Lexmark 3200 Service Manual page 18

Sensor input
The sensor input includes home position sensor and ADF cover sensor.
1. Home position sensor
The home position of the carrier motor is detected by photo sensor. The photo
transistor transmission to the photo sensor receiver circuit is shown below .
The home position is detected when the carrier passes between the LED and the photo transistor.
2. ADF cover sensor
The operation of the ADF cover sensor is the same as that of the home position sensor.
+5V +5V
R R
Figure 1.5 Home position sensor
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