
❍
❍
❍
❍
❍
❍
❍
❍
9
Side seal R base sheet
✕
▲
✕
▲
✕
▲
✕
▲
10 Cleaning brush
✕
✕
✕
✕
✕
✕
✕
✕
1
6
8
7
10
4
2
5
3
4
9
AR-M550/M620 DETAILS OF EACH SECTION 6 - 77
(2) Maintenance and parts replacement
(List of Replacement Parts)
AR-M550U/M550N (PM: 250K)
When
calling
250K 500K 750K 1000K 1250K 1500K 1750K 2000K
Remark
AR-620U/M620N (PM: 300k)
300K 600K 900K 1200K 1500K 1800K 2100K 2400K
Unit name
No.
Part name
Drum
peripheral
section
peripheral
section
9
Sawtooth
❍
▲
▲
▲
▲
▲
▲
▲
▲
10 Screen grid
✕
▲
▲
▲
▲
▲
▲
▲
▲
11 MC cleaner
▲
▲
▲
▲
▲
▲
▲
▲
9
10
11
No.
Unit
Parts
a
Process unit
1
OPC drum
✕▲
2
Separation pawl
✕▲
3
Cleaning blade
✕▲
4
Toner receiving seal
✕▲
5
Side seal F/R
▲
6
Cleaning brush
✕
7
Process adsorption plate
8
Drum separation pawl solenoid
9
OPC drum cleaner temperature
sensor
sensor
10
Discharge lamp
✕❍
11
Image density sensor
✕❍
12
OPC drum marking sensor
✕❍
a-1
a
a-10
a-12
a-8
a-9
a-7
a-11
a-6
a-5
a-3
a-2
a-4
a-5
AR-M550/M620 DETAILS OF EACH SECTION 6 - 78
a. Process unit
1) Open the front door.
2) Open the process cover.
3) Open the left door.
4) Remove the MC charger unit.
5) Remove the blue screw.
6) Unfix the drum to remove the bearing.
7) Pull out the process unit by clasping the bolt head.
a-1. OPC drum
1) Disconnect the connectors.
2) Remove the blue screw to open the lower frame.
3) Gently remove the drum, guide and all.
4) Remove the guide.
NOTE:
(OPC layer break-off on both sides of the OPC drum)
The OPC layer of a certain area of the OPC drum may break off due to
rotational friction. The OPC layer break-off generated in the area
shown below will not affect print images. Therefore, the drum can be
used without replacement.
rotational friction. The OPC layer break-off generated in the area
shown below will not affect print images. Therefore, the drum can be
used without replacement.
12mm
14mm
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