Read Panasonic KX-TG2560B / KX-TG2560S Service Manual online
40
KX-TG2560B/KX-TG2560S
5. DTMF Signal
When the DTMF data from the Handset is received, the DTMF signal is output from pin 36 of the DSP and sent to the line
through Q105.
6. Line Sending Signal
The AF signal output from the AF terminal of the RF unit is adjusted to the appropriate level by VR402 and input to IC401. The
RX DATA signal from the handset is muted at this point by IC401 Exp to prevent the RX DATA from leaking onto the line. IC401
comprises a 3 kHz LPF and an expander IC. The signal compressed by the handset is expanded, recreating it as a normal signal.
The output from the expander passes through IC701, and is input to telephone line.
7. Line Receiving Signal
The audio signal from line passes through IC701 and is input to IC401. IC401 comprises an amplifier, limiter, mute circuit,
compressor, and 3 kHz LPF. It performs signal processing. The audio signal output from pin 6 of IC401 is mixed with the TX DATA.
At this point (in the talk mode), the DTMF tones, pulse dial tones, and data transferred between the Handset and base
unit is input to the modulator circuit.
Circuit Diagram
36
45
12
9
IC701
R711
R412
C709
Q105
C718
IC401
C407
C710
R718
R413
R414
C409
R418
VR402
EXP
R410
R417
C419
C423
13
AF OUT
Circuit Diagram
38
39
35
1
2
IC701
R113
C721
IC401
C711
C720
R723
VR401
R724
R415
R717
C410
R421
C411
1
TXMOD
C107
R408
C425
3
6
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