Switching Power Supply Circuit For Indoor Unit - Hitachi RAF-25NH4 Service Manual

(2) Switching power supply for indoor unit
Fig. 4-3 shows the switching power supply circuit for the indoor units.
Input voltage after
rectification, approx.
325V DC
It is supplied via
※
CN1 from control
P.W.B..
The switching power supply circuit consists 2 circuits , and is carried on the SW-D-P.W.B.
The circuit for A cycle generates 35V of the power supply voltage for the indoor unit 1¥ 2, and 12V and 5V for the drive of
electric expansion valve. Similarly . the circuit for B cycle generates 35V of the power supply voltage for the indoor unit 3 ¥ 4,
and 12V and 5V for the drive of B cycle electric expansion valve. The voltage specification of each output is in fig . 4-2 below.
Fig . 4-2 Voltage specification.
Output name
35 V A
BEN 12V A
BEN 5V A
35V B
BEN 12V B
BEN 5V B
3A, fuse
Fig. 4-3 Switching power supply circuit for indoor unit
Output specification
35 (± 2.5) V
12 (± 2.0) V
5 (± 0.5) V
35 (± 2.5) V
12 (± 2.0) V
5 (± 0.5) V
SW transformer 2
SW transformer 3
Main load circuit
Indoor unit 1 ¥ 2, Reversing valve for A cycle
Electric expansion valve 1 ¥ 2 for A cycle
Control circuit for electric expansion valve of A cycle
Indoor unit 3 ¥ 4 (only unit 3 operates for 3 rooms)
Electric expansion valve 1 ¥ 2 for B cycle
Control circuit for electric expansion valve of B cycle
220
A cycle
B cycle