Toshiba FT-8981A Service Manual page 20

7. The voice of the caller cannot be heard (incoming call).
Can the base and handset be
connected?
OK
The 1 kHz, −10.5dBm
sine waveform is applied
to TELL-line of the base,
can the 1 kHz sine
waveform from the Q3
collector be fed?
OK
Check whether there is the
1 kHz sine wavefor m at
Pin 24 of IC2.
OK
Check whether there is the
1 kHz sine wavefor m at
Pin 20 of IC2.
OK
Check whether there is the
1 kHz sine wavefor m at
RT2.
OK
TX output signal from the
base is detected by the liner
detector, can the 1 kHz sine
waveform be fed?
OK
Check whether there is the
1 kHz sine waveform at Pin 9
of IC603 on the handset unit.
OK
Check whether there is the
1 kHz sine waveform at Pin 3
of IC602 and Pin 5 or 6 of
IC602.
OK
Check whether there is the
1 kHz sine waveform at the
Q615 collector.
OK
Check whether there is the
1 kHz sine waveform at Pin
1, 2 of SP801.
OK
Check SP801 and W801,
W802.
NG See 3. The base and handset
cannot be connected.
Check the base TEL-line
NG
circuit and RELAY control
circuit.
NG Check Q15 and its
peripheral circuit.
Check IC2 and its peripheral
NG
circuit.
NG Check RT2 and its
peripheral circuit.
NG
Check base RF section.
NG Check IC603 and its
peripheral circuit.
OK
NG Check IC602 and its
peripheral circuit.
NG Check Q615 and its
peripheral circuit.
NG Check Q604, Q605 and
their peripheral circuits.
— 22 —
NG
Check handset RF section.