– 76 –
4. Power Circuit for P.W.B.
●
Fig. 4-1 shows the power circuit for P.W.B. and waveform at each point.
22
18
19
+
D908
R917
R915
D909
R918
L903
REG1
C911
20
21
+
D907
C910
R914
C912
16
17
+
C903
C907
+
+
C914
14
13
R916
L902
35V
17V
5V
FM–15V
I/F0V
0V
0V
0V
FM–0V
C913
D910
REG2
Q706
C924
R920
R921
R922
PQ2
1
1
2
4
3
4
3
1
2
2
3
PQ1
VR1
R923
C906
C918
R911
D906
C908
PQ1
12
C
11
D904
R908
R909
D903
D905
D911
R910
R901
C901
R902
R903
R002
Diode stack 2
(RC2)
R904
2
5
3
4
1
+
+
IC901
C011
C010
R011
R010
C905
D902
R906
L901
R907
Switching transformer (T1)
Fig. 4-1 Power circuit for P.W.B.
1
9
+
C919
+
C921
C920
12V
D912
R919
R925
R924
ZD904
C909
15
1
2
JW8
JW8
4
3
●
In the power circuit for P.W.B., power supply for microcomputer, peripheral circuits, and system power
module driver circuit and, as well as DC 35V, are produced by switching power circuit.
●
Switching power circuit performs voltage conversion effectively by switching transistor IC901 to convert
DC 330V voltage to high frequency of about 20kHz to 200kHz.
●
Transistor IC901 operates as follows:
(1) Shifting from OFF to ON
●
DC about 330V is applied from smoothing capacitors C010
Œ
and C011
œ
in the control power circuit.
With this power, current flows to pin of IC901 via R903 and R904 and IC901 starts to tum ON. Since
voltage in the direction of arrow generates at point at the same time, current passing through R910 and
D903 is positive-fed back to IC901.
4
C
Summary of Contents for RAC-65NH5
Page 36: ...CIRCUIT DIAGRAM 37 ...
Page 37: ...CIRCUIT DIAGRAM MODEL RAC 65NH5 39 ...
Page 87: ... 99 SELF DIAGNOSIS LIGHTING MODE ...
Page 89: ... 101 2 Outdoor unit does not operate but receives remote infrared signal ...
Page 91: ... 103 6 Check the main P W B power circuit ...
Page 92: ... 104 CHECKING THE REMOTE CONTROLLER ...
Page 97: ... 109 ...
Page 107: ...HITACHI PM NO 0000E Printed in Malaysia RAK 65NH5 RAC 65NH5 ...