5 Theory of Operation Basic operation......................................................................................................................................50 Sequence of operation (scanner) ........................................................................................50 Formatter system...................................................................................................................................51 Sleep mode...........................................................................................................................51 CPU.......................................................................................................................................51 Memory ................................................................................................................................51 Control panel.........................................................................................................................52 Scanner controller board......................................................................................................52 Engine control system ..........................................................................................................................53 Engine power supply circuit .................................................................................................53 Flatbed unit and ADF system ...............................................................................................................54 Electrical system...................................................................................................................54 Motors and fans ...................................................................................................................55 Optical assembly...................................................................................................................55 ADF feed system..................................................................................................................57 Jam detection........................................................................................................................57 Residual-media jam.............................................................................................57 ADF pickup jam....................................................................................................58 ADF jam...............................................................................................................58 Registration-sensor jam......................................................................58 Read-sensor jam.................................................................................58 Exit-sensor jam....................................................................................58 ADF cover-open jam............................................................................................58 ADF open jam......................................................................................................58 6 Removal and replacement Removal and replacement strategy.......................................................................................................60 Required tools.......................................................................................................................60 Before performing service ....................................................................................................60 After completing service ......................................................................................................61 Screws that are used in the digital sender............................................................................61 User-replaceable parts..........................................................................................................................62 Separation pad......................................................................................................................63 Pickup roller assembly..........................................................................................................65 Pickup-roller cover ...............................................................................................................66 ADF mylar shield...................................................................................................................67 Mylar-holder assembly..........................................................................................................70 Control panel.........................................................................................................................71 Control-panel overlays..........................................................................................................72 Formatter assembly..............................................................................................................73 Hard disk...............................................................................................................................74 Hard-disk drive cable............................................................................................................76 Memory DIMM......................................................................................................................77 Compact flash card ..............................................................................................................78 Hinge flaps............................................................................................................................79 Paper input tray.....................................................................................................................80 External components and covers .........................................................................................................81 Control panel lower cover.....................................................................................................81 Control panel upper cover....................................................................................................83 v