Explanation Of Analog Section Block Diagram; Explanation Of Analog Section Block Diagram - Panasonic KX-F900 Service Manual

KX-F900
6. EXPLANATION OF ANALOG SECTION BLOCK DIAGRAM
(1)Function
The analog section serves as interface with the telephone line. The digital board (ICt 1) for transmission reception of FAX
signals, and the speech network IC (ICl 09) are connected to the NCU section. Switching between the digital board (IC11) and
the other sections is executed by means of a multiplexer in the NCU section. The control signals to the individual analog sections
are output mainly from the ASIC ICl, and the status information for the various sections also is held in the ASIC ICl.
Simple explanations for the various sections are given below.
2) Circuit Operation
[NCU Section]
Interfacewith the telephone line and external telephone.This is composed of bell detection circuit,pulse dial generation cir-
cuit, EXT.TAMOFF-HOOK detect circuit,voxcircuit,amplifiercircuitfor linetransmission and reception, s idetonecircuitmul-
tiplexercircuit,etc. See belowfor details.
[Modem (ICll)]
Thisis used for FAX signaltone modulation, DTMF signaltransmission, r ing tone generation, and line transmission beep
generation. T he DTMF signaland Beep are placedontothe TX system.The ringtone passesthroughthe analog switch.
Outputtothe speaker via the poweramplifier(IC241).
[Speech Network IC (IC109)]
Thisis special IC combining the hands-free and handsetcircuits in 1 chip. The handset and microphone are connected to
this circuit.At the timeof hands-freeoperation, t he SP outputisoutputtedafter passage through the poweramplifier(IC241)
and the DTMF monitortone and the pulsedial monitortone outputfrom IC11 (DigitalBoard)and IC151 (AnalogBoard)are
givenas inputto this IC and becomethe monitor tone at the time of handsetdialing.
o_
_0
c
m
,--!
O
"_1
m
33
3:,
--I
0
z
-153-