Alinco DJ-191, Service Manual, Page: 6 / 47

4. S(Signal)Meter Circuit
The DC potential of pin 13 of IC104 is input to pin 3 of the CPU (IC5),
converted from an analog to a digital signal, and displayed as the S-meter
signal on the LCD.
5. DTMF Encoder
The CPU (IC5) is equipped with an internal DTMF encoder. The DTMF
signal is output from pin 12, through R90 and R91 (for level adjustment),
and then through the microphone amplifier (IC6), and is sent to the varicap
of the VCO for modulation. At the same time, the monitoring tone passes
through the AF circuit and is output from the speaker.
6. DTMF Decoder
Part of the audio signal demodulated by IC104 is input to pin 1 of DTMF IC
(IC8). The internal signal judging circuit in IC 8 then checks if the signal is
valid or invalid. The judged signal is converted into a 4-bit code and sent to
pin 29 of 1C5.
7. Tone Encoder
The CPU (IC5) is equipped with an internal tone encoder. The tone signal
(67.0 to 254.1 Hz) is output from pin 11 of the CPU to the varicap of the
VCO for modulation.
5) CPU Terminal Functions: M38267M8L (XA0413)
C C C 3 C 3 C 5 0 C 3 C 3 C 5 C 5 C 5 C 5 C 5 0 0 0 0 0 0 0 0 0
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C flC flC flC /)c /)c /)c /)C /)Q = Q = Q = Q = Q = Q = Q » Q s Q - G - G - Q - G _ G - Q . Q . Q _ Q _ Q . & Q _ Q _
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