HP LaserJet 4 Service Manual - Page 141

Printing from the MP Tray (Tray 1) MP tray selection is provided by the Formatter PCA, as configured by the operator's control panel or by a software application. The MP tray (Tray 1) feed system's paper motion begins when the DC Controller PCA, after receiving a PRNT signal, starts the Scanner Motor (M5) and the Main Motor (M1). When the fusing roller reaches the minimum operating temperature (183° C), the MP pickup roller clutch solenoid (SL2) is energized for 1 second, allowing the MP pickup roller to make one rotation. Clutches and solenoids work together to start and stop gears and rollers used for paper movement. The MP pickup roller then feeds a sheet of paper from the MP tray (Tray 1). The Formatter PCA sends the VDO signal to the print engine within a specific time period after the paper reaches the Input/Registration Paper Sensor (PS1). This aligns the leading edge of the toner image on the photosensitive drum with the leading edge of the paper. After the paper passes the drum and the fusing rollers, it triggers the Paper Exit Sensor (PS3). The paper then is directed to the output tray. If the paper does not reach or clear each sensor within a specified time, the microprocessor on the DC Controller PCA assumes a paper jam occurred and informs the Formatter PCA. Figure 5-18 MP Tray (Tray 1) to Output Tray Paper Path Functional Overview 5-29