Thank you for providing quickly a manual so old! very good job clear and understandable!
Text excerpt from page 19 (click to view)
4. Cannot make a phone call (pulse).
Can the base and handset be connected? OK While in TALK MODE, press NG dial key of the handset. Check whether square waveform from pin 46 of IC8 is fed. OK Check R83, D11, Q11, RL1 and the peripheral circuit. Check IC8 and its peripheral circuit. NG See 3. The base and handset cannot be connected.
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 23 of IC2 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 IC3, Q3, Q4 and the peripheral circuit. NG Check IC2 and its peripheral circuit. NG See 3. The base and handset be cannot be connected.