Hitachi RAS-18LH2 Service Manual page 46

3. Buzzer Circuit
When the buzzer is to be activated, buzzer output pin
OFF repeatedly at 4kHz and Q302 is turned ON/OFF accordingly. A 4kHz voltage is applied to the buzzer
and the diaphragm of the buzzer vibrates to output 4kHz sound.
4. Initial setting (IC301)
The pre-heating operation start value, ratings of the compressor, maximum rotation speed, etc. are preset
in the micro computer.
5. Receive circuit
Infrared signals from the wireless remote controller are received by the light receiving unit and output after
being amplifi ed and shaped.
of the micro computer alternates between ON and
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