User's Manual

Lucent Technologies — Proprietary
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401-660-100 Issue 11 August 2000
22-27
Linear Amplifier Circuit (LAC) Maintenance
connected, or until all of the LACs have been disconnected. Reconnect
each LAC to the alarm bus by itself, one LAC at a time, until all faulty LACs
are isolated.
11. Once the LAC which generates SANITY alarms is isolated, reset its
microprocessor by powering it down, waiting 10 seconds, and re-setting the
breakers. After resetting the LAC, bring up two radios and allow at least 2
minutes for any alarms to clear.
!
CAUTION:
Make sure that all radios are turned off before re-applying power to the
LAC.
12. If SANITY alarms remain after the LAC has been reset, double check its
address, and inspect the LAC alarm cable and connections (See
Figure 22-9). Connect it to the bus by itself and check the integrity of the
LAC alarm cable by moving it to another LAC. If the alarm moves with the
cable, replace the cable. If the alarm clears, move the cable back and
suspect a problem with the LAC.
13. Power down the suspect LAC and disconnect the alarm cable from the top-
most 9-pin D-sub connector at the back of the AYG3 pack (J10) (See
Figure 22-10).
a. Using an ohmmeter, measure the resistance from Pins 1 and 2 to
ground on LAC connector J10. (Use the connector shell for ground.)
Both resistance values should be greater than 20K ohms. If either
value is less than 20K ohms, there is a problem with the LAC.
b. Likewise, measure the resistance from Pins 3 and 4 to ground. Both
resistance values should be between 4K ohms and 200K ohms. If
either of the resistance values is outside this range, there is a
problem with the LAC.
14. If the LAC resistance values check out OK, remove the cover over the
microprocessor, on the side of the AYE1 pack in the LAC. Check for bent
pins on the processor chip, or other obvious problems.
15. Once all faulty LACs in the LAF have been isolated, reconnect the other
LAF(s) to the alarm bus. Verify with the MSC that none of the LACs in the
reconnected LAF(s) are generating alarms and that only the disconnected
LACs are generating SANITY alarms. If any LACs in the reconnected
LAF(s) generate alarms, repeat Steps 8 through 11 above to find the
problem.
16. Reconnect each suspect LAC to the bus, one at a time, verifying that each
one generates a SANITY alarm at the MSC and/or causes other LACs to
generate alarms.