User's Manual

Lucent Technologies — Proprietary
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22-34
401-660-100 Issue 11 August 2000
Linear Amplifier Circuit (LAC) Maintenance
2. A short circuit on the circular AYM board.
3. A failure of the power unit within the Linearizer (LZR) that provides 5 volt
bias to the LAMs.
Procedure:
1. Have the MSC take all radios on the LAC out of service (all radios OFF).
2. Remove DC power from the LAC by opening its breakers.
3. Disconnect all LAM ribbon cables.
4. Reapply power. If the alarm does not clear, the problem is within the LAC.
Replace the LAC.
5. If the alarm clears, suspect a fault in one of the LAMs. Isolate the faulty
LAM by reconnecting the LAMs, one at a time, until the alarm returns,
identifying the bad LAM. Replace the bad LAM.
Fan Alarm
Procedure
Preamp Fan
All preamp fans in the LAF are powered from two of the four 20A DC feeders
which supply power to the LAC 0 position in the frame.
Preamp fans will not
have power if the breakers to LAC 0 are open.
!
CAUTION:
To avoid overheating the preamps, do not power down LAC 0 for more than
a few minutes if other LACs are powered. If LAC 0 needs to be powered
down for an extended period of time, disconnect the J1 power cable from
LAC 0 (LAC 4 in LAF1), and close the
two
20A breakers which supply
connector J1.
Symptoms:
C-Series LACs:
1. Major Alarm
2. LAC LEDS = FANS and PREAMP
A/B-Series LACs:
1. Minor Alarm
2. LAC LEDS = LINEARIZER