7. The voice of the caller cannot be heard (incoming call).
Can the base and handset be connected? OK The 1kHz 97.5mV sine waveform is applied to TEL-line of the base, can the 1kHz sine waveform from the Q1 collector be fed? OK Check whether there is the 1kHz sine waveform at Pin13 of IC1. OK Check whether there is the 1kHz sine waveform at Pin9 of IC1. OK TX output signal from the base is detected by the liner detector, can the 1kHz 3kHz Dev. sine waveform be fed? OK Check whether there is the 1kHz sine waveform at Pin16 of IC501. OK Check whether there is the 1kHz sine waveform at Pin19 and 20 of IC501. OK Check whether there is the 1kHz sine waveform during for Pin1 and 2 of J501. OK NG NG Check IC501 and Pin17~20 peripheral circuits of IC501. NG Check IC501 and Pin15~16 peripheral circuits of IC501. NG NG Check IC1 and Pin9~11 peripheral circuits of IC1. NG Check IC1 and Pin13~14 peripheral circuits of IC1. NG Check the base TEL-line circuit and RELAY control circuit. NG See 3. The base and handset be cannot be connected.
