ETS2228 Maintenance Manual
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Page 9, Total 43
Figure 4 Handset MIC Circuit
2
）
Handle Receiver Interface. Bead and capacitor constitutes the filter circuit.
Figure 5 Handle Receiver Interface
3
）
Hands-free Interface Circuit
The audio amplifier amplifies EAR2 signal to speaker, the switch of speaker is controlled by the bias
voltage of MIC2_P. And when the bias voltage of MIC2_P is zero, the voice channel and the audio
amplification is shut-down, which the system is in idle status. Possible faults of the hands-free channel:
no ringing, then check whether U603 is wrong or not.
