DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126
Issue 4
June 1999
Maintenance Object Repair Procedures
9-1704TDM-BUS (TDM Bus)
9
TDM Bus Fault Detection and Isolation
TDM Bus are usually caused by one of the following:
■ A defective circuit pack connected to the backplane
■ Bent pins on the backplane
■ Defective bus cables or terminators
It is possible that a circuit pack can cause a TDM Bus fault and still exhibit
trouble-free operation. For example, insertions of any circuit pack into a slot with
TDM Bus terminations may bend the backplane pins and short two leads
together. Since the TDM Bus is a shared resource, identification of the cause of a
TDM Bus fault can be difficult. If a TDM Bus problem is suspected, run the
test
tdm P
command. If any of the resulting tests fail, you must perform a manual
TDM Bus isolation procedure to identify the cause of the problem.
!
WARNING:
Since the TDM Bus fault isolation procedure involves removing circuit packs
and possibly disconnecting entire carriers, the procedure is extremely
destructive to the port network that contains the TDM Bus being tested. If
possible, arrange to perform this procedure at a time when traffic is
minimal.
As circuit packs are removed or entire carriers are disconnected, any active calls
terminating on those circuit packs or carriers will be dropped. If you have any
hints about a particular circuit pack that may be causing the TDM Bus problem
investigate those before performing this procedure (for example, look at any
circuit packs that were inserted into the PN just before the TDM bus problem
appeared.
When straightening or replacing backplane pins in a carrier that contains a
CFY1B Current Limiter, power to the
cabinet
must be removed. When
straightening or replacing backplane pins in a carrier that does NOT contain a
CFY1B Current Limiter, power to that
carrier
must be shut off. Failure to follow this
procedure may result in damage to circuit packs and power supplies, and can
be hazardous to the technician.
NOTE:
Maintenance software requires TN748 or TN420 Tone Detector circuit pack
to test the TDM Bus. Before starting these procedures, make sure that one
of these is installed in the port network being investigated.
Procedure 1
This procedure is an attempt to isolate the TDM Bus fault to circuit packs that are
essential to the system operation. For each of the following circuit packs in the
port network where the TDM Bus fault appears, perform Procedure 1.
