Brother LX-300 Service Manual page 115

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Specification Switching Circuit
This circuit reads the specification switching information.
The specification switching is conducted by a ROM program built into the main CPU
according to the solder point settings on the PCB.
* Note that the solder point specifications change according to the CPU display
format.
Check the solder specifications in the P/L PCB diagram.
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Detector Circuits
These circuits detect the status of the switches and keys that operate the unit (Two-
connection switch, Start key, Stop key, Dial switch, Continuous key, and Extra
border key) and the sensors that determine the film type, document length and width,
and cover open/closed status. The Main CPU controls the motors, LEDs and
buzzer according to these input signals.
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Motor Drive Circuits
These circuits convert the motor control signals output from the main CPU output
ports to 24V drive signals and supplies these voltage signals to each motor.
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Power Supply Circuits
These circuits convert the unstabilized DC power supply input from the Jack PCB
into a stabilized +5V DC power supply for the logic ICs, including the main CPU,
and into a stabilized +24V DC power supply to drive the motors.
Fig. 5.3-6 Specification Switching Circuit
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