INSERTION LOSS MEASUREMENTS
10000
15.00
50000
25.50
100000
30.00
150000
32.75
196000
35.00
200000
35.25
250000
37.50
325000
42.00
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.
Turn-up Guide
1.
Set option switches according to specific circuit design
2.
Install HTU-C and HTU-R
3.
The status LED should be green, no alarm indications on the four-character display (FCD) and
synchronization has occurred
(a)
HTU-C will display LLOS if not connected to network (no DSX present; LED will be solid red).
(b)
HTU-R will have red ALM LED if customer not connected. LP1, LP2, line coding (B8ZS or
AMI) and framing (ESF or SF) (if not UNFR) LEDs should be illuminated.
4.
If Status LED is green:
(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 occuring. See Troubleshooting Guide.
5.
If everything checks out, proceed with BERT testing.
Troubleshooting Guide
The HTU-C status LED is flashing green and the FCD indicates "LERR," "HER1," "HER2" or "LBPV"
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 net-
work 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
Frequency
Maximum
(kHz)
Loss Data (dB)
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.
■
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.
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
Circuit with 2 HREs (open at frame)
185 - 190
N/A
N/A
N/A
N/A
N/A
Circuit with 0 or 1 HRE (open at frame)
145 - 150
N/A
N/A
N/A
N/A
N/A
HTU-C / HTU-R
145 - 150
145 - 150
130 - 145
N/A
N/A
125 - 130
HTU-C / HRE1 / HTU-R
130 - 135
110 - 135
110 - 135
N/A
N/A
100 - 135
HTU-C / 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).
R
S
2
3
2
STATUS
MODE
SELECT
HTU-C
1246003L8
HTU-R
1246026L4
TX
M
O
N
RX
B
R
G
LOC
ALM
DS1
LP2
LP1
LLB
(YEL)
RLB
(GRN)
B8ZS
(YEL)
AMI
(GRN)
ESF
(YEL)
SF
(GRN)
R
S
2
3
2
REM
LBK
H
D
S
L
TURN-UP & TROUBLESHOOTING GUIDE
PRICING AND AVAILABILITY 800.827.0807
TECHNICAL SUPPORT 800.923.8726
RETURN FOR REPAIR 256.963.8722
www.adtran.com
