Toshiba FT-8509 Service Manual page 21

5. TROUBLE WITH INTERCOM MODE
5-1. The voice from the Base unit cannot be heard on the Handset.
Check whether there is an
audio waveform on Pin 4 of
IC7.
OK
Check Pin 7 of IC6.
5-2. The voice from the Handset cannot be heard on the Base unit.
Check whether there is an
audio waveform on Pin 1 of
IC6.
OK
Check whether there is an
audio waveform on Pin 15 of
IC7.
OK
Check WF701 and SP701.
NG
Check MC251 and IC7.
NG
Check IC6.
NG
Check IC7.
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