User's Manual

Lucent Technologies — Proprietary
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22-8
401-660-100 Issue 11 August 2000
Linear Amplifier Circuit (LAC) Maintenance
!
CAUTION:
Be careful that LAC alarms generated as a result of recent maintenance
activities are not mistakenly interpreted as legitimate LAC alarms. This can
be avoided by printing out the LACSUM file,
not
LACSUM.Ext, at the
beginning of the maintenance window.
Continuous Alarms
Continuous alarms are potentially service affecting and should be attended to
promptly. Since continuous alarms are reported once an hour, the number of
occurrences recorded will depend upon the time period covered by the LACSUM
report. A full 24-hour summary report would show 24 occurrences for a
continuous alarm. In the example above, cell 1, LAC 3 lists 14 occurrences over a
14-hour period, which may indicate a continuous alarm. Suspected continuous
alarms should be confirmed by looking at the detailed LACALM report, as
illustrated in the preceding example.
MINOR Alarms
The table summarizes the possible causes of MINOR alarms. These causes are,
in order of likelihood: LAM alarms, Processor alarms, and Low-Level Thermal
alarms. Intermittent MINOR alarms are generally not service affecting, but may
lead to a service-affecting condition if they persist. A small number of intermittent
MINOR alarms (less than 5 per day) is not usually cause for concern since they
can be expected to occur, occasionally, as a result of transient traffic conditions. If
they continue to occur over a number of days, or increase in frequency over time,
a site visit may be warranted.
NOTE:
A/B-Series LACs report fan failures and LAM bias power failures as MINOR
alarms. Beginning with the 1C LAC, these conditions are reported as
MAJOR and CRITICAL alarms, respectively. See the Fan Alarm Procedure
and LAM Bias Fault Procedure for further details.
LAM alarms are the most frequent cause of MINOR alarms and are commonly
caused by a bad LAM or its associated fuse. Large numbers of intermittent
MINOR alarms are usually due to a faulty LAM or a loose LAM fuse, whereas a
continuous MINOR alarm is usually due to a blown LAM fuse. A bad LAM or fuse
is indicated at the cell site by a lighted LAM LED on the circular power distribution
(AYM) board. If no LAM LEDs are visible upon entering the site, use the Radio
Control Procedure to uncover suspected LAM alarms.
Processor alarms are less frequent and are indicated at the cell site by a lighted
LINEARIZER LED on the LAC. If the Radio Control Procedure fails to identify a
bad LAM, the Processor Alarm Query Procedure should be performed to