Section 363-746-100
Revision 01
Page 9
TABLE 3. FRL-746 RT LINE UNIT TROUBLESHOOTING
Indication
Problem
Action
POWER
LED
off
1. One or both HDSL lines
are no longer connected
between the COT and
RT. Verify the
connections at the RT
and COT.
a. Make the following measurement on the RT Enclosure backplane:
•
130 Vdc to 250 Vdc between A_HDSL_T and B_HDSL_T
b. Make the following measurements on the COT Shelf backplane:
•
-130 Vdc, ±10%, between A_HDSL_T1 and Chassis Ground
•
0 Vdc to +120 Vdc, between A_HDSL_T2 and Chassis Ground
(Note: Use B_HDSL_T1 and B_HDSL_T2 for System #2)
2. The COT Line Unit fuse
F1 has blown.
Replace the fuse.
3. The RT Line Unit power
supply has failed.
Replace the RT Line Unit.
4. The COT HDSL power
supply has failed.
Replace the COT Line Unit.
Indication
Problem
Action
LOOP 1
(2) SYNC
LED
flashing or
off
1. The HDSL line is
attempting to synchronize
with the Central Office
unit or cannot detect the
HDSL signal from the
Central Office unit. This
is usually an indication
that there is a problem
with the HDSL circuit
between the COT and RT
(assuming the FAULT
LED is
off).
2. COLU and RTLU
incompatible i.e. one is a
T1 version and the other
is an E1.
a) Verify the HDSL circuits are terminated properly and with the
correct orientation.
b) Measure the loop resistance of each HDSL circuit (shorting the
pair at the far end). The loop resistance must be less than that
shown in Table 1.
LOOP 1
(2)
MARGIN
LED
on
The HDSL line margin level
is below a preset level.
See the previous discussion on the SYNC LED
flashing or off.
FAULT
LED
on
Faulty FRL-746 RT Line
Unit.
Replace the RT Line Unit.
