HP 4300 Service Manual - Page 103

Tray 2, 500-, 1,500-sheet feeder media size detection Media size in the cassette are detected by three switches. The switches are active after the cassette is placed in the tray 2 feeder. (this also applies to the optional 500- and 1,500-sheet feeder). The DC controller PCA microprocessor detects the size and presence of the media by the combinations of the switches. Table 32. Tray 2 and 500-sheet feeder media size switch settings Paper size Media size switch setting Upper Center Lower No cassette installed Off Off Off A4 Off Off On LTR Off On Off B5 Off On On A5 On Off Off EXE On Off On LGL On On Off UNV On On On Table 33. 1,500-sheet feeder media size switch settings Paper size Media size switch setting Upper Center Lower No cassette installed Off Off Off A4 On Off On LTR Off On On LGL On On Off The tray 2 cassette can detect the media size using the switches describe above, however the user can define the media size for the tray using the control-panel (see "Paper Handling menu" on page 42). In this case the printer may not correctly detect the media size if the user's defined size does not match the tray settings. To prevent a false size detection, the printer measures the time it takes for the media to pass from its leading edge to its trailing edge and determines the media size that was fed from the tray. When the measured size differs from the user's defined size or from the media size switches, a message will appear on the control-panel display (see "Alphabetical printer messages" on page 258). Q2431-90912 Chapter 5 Theory of operation 83