Description Of Main Circuit Operation; Power Circuit Diagram - Hitachi RAF-25NH4 Service Manual

ESCRIPTION OF MAIN CIRCUIT OPERATION
MODEL RAF-25NH4, RAF-50NH4
1. Power circuit
35V
1CP2
R121
1CP1
Q115
＋ ＋
− −
0V
OVER-CURRENT
CONTROL CIRCUIT
Power to operate indoor unit (DC35V) is generated at the power supply in outdoor unit and it is sent to indoor unit
through the connecting cord C and D.
Then, DC 12V (12V line) is generated using DC/DC converter from the voltage sent from outdoor unit, as the
control voltage of 12V is required to drive the stepping motor and others.
Furthermore, 5V (5V line), which is necessary to drive the microcomputer and to control the fan motor, is generated
using three-terminal regulator IC121.
DC/DC
CONVERTER
Q111
L111
R114
Q113
Q112
5 5
R115
2
7
IC111
D111
6
3
1 4
Q114
12V
FAN-MOTOR
POWER-SUPPLY
CONTROL CIRCUIT
CJ101
D121
C133
＋
IC121
IN OUT 5V
GND
＋
− C122
0V
THREE TERMINAL
REGULATOR
Fig. 1−1
168
CJ102
Q131
CN10
XA-5P-TOP(RED)
6
INDOOR
UPPER FAN
5
MOTOR
M
4
3
2
1
CN15
XA-5P-TOP
6
INDOOR
LOWER FAN
5
MOTOR
4
M
3
2
1
POWER SUPPLY
25
CONTROL OUTPUT1
54
LOWER FM FEEDBACK
DCFAN
39
OUTPUT LOWER FAN
53
UPPER FM FEEDBACK
DCFAN
40
OUTPUT UPPER FAN