LG GDK-20W User Manual

GDK-20W DIGITAL WIRELESS KEY TELEPHONE SYSTEM     
 

 

 

 
The KSU is a plastic cabinet designed for wall mounting. The KSU contains a MBU(Main Board Unit) and POWER 
Transformer and Mechanical parts. 

 
 

 
A Power Supply Circuit is required in the Key Service Unit. The Power Supply Circuit converts local AC power(220~240V 
AC @ 50~60Hz) to DC voltages, regulates the voltages, and provides the appropriate DC voltages to the MBU for 
distribution to other system components. Three DC outputs are provided : ±5V DC, +30V DC.   

 

The MBU, incorporates, master clock, one alarm detection circuit, one general purpose relay, watchdog circuitry and 4 
ports digital terminal interface circuits and 2 ports SLT circuits as well as the system's PCM voice processing and main 
micro-processor. And the MBU contains one wireless terminal interface circuit that is used to install one base station to 
support 4 simultaneous DECT calls. 
The micro-processor is a 16 bit high speed CPU that receives and transmits signaling information from/to other PCBs, 
controls feature activation, and PCM time-slot interchange. For digital voice processing, two ROM's contain PCM tone, 
gain table, etc. 
 
There are two commonly used slots, SLOT2 and SLOT3, and four fixed slots for extending the system capacity.    From 
the left side, the SLOT1 is used to install the DVIB/

DVIBE

. The SLOT2 and SLOT3 are used to install 

LCOB2/LCOB/

LCOBE/LCOBA/LCOB4

 and STIB2 / STIB. The SLOT4 is used to install the PMU basically. The SLOT5 is 

used to install the WTIB and the SLOT6 is used to install the MFB. 
 

The permitted terminals are as following. 

 
  Keyset:   KD-36D, KD-36N, KD-24D, KD-24N 

KD/E-36EXE, KD/E-36ENH, KD/E-24EXE, KD/E-24ENH, KD/E-8BTN 
LKD-2NS, LKD-8DS, LKD-30DS, etc 

 

DECT terminal: GDC-330H, GDC-335H, GDC-340H 

 
 

 
The PMU is installed to SLOT4 basically and incorporates the system's memory, one internal and one external MOH 
ports, Real time clock circuit and two DTMF receivers. Each receiver is time-shared under the control of the system 
software. 
The LEDs in upper side of the PMU panel indicates system’s power on/off state and data communication state. Also, the 
PMU contains 512Kbytes of RAM and 1Mwords of Flash memory. 
The RAM associated with the system database and the real-time-clock is protected from power loss by a long life high 
energy lithium battery. 
Two(2) Flash memory(U1 & U2, 512Kwords respectively) contains the basic system operating software.   

 

 

 
The GDK-20W system provides two kinds of ring signals. One is 50Hz sine wave signal generated from power 
transformer, another is 25Hz square wave signal from RGU. 
The RGU is installed to connector,CN23,of MBU and generates 75Vrms ring signal that can be applied to the two(2) 
SLTs simultaneously.   

 

 
 

 
The Multi Function Board(MFB) Provides a RS-232C interface port with 9 pin connector. The maximum baud rate is 
38400bps. The MFB is useful for system maintenance, PC based admin, SMDR print out and local software up-grade. 
It is recommended that the RS-232C serial cable whose length is below 10 meters is used. 

 

The MFB includes circuitry for float charging an externally connected 24 volt battery and controls the 
operation of the battery back-up circuits. And the MFB will provide system operating voltages from the