Ncu Pcb - Brother IntelliFax-3550 Service Manual

3.4

NCU PCB

The NCU PCB switches the communications line to telephone or built-in MODEM, under the
control of the main PCB.
1 2
2
9
2
1
Surge absorber
2
Noise filters
3
Line relay (CML relay)
4
Line transformer
5
Circuit related to the line transformer
6
High-impedance transformer circuit
7
Calling signal detector
8
Loop current detector
9
Dial pulse generator
:
Telephone circuit
A
Reference voltage generation circuit for the operational amplifier in
4
3
7
8
:
NCU PCB Circuit Diagram (U.S.A. versions)
6
III – 24
5
A
.