Ncu Pcb - Brother FAX218 Service Manual

3.3 NCU P CB
The NCU PCB switches the communications line to telephone or built-in MODEM, under the
control of the main PCB.
Surge
LINE
absorber
EXTERNAL
TELEPHONE
HANDSET
Modular jacks
Photocouplers
Dial pulse
generator
Loop current
detector
Telephone
circuit
Surge absorbers
Diode bridge
DC loop
Line relay
circuit
Diode bridge
Relay
Photocouplers
III - 20
Line
MAIN PCB
transformer
High-impedance
MAIN PCB
transformer
Calling signal
MAIN PCB
detector
MAIN PCB
Transformers
Amplifier