Maintenance Object Repair Procedures
555-233-123
10-1562 Issue 4 May 2002
A Minor alarm results if the Stratum 3 clock can still provide timing to the
PBX; otherwise, a Major alarm is raised because the Stratum 3 clock is not
providing timing and the PBX is referencing the local oscillator on the
TN780 Tone-Clock circuit pack. If only the Active TN780 Tone-Clock circuit
pack were faulty, the Standby TN780 Tone-Clock circuit pack would
become active and still synchronize to the Stratum 3 clock. When the
system switches to the Standby Tone-Clock circuit pack, the alarm is
resolved, and it raises a TDM-CLK (TDM Bus Clock) alarm to indicate that
the TN780 Tone-Clock circuit pack may be defective.
If the alarm is minor:
Look for a red LED on either or both TOC cards. If there is a red
LED, then replace the card. If there is no red LED, then, using the
Stratum 3 Wiring Guide, check that the wiring installation is correct.
After replacing the card or correctly rewiring the installation, clear
the alarm by first issuing the disable synchronization-switch
command followed by the enable synchronization-switch
command. Wait two minutes and then execute the status
synchronization command. If Maintenance Name on the status
screen shows “STRAT-3,” then the problem is resolved. If not, then
escalate the problem.
If the alarm is major:
Check connections between the Stratum 3 clock and the PBX. If
there are no loose connections, using the Stratum 3 Wiring Guide,
check that the wiring installation is correct. After reconnecting the
loose connection or correctly rewiring it, clear the alarm by first
issuing the disable synchronization-switch command followed by
the enable synchronization-switch command. Wait one minute,
and then execute the status synchronization command. If
Maintenance Name on the status screen shows “STRAT-3,” then the
problem is resolved. If not, then escalate the problem.
If the Standby Tone-Clock circuit pack become active:
Check connection between the Stratum 3 clock and the TN780
Tone-Clock circuit pack from which the system has just switched. If
there are no loose connections, then, replace the TN780 Tone-Clock
circuit pack. Refer to the “How to Replace a Tone-Clock Circuit
Pack” section in the TDM-CLK (TDM Bus Clock) Maintenance
documentation. Before switching back to the new TN780
Tone-Clock circuit pack, use the test tone-clock PC long command
to check that the Tone-Clock is receiving a signal from the Stratum 3
clock. The notation “PC” denotes a port network number and carrier.
If all tests pass, switch to the new Tone-Clock circuit pack via the set
tone-clock PC override command. If Test #651 fails, then the
original TN780 Tone-Clock should be reinserted, and the cable
between the Stratum 3 clock and the TN780 Tone-Clock circuit pack
should be replaced. If Test #651 continues to fail, then escalate the
problem.
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