Operator`s manual

4.5.21: Left Margin Sensor Removal and Replacement - Figure 4.10
The left margin sensor is an electronic “photo-interrupter.” It contains a light emitting
diode (LED) on one side as a light source and a photo-transistor on the other side which
acts as an on/off switch. The LED light source turns on the photo-transistor any time the
carriage plate sensor flag is away from the sensor and the light travels through
unobstructed. When the flag is in the sensor, the light is blocked and the photo-transistor
turns off.
The microprocessor on the controller board reads the status of the photo-transistor to
determine if the carriage is at the true left margin. This is a reference point and carriage
position is calculated relative to this position.
Being a semi-conductor electronic device, the sensor is subject to failure. If this should
happen, it is easily replaced as described below:
1. Move the carriage (160) away from the margin sensor (150) to allow ample
working room.
2. Remove the electronic chassis (62) from the print mechanism (see Paragraph
4.5.4).
3. Locate the margin sensor cable connector in the cable harness which is behind the
platen. Cut any wire ties necessary to free the sensor cable from the harness. Pull
the sensor cable out of the endplate opening.
Figure 4.10: Left Margin Sensor
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