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AR-M550/M620  DETAILS OF EACH SECTION  6 - 61

∗

This unit must not be disassembled in the market.

The number of mirror surfaces and the motor RPM are reduced to
reduce noises and increase reliability.

7

BD PWB

Detects the timing of laser scan start. This device is used to detect a laser trouble. 

8

No. 2 mirror

Converges laser beams to focus. 

9

Plane lens

Assures the optical path for laser beams.

10

Convergence lens for BD

Converges laser beams onto the BD PWB.

No.

Name

Code, signal name

Function

RW

Control signal 

+5VLD

5V power for laser diode

RW

Control signal

/READY

Polygon mirror motor READY signal ("L" in the constant speed rotation)

RW

Control signal 

/PMCLK

Clock signal for driving the polygon mirror motor

RW

Control signal

/START

Polygon mirror motor drive start signal

RW

Control signal 

/VIDEO

VIDEO (Image signal)

RW

Control signal

/SYNC

Sync signal (SYNC) from BD, sync signal for 1 line

No.

Name

Function

Model

Number of 

mirror surfaces

Rotation 

speed

Bearing

Remark

55PPM

14 surfaces

34000rpm

AIR

Superior in silence

62PPM

14 surfaces

34000rpm

AIR

Effective scan width:

297mm

Resolution:

600dpi

Beam diameter:

Main scan = 60 -  85 

µ

m

Sub scan = 75 - 110 

µ

m

Laser power:

0.385±0.04mW

LD wave length:

770 - 795nm

AR-M550/M620  DETAILS OF EACH SECTION  6 - 62

(List of Replacement Parts)

1) Pull out the multi paper feed tray, and remove the manual paper

feed cover F.

2) Pushing the lower part, remove the right cabinet center.

3) Disconnect the connector, and remove the process cooling fan

unit.

1) Remove the right cabinet middle. (See “a. Process cooling fan unit”

2) Disconnect the connector, release the pawl, and remove the

machine temperature sensor.

1) Remove the process cooling fan unit. (See “a. Process cooling fan

2) Disconnect the connector, and remove the process cooling fan

motors 1(A), 2(B), and 3(C).

1) Remove the process cooling fan unit. (See “a. Process cooling fan

2) Disconnect the connectors to remove the LSU unit.

No.

Unit

Parts

a

Process cooling fan unit

1

Machine temperature sensor

2

Process cooling fan motor 1 
(LSU, process section)

3

Process cooling fan motor 2 
(LSU, process section)

4

Process cooling fan motor 3 
(LSU, process section)

b

LSU

a-1

a-2

b

a

a-3

a-4

A

B

C

AR-M550/M620  DETAILS OF EACH SECTION  6 - 63

Toner is attached to electrostatic latent images formed by the laser
beams which were radiated to the OPC drum charged by the main
charger, forming toner images. 

The toner images formed on the OPC drum are transferred to paper by
the transfer belt.

1

2

5

3

4

No.

Name

Operation

1

Toner hopper unit, toner bottle unit

Provides toner to the developing unit, and collects waste toner in the front section of the toner 
bottle unit (waste toner box section). 

2

Developer unit

Mixes toner and carrier, and attaches toner to electrostatic latent images to form visible images.  

3

Process drum unit

Forms images (electrostatic latent images, visible images) on the OPC drum. 

4

Transfer unit

Transfers toner images to the OPC drum. 

5

Main charger unit

Charges the OPC drum surface negatively and evenly. 

No.

Name

Functions

1

Laser beams

Forms electrostatic latent images on the OPC drum. (Writing resolution: 600dpi)
Radiated from the LSU. The output can be set with the simulation. (Basically not changed from the default.)

2

OPC drum

Electrostatic latent images are formed by laser beams. Toner is attracted to the latent electrostatic images 
and transferred to paper. An OPC drum is employed. The diameter is 80mm. 

3

Main charger

Applies a high voltage to charge the OLPC drum. The saw teeth type is employed. 

4

Screen grid

Carries electric charges from the main charger to the OPC drum evenly. 

5

MG roller

Forms a magnetic brush with developer, and applies toner to the OPC drum. -500V

6

Developing doctor

Keeps the thickness of developer or toner layer on the MG roller at a fixed level. 

7

Toner concentration sensor

Detects toner in the developing tank. The transmission type sensor is employed. 

-590v

-6.2kv(700

µ

A)

-2.0kv

-300v

+500v

-150v

AC4.5kv
(P-P)

+2.0kv

(35

µ

A)

(1.5 - 2.0kv)

10

8

Ω

Transfer belt
cleaning mode

Cleaning roller
cleaning mode

Cleaning mode

Transfer mode

Cleaning 
mode

Developing 
mode

4

3

5

1

3

6

8

2

9

11

12

10

7

AR-M550/M620  DETAILS OF EACH SECTION  6 - 64

Adoption of the rotating toner bottle enables large capacity with a com-
pact toner bottle size. 

When the remaining toner detection sensor in the toner hopper unit
detects no toner, the toner bottle turns to supply toner to the toner hop-
per. Following supply, since the sensor detects full or empty status
inside the toner hopper based on a standard quantity of approximately
150 g of toner, even if the toner cartridge becomes empty, copying is
not immediately suspended because toner inside the toner hopper is
used (approximately 5K/6% print duty documents).

The employment of new toner has reduced the toner consumption per
page by 20 -30%.

8

Transfer roller

Applies a voltage to transfer toner from the OPC drum to paper. 

9

Drum separation pawl

Separates paper from the OPC drum mechanically. 

10

Cleaning blade

The protection circuit to prevent against electric leak of high voltage through the paper guide when the 
humidity is high. 200 Ohm each. 

11

Resist roller

Deflects paper to adjust the paper feed timing to the process section. 

12

Paper dust cleaner

Remove paper dust from the resist roller to reduce paper dust entry to the process section.

No.

Name

Functions

Destination

Toner filling amount

Life with 6% print duty 

documents

Except Japan

1,430g

72,000 sheets

Japan

Provisionally 1,180g

50,000 sheets or more