ipLDK-60 SERVICE MANUAL
DIGITAL KEY TELEPHONE SYSTEM
16
SECTION 3. Circuit Description
3.1 Main Board Unit with CO
3.1.1 General
The MBU is the Main Board Unit of IPLDK-60. It provides basic CO, Station and extension interface circuits, physical
connection with various boards, and also miscellaneous functions.
The MBU is composed of a main processor and its peripheral circuits, the three CO interface circuits, a Digital Keyset
Unit (DKT) interface circuit, 7 hybrid circuits that are selected to DKT or SLT ports by Modular Jack pin assignments, a
Ring Generator circuit, a system battery backup circuit, two general purpose relay contact, an internal MOH, an external
MOH, an external PAGE, an alarm sense and the master clock generation circuit, as well as system’s PCM voice
processing circuit that has custom switching device, ACT2,
for PCM tone generation and PCM Gain control .
And it also has various connectors to install CO, extension and function boards, switches, modular jacks and etc.
Basically, the MBU provides the capacity of 3/08, that is three CO interface circuits and eight extension terminal
interface circuits that are composed of 1 DKT port and 7 Hybrid ports.
The capacity of IPLDK-60 system can be extended to maximum 12/48 that means the twelve CO interface ports and the
forty-eight extension ports by adding EKSU, CHB308 and CSB316 board.
The system features can be added by installing function boards at connectors that are prepared on the MBU.
