Ricoh Aficio BP20N Service Manual Download

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G144/G145 iv

Paper Feed Mechanism........................................................................6-5
Drive Mechanism ..................................................................................6-5
Laser Scanning Unit..............................................................................6-5
Development Unit .................................................................................6-5
Transfer Unit .........................................................................................6-5
Fusing Unit............................................................................................6-5
Electrical Components (PBA) ...............................................................6-6

6.3 SYSTEM LAYOUT ....................................................................................6-7

6.3.1 PAPER FEED UNIT..........................................................................6-8

Paper Separation Method .....................................................................6-8
Paper Tray ............................................................................................6-8
Pick-up roller.........................................................................................6-8
By-pass tray..........................................................................................6-8
Optional Paper Feed Unit .....................................................................6-8

6.3.2 TRANSFER UNIT .............................................................................6-9
6.3.3 DRIVE...............................................................................................6-9
6.3.4 FUSING UNIT...................................................................................6-9

Thermostat............................................................................................6-9
Thermistor.............................................................................................6-9
Hot Roller..............................................................................................6-9
Pressure Roller .....................................................................................6-9
Safety Features ..................................................................................6-10
Safety Devices....................................................................................6-10

6.3.5 LASER SCANNNING UNIT (LSU)..................................................6-10
6.3.6 TONER CARTRIDGE .....................................................................6-11
6.3.7 NEW AIO DETECTION ..................................................................6-12
6.3.8 TONER END DETECTION.............................................................6-12

6.4 ASIC(SPGP)............................................................................................6-13

6.4.1 MEMORY .......................................................................................6-13
6.4.2 FLASH MEMORY ...........................................................................6-13
6.4.3 SDRAM...........................................................................................6-14
6.4.4 SENSOR INPUT CIRCUIT .............................................................6-15

Paper Empty Sensor...........................................................................6-15
By-pass Tray Sensor ..........................................................................6-15
Paper Feeding ....................................................................................6-15
Paper Exit Sensor ...............................................................................6-15
Cover Open Sensor ............................................................................6-15
DC Fan/Solenoid Driving Circuit .........................................................6-15
Motor Drive Circuit ..............................................................................6-16
Transfer ..............................................................................................6-16
Fusing .................................................................................................6-16
LSU.....................................................................................................6-17

6.5 SMPS AND HVPS ...................................................................................6-18

6.5.1 HVPS (HIGH VOLTAGE POWER SUPPLY) ..................................6-19

1. Transfer High Voltage (THV+) ..........................................................6-19
2. Charge Voltage (MHV) .....................................................................6-19
3. Cleaning Voltage (THV-)...................................................................6-19
4. Developing Voltage (DEV)................................................................6-20
5. Supply...............................................................................................6-20