ADTRAN DS3 MX DS3 MUX TROUBLESHOOTING, Loopback Information, Troubleshooting Information, Code

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 cross-connect. The Line Build Out option should be set to Short for a total coax length of 0-225 feet and Long for 226-900 feet. The clock source must be local for a coaxial loopback. Verify that the STATUS LED turns GREEN after about ten seconds. The Status menu should show that the DS3 TX and RX Status is NORMAL. Also, zero errors should be seen in the first 15-minute column of the DS3 Qrtr-Hourly report under the Performance Monitoring menu. Select “Reset Performance Registers” if necessary to clear previously reported errors.

■An External Coax DS3 Line Loopback can be performed to verify proper far-end equipment DS3 data operation by looping the DS3 transmit coax from the far-end to the receive coax, either locally near the Total Access shelf or at the DS3 cross-connect. The far-end clock source must be local for a coaxial loop- back. The far-end equipment Line Build Out option must be set for the length of coax present. The far-end equipment must be checked for receive DS3 signal status and no errors.

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.

■-48V fuse on Mux is blown.

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 OOS-Unassigned.

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 On-line, force switch to the other Mux.

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 far-end equipment for proper TX signal. Perform External Coax DS3 Line Loopback.

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 far-end equipment.

■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 far-end equipment.

1.Check for correct TX LBO setting on both Mux units.

■Far-end’s receive DS3 signal is bad.

1.Force a Mux protection switch. If the trouble clears, the Mux which is now Off-line has a bad DS3 TX output.

2.Unseat and reset the now Off-line mux.

3.Force the Off-line Mux back On-line and see if the trouble clears.

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 far-end equipment can talk to itself over the entire length of coax with the ON LINE Mux receiving and then re-transmitting the same data. All loopbacks will disrupt any normal traffic on the coax. The DS3 receive line interface unit per- forms this loopback. It performs receive clock and data recovery and B3ZS decoding/encoding before re-transmitting the data.

■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) 457-5007, Document #414.