Brother LX-1200, Service Manual

Page: 113 / 175

5-7
S
Clock Circuit
The main CPU incorporates a clock-generation circuit which uses externally
mounted components. This circuit and the main CPU internal circuit generate an
8 MHz clock signal.
Fig. 5.3-2 Clock Circuit
S
Reset Circuit
This circuit resets the main CPU when the power is turned ON or OFF.
S-80943ANMP-DD7 is used as the reset IC in this circuit.
When the power is turned ON, the reset IC holds the reset output Low for
approximately 5 ms after the +5V DC power supply applied voltage reaches 4.3 V.
After this period the reset output becomes High to clear the main CPU reset status.
When the power is turned OFF, after the +5V DC power supply applied voltage
drops to 4.3 V, or below, the reset IC sets the reset output Low to reset the main
CPU.
Fig. 5.3-3 Reset Circuit