Samsung OfficeServ 12 Service Manual

Also see for OfficeServ 12: General description

© SAMSUNG Electronics Co., Ltd. 20TransformerThis is one of the important elements of a regular trunk interface. A transformer separatesthe primary power source from the secondary power source.DC Loop CircuitThe primary part of a regular trunk interface has a circuit that forms a DC loop. The circuitconsumes DC to supply much current and passes AC signals by minimizing the loss.The switch then detects the DC loop. This is called the loop-start method sincecommunication starts once the DC loop is formed.Calling Signal/Loop Detection SignalA calling signal is entered only when a loop is not formed.(This may not be applicabledepending on the ring trip characteristics of the switch.) The calling signal is transmitted tothe DC loop circuit through the condenser, resistance, and Zener diode. The signal istransmitted to the secondary part through an optical device(e.g., TLP121GB, Opto-coupler),and CPU loads the signal through TMC. An optical device is used to separate the power ofthe primary part from that of the secondary part.Loop RelayA calling signal is transmitted to a loop relay through the condenser, resistance, and Zenerdiode. This relay is used to form or disconnect a loop, and inter-works with theaforementioned DC loop circuit. If a relay is connected, a loop will be generated. If a relayis disconnected, a loop will be disconnected. The contact of a relay is opened or closed totransmit a pulse signal for sending a phone number. A relay operates at a voltage of +5 V,and is controlled by the CPU through TMC.MPD/PRS InterfaceA regular trunk interface can detect MPD(Metering Pulse Detection)/PRS(Polarity ReverseSignal) signals. These services can be provided whenever required by connecting acorresponding hybrid component to the socket located on the board. The hybrid componentfor detecting MPD or PRS is shared with the DCS(Digital Communication System) systemcomponent. Since each port has only one socket, one of the two elements must be selected.