Panasonic KX-TC1743B, Service Manual

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15.5. Sending Signal
The voice signal from the microphone input to DSP (46-47). CN203 is the headphone jack. When
the headphone is connected, the Q206 detect it. The input from the microphone of the handset
(MIN, MIP) is cut and the microphone signal from the headphone is input to DSP (36). Also the
power for the microphone is supplied from Q211, and the power is turned OFF on standby.
15.6. Reception Signal
The voice signal from the base unit is output to DSP (33) (HSSOUT). This signal is led to the
headset jack (CN201) and DSP (44) (HSMIP). The signal input to DSP (44) is inverted and output
to DSP (34) (LOUTO).The signal through the headset jack is inverted, then output from DSP (34)
to drive the speaker. When the headset is inserted to the jack, the voice signal is cut at the jack,
so the sound does not come out from the speaker, but from the headset only.
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