Hitachi RAF-50FX8 Service Manual page 126

9. Reset Circuit
Main
P.W.B.
62
+
0V
Reset circuit performs initial setting of the microcomputer program before power is turned on.
Microcomputer resets program with reset voltage set to Lo, and program can be operated with Hi.
Fig. 9-1 shows the reset circuit and Fig. 9-2 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 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.
12
6
0
12
6
0
12V
R284
2
JW10
3
IC5(1/2)
0V
R288
0V
0V 0V
12V line
5V line
Reset voltage
5V
8
0V
-
1
R252
+
0V
Fig. 9-1
12V line
5V line
Reset voltage
Time
Time
Fig. 9-2
– 146 –
HIC
Microcomputer
(AX-8T11)
48
RESET