User's Manual
ADCP-75-158 • Issue 1 • July 2003 • Section 5: Maintenance
Page 5-9
© 2003, ADC Telecommunications, Inc.
LED: STM Color: Red Alarm Type: Major
PROBLEM: A major alarm fault detected by the STM.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. Fiber optic link fault.
2. The HU is not powered.
3. HU and STM band mismatch.
4. The STM has failed.
1. Follow procedure specified when the PORT 1/
PORT 2 LED is red.
2. Check HU LED indicators and refer to Table 5-7
3. Replace HU or STM with correct unit.
4. Replace the STM.
LED: PA Color: Yellow Alarm Type: Minor
PROBLEM: The LPA is overheating.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. Air intake or exhaust opening to the remote
unit cabinet is blocked
2. Ambient temperature > 50º C/122º F.
3. Faulty LPA fan.
1. Remove cause of air-flow blockage.
2. Reduce ambient temperature.
3. Replace LPA fan (See Section 5.5).
LED: PA Color: Red Alarm Type: Major
PROBLEM: The LPA in not detected, the RF power is low or not present, or the LPA detects a major alarm.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. The LPA is not present.
2. The LPA RF output is turned off.
3. The forward path RF cables or connectors are
faulty.
4. The LPA is in the forced shutdown state.
5. The LPA is losing gain due to an internal fault.
6. The STM duplexer has failed.
1. Install LPA.
2. Place LPA MUTE/NORM/RESET switch in the
NORM position.
3. Inspect cables and connectors and repair or
replace if faulty.
4. Check LPA display for messages and then refer to
Table 5-9. Replace the LPA if it is faulty.
5. Replace LPA.
6. Replace the STM.
LED: VSWR Color: Red Alarm Type: Major
PROBLEM: The forward path VSWR is above the threshold.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. Faulty antenna or antenna system.
2. Faulty antenna cable.
3. The STM has failed.
1. Check the antenna circuit for shorts or opens
(including lightning protector).
2. Check the antenna cable for faulty connections.
3. Replace the STM.
LED: PORT 1/PORT 2 Color: Red Alarm Type: Major
PROBLEM: Excessive errors are detected in the reverse or forward path optical signal or no forward or reverse
path optical signal is detected.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. Faulty forward or reverse path optical fiber.
2. Faulty optical transmit port at the HU or
STM; or faulty optical receive port at the HU
or STM.
1. Test optical fiber. Clean connector if dirty. Repair
or replace optical fiber if faulty. (See Section 4.1).
2. Test optical ports. Replace HU or STM if port is
faulty (See Section 4.2).
Table 5-8. STM Fault Isolation and Troubleshooting, continued