Description Of Main Circuit Operation - Hitachi RAF-25FX8 Service Manual

DESCRIPTION OF MAIN CIRCUIT OPERATION

MODEL RAF-25FX8, RAF-35FX8
1. Power circuit
35V
Ｉ Ｃ Ｐ ２
３ ５ Ｖ
Ｒ １ ２ １
Ｉ Ｃ Ｐ １
Ｑ １ １ ３
Ｑ １ １ ５
＋
＋
−
−
Ｑ １ １ ６
0V
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 suction deflector 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.
Ｑ １ １ １
Ｌ １ １ １
Ｒ １ １ ４
Ｑ １ １ ２
８
５
Ｒ １ １ ５ ＋
７ ２
−
Ｉ Ｃ １ １ １
６
３
１ ４
１ ２ Ｖ
Ｄ １ ２ １
Ｉ Ｃ １ ２ １
Ｉ Ｎ Ｏ Ｕ Ｔ ５ Ｖ
Ｇ ＮD
＋
−
０ Ｖ
Fig. 1-1
– 90 –
Ｃ Ｎ １ ０
Ｘ Ａ− ６ Ｐ − Ｔ ｏ ｐ
６
Ｉ ｎ ｄ ｏ ｏ ｒ Ｆ ａ ｎ
Ｍ ｏ ｔ ｏ ｒ
５
４
Ｍ
３
２
１
14 FM Rotation No.
Feedback
Indoor Fan
40
PWM Output