AT&T System 25 - Manual (Page 187)

MAINTENANCE
Sometimes, faults recorded in the error log and user-reported troubles will
exist at the same time. The logged faults should always be cleared first, if
possible. This procedure often clears the user-reported troubles without any
additional maintenance.
Clearing the most serious logged fault may clear some or all of the other
faults. Descriptions of the errors in the error log section indicate their relative
u r g e n c y .
Error log records should be manually recorded before clearing a recorded
error or alarm. If a faulty CP is located in the process of clearing a problem, it
must be replaced with a known good CP. The associated error record should
be included with the CP when it is returned for repair. If the SAT has an
associated printer, the error records can be printed instead of being manually
r e c o r d e d .
Traditional troubleshooting methods still have a valid place in maintaining a
system as advanced as System 25. And sometimes these methods are
sufficient to locate and clear faults. These methods include voice terminal
substitution, visual inspections,
operating procedures with users.
continuity checks, and clarification of
Total System Failures
As the flowchart in Figure 4-1
circuitry (that is, CPU/Memory
immediately. This procedure may shows, a failure of
and Service Circu
clear other problems
Port Problems
the common control
it) must be repaired
in the system as well.
Port CP failures can usually be cleared by replacing the CP that has a lighted
red LED (if reseating was unsuccessful). When replacing suspected defective
CPs, wait until the amber LED (indicating CP is in use) goes dark before
removing the pack.
4-11