Interconnect Problems
Summary:
Wiring from the C.O. to the demarcation block, from the block to the TCIV, COA and LLM
circuitry within the TCN, programming, and wiring to the remote station may all affect the
operation of interconnect lines.
Step 1.
Step
2.
Step
3.
Step
4.
Step 5.
Step
6.
Step 7.
Obtain or make an interconnect planning layout as described in the Interconnect Planning
Section.
Verify interconnect trunk programming is as required.
If B: attributes specify “external service request”, a special connection is required at
the COA (refer to Drawing KC1475). If this connection is not made, calls to affected
trunks will terminate after answering when the
COA
timer shuts-off.
Use the #73 Diagnostic for trunks (part one of this section) and check for the following:
Idle: 48 Vdc on
COA
terminals CT and CR.
Busy:
6-8 Vdc on COA terminals CT and CR.
Other: Less than 2 Vdc indicates a central office time-out fault. Disconnect
for 2 seconds to get 48 Vdc back. (See Special Notes on Central
Office Trunks under the Line Type Tests section in this manual.)
Verify the problem line is idle and there is
12
Vdc on LLM terminals
T
and
R.
Place a call to the problem line from the outside and check for the following:
Ringing:
6 Vdc on LLM terminals T and R.
COA
LED TC glows steadily.
Connect the problem line to the incoming call and verify
COA LED CO glows steadily. This
LED indicates CO or PBX loop current and will not glow if a break exists in the loop.
Check the CO line integrity by connecting a telephone directly to the demarcation block and
placing test calls from and to the remote CO or PBX. If this test is unsuccessful, the problem is
the phone company’s responsibility to repair.
Note: If a “ground start” trunk, a 2 second ground on the ring lead is required to acquire dial
tone.
1989 Rauland-Borg Corporation (Orig. 10/88; Rev. l/89)
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