AU-X095 - Sharp Air Conditioner Service Manual (repair manual). Page 7

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7
AH-X075E/X095E
AU-X075E/X095E
AY-X075E/X095E
AE-X075E/X095E
Serial Signal Circuit
The 220/240 V AC shown in the above diagram is generated when the indoor power socket is plugged in. It undergoes
half-wave rectification by diode D6, then is smoothed by the electrolytic capacitor C18, and a stable voltage of 24 V DC
is provided at the Zener Diode ZD2. The above circuit provides a 24 V DC power supply to the serial communication
circuit.
When the indoor CPU turns on the outdoor main relay, the outdoor power supply is turned on and the outdoor CPU
enters serial signal wait state - i.e. the circuit between terminals (N) and (2) in the diagram above becomes conductive
and the circuit waits for a signal from the indoor circuit. The indoor circuit sends signals to the outdoor circuit by setting
CPU IC1 pin 15 to LOW/HIGH output, which sets photo coupler PC2 ON/OFF. When the indoor circuit has finished
sending its signals, it sets CPU IC1 pin 15 to LOW setting PC2 to the ON state. This switches the indoor circuit to signal
wait state from the outdoor circuit. The signals from the outdoor circuit are input to indoor CPU IC1 pin 14 by turning
photo coupler PC1 ON and OFF.
Buzzer Circuit
This circuit generates the beeps when the remote control signal is received. One beep is generated when an approximately
4 kHz pulse is generated for approximately 0.1 seconds from CPU IC1 pin 13. The CPU cannot drive the buzzer
directly, so Q2 is used to drive the buzzer.
+
C15
C19
C18
ZD2
R27
R26
D6
N
R25
R23
D7 R44
R42
R43
R41
R40
PC2
PC1
5V
R19
R24
2
AC 220/240V
CPU (IC1) pin 15
CPU (IC1) pin 14
Terminal Block
R18
Q2
BZ
12V
CPU (IC1) pin 13
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