Brother LX-200, Руководство по обслуживанию

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5-16
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Trimming Motor Start Point Detect Circuit
This circuit rotates the trimming cam and Y-cutter cam forward and backward with
the trimming motor (T/C motor) to detect the position of each cam.
The trimming switch (TRG) is designed to turn OFF 150 steps before the trimming
cam standby position (T-cutter top position). Consequently, TRG switch is normally
ON.
The Y-cutter switch (Y-G) is designed to turn OFF at the Y-cutter top position. When
the power is turned on, the circuit checks that the Y-G switch is OFF. If the switch is
ON, the trimming motor reverses until the switch turns OFF. The position of the
TRG switch is not checked at power ON.
Fig. 5.5-3 Trimming Motor Start Point Detect Circuit
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Y-CA Motor Drive Circuit
This circuit drives the Y-CA motor using 2-2 phase excitation from the +24V DC
stabilized constant voltage and maintains a low voltage during Y-cutter operation.
The stepping motor excitation phases A, B, C, and D are controlled by main CPU
ports P03, P02, P01, and P00, respectively. The seven transistor arrays
incorporated into QA3 drive the Y-CA motor.
The drive voltage is controlled by the main CPU port P65, which a24V DC to
the Y-CA motor through transistors Q3 and Q4.
Fig. 5.5-4 Y-CA Motor Drive Circuit