While in TALK MODE, press NG dial key of the handset. Check whether square waveform from pin 80 of IC4 is fed. OK Check Q21, RL1 and their peripheral circuits.
Check IC4.
5. Cannot make a phone call (tone).
Can the base and handset be connected? OK While in TALK MODE, press dial key of the handset. Can tone waveform from Pin 36 of IC4 is fed? OK Can tone signal be heard from the handset speaker? OK Check the base TEL-line circuit and RELAY control circuit. NG Check Q13, IC1, Q3 and their peripheral circuits. NG NG See 3. The base and handset be cannot be connected.
