User's Manual

Lucent Technologies — Proprietary
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401-660-100 Issue 11 August 2000
22-25
Linear Amplifier Circuit (LAC) Maintenance
10. Once a problem LAC is isolated, reset its microprocessor by powering it
down, waiting 10 seconds, and re-setting the breakers. After re-setting 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.
11. If the LAC continues to report inconsistently after it 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 problem moves with
the cable, replace the cable. If the problem clears, move the cable back and
suspect a problem with the LAC.
12. 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 22-6).
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 between 4K ohms and 200K ohms. If either of the
resistance values is outside this range, there is a problem with the
LAC.
13. 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.
14. Once all faulty LACs have been isolated, reconnect the other LAF and/or
LACs to the alarm bus. Verify with the MSC that none of the connected
LACs are generating alarms and that only the disconnected LACs are
generating SANITY alarms.
15. Replace all faulty LACs, making sure to correctly set the address on any
new LACs. Verify that all LAC SANITY alarms have been cleared. Use the
LAQS equipment, Menu Option 5, to verify the integrity of the LAC alarm
bus.
NOTE:
If replacements are not available, leave all defective LACs disconnected
from the alarm bus until they can be replaced.