Brother MFC640CW Service Manual page 291

Problems due to machine malfunction
Check
Main PCB
ADF
Document rear
sensor
Possible causes
The motor driver IC is defective.
The spring plates of the ADF parts
are deformed.
The ADF parts are deformed or
worn.
- The document rear sensor is
defective.
- The document rear sensor
actuator is deformed.
9 - 4 0
Problems that may result
Documents will not be able to
be drawn in.
Documents will stop halfway
through feeding.
Two or more sheets of
documents will be fed through
at once.
Documents will stop halfway
through feeding or the machine
will not be able to recognize
them.
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