Samsung SF-4500 Service Manual page 55

6-1-7 FAX Transceiver
6-1-7-1. GENERAL
This circuit processes transmission signals of modem
and between LIU and modem.
This circuit is added only to SmartJet 2000,
SF-4300C.
6-1-7-2. MODEM (U15)
KS16117 is a single chip fax modem. It has functions
of DTMF detection and DTMF signal production
as well as functions of modem. TX OUT is
transmission output port and RX IN is received data
input port. /POR signal controlled by MFP
controller (U16:KS32C6200) can initialize
modem(/RST_OUT) without turning off the system.
D0 - D7 are 8-bit data buses. RS0 - RS4 signals to
select the register in modem decide the mode. /CS is
a
signal to select modem chips. /RD and /WR signals
control READ and WRITE respectively. /IRQ is a sig-
nal for modem interrupt.
Transmission speed of KS16117 is supported up to
14.4k.
MODEM
KS16117
(U15)
6-24
6-1-7-3. TRANSMITTER
This circuit processes transmission output, analog
signal of modem(KS16117).
Output signal in each mode goes out of modem
(TXOUT:U15-44). After D/A signals are smoothed
and filtered through active filter (U12-2), they are
buffered under OP AMP(U12-6) and put out to LINE
through LIU board.
6-1-7-4. RECEIVER
In the receiving mode, analog signals coming in
through LIU board are amplified at OP AMP
(U13-6), and then transmitted to input terminal of
modem (RXIN:U15-45) through smoothing filter
(U13-2).
U12
U13
Fig.6-1-18. FAX TRANSCEIVER
FAX TRANSMISSION
LIU
FAX RECEPTION
Samsung Electronics