13
7511-A2-GN10-10
January 1999
Symptom
Recommendations
Possible Cause
Not receiving data;
DSU is not
responding.
DDS line rate has
changed
Excessive BPVs
Excessive loop loss
1. Verify that your subscriber loop is
running at 56 kbps or
64 kbps CC.
2. Run Loopback tests. Refer to
Chapter 4,
Testing, in the User’s
Guide.
3. If network testing exposes
excessive BPVs, verify that you
do not have a bad cable If the
,
y
y
do not have a bad cable. If the
cable is good, contact the
network service provider.
4. If network testing exposes
excessive loop loss, install a
higher quality cable. Refer to
Appendix B,
Technical
Specifications, in the User’s
Guide.
The Test LED does
not light up when
you attempt to start
a Remote Digital
Loopback; the RL
LED turns off.
The remote unit failed to
acknowledge the
V.54 Loop Up command.
Check the remote unit. If it has a
V.54 Sequence Detection
configuration option, verify that it is
enabled.
An LED is not lit.
LED is burned out.
While the DSUs are not in use,
cycle power to the card by pulling it
slightly out of the carrier then
replacing it. If the LED in question
does not flash with the other LEDs,
contact your service representative.
The Test Mode
switch has no effect.
Switch S2-8 is ON. Switch
S2-8 is for Manufacturing
use only and may affect the
DSU’s behavior.
Move Switch S2-8 to the Off
position.
Unexpected
behavior in general.
Switch settings are
incorrect.
Ensure that switches on the circuit
card are fully on or fully off as
appropriate for your application.
!
Important Safety Instructions
1. Read and follow all warning notices and instructions marked on the product
or included in the manual.
2. Slots and openings in the cabinet are provided for ventilation. To ensure
reliable operation of the product and to protect it from overheating, these
slots and openings must not be blocked or covered.
3. Do not allow anything to rest on the power cord and do not locate the product
where persons will walk on the power cord.
