User's Manual

ADCP-75-130 • Issue 3C • August 2006
Page 49
© 2006, ADC Telecommunications, Inc.
Table 11. DHU Fault Isolation and Troubleshooting Guidelines (Continued)
Alarm Type LED LED COLOR
Major OVERDRIVE Red
Problem: Forward path RF input level too high.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. Incorrect attenuation in forward path RF
coaxial link.
1. Adjust attenuation at RIU or LIU.
Alarm Type LED LED COLOR
Minor OK/NOK Yellow
Problem: The DHU is receiving a minor alarm signal from the DEU.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. The connected DEU is overheating (2). 1. Check DEU UNIT indicator and then refer to the
appropriate troubleshooting section for procedures.
Alarm Type LED LED COLOR
Major OK/NOK Blinking Red
Problem: The DHU is not receiving an optical signal from the DRU or DEU.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. Forward and reverse path optical fibers
reversed between DHU and DRU (1); or
between DHU and DEU (2).
2. Faulty reverse path optical fiber between DHU
and DRU (1).
3. Faulty optical receive port at DHU or faulty
optical transmit port at DRU (1).
4. Faulty forward or reverse path optical fiber
between DHU and DEU (2).
1. Check fiber connections for correct polarity and
reverse connectors at either unit if mismatched.
2. Clean optical connector and then test optical fiber.
Repair or replace if faulty (see Subsection 6.4.2).
3. Make sure transceiver is fully plugged in and then
test optical port. Replace optical transceiver if
port is faulty (see Subsection 6.4.1).
4. Clean optical connectors and then test optical
fibers. Repair or replace if faulty (see
Subsection 6.4.2).
Alarm Type LED LED COLOR
Major OK/NOK Red
Problem: The DHU is receiving a major alarm signal from the DRU.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1. Faulty forward path optical fiber between
DHU and DRU (1).
2. Faulty optical transmit port at DHU or faulty
optical receive port at DRU (1).
3. The DRU is faulty (1 and 2).
4. Faulty forward or reverse path optical fiber
between the DEU and DRU (2).
1. Clean optical connector and then test optical fiber.
Repair or replace if faulty (see Subsection 6.4.2).
2. Make sure transceiver is fully plugged in and then
test optical port. Replace optical transceiver if
port is faulty (see Subsection 6.4.1).
3. Check DEU UNIT indicator or DRU STATUS
indicator and then refer to appropriate trouble-
shooting section for procedures.
4. Check the status of the OK/NOK LED on the
DEU and then Refer to Table 12.