8-40 Phaser 4400 Laser Printer Service ManualFunction of Major ComponentsThe two figures on page 8-39 show the major components of the Stacker. Drive Motor Assembly ó Drives the Stacker Mid Roller Assembly and theExit Roller Assembly. Offset Motor Assembly ó Shifts the Offset Roller Assembly. Stack Full Sensor and Stack Full Actuator ó Detects when the stacking ofthe Exit Tray exceeds 500 sheets of paper. Stacker PWB ó Controls Stacker operations. Offset Roller Assembly ó Drives printed pages into the Stacker Tray,offsetting each from the normal position. Stacker Exit Sensor Assembly ó Located between the Mid Stacker RollerAssembly and the Offset Roller Assembly, it detects when paper passes intothe Tray Exit. Home Sensor ó The Stacker Home Sensor detects when the Offset RollerAssembly is in the home position. It is turned On when the Core Gear islocated at the sensing point of the Stacker Home Sensor. Direction Solenoid and Lever ó Switches the paper path between thenormal paper path and the Stacker paper path.Stacker ControlOffset Motor ControlWhen the end of a sheet of paper reaches the Stacker Exit Sensor Assembly, thesensor signal goes Low. The Offset Motor Assembly begins rotating clockwise for aspecified time after the signal goes Low. This clockwise rotation shifts the sheet ofpaper from the normal position. At the specified time after the Sensor Assembly Exitgoes Low, the Exit Motor Assembly begins rotating in the counterclockwisedirection, moving the Offset Roller Assembly back into home position, until theSensor Stacker Home signal (/Stacker HOME) goes Low. When the power is firstswitched on, the Offset Motor Assembly performs this offset operation once to makesure the Offset Roller Assembly is in the home position.Duplex OperationWhen the printer is running in Duplex mode, the paper partially feeds out into thestandard Exit Tray (under the Stacker Assembly). The paper then reverses direction,is printed on the second side, and sent to the Exit Tray of the Stacker.Full Stack DetectionThe Engine Logic Board examines the state of the Full Stack Sensor after the SensorAssembly Exit signal goes Low. The Engine Logic Board detects that the Exit Tray isfull when the Stack Full Sensor remains High for a set number of successive ExitSensor Assembly actuations (sheets of paper exiting in the Stacker). The Stack Fullcondition stays in affect until the Stack Full Sensor goes Low.
