Hitachi RAS-E10H2 - Page 36

5.
Initial Setting Cir
cuit (IC401)
• W
hen
po
w
er
is
supplied,
the
microcomputer
reads
the
data
in
IC401
or
IC402
(E
2
PR
OM)
and
sets
the
preheating
activ
ation
v
alue
and
the
r
ating
and
maximum
speed
of
the
compresso
r,
e
tc.
to
their
initial v
alues
.
•
Data
of
self-diagnosis
mode
is
stored
in
IC401
or
IC402;
data
will
not
be
erased
ev
en
when
po
wer
is
tur
ned off
.
6.
P
o
wer Suppl
y
First,
35V
po
we
r
which
operates
the
indoor
unit
is
generated
by
t
he
po
w
er
source
section
of
the
outdoor
unit
and
supplied to the indoor unit through the C and D lines of the connecting cable.
Second,
use
the
DC/DC
con
ve
r
ter
and
the
35
V
po
we
r
supply
from
the
outdoor
unit
to
generate
12
V
contro
l
po
wer
, which dr
iv
es the stepping motor dur
ing the operation.
In
addition,
use
the
regulator
IC
121
to
generate
5
V
po
wer
required
fo
r
dr
iving
the
micro
computer
and
controllin
g
f
an motor
.
If
the
terminal
block
was
overheated
due
to
a
connecting
cable
improper
connection,
the
thermal
fuse
built
in
the
te
rm
inal
bl
oc
k
will
bu
rn
t
to
shut
off
the
12
V
line
and
stop
the
operation of
the
indoor
unit.
Then,
the
outdoor
uni
t
cannot
be
communicated
with
the
indoor
unit
and
a
communication
error
occurs
(the
outdoor
LD301
will
blink
9
times), stop all operations
.
Fig.
6-
1
Fig. 5-1
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
}
Voltage at point A
Waveform
T1 = Low speed
T2 = High speed
T2
T1
Voltage at point
B
Waveform
T1
Voltage at point
C
Waveform
Speed
(min
-1
)
T2
Voltage at point B (V
)
(1400)
10 2 3 4 5
T1
T2
Micro computer
Fan motor
Fig. 7-1
DC fan
motor output
DC fan motor
Speed
feedback
Fig. 7-2
Fig. 7-3
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