Hitachi RAC25NH4, Service Manual

Page: 56 / 115

– 66 –
7. Initial Setting Circuit (IC401)
●
When power is supplied, the microcomputer reads the data in IC401 or IC402 (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 or IC402; data will not be erased even when power is
turned off.
Fig. 7-1
Microcomputer
External ROM
SCL
SDA
0V
0V 0V
5V
5V 5V
C401
IC401 or IC402 (E
2
PROM)
R404 R403
27
26
1
2
3
4
8
7
6
5
}