Ncu Pcb - Brother FAX255 Service Manual

3.3

NCU PCB

The NCU PCB switches the communications line to telephone or built-in MODEM, under the
control of the main PCB.
U.S.A. versions
Surge
LINE
absorber
EXTERNAL
TELEPHONE
HANDSET
Modular jacks
Dial pulse
generator
Loop current
detector
Telephone
circuit
Surge absorbers
Photocouplers
Line relay
(CML relay)
High-impedance
transformer
Calling signal
detector
Transformer
Diode bridge
Amplifier
III – 20
Line
MAIN PCB
transformer
MAIN PCB
MAIN PCB
MAIN PCB
Relay
Transformer