Paper feed system The printer in figure 29 on page 119 has two standard paper sources: the 100-sheet tray (tray 1) and the 500-sheet tray (tray 2). Up to two additional optional paper trays can be included. Both the size of the paper in the tray and the presence of a tray are detected by the three switches (SW600, 601, 602) on the paper size detection circuit assembly. All of the rollers on the paper path are driven by the main motor (M101). While the main motor rotates, the tray pickup solenoid is turned on, the tray pickup roller rotates, and a sheet of print media is fed into the printer. Then, the sheet passes the registration assembly, which compensates for the skew of the sheet.
After the top of page sensor (PS103) detects the leading edge of the sheet, the vertical synchronization signal (/TOP) is sent from the engine controller board to the formatter. After the formatter receives the /TOP signal, the /VDO signal is sent; this synchronizes the leading edge of the image on the drum with the leading edge of the sheet. The sheet of print media goes through transfer, separation, and fusing stages; passes through the delivery unit; and is delivered to the top output bin or rear output bin. There are five photosensors (PS102, PS103, PS106, PS107, PS108) in the paper path that detect the presence of media.
If a sheet does not reach or pass these sensors within a prescribed time interval, the microprocessor on the engine controller board detects a jam. EN Chapter 5 Theory of operation 117