Ricoh B064 Service Manual page 21

6.4.6 IMAGE PROCESSING TROUBLESHOOTING ..............................6-33
6.5 LASER EXPOSURE................................................................................6-36
6.5.1 OVERVIEW ....................................................................................6-36
OPTICAL PATH..................................................................................6-37
6.5.3 FOUR-BEAM EXPOSURE .............................................................6-38
6.5.4 COOLING FAN...............................................................................6-39
6.5.5 LD SAFETY SWITCHES ................................................................6-40
6.6 DRUM UNIT ............................................................................................6-41
6.6.1 OVERVIEW ....................................................................................6-41
6.6.2 OPC DRUM ....................................................................................6-42
6.6.3 DRUM DRIVE .................................................................................6-42
6.6.4 DRUM CHARGE.............................................................................6-42
6.6.5 CHARGE CORONA WIRE CLEANING ..........................................6-43
6.6.6 DRUM PICK-OFF MECHANISM ....................................................6-44
6.6.7 DRUM CLEANING..........................................................................6-45
6.6.8 DRUM VENTILATION AND OZONE FILTER.................................6-46
6.6.9 TONER RECYCLING .....................................................................6-47
6.6.10 WASTE TONER COLLECTION ...................................................6-48
Mechanism .........................................................................................6-48
Error Detection....................................................................................6-48
6.6.11 PROCESS CONTROL..................................................................6-49
What Happens at Power On ...............................................................6-49
Drum Potential Sensor Calibration......................................................6-50
Development Bias, Bias Grid, and LD Adjustment..............................6-51
ID Sensor Calibration (Vsg) ................................................................6-53
TD Sensor Calibration (Vref)...............................................................6-53
6.7 DEVELOPMENT AND TONER SUPPLY ................................................6-54
6.7.1 OVERVIEW ....................................................................................6-54
Development Unit ...............................................................................6-54
Toner Supply ......................................................................................6-55
6.7.2 DEVELOPMENT UNIT ...................................................................6-56
6.7.3 DEVELOPER/TONER MIXING (AGITATION)................................6-57
6.7.4 DEVELOPMENT BIAS ...................................................................6-58
6.7.5 TONER SUPPLY ............................................................................6-59
6.7.6 DEVELOPMENT UNIT DRIVE AND VENTILATION ......................6-60
6.7.7 TONER END SENSOR ..................................................................6-61
6.7.8 SHUTTER MECHANISM................................................................6-61
6.7.9 TONER BOTTLE SUPPLY AND VENTILATION ............................6-62
6.7.10 TONER SUPPLY CONTROL .......................................................6-63
Sensor Control Mode ..........................................................................6-63
Pixel Count Toner Supply Mode .........................................................6-64
TD Sensor Initialization .......................................................................6-65
Determining Vref .................................................................................6-65
Toner Supply without ID Sensor and TD Sensors ..............................6-66
Abnormal TD Sensor Output...............................................................6-66
Abnormal ID Sensor Output................................................................6-66
Toner End Detection ...........................................................................6-67
Toner End Recovery ...........................................................................6-67
6.8 IMAGE TRANSFER AND PAPER SEPARATION ...................................6-68
SM ix B064/B065