Xerox WorkCentre XK50cx, Service Manual

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??????? 4-13
Circuit
4-1-5 FAX Transceiver
4-1-5-1. GENERAL
This circuit processes transmission signals of modem and between LIU and modem.
4-1-5-2. MODEM (U18)
FM336 is a single ship fax modem. It has functions of DTMF detection and DTMF signal production as well as
functioins of modem. TX A1, 2 is transmission output port and RX IN is received data input port. / POR signal
controlled by MFP controller (U15:KS32C6400) can initialize modem (/M_RST) without turning off the system.
D0-D7 are 8-bit data buses. RS0-RS4 signals to select the register in modem chips. /RS and /WR signals control
READ and WRITE respectively. /IRQ is a signal for modem interrupt.
Transmission speed of FM336 is supported up to 33.6k.
The modem is connected to LINE through transformer directly.
Fig.4-1-10 FAX TRANSCEIVER