Hitachi RAD-18NH7A - Page 47

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5. Initial Setting Circuit (IC401)
● When power is supplied, the microcomputer reads the data in IC401 (E
2
PROM) and sets the preheating
activation value and the rating and maximum speed of the compressor, etc. to their initial values.
● Data of self-diagnosis mode is stored in IC401; data will not be erased even when power is turned off.
Fig. 5-1
Microcomputer
External ROM
SCL
SDA
0V
0V
0V
5V
5V 5V
C401
IC401 (E
2
PROM)
R404 R403
27
26
1
2
3
4
8
7
6
5
}
6. Temporary Switch
● The temporary switch is used to operate the air conditioner temporarily when the wireless remote control
is lost or faulty.
INDICATION P.W.B.
Option
5V
Temporary
Switch 1
Temporary Switch 2
C1
1
2
3
4
7
CN9
CN11A
5V
0V 0V
48
HA input
HA output
Micro computer
C2
M1
M2
R601
R602
C601
R701
33
Fig. 6-1