Hitachi RAS-50YH4 Service Manual page 79

10. Reset Circuit
Main
P.W.B
62
+
JW10
0V
The reset circuit initializes the microcomputer program when Power is "ON" or "OFF".
●
Low voltage at pin
●
Fig. 10-1 shows the reset circuit and Fig. 10-2 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 and
●
reset voltage input to pin
Reset voltage will be hold "Hi" until the 12V line voltage drops to 9.90V even though the power shuts down.
●
12
6
0
12
6
0
HIC
12V
R284
0V 0V 0V 0V
resets the microcomputer, and HI activates the microcomputer.
48
of microcomputer is set to Hi.
48
12V line
5V line
Reset voltage
5V
8
2
–
1
+
3
IC5 (1/2)
R288
Fig. 10-1
12V line
5V line
Reset voltage
Fig. 10-2
– 89 –
Microcomputer
R289
R252
48
RESET
0V
Time
Time