Specifications

Chapter 3 Testing & Diagnostics
3-9
The Test LED is Yellow The Access Bank is in Network Loopback - sending the
received T1 signal back toward the line. This may be due
to either an in-band five-bit loopback code of 10000
received from the T1 line, or the Network Loopback Switch
being set to Network Loopback at the front of the Access
Bank.
1. Be sure the Network Loopback switch is set to Normal.
2. Turn the Self Test switch to the Self Test position and
back to Normal to reset a carrier sent loopback condition.
The Test LED Remains RED for more than 16
seconds after Self Test is started.
Self Test Switch Activated, T1 Self Test Failed due to one
or more of:
T1 Loss of Signal, Out of Frame, Improper Line Code
Received, ESF or BPV errors received.
Contact CAC.
T1 Line LED is Red Loss Of T1 Signal From The Line. The Access Bank is not
receiving a T1 signal.
1. Check the T1 Network Interface cable at the Access
Bank and the demarcation to be sure it is properly plugged
in.
2. Run the Self Test. If Test LED comes up green, contact
your carrier.
T1 Line LED is Yellow Check to see that the line coding switch (#5 in the T1
Control Switch) matches the line coding sent by the carrier
Bipolar Violations Received during one second intervals.
A yellow flash of 1 second indicates that at least one BPV
was received in error (not due to B8ZS coding) during this
one second interval. If it is persistent, contact your carrier.
Framing LED is Red AIS (Unframed All Ones) Received From The T1 Line.
This may indicate a loss of T1 connection somewhere in
the carrier facility or on a point-to-point T-span may
indicate that the far end equipment has lost power or is
disconnected.
1. For a point-to-point span, contact remote end to check
equipment there.
2. If remote end is OK, or from a span directly to your
carrier, contact your carrier to have T1 line checked.
Framing LED is Red Flashing Network T1 Is Out Of Frame. The received signal can not
be framed to ESF or D4, as configured by T1 Option
Switch 4.
1. Check the T1 control switch #4 to be sure it matches the
framing you should be getting from your carrier.
2. Run the Self Test. If Test LED comes up green, contact
your carrier to have the T1 line checked.