Brother LX-200 Service Manual page 120

Paper Width Detector Circuit
This circuit detects the width of the document and determines the Y-carriage
position. It also determines the Y-carriage standby position when the power is ON
or the cover is closed.
This circuit comprises the transmissive photosensor YCA-F mounted on the Paper
size detector PCB that is attached to the Y-carriage. If the Y-carriage is in its
standby position, the sensor lever cuts the photosensor. When the main CPU output
P31 (YCA-LED) is Low, the input signal P63 (YCA-F) becomes Low.
When a document is inserted, the Y-CA motor rotates to move the Y-carriage to the
edge of the document, where it moves the sensor lever cutting off the photosensor
and thereby detects the edge of the document. The selected automatic cutting mode
is also used to determine the Y-carriage (Y-cutter) position.
When the document edge is detected, the main CPU input signal P63 (YCA-F)
becomes Low. However, as P31 is normally at High status, the photosensor does
not operate and the main CPU input signal P63 (YCA-F) remains High, irrespective
of the Y-carriage position.
Fig. 5.4-4
Paper Length Detector Circuit
This circuit detects the length of the document and determines the X-cutter position.
The paper length detect switch P-END (paper sensor) is attached to the paper feed
roller unit. When a document is inserted, the sensor lever turns ON the switch and
the CPU input signal becomes Low status.
Fig. 5.4-5
Paper Width Detector Circuit
Paper Length Detector Circuit
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