Hitachi RAC-25YH4, Service Manual, Page: 80 / 121

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6-2. Reset Circuit
The reset circuit initializes the microcomputer program when Power is “ON” from “OFF”
Low voltage at pin (48) resets the microcomputer, and HI activates the microcomputer
Fig. 6-7 shows the reset circuit and Fig. 6-8 shows waveform at each point when power is turned on and
off.
When power is turned on, 12V line and 5V line voltages rise and 12V line voltage reaches 10.9V an
reset voltage input to pin (48) of microcomputer is set to Hi.
Reset voltage will be hold “Hi” until the 12V line voltage drops to 9.90V even though the power shuts
down.
Fig. 6-7
Fig. 6-8
MAIN P.W.B.
RESET OUT.
10.9V
9.9v
RAS_25_35_AW_055-086 2003.12.31, 10:59 AM 78