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4. Power Supply Circuit
●
Fig. 4-1 shows the power circuit.
●
There are two switching power supply in Power PWB.
●
Switching power supply 1 is generating the secondary power for control circuits.
●
Switching power supply 2 is generating the DC12V for expansion valve and DC35V for indoor unit 1 and 2.
●
Switching power supply 3 is generating the DC12V for expansion valve and DC35V for indoor unit 3 and 4.
●
Switching power supply performs voltage conversion effectively by switching transistor IC1 to convert DC330V
to high frequency of approximately 20kHz to 200kHz.
●
Transistor IC1 operates as follows:
Fig. 4-1 Power circuit for P.W.B.
3A
FUSE
C790
C705
C776
C734
FB3
R771
R770
R772
C767
C766
D733
C768
D732
C771
R790
R720
C774
C775
C780
R778
R777
R773
D730
C769
R775
C776
D731
R774
(
6
C770
D735
C773
L702
— B
— B
— B
— B
C777
R779
D736
3
IC3
— A
— A
— A
— A
Summary of Contents for RAM-71QH5
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Page 24: ...CIRCUIT DIAGRAM MODEL RAM 71QH5 25 ...
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Page 27: ... 31 ...
Page 28: ... 33 Outdoortemperature STAROTP_C TSKTM1_C1 Outdoortemperature STAROTP_C TSKTM1_C2 ...
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Page 34: ... 43 RAM 71QH5 ...
Page 42: ... 51 ...
Page 52: ... 61 ...
Page 60: ... 69 ...
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Page 74: ... 86 Lighting mode self diagnosis lamp Location of self diagnosis lamp 1 RAM 71QH5 ...
Page 75: ... 87 Lighting mode self diagnosis lamp 2 RAM 71QH5 ...
Page 76: ... 88 TROUBLESHOOTING OF THE SYSTEM POWER MODULE ...
Page 77: ... 89 ...
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Page 83: ... 94 HITACHI PM NO 0459E Printed in Malaysia RAM 71QH5 ...