Ricoh FT4430 Service Manual page 90

PAPER SIZE DETECTION
[Actuator Plate Combination Table]
Five microswitches in the cassette entrance detect the cassette tray paper
size. The paper size switches [A] are actuated by a plate on the front of the
cassette. Each paper size has its own unique combination of notches in the
actuator plate [B]. The CPU reads which microswitches have been
deactivated (HIGH - LOW) by the actuator plate to determine which size
cassette has been inserted.
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