Power Supply Circuit; Power Circuit For P.w.b; Shifting From Off To On - Hitachi RAM-55QH5 Service Manual

4. Power Supply Circuit

Fig. 4-1 shows the power circuit.
G
There are two switching power supply in Power PWB.
G
Switching power supply 1 is generating the secondary power for control circuits and DC35V indoor unit 1.
G
Switching power supply 2 is generating the DC12V for expansion valve and DC35V for indoor unit 2 and 3.
G
Switching power supply performs voltage conversion effectively by switching transistor IC1 to convert DC330V
G
to high frequency of approximately 20kHz to 200kHz.
Transistor IC1 operates as follows:
G
Fig. 4-1 Power circuit for P.W.B.
– 83 –