Hitachi RAC-18WPD, Service Manual

Page: 54 / 93

Approx.
V
9
[Typical communication waveform]
Approx. 400 ms.
Enlarged reception waveform
Fig. 5-2
An infrared signal from the remote control unit is converted to an electrical signal by the remote
control light-receiving unit (IC211) and is received by the microcomputer. Data is transmitted as
digital data 0 and 1 by changing the interval of the basic pulses at about 420 s.
Remote control reception input
(pin of microcomputer)
Beep (reception tone)
INPUT
+
GND
66
• When the buzzer sounds, an approx.
3.9kHz square signal is output from
buzzer output pin 32 of the micro
computer. After the amplitude of this
signal has been set to 12Vp-p by a
transistor, it is applied to the buzzer.
The piezoelectric element in the buzzer
oscillates to generate the buzzer's sound.
R640
C632
The indoor fan motor and drive circuit are connected to the primary power supply. They therefore have voltage to ground.
Guard against electric shocks.
While the product is energized, do not under any circumstances detach or reattach a connector. Any such practice would
cause a high voltage to run, resulting in the indoor fan motor and board circuit being destroyed. (Check the discharge of
the C003 before detaching or reattaching the connectors.)
Caution
Caution
5
66
32
54