User Manual

ADCP-75-110 • Issue 2B • July 2001
Page 47
© 2001, ADC Telecommunications, Inc.
5.3 Fault Isolation and Troubleshooting
Table 11 provides fault isolation and troubleshooting guidelines. When a problem is reported,
note the type of alarm generated (minor, major, or none) and any problems that may be
observed. Then check the LED indicators on the DHU and note any that are red, yellow, or
off. If a Port 1–6 OK/NOK LED indicator is any color but green, check the LED indicators on
the connected DEUs and/or DRUs. When the required information has been obtained, locate
the problem in Table 11, check out the suggested possible causes, and take corrective action as
required.
Table 11. Fault Isolation and Troubleshooting
Alarm Type Minor
LED Indicators DHU or DEU: UNIT - Yellow - All other LEDs are green
Problem The DHU or DEU is overheating.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. Air intake or exhaust openings to DHU or
DEU chassis blocked.
2. Ambient temperature > 50º C/122º F.
3. Faulty fan.
1. Remove cause of air-flow blockage.
2. Reduce ambient temperature.
3. Replace fan (see Subsection 5.5).
Alarm Type Major
LED Indicators DHU or DEU: UNIT - Red
Problem The DHU or DEU detects an internal circuitry fault.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. Faulty DHU or DEU. 1. Replace DHU or DEU.
Alarm Type Major
LED Indicators DHU or DEU:
DRU:
OK/NOK - Red or blinking Red - All other LEDs are green
STATUS - Off
Problem The DRU is not powered.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. DC power cable open.
2. No power or insufficient power output from
ac/dc power converter, DHU, or DEU.
3. Faulty DRU.
1. Test cable for continuity and repair or replace if
faulty.
2. Check DC voltage level at the DRU (see Subsection
5.4.3). Replace converter, DHU, or DEU (whichever
applies) if voltage is not within 34 to 48 Vdc.
3. Replace DRU.
Alarm Type Major
LED Indicators DHU or DEU:
DRU:
All LEDs are green
STATUS - Red or blinking Red
Problem The DRU is not receiving an optical signal from the DHU or DEU.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. Faulty forward path optical link between
DHU or DEU and DRU
2. Faulty optical transmit port at DHU or
DEU; or faulty optical receive port at DRU.
1. Test optical link and repair or replace if faulty
(see Subsection 5.4.2).
2. Test optical ports. Replace DHU, DEU, or DRU
if port is faulty (see Subsection 5.4.1).
(continued)