Canon fax basic 2000 Manuale Di Servizio

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FACSIMILE SYSTEM

3. NCU BOARD

“NCU board” is an abbreviation for Network Control Unit board. This

board is located at the telephone line - facsimile interface. This board func-

tions to detect signals arriving from the telephone line to transfer them to

the MODEM on the SCNT board, and to switch the line between the fac-

simile and telephone.

Fig. 6-3   Location of NCU Board

The main functions of the NCU board are as follows:

• Off-hook detection

• Formation of DC loop

• Detection of calling identification (CI)

• Line signal monitor

• Dial control

• 2-wire/4-wire conversion

• Protective circuits

• Telephone connection control

L1

L2

T22

T21

T12

T11

MODEM

Exchange

NCU board

Facsimile

SCNT board