ADTRAN HTU-C / 3192 warranty Insertion Loss Measurements, Running Excessive Errors on the Loop

TURN - UP & TROUBLESHOOTING GUIDE

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INSERTION LOSS MEASUREMENTS

Frequency	Maximum
(kHz)	Loss Data (dB)
10000	15.00
50000	25.50
100000	30.00
150000	32.75
196000	35.00
200000	35.25

NOTE: If your TIMs is unable to transmit 200 kHz tone, set the TIMs to one of the frequencies shown above and compare the received signal to the maximum loss at that frequency.

HTU-C VMDF HRE 1 HRE2 HTU-R

	A	B	C	D	E	F
	t-t Voltage	t-t Voltage	t-t Voltage	t-t Voltage	t-t Voltage	t-t Voltage
Open at Frame HV	185 - 190	N/A	N/A	N/A	N/A	N/A
Open at Frame LV	145 - 150	N/A	N/A	N/A	N/A	N/A
HTU-C LV / HTU-R	145 - 150	145 - 150	130 - 145	N/A	N/A	125 - 130
HTU-C LV / HRE1 / HTU-R	130 - 135	110 - 135	110 - 135	N/A	N/A	100 - 135
HTU-C HV / HRE 2 / HTU-R	185 - 190	160 - 185	160 - 185	140 - 185	140 - 185	130 - 185

NOTE: All measurements taken with HTU-C installed. With the HTU-C unseated or with protector removed at VMDF, t-r resistance will be cable resistance plus 3 ohms (for either HRE or HTU-R).

Turn-up Guide

1.Set option switches according to circuit design and local practice.

2.Install HTU-C and HTU-R.

3.See reverse side of this job aid to ensure all LEDs are correct and synchronization has occurred.

a)HTU-C will have red ALM LED if not connected to network. LP1 and LP2 should be solid green.

b)HTU-R will have red ALM LED if no customer connected. LP1, LP2, line coding and framing (if not UNFR) LEDs should be illuminated.

4.If all LEDs are correct:

a)Verify that the signal quality is the same on each loop. Ensure signal quality indicators do not fluctuate.

b)Verify that the loop loss is within design limits. If there is a difference of more than 1 dB between the two loops, a problem exists with the cable pairs.

c)If errors occur, use the Current System Status and Performance History screens to determine where they are occurring. See Troubleshooting Guide section.

5.If everything checks out, proceed with BERT testing.

Troubleshooting Guide

The HTU-C DSX LED is Flashing, but no Errors are Indicated by the HTU-R

■A BPV, Frame Error (SF) or CRC Error (ESF) has been detected at the DSX-1 interface. Possible network or wiring problem between the HTU-C and the DSX. This is not an indication of problems on the HDSL loops.

The HTU-R DS1 LED is Flashing, but no Errors are Indicated by the HTU-C

■A BPV, Frame Error (SF) or CRC Error (ESF) has been detected at the DS1 interface. This indicates a wiring problem or a B8ZS/AMI mismatch between the HTU-R and the customer equipment. This is not an indication of problems on the HDSL loops.

The HTU-R has Power, but LP1 and LP2 LEDs are Dark. The Unit cannot Sync with the HTU-C

■Simplex power for powering the HTU-R can be passed over cable pairs that contain load coils or that are too long for HDSL synchronization. Using a TIMs, verify the circuit is within design limits.

■The HTU-R will power up as long as there is at least one good conductor on each loop. To test, remove the protector plug at the MDF and measure t-r resistance to the HTU-R on both loops. The HTU-R will place a 3 ohm short between t-r on both loops. An extremely high impedance indicates an open conductor. An extremely low reading on one loop may indicate a t-r short in the field. In the field, measure t-t and t-r voltage with the HTU-C installed and compare to the chart above. If these voltages are not present, open pairs or mis-wiring is indicated. As with other circuits, standard resistance measurements between each conductor and ground should also be used to test for a grounded conductor.

■If the HTU-C is optioned for LV and there are two HREs in the circuit, the HTU-R could fail to power up normally. The LEDs on the HREs or HTU-R will flash at a rate of 3 times/second. Make sure the voltage option on the HTU-C is set to HV.

■A high resistance open which degrades to the point that it causes the circuit to lose sync can be “resealed” by reseating the HTU-C. Test the cable pairs before reseating the HTU-C.

Running Excessive Errors on the Loop

■Measure t-r resistance as described above. If the pairs are unbalanced by more than 4 ohms, or a measurement varies a great deal, this could indicate a high resistance open or an intermittent fault on the loop with the higher measurement. A TDR is typically required to locate this splice for repair.

■Excessively long bridged taps can also cause errors. Check the records and/or use a TDR to verify the location and length of bridged taps.

■Using ADTRAN’s “Performance History” screen, it is often possible to see that many more errors are being received on a particular loop or at a particular unit. The fault will typically be very close to the unit receiving the most errors.

No Power at the HTU-R

■This could be caused by a loop with two open conductors. Measure t-r resistance from the MDF to the HTU-R or use the voltage chart to see which pair is open.

■Check the HV/LV option on the HTU-C and re-option if necessary.