150-451-104-02, Revision 02
Installation
HDU-451 List 4
September 18, 1998
11
3
Push the unit into the card edge connector until it is entirely within the
card guide. The unit should snap into place, indicating that the unit is
properly seated.
4
Check the indicator lights on the front panel:
•
If the HLU in the CO is operational, the HDSL IN LED indicators
light within 30 seconds.
•
If the HRU at the customer site is installed and operational, the
HDSL OUT LED indicators light and remain lit within 1 minute.
If the LEDs do not light properly, continue with the
section for possible problems and solutions.
T
ROUBLESHOOTING
This section provides step by step troubleshooting procedures for common
problems.
The four-character front panel display on the line unit that powers the doubler
provides additional information that may be useful in solving a problem.
shows the messages that can appear on the line unit front
panel display.
Isolating a Problem
The front panel HDSL IN (loop) 1 and (loop) 2 LEDs identify the cable pairs
coming into the doubler from the upstream location. The pairs are identified
by the polarity of the simplex voltage that is applied to them by the upstream
unit, the HLU or the HDU-451. Loop 1 has the - simplex voltage. Loop 2 has
the + simplex voltage.
To isolate the source of a problem, swap the input pairs. In this case, the
HDU-451 continues to identify loop 1 as the - pair and loop 2 as the + pair. If
the problem remains with the same pair, as identified by the HDU, before and
after the pairs are swapped, the problem is upstream or towards the pair.
For example, assume the HDSL IN 1 LED is flashing red, indicating errors
on loop 1. If the pairs are swapped and the HDSL IN 1 LED continues to flash
the indicated problem is towards the upstream cable pair or attached
equipment. If the HDSL 2 IN LED begins flashing, the problem lies towards
the HDU-451 unit itself.
