HP Mopier 320 Service Manual - Page 192

Lifter Operation The lifter plate in the 2000-sheet Input Tray's paper tray is held by two wires that are wound on four pulleys by the Lifter Motor. When the paper tray is open, the pulley gears disengage from the motor gears, and the Lifter lowers by its own weight. The presence or absence of the tray is detected by switches SW701 through SW704 on the unit's Paper/Tray Size Switch Assembly. After the paper tray is closed, the Lifter Motor lifts the paper stack into position; this action is detected by the PS34 sensor. The PS34 sensor also maintains the height of the paper stack. As paper is picked up by the rollers, the number of sheets decreases. Once the paper stack decreases to a certain level, the PS34 sensor registers a low condition. Then the Paper Deck Driver turns on the Lifter Motor again and lifts the paper stack until the PS34 sensor registers sufficient paper in the tray. Power Supply The 2000-sheet Input Tray has an internal Power Supply that activates when the printer's power switch is turned on. The Paper Handling Controller on the printer sends a power-on signal to the Power Supply on the 2000-sheet Input Tray through the Controller PCA on the 2000-sheet Input Tray. When the signal is high, the Power Supply provides both +24V and +5V to the Paper Deck Driver. The +24V drives the motors, clutches, and solenoids for the lifter, feed, and pickup systems. The +5V drives the sensors and PCA electronics. Printing from the 2000-sheet Input Tray (Tray 4) or 2 x 500-sheet Input Tray (Trays 4 and 5) Trays 4 and 5 feed the paper upward through a guide slot in the Lower Right Door Assembly to the Paper Input Unit. Once there, the operation is the same as printing from Trays 2 and 3, described in "Printing from Tray 1" on page 153. C4229-90911 Paper Paths and Components 159