Ricoh DD 5450, Field Service Manual, Page: 117 / 403

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Chapter 3 Master Making/Master Feed/Ejection Section
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(3) Master top sensor
Description
The master top sensor is located at a fixed
distance relative to the master. By means of
reflected light, this sensor detects the presence of
the master on the master path.
If the photointerrupting condition (master not
present) is not obtained during master making,
"MASTER SET ERROR" is displayed.
Master
Master
top sensor
Operation
When there is no master, the sensor is in the state of photopassing (5V).
When master is placed inside, the sensor is in the state of photointerrupting (0V).
When no master is detected, the message "NO MASTER" is displayed on the LCD panel.
Circuit
Blue
White
Red
Main PCB unit
Reflected light: 0V
No reflected light: 5V
2