Epson C 2900 Manual

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3.5 ROS ASSY 
3.5.1 Major functions
- ROS ASSY
ROS ASSY is an exposure unit that generates laser beams to form electrostatic latent image on the 
drum surface.
In this manual, the ROS ASSY is referred to as ROS.
The ROS mainly consists of the following parts:
•  LD PWB
•  Scanner ASSY
•  SOS PWB
•  Lens
•  Mirror
•  Window
• LD PWB
The LD PWB is comprised of four LDs (laser diodes) corresponding to Y, M, C, and K.
Each LD converts the electric signals of incoming image data into laser wave or pulse. In order to 
stabilize the laser light quantity during formation of an electrostatic latent image, the LD PWB 
always monitors the laser light quantity to adjust it to the appropriate level. This is called APC 
(auto power control).
• Scanner Assy
The Scanner Assy is comprised of the Scanner Motor that rotates at a constant speed and the 
Polygon Mirror that is mounted on the motor shaft.
The laser light output from the LD is irradiated onto the Polygon Mirror via the Mirror.
The Polygon Mirror, provided with six reflecting mirror faces, changes the reflection angle of the 
laser light as it rotates by the Scanner Motor, thereby allowing the laser light to scan the drum 
along its axial direction. Scanning is performed using one reflecting mirror face for each line.
• SOS PWB
The SOS sensor on the SOS (start of scan) PWB converts an incoming laser beam, upon detec-
tion, to an electric signal as the reference signal for starting scanning and transmits this signal to 
the PWBA MCU.
The SOS sensor signals are used to synchronize the starting point of the laser-beam scanning 
with the starting point of the image writing.
• Lens / Mirror / Window
The laser light reflected from the Polygon Mirror reaches the drum surface via the Lens, Mirror, 
and Window. The Lens corrects aberration, the Mirror secures an optical path, and the Window 
prevents foreign matters from entering the ROS. 
						

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LD PWB Polygon Mirror
Scanner Assy
SOS PWB Lens
LensMirror
Mirror Mirror
Mirror
Window ROS ASSY Rear view illustration
SOS Sensor
MiS06039SA 
						

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3.6 TONER CARTRIDGE & DISPENSER
3.6.1 Major functions
- CONNECTOR CRUM (PL5.1.14)
The CONNECTOR CRUM reads and writes the data of the CRUM.
Printer specific information is stored.
- MOTOR ASSY DISP YMCK (PL5.1.3)
The dispense motor supplies the drive to the Agitator and Auger in the TONER CARTRIDGE, and 
supplies toner to the developer.
MOTOR ASSY DISP (K)
MOTOR ASSY DISP (C)
MOTOR ASSY DISP (M)
MOTOR ASSY DISP (Y) TONER CARTRIDGE (K)
CONNECTOR CRUM (K)
TONER CARTRIDGE (C)
CONNECTOR CRUM (C)
TONER CARTRIDGE (M)
CONNECTOR CRUM (M)
TONER CARTRIDGE (Y)
CONNECTOR CRUM (Y)
MiS06040SA 
						

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3.7 Drum Cartridge
3.7.1 Major functions
- Drum Cartridge (PL4.1.21)
Drum Cartridge carries out a series of operation in the print process such as charging, and transfer.
Drum Cartridge mainly consists of the following parts.
Developer is an equipment which develops images in the print process.
• Drum (Y) • Developer (Y)
• Drum (M) • Developer (M)
• Drum (C) • Developer (C)
• Drum (K) • Developer (K)
- CRUM
Drum Cartridge specific information is stored.
- Erase Lamp (LED ASSEMBLY) 
The light of the LED is reflected by the HOLDER ASSY Erase.
The light of the LED eliminates the charge on the drum.
MiS06023KA Erase Lens Drum Cartridge
Erase Lamp (K) LED ASSY  ERASE
Erase Lamp (C)
Erase Lamp (M)
Erase Lamp (Y)
Drum
Drum (K)Erase Lens
Drum (C)
Drum (M)
Drum (Y) 
						

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Drum Cartridge
Drum (K)
Drum (C)
Drum (M)
Drum (Y)
Developer (K)
Developer (C)
Developer (M)CRUM
Developer (Y)
Rear view illustration
LED ASSY  ERASE
MiS06041SA 
						

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3.8 Drive
3.8.1 Major functions
- DRIVE ASSY MAIN (PL7.1.2) (Refer to 6.1 DRIVE ASSY MAIN)
Supplies the drive to parts as follows.
• DRIVE ASSY PH
• TRANSFER ASSY
• CHUTE ASSY FDR REGI
• Drum Cartridge
• DRUM (Y, M, C, K)
- DRIVE ASSY SUB
Supplies the drive to parts as follows.
• FUSER UNIT
• DEVELOPER (YMCK)
DRIVE ASSY  SUBDRIVE ASSY  MAIN
DRIVE ASSY  PH
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Confidential - DRIVE ASSY PH (PL7.1.4)
DRIVE ASSY PH transmits the driving force from the DRIV ASSY SUB (PL7.1.1) to relevant parts.
The transmission channel is changed by the COLOR MODE SWITCHING SOLENOID in the DRIVE 
ASSY PH to allow the driving force of the DRIVE ASSY MAIN (PL7.1.2) to reach the Black Devel-
oper only.
This is performed to ensure that the Yellow, Magenta, and Cyan Developers cannot be rotated by 
the DRIVE ASSY SUB during B/W printing. 
The COLOR MODE SWITCHING SENSOR detects the status of the transmission route (whether it 
is set for B/W or full color).
MiS06026KA
[ FULL COLOR MODE ]
MAGNET ROLL (Y) MAGNET ROLL (M)
MAGNET ROLL (C)
MAGNET ROLL (K)DRIVE ASSY  SUB
DRIVE ASSY  PH Sub Motor
COLOR MODE
SWITCHING SENSOR
COLOR MODE
SWITCHING SOLENOID CAM C
GEAR C
GEAR D2 GEAR D4
GEAR D3 IN
Drive to
MAGNET ROLL
(Y), (M), (C)
Drive from
Sub Motor GEAR D3 OUTCAM C
FLANGE D3 
						

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MiS06027KA
MAGNET ROLL (K)DRIVE ASSY  SUB
DRIVE ASSY  PH Sub Motor
GEAR D2 GEAR D4
GEAR D3 IN
Cutting of drive
Drive from
Sub Motor GEAR D3 OUTCAM C
FLANGE D3
[ BLACK and WHITE MODE ]
COLOR MODE
SWITCHING SENSOR
COLOR MODE
SWITCHING SOLENOIDCAM C
GEAR C 
						

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3.9 Electrical
3.9.1 Major functions
- FAN (PL8.1.1)
Dissipates heat out of the printer to prevent the printer from overheating.
-SWITCH
The SWITCH turns ON/OFF the AC power supply of the printer.
- Low Voltage Power Supply (LVPS:PL8.2.1)
The LVPS is provided in two types, 120V and 240V.
Supplies AC power from the power source to the Fuser Unit heater and generates and supplies sta-
ble low voltage DC power used for the logic circuit, etc.
LVPS contains control circuit for the heater of the Fuser Unit, in addition to the power circuit.
- Machine Control Unit (MCU:PL8.2.13)
Controls printing operation based on the communication with the print controller and information 
from the sensor/switch.
Major functions are as follows:
• Communication with the ESS.
• Receive of information from the sensors or switches.
• Control of Motor in DRIVE ASSY MAIN and DRIVE ASSY SUB.
• Distributing low voltage DC power output from LVPS to each component
• Control of ROS ASSY
- High Voltage Power Supply (HVPS:PL4.1.19)
Supplies high voltage to the following parts in the TRANSFER ASSY and Developer to perform 
charging, development, and primary transfer.
• BCR
• BTR
• Developer
- PWBA EEPROM (PL8.2.16)
Information unique to the printer is stored.
- Electronic Sub System (ESS:PL8.1.7)
The ESS connected to the MCU controls the entire system (Diagnostic, Interface and Image pro-
cessing).
- HUMIDITY SENSOR (SENSOR HUM:PL8.2.7)
HUMIDITY SENSOR reads the temperature/humidity within the printer and converts the values to 
voltage values.
- OPERATOR PANEL (CONSOLE ASSY PANEL:PL1.2.3)
OPERATOR PANEL displays the state of the printer using LED. 
- INTERLOCK SWITCH (HARN ASSY INTERLOCK:PL8.2.5)
INTERLOCK SWITCH is a switch that cuts the +24VDC power supply to the HVPS or Motor, etc. 
upon the opening of the Front Cover. 
						

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Confidential - WIRELESS ADAPTER (PL8.1.16)
An adapter for enabling the network connectivity of the printer by wireless.
- SIDE COVER SWITCH (PL5.1.9)
SIDE COVER SW is a switch that detects the right side cover open.
FA N
SWITCHPWBA EEPROM
HUMIDITY SENSORLow Voltage Power Supply
High Voltage
Power Supply OPERATOR PANEL
MEMORY
CARD
Electronic Sub SystemMachine
Control Unit
WIRELESS ADAPTER
INTERLOCK SWITCHSIDE COVER SWITCH
MiS06043S A