Avaya MCC1 Maintenance Procedures page 172

Troubleshooting
Fiber link fault isolation
Test #242 can be run as part of the test board UUCSS long command for an EI circuit pack. Besides
testing on-board components, this test is helpful for isolating problems between a circuit pack and the
lightwave transceiver. The loopback shown in this diagram shows only part of what Test #242 does. If no
lightwave transceiver is connected to the EI circuit pack, an on-board loopback is performed on the EI
circuit pack. For more information about Test #242, see
Maintenance Alarms Reference (555-245-102).
Figure 24: Tests for isolating fiber faults
TDM BUS
Tone
Clock
Tone
Detector
If DS1-CONVs exist on the fiber link (check with list fiber-link), then additional DS1CONV loopback
tests can be run to further isolate the problem. The loopback tests are shown in
Loopbacks, on page 172. For more information about DS1-CONV Loopback Tests (#788 and #789), see:
• Far-End DS1 Converter Circuit Pack Loopback Test (#788)
• Far-End Lightwave Transceiver Loopback Test (#789)
For more information about DS1 Facility Loopback tests (#797 and #799), see:
• Far-End Internal Loop-Back Test (#797)
• Near-End External Loop-Back Test (#799)
Figure 25: DS1 CONV Loopbacks
Table 59, DS1 interface cable connectors,
connect the TN574 DS1 CONV circuit pack to DS1 facilities.
172
back skin
of cabinet
TN570
Expansion
Interface
Test #238 (framing)
Test 799
LB 1
DS1C
1
CSU 1
Tests 788, 780, 797,
and 799 start here:
on page 173 shows the pin assignments for the cable used to
EXP-INTF (Expansion Interface Circuit Pack)
fiber-optic
cable
Test
Test
#756
#242
lightwave
transceivers
Test 799 Test 797 loops at internal
LB 2 interface for the DS1 facility
CSU 2
DS1 Facility
back skin
of cabinet
TN753
Test
Switch
#757
Node
Interface
Test #989 (framing)
Figure 25, DS1 CONV
lightwave
transceiver
. . . . . .
. .
DS1C
. .
.
2
. .
. .
. . . .
Test 788 Test 789
loops here loops here
Maintenance Procedures
December 2003
in