Hitachi RAK-35RPD Service Manual page 54

Caution
The indoor fan motor and drive circuit are connected to the primary power supply. They therefore have voltage to ground.
Guard against electric shocks.
Caution
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.)
• 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.
5
[Typical communication waveform]
Remote control reception input
(pin 66 of microcomputer)
Beep (reception tone)
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.
Approx. 400 ms.
Enlarged reception waveform
Approx.
32
+
GND
Fig. 5-2
54
R640
66
INPUT