Brother PT-2500PC, Service Manual

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III - 8
[ 1 ] Circuit operation
The cutter motor drive sequence is described below.
The cutter stays in the home position when it is not in operation (The cutter sensor input
level is Low).
If the CPU issues a tape cutting command, this drive circuit rotates the DC motor
clockwise for cutting the tape. The moment the cutter starts and goes out of the home
position, the cutter sensor level goes High. When this sensor level goes Low again, the
CPU recognizes that the cutter has returned to the home position after cutting the tape
and then applies brake to the DC motor.
If the sensor level goes High again during braking, it indicates that the cutter has passed
through the home position. So the CPU rotates the DC motor counterclockwise and
applies brake when the sensor level goes Low.
This way, when the sensor level goes High or Low, the CPU rotates the DC motor
clockwise or counterclockwise, respectively. If the sensor level remains Low for 100 ms
when the brake is applied, the CPU judges that the cutter stops in the home position.
If the cutter lies out of the home position due to abnormal end of the previous operation,
the CPU rotates the DC motor counterclockwise to return the cutter to the home position
(initializing the cutter) before printing.
If the cutter sticks in the home position for 300 ms or does not return to the home
position for 1000 ms after the DC motor starts rotating clockwise, the CPU regards it as
an error and starts error processing.
If the cassette cover is opened (which is detected by the cover open sensor), the DC
motor does not operate.
[ 2 ] Error processing
If a cutter error occurs, the CPU turns the LED1 (red) on and disables all operations.
Turning the ON/OFF switch off and on will start error processing to return the cutter to
the home position.