Kyocera FS-1900 Service Manual page 77

4-1 Electrophotographic system .......................................................................................................... 4-3
4-1-1 Electrophotographic cycle ......................................................................................................... 4-3
(1) Main charging ............................................................................................................................ 4-4
Components of drum and main charger unit .................................................................................. 4-4
Amorphus-silicon drum ................................................................................................................... 4-5
Charging the drum .......................................................................................................................... 4-6
(2) Exposure ................................................................................................................................... 4-7
Laser scanner unit .......................................................................................................................... 4-8
Drum surface potential .................................................................................................................. 4-10
(3) Development ............................................................................................................................ 4-11
(4) Transfer .................................................................................................................................... 4-14
(5) Fusing ...................................................................................................................................... 4-15
Fuser unit mechanism ................................................................................................................... 4-16
(6) Cleaning .................................................................................................................................. 4-17
4-2 Paper feeding system .................................................................................................................... 4-18
4-2-1 Paper feed control ................................................................................................................... 4-19
(1) Paper feeding mechanism ....................................................................................................... 4-20
Drive and paper transfer unit......................................................................................................... 4-20
MP tray paper feed unit ................................................................................................................. 4-21
Fuser unit and face up/down output .............................................................................................. 4-22
4-3 Electrical control system .............................................................................................................. 4-23
4-3-1 Electrical parts layout .............................................................................................................. 4-23
(1) Circuit boards, sensors and switches ...................................................................................... 4-23
(2) Motors, solenoids, clutches and others ................................................................................... 4-24
(3) Drum unit and developer ......................................................................................................... 4-25
4-3-2 Operation of circuit boards ...................................................................................................... 4-26
(1) Main board ............................................................................................................................... 4-26
(2) Engine board ........................................................................................................................... 4-27
Eraser lamp control circuit ............................................................................................................ 4-28
Toner motor control circuit ............................................................................................................. 4-29
Heater lamp control circuit ............................................................................................................ 4-30
(3) Sensor board ........................................................................................................................... 4-32
Paper gauge sensing circuit .......................................................................................................... 4-32
Interlock circuit .............................................................................................................................. 4-33
Paper size detecting circuit ........................................................................................................... 4-35
(4) Power supply unit .................................................................................................................... 4-37
(5) High voltage unit ...................................................................................................................... 4-38
Chapter 4 Contents