DS1-FAC (DS1 Facility)
Issue 1 May 2002
8-673555-233-143
For the following repair procedure, see Figure 8-25 on page 8-675 and the
diagrams in the related test descriptions.
1. If the DS1 facility side LOS indication on CSU A is off (inactive),
check for a problem between the DS1 CONV A circuit pack and the
CPE side of CSU A. Connectors, cables, and the CSU may need to
be replaced.
2. If the DS1 facility side LOS indication on CSU A is on (active), check
for a problem between the CSU A and the CSU B. Contact T1
Network Service to resolve the problem.
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3. If the CPE side LOS indication on CSU B is on (active), check for a
problem between the CPE side of CSU B and the DS1 CONV B
circuit pack. Connectors, cables, and the CSU B may need to be
replaced.
4. If the CSU A and the CSU B do not provide visual CPE side and
DS1 facility side LOS indications, follow the repair procedure that is
given for Error Type1025 (loss of frame alignment). Apply the
procedure first to the DS1 CONV B side instead of the DS1 CONV A
where the error is reported (external loop-back test is not expected
to pass if we execute it at this end as long as we have the LOS
indication).
Repair procedure for Error Type #1025 (loss of frame alignment)
includes execution of the Near-End External Loopback test (#799).
If this is not a critical-reliability system and if there is only one DS1
facility, then Test #799 can only be executed at the end that is closer
to the media server relative to the DS1 CONV circuit pack at the end
of the DS1 CONV complex. If the test cannot be executed for that
reason, then still make the external loop back as if the test was
going to be executed, but instead of executing the test, check the
green LED at the face plate of the DS1 CONV B that is associated
with this DS1 facility. If the green LED is off, then replace the
connectors, cables, and the CSU B.
5. If the problem still persists, replace the DS1 CONV circuit pack at
the other end of the DS1 CONV complex.
6. If the problem still persists, replace this DS1 CONV circuit pack.
If D4 framing is used, an in-band alarm signal (RFA) is transmitted that
corrupts transmit data in response to this alarm.
1. DS1 facility may be a private line or it may be connected to the Network. Network Interface
(NI) point is where the customer’s maintenance responsibility ends and the DS1 facility
vendor’s maintenance responsibility begins. This point ideally is the T, R, T1, and R1
terminals on the rear of the CSU to which the wires of the DS1 facility vendor’s DS1 facility
is attached. If the NI does not occur at this point, then any cabling between the CSU
terminals and the NI is also considered to be part of the CPE. This cable typically runs
between the DS1 facility terminals of the CSU and a cross-connect field where the DS1
facility vendor has terminated the DS1 facility. Maintenance responsibility for this portion of
the DS1 facility resides with the customer unless other arrangements are made.
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