Network Control Unit (Ncu) Pcb - Muratec F-360 Field Engineering Manual

2.3 Network Control Unit (NCU) PCB

The NCU PCB provides the connection to the telephone line. It consists of the interface circuit, dial pulse
generator, ring signal detector and telephone control circuit.
MODULAR
PCB NCU PCB
Major components of the NCU
CML relay
Connects the telephone line to the phone or fax.
S relay
Used to send dial pulse signals in pulse dialing.
OH & Tone detector
Detects the On-hook condition of the second telephone unit.
H relay
Connects the Tel1 and Tel2 line to the fax machine.
24V generator
Supplies 24 volts to the relays.
Ring signal detector
A photo coupler that detects an incoming ring.
GENERATOR
NCU PCB block diagram
2-5
TXA
RXA
S
DP
TONE
OH
CI
+24V, +5V, GND
+12V, -12V