Toshiba FT-8989, Service Manual

Page: 23 / 66

24
7. The voice of the caller cannot be heard (incoming call).
Can the base and handset be
connected? See 3. The base and handset
cannot be connected.
OK
NG
The 1 kHz, 77.5mV sine
waveform is applied to TEL-
line of the base, can the 1 kHz
sine waveform from the Q3
collector be fed? Check the base TEL-line
circuit and REPLAY control
circuit.
NG
Check whether there is the
1 kHz sine wavefor m at
pin 24 of IC3. Check IC4 and its peripheral
circuit. NG
OK
OK
Check whether there is the
1 kHz sine wavefor m at
pin 20 of IC3. Check IC3 and its peripheral
circuit. NG
OK
TX output signal from the
base is detected by the liner
detector, can the 1 kHz sine
waveform be fed?
Check base RF unit.
NG
OK
Check whether there is the
1 kHz sine waveform at pin 9
of IC606 on the handset unit. NG
OK
Check whether there is the
1 kHz sine waveform at pin 3
of IC601. Check RT602, Q601 and
their peripheral circuits. NG
OK
Check whether there is the
1 kHz sine waveform at the
pin 18 of IC601. Check IC601 and its
peripheral circuit. NG
OK
Check whether there is the
1 kHz sine waveform at R678
or R708. Check Q602, Q603 and its
peripheral circuit. NG
OK
Check SP801 and WA801,
WA802.
Check handset RF unit and
the peripheral circuit of IC606.
Check whether there is the
1 kHz sine waveform at R48. Check RT3 and its
peripheral circuit. NG
OK