Ricoh JP3000, Service Manual, Page: 93 / 693

DRUM
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SM C231/C237/C238
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2.5.2 DRUM DRIVE MECHANISM
The drum is driven by the main motor (a dc motor) through a timing belt [A] and
gears [B]. The main motor has an encoder (not shown) which sends pulses to the
main motor control board. The CPU on the board monitors the pulses and controls
the drum speed and stop positions.
The drum has two stop positions: the master eject (drum home) position and the
master feed position. These stop positions are determined by checking the feed
start timing sensor [C]. The CPU starts counting the main motor encoder pulses
after the feed start timing sensor is actuated.
When the drum is stopped at the master eject position, the master eject position
sensor [D] is actuated. When the master eject operation is started, the CPU
confirms that the drum is at the master eject position by checking this sensor.
There are other two sensors that check the drum position. The paper exit timing
sensor [E] and 2nd feed timing sensor [F] which are used to send the CPU (on the
MPU) the paper jam detection timing signals of the paper exit and the registration
area. (The actual jam checking is performed by the paper exit sensor and
registration sensor.)
C231D539.WMF
[A]
[B]
[C]
[D]
[E]
[F]