EN Chapter 5 Theory of operation 117
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.
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