GDK-100
DIGITAL KEY TELEPHONE SYSTEM
76
3.4.5 Analog CO Line Board Installation
There are several types of analog CO line boards available. These boards include the LCOB and DIDB.
Additional CO interface boards such as AC15, EMIB, DIDB and BWDIDB may be available for support of
local market conditions and regulatory requirements.
Every CO line board contains several types of connectors for the line connection on the front edge of the
boards themselves.
3.4.5.1 LCOB Installation
LCOB provides 4 Loop Start CO line interfaces. The board can be optionally equipped with Call Metering
Unit (CMU) boards to monitor call duration and a Call Progress Tone Unit (CPTU) daughter board to monitor
call progress signals. A CMU must be provided for each Loop Start CO Line which requires call metering. In
addition, the appropriate type of CMU must be employed. See CMU in section 2.
If required, install the CMUs and CPTU on the CO interface board as shown in Figure 3.4.5.1 and insert the
boards in the selected card slot.
Function of LED
LED
Function
Remark
LED1
The status of line 1, ON: in use, Green
LED2
The status of line 2, ON: in use, Green
LED3
The status of line 3, ON: in use, Green
LED4
The status of line 4, ON: in use, Green
Function of various connectors
Connector
Function
Remark
CN1 and CN2
DTRU connection
CN3 and CN4
CPTU/A or CPTU/B connection
CN100 and CN104
The connectors for a CMU on line 1
See Note
CN101 and CN105
The connectors for a CMU on line 2
See Note
CN102 and CN106
The connectors for a CMU on line 3
See Note
CN103 and CN107
The connectors for a CMU on line 4
See Note
CN108
RJ21 type male connector for CO line connection.
Clause 3.5
!
Note:
1. The pin #6 and #7 of CN104, CN105, CN106 and/or CN107 should be shorted by shorting
traps (short pin) when CMU12(12 KHz meter pulse) including CMU12PR or CMU16(16 KHz
meter pulse) is not installed on the interface circuit(s). Otherwise the receiving voice path of the
related line will be open.
2.
The 0 ohm resistors are usually mounted on R168-R171 of LCOB for the countries using only
CMU PR(Polarity Reversal) and/or 50L(50 Hz longitudinal). If these CMUPR, CMU50L or
CMU50PR are not installed on any CO interface circuit neither R168-R171 are mounted on
LCOB, the pin #6 and #7 of CN104, CN105, CN106 and/or CN107 should be also shorted by