User Manual

ADCP-75-179 • Preliminary Issue A • September 2004 • Section 4: maintenance
Page 4-9
© 2004, ADC Telecommunications, Inc.
3.2 STM Troubleshooting
Use this section to troubleshoot alarms that originate with the STM. When a Minor alarm
occurs, one (or more) of the STM LED’s will turn yellow and the EMS software will indicate a
minor fault/alarm. When a Major alarm occurs, one (or more) of the STM LED’s will turn red
and the EMS software will indicate a major fault/alarm. Locate the LED and the corresponding
fault/status indicator in Table 4-6 and then take the corrective action indicated.
PROBLEM C: The RF input signal level is below the underdrive threshold.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. Composite output signal from EBTS is too low.
2. Faulty coaxial connection between the HU
and the EBTS.
3. Incorrect attenuation in forward path RF
coaxial link.
1. Check EBTS composite output signal level and
adjust if too low.
2. Correct EBTS cables if faulty.
3. Check Host Forward Attenuator setting and
adjust if attenuation is too high.
PROBLEM D: The RF input signal is above the overdrive threshold.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. Composite output signal level from EBTS is
too high.
2. Incorrect attenuation in forward path RF
coaxial link.
1. Check EBTS composite output signal level and
adjust if too high.
2. Check Forward Attenuator setting and adjust if
attenuation is too low.
PROBLEM E: No light received over the reverse path or excessive errors received over the reverse path
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. Faulty reverse path optical fiber.
2. Faulty optical transmit port at the STM;
or faulty optical receive port at the HU
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).
PROBLEM F: The HU does not respond to control or monitoring commands sent by the EMS.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. The HU is not powered.
2. The cable connection between the HU and the
EMS computer is faulty.
3. The CAN cable connections between the HUs
in a multiple HU installation are faulty.
1. See Problem A this table.
2. Inspect EMS cable and repair or replace if faulty.
3. Inspect each CAN cable and repair or replace if
faulty.
Table 4-5. Host Unit Fault/Alarm Corrective Action, continued