Brother LX-300 Service Manual page 123

S
SG Motor Home-position Detector Circuit
This circuit detects when the SG motor is at the Trimming cam home position.
Fig. 5.5-3
S
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 LF motor operation.
The stepping motor excitation phases A, B, C, and D are controlled by main CPU
ports P43, P42, P41, and P40, respectively. The seven transistor arrays
incorporated into #5 drive the Y-CA motor.
The drive voltage is controlled by the main CPU port P54, which applies +24V DC to
the Y-CA motor through transistors Q16.
SG Motor Home-position Detector Circuit
Fig. 5.5-4 Y-CA Motor Drive Circuit
5-17