Xerox WorkCentre Pro 412 Service Manual page 78

Circuit Description
5-3-11 FAX Transceiver
5-3-11-1 General
This circuit processes transmission signals of modem and between LIU and modem.
5-3-11-2 Modem (u44)
FM336 is a single chip fax modem. It has functions of DTMF detection and DTMF signal production as well
as functions of modem. TX A1, 2 is transmission output port and RX IN is received data input port. / POR
signal controlled by MFP controller (U3:KS32C61200) 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.
WorkCentre Pro 412 & WorkCentre M15/M15i FAX Transceiver
FaxCentre F12 FAX Transceiver
5-40 3/03 WorkCentre Pro 412, FaxCentre F12 &
WorkCentre M15/M15i