HP LaserJet 4250 Service Manual - Page 133

Printing from tray 2 When the dc controller PCA receives the print command, the main motor (M101) and scanner motor start their rotation. When the main motor reaches its prescribed speed, the feed roller clutch (CL101) and tray 2 pickup solenoid (SL101) are activated. (The main motor rotation drives the tray 2 pickup roller, tray 2 feed roller, tray 2 separation roller, and paper-feed rollers.) The tray 2 pickup roller, which the pickup solenoid activates, rotates once and picks up the media in the tray. The separation roller prevents additional sheets from feeding with the first sheet, and the media is fed to the pre-feed sensor (PS102). The sheet then reaches the registration assembly, where its skew is corrected. The sheet then passes through the transfer, separation, and fusing stages; through the delivery unit; and to the output bin. Tray 2, 500-sheet feeder, and 1,500-sheet feeder media-size detection Three switches detect the size of media in the cassette. The switches are active when the cassette is placed in the tray 2 feeder, 500-sheet feeder, or 1,500-sheet feeder. The dc controller PCA microprocessor detects the size and presence of the media by reading the combinations of the switches. Table 5-3 Tray 2 and 500-sheet feeder media-size-switch settings Paper size No cassette installed A4 LTR B5 A5 EXE LGL UNV Media-size-switch setting Upper Off Off Off Off On On On On Center Off Off On On Off Off On On Lower Off On Off On Off On Off On Table 5-4 1,500-sheet feeder media-size-switch settings Paper size No cassette installed A4 LTR LGL Media-size-switch setting Upper Off On Off On Center Off Off On On Lower Off On On Off Paper-pickup-and-feed system 119