Panasonic KX-FHD332C, Service Manual

Page: 184 / 249

IC509(1 2), amplifier IC511(2 1) and the NCU section to the
telephone line.
Refer to
CHECK SHEET ().
2. Facsimile Reception
The analog image data which is received from the telephone line
passes through the NCU section and enters pin 45 of the modem
(IC505). The signals that enter pin 45 of the modem (IC505) are
demodulated in the board to digital image signals, then placed on
the data bus.
In this case, the image signals from the telephone line are
transmitted serially. Hence, they are placed on the bus in 8 bit
units. Here, the internal equalizer circuit reduces the image
signals to a long-distance receiving level.
This is designed to correct the characteristics of the frequency
band centred around 3 kHz and maintain a constant receiving
sensitivity.
It can be set in the service mode.
Refer to
CHECK SHEET ().
3. DTMF Transmission (Monitor tone)
The DTMF signal generated in the modem (IC505) is output from
pin 44, and the NCU section to the telephone line the same as
facsimile transmission signals.
(DTMF Monitor Tone)
Refer to
CHECK SHEET ().
4. Busy/Dial Tone Detection
The path is the same as FAX receiving. When it is detected, the
carrier detect bit of the resistor in the modem (IC505) becomes 1,
and this status is monitored by ASIC (IC501).
7.8. ANALOG SECTION
1. Function
The analog section serves as an interface between the telephone
line. The digital board (IC505) for transmission and reception of
FAX signals, switches between the digital board (IC505) and other
sections by means of a multiplexer in the NCU section. The
control signals to the individual analog sections are output mainly
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