Kyocera Mita FS-1900, Service Manual

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4-32
FS-1900
(3) Sensor board
Paper gauge sensing circuit
Paper gauge operates in four levels of paper remaining in the cassette. The height of the paper stack
in the paper cassette changes the angle of the actuator. At the end of the actuator is a reflecting
mirror which reflects or interrupts the light emitting from photointerruptor sensors PH702 and
PH703 accordingly.
These two sensors generate four digital signals which will be digital-analog-converted and input to
A/D port of CPU. CPU then issues signals according to the level of the analog signals. The resultant
signals are used to monitor the amount of paper in the cassette through the network management
utilities.
Figure 4-3-10 Paper gauge sensor(s)
Paper transfer unit
Sensor board
Acutuator
(Reflecting mirror)
Paper gauge
sensor 2 (PH703)
Paper gauge
sensor 1 (PH702)
PH702
PH703
Empty
1/4 to 1/2
1/2 to 3/4
3/4 to full
PH702 PH703
L
H H
H
L
L
L
H
Actuator
position
Paper
gauge
D/A converted
output
Sensing input
approximately
5 V
approximately
2.25 V
approximately
1.95 V
approximately
3.9 V