Canon FAX L1000, Service Manual, Page: 206 / 610

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FAX-L1000 Chapter 3: Technical Reference
Memory functions
User data, service data, data registered before shipment from the factory, and
communications management information, are stored to the SRAM. Image data are stored
to the DRAM.
Memory backup
The SCNT board is provided with a function for backing up data in control/image
processing memory (SRAM) and image storage memory (DRAM) by lithium battery, and
rechargeable battery, even if a power interruption occurs, or the power cord is
disconnected by accident.
ESS (Energy Save Standby) control
The SCNT board controls the ESS function which reduces power consumption when the
main unit is at standby.
b) NCU board
The NCU board performs the following functions.
Hybrid circuit
Signals sent from the system controller to the telephone line are prevented from entering
the reception circuit.
Dial pulse generator
The dial pulse generator generates a dial pulse to send a dial signal from the fax through
the dial line by turning the relay on and off using the control signal from the SCNT board.
Off-hook detection circuit
Detects the off hook state from the DC current flowing to the circuit, when the extension
telephone (or option handset) is off hook.
Line voltage conversion circuit
The line primary on the NCU board is controlled by a +48 V DC line voltage, therefore,
the line voltage conversion transformer converts the voltage of the control TTL for the
lone secondary.
c) Modular board
Line interface
Signals from the two modular jacks for the telephone line and extension telephone (or
option handset), are transferred to the line voltage conversion circuit on the NCU board
and the signals from the fax are transferred to the telephone line.