Maintenance Object Repair Procedures
555-233-123
10-766 Issue 4 May 2002
These symptoms can also be the result of other problems (for example, one half
of the fiber being unable to transmit data). If the system exhibits these symptoms,
execute the following procedure:
1. Verify that the EPN stays down for at least one minute.
If the Expansion Interface Link comes back in service after a short time,
without switching the Active Tone-Clock, the problem probably was the
on-line synchronization source became invalid (see SYNC Maintenance
documentation for more information).
However, if the Expansion Interface Link(s) has not come back into service
after one minute, the synchronization source is not the cause of the
problem. Proceed to Step 2.
2. Check for errors via the display errors command with the Category field
set to “tone” and the Active alarms field set to “n.” Some of the alarms on
EPN objects might have been resolved if the EPN went down. Refer to the
appropriate MO Maintenance documentation for descriptions of any of the
errors occurring at about the same time as the EXP-LINK errors. Resolve
any active alarms. Also, if Error Type 18 was logged against the SYNC MO
when the EPN went down, the problem was probably that the
synchronization on-line reference became invalid. Since reference
switching was disabled, the Tone-Clock did not switch from the invalid
reference. Therefore, the Tone-Clock circuit pack put out a system clock
that was “out of spec.” Issue the enable synchronization-switch
command. If the EPN is down, reseat the Tone-Clock circuit packs on the
EPN. This action should restore the EPN to service.
Execute Steps 3 and 4 in the order most convenient to you and least
destructive to the customer.
3. Check if the fiber optic cable is transmitting properly via the following
procedure on one of the out-of-service links:
a. Carefully record the symptoms (yellow LED pattern and tests failing)
that were occurring on the PPN Expansion Interface circuit pack and
the EPN Expansion Interface circuit pack. Clearly indicate which
symptoms are occurring on which Expansion Interface circuit pack.
!
WARNING:
Before proceeding, note which is the current transmit fiber and which
is the current receive fiber for proper reconnection.
b. Disconnect the transmit and receive fiber pair from the lightwave
transceiver on the back of the PPN Expansion Interface circuit pack
slot (see Figure 10-30 on page 10-657).
c. Connect what was formerly the transmit fiber to the receive jack.
d. Connect what was formerly the receive fiber to the transmit jack.
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