Packet Bus Fault Isolation and Correction
555-233-123
9-32 Issue 4 May 2002
Procedure 4
Procedure 4 tries to isolate the failure to a particular set of carriers. Only the circuit
packs in those carriers are checked. Procedure 4 is used if the preceding
procedures fail, because it can help locate multiple circuit pack failures as well as
failures of the carrier hardware. The procedure is also used if there are open leads
on the Packet Bus. (The faults detected by Procedures 1 through 3 cannot cause
open leads.)
In Procedure 4, the TDM/LAN Cable Assemblies and TDM/LAN termination
resistor packs are replaced. If this action does not resolve the Packet Bus fault,
the carriers are reconfigured by moving the termination resistor packs in such a
manner that certain carriers are disconnected from the bus. This is done by
moving the termination resistors on the carrier backplanes. To terminate the
Packet Bus at the end of a particular carrier, first unplug the cable that connects
the carrier to the next carrier and then replace the cable with a termination resistor
(see Figure 9-6 on page 9-21). When the length of the Packet Bus is modified via
this procedure, circuit packs that are essential to system operation (for example,
Processor Complex, Tone-Clock) must still be connected to the new “shortened”
Packet (and TDM) Bus. In addition, the Maintenance/Test circuit pack (in
standalone mode) must be connected to the “shortened” bus.
!
WARNING:
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. After
cabling changes are made and verified, power must be restored to the port
network. Use the TN771 Standalone mode to determine if the Packet Bus
fault is resolved.
!
CAUTION:
Circuit packs in carriers that are not part of the shortened bus are not
inserted. As a result, these circuit packs are not alarmed. Ignore these
alarms for now. All alarms should be resolved when the cabinet is restored
to its original configuration.
To Next Page
Loading...
