Avaya CMC1, Maintenance Procedures

Page: 244 / 426

Packet and serial bus maintenance
Isolating and repairing packet-bus faults
244 Maintenance Procedures
December 2003
6 Repeat this procedure for the other Tone-Clock. If both have already been checked, continue with
Step 7 .
7 If every PN control circuit pack has been checked and the problem is still not resolved, continue
with
Procedure 4: isolating failures on page 244.
Procedure 4: isolating failures
Procedure 4 is used when the preceding procedures fail or when open leads are present. It is helpful in
identifying multiple circuit-pack faults and carrier hardware faults. It attempts to isolate the failure to a
particular set of carriers and checks only the circuit packs in those carriers.
In Procedure 4, the TDM/LAN cable assemblies and TDM/LAN terminating resistors are replaced. If this
action does not resolve the packet-bus fault, the carriers are reconfigured by moving the terminating
resistors on the carrier backplanes in such a manner that certain carriers are disconnected from the bus. To
terminate the packet bus at the end of a particular carrier, unplug the cable that connects the carrier to the
next carrier and replace the cable with a terminating resistor (see
Figure 72, Carrier rewiring
example—rear view of MCC1, on page 244). When the length of the packet bus is modified with this
procedure, circuit packs that are essential to system operation (and the TN771D Maintenance/Test circuit
pack in stand-alone mode) must still be connected to the new ‘shortened’ packet and TDM buses.
!
DANGER :
Power must be removed from the entire port network before any cables or
terminators are removed. Failure to do so can cause damage to circuit packs and
power supplies, and can be hazardous to the technician.
NOTE:
Circuit packs in carriers that are not part of the shortened bus are not inserted. As a result,
these circuit packs are not alarmed. For now, ignore alarm status for these circuit packs.
Every alarm should be resolved when the cabinet is restored to its original configuration.
Figure 72: Carrier rewiring example
—
rear view of MCC1
TDM/LAN Bus Cable TDM/LAN Bus Terminator
Normally
Configured
Cabinet
(All 5 Carriers
Used)
Bus Shortened
to Carrier A Only
(Control Carrier)
Shortened Bus
Extended to
Include
A and B
Carriers
Carrier D
Carrier E
Fans
Carrier A
Carrier B
Carrier C