
DS3 MUX TROUBLESHOOTING
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LOOPBACK INFORMATION
External Coax DS3 Loopbacks
Two types of External Coax DS3 loopbacks can be used to isolate trouble and verify proper DS3 data path operation. For accurate isolation, this type of loopback is preferred over the menu selected loop- backs since it checks the entire signal path and isolates the equipment at each end. An external coax loopback cannot reliably be done if the total length of coax exceeds 900 feet. Both of these types of loopback disrupt normal traffic on the coax.
■An External Coax DS3 Local Loopback can be
performed to verify proper DS3 Mux data operation by looping the DS3 transmit output to the DS3 receive input either locally with a short coax or at the DS3
■An External Coax DS3 Line Loopback can be performed to verify proper
TROUBLESHOOTING INFORMATION
1.POWER LED ON RED continuously.
■Equipment fault.
1.Momentarily unseat and then reseat the Mux to clear LED.
2.Replace Mux if trouble persists.
2.POWER LED OFF and Power LEDs of all other cards in shelf are ON.
■
1.Replace the Mux. Fuse is not field replacable.
3.POWER LED is ON YELLOW, Status LED is OFF and Mux does not pass traffic.
■Mux is provisioned for
1.Provision Mux to be In Service.
4.No alarms are ON in Mux and it does not pass traffic.
■The DS3 channels are not mapped to access card slots.
1.Provision each channel to the desired slot.
5.LEDs do not turn ON when pushing Test/Enable button.
■There is an equipment fault.
1.If Mux is still
2.Momentarily unseat and reseat the Mux to clear trouble.
3.Replace Mux if trouble persists.
6.Status LED is ON RED in Mux A and B and Status menu shows DS3 RX LOS.
■DS3 receive signal is not present.
1.Check for correct RX coax connection. Ensure TX and RX coaxes are not reversed.
2.Check for faulty coax or coax connector.
3.Check
4.Perform an External Coax DS3 Local Loopback to verify that Mux units and shelf are OK.
7.STATUS LED is on red in Mux A and B and Status menu shows DS3 RX OOF.
■Receive DS3 signal is present but valid DS3 framing is not being received.
1.Check for correct TX LBO setting on far end equipment.
2.Check far end equipment for proper TX signal. Perform External Coax DS3 Line Loopback.
TROUBLESHOOTING CONT.
9.No alarms are active in either Mux but receive DS3 PM errors occur in both Mux units.
■Marginal DS3 receive signal
1.Check for correct TX LBO setting on
■Total length of coax cable > 900 feet (728A or 734A).
1.Reduce cable length to < 900 feet.
■AC current is flowing in RX coax shield due to a frame ground potential difference at ends of cable.
1.Improve grounding or isolate one end of coax shield from frame ground.
■Check to ensure the clock source is not identical at both ends (i.e., both ends set to Local or both ends set to Loop).
10.Status LED is ON YELLOW in one or both Mux units.
■Marginal DS3 receive signal at
1.Check for correct TX LBO setting on both Mux units.
■
1.Force a Mux protection switch. If the trouble clears, the Mux which is now
2.Unseat and reset the now
3.Force the
4.Replace Mux if trouble persists.
■Check to ensure the clock source is not identical at both ends (i.e., both ends set to Local or both ends set to Loop).
11.DS3 PM errors occurring and/or DS3 status indicates OOF.
■Check to ensure the clock source is not identical at both ends (i.e., both ends set to Local or both ends set to Loop).
1.Change clock source to loop if the current clock source is local or vice- versa.
COMPLIANCE REQUIREMENTS
■This product is intended for installation in a restricted access location in a Type “B” or “E” enclosure only.
CODE | INPUT | OUTPUT |
Power Code (PC) | F | C |
Telcommunication Code (TC) | – | – |
Menu Selected DS3 Loopbacks
■A Mux Menu Selected DS3 Line Loopback can be used to verify that the
■A Mux Menu Selected DS3 Local Loopback should not be used to verify the DS3 data path since it does not test the entire DS3 data path. A Local Loopback should be used only to internally loopback the DS3 signal on the Mux to verify Access card T2/E1/T1 data paths.
3.Perform an External Coax DS3 Local Loopback to verify that Mux units and shelf are OK.
4.Ensure framing format for both units is the same.
■Check to ensure the clock source is not identical at both ends (i.e., both ends set to Local or both ends set to Loop).
8.Status LED is ON RED in one Mux only, OR, No alarm LEDs on in either Mux
but receive DS3 PM errors occur on one Mux.
■Faulty Mux DS3 receiver.
1.If this Mux is still ON LINE, force a protection switch to the other Mux.
2.Momentarily unplug and then plug in Mux to see if trouble clears.
3.Replace Mux if trouble persists.
Installation Code (IC) | A | – |
WARRANTY
Warranty for Carrier Networks products manufactured by ADTRAN and sup- plied under Buyer’s order for use in the U.S. is ten (10) years. For a complete copy of ADTRAN’s U.S. Carrier Networks Equipment Warranty statement, call (877)