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Routine Maintenance Procedures
The MMCH does not detect the loop and continues to VAS. In most scenarios, the
switch occurs, but within a few seconds, the broadcaster's return video becomes
its own image. Once the broadcaster stops speaking, the system "false" switches
to an apparently random port that was not speaking.
Install DS1 CPE Loopback Jack (T1
Only)
Using the DS1 CPE Loopback Jack (apparatus code 700A, comcode
107988867), a technician can test the DS1 span between the system and the
network interface point. The loopback jack is required when DC power appears at
the interface to the ICSU. The loopback jack isolates the ICSU from the DC power
and properly loops the DC span power.
NOTE:
The loopback jack operates with any vintage of TN767E (or later) or TN464F
(or later) DS1 circuit packs and with G3V3 EDI Release 3 (or later) software.
The loopback jack operates with the 120A2 (or later) Integrated Channel
Service Unit (ICSU) only; not the 31xx series of Channel Service Units or
other external CSUs or earlier ICSUs.
Loopback Jack Installation
Configurations Using a Smart Jack
The preferred location of the loopback jack is at the interface to the Smart Jack.
This provides maximum coverage of CPE wiring when remote tests are run using
the loopback jack. If the Smart Jack is not accessible, install the loopback jack at
the extended demarcation point.
1. If there is no extended demarcation point, install the loopback jack directly
at the network interface point as shown in
2. If there is an extended demarcation point and the Smart Jack is not
accessible, install the loopback jack as shown in
3. If there is an extended demarcation point, but the Smart Jack is accessible,
install the loopback jack as shown in
Configurations Without a Smart Jack
1. Install the loopback jack at the point where the cabling from the ICSU plugs
into the "dumb" block. If there is more than one "dumb" block, choose the
one that is closest to the Interface Termination feed or the fiber MUX. This
provides maximum coverage for loopback jack tests. Refer to
on page 5-67
5-58
Issue 4 May 2002
and
Figure 5-15 on page
Figure 5-11 on page
Figure 5-12 on page
Figure 5-13 on page
5-66.
5-68.
5-64.
5-65.
Figure 5-14
555-233-123
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Table of Contents
Troubleshooting
