PairGain PG-Flex 8 FLC-704 User manual

PG-FLEX 8 CHANNEL COT POTS UNIT
MODEL FLC-704
Model List Number Part Number CLEI Code
FLC-704 2 150-1304-02 N/A
PAIRGAIN TECHNOLOGIES, INC.
ENGINEERING PLANT SERIES TECHNICAL PRACTICE
SECTION 363-704-102-02
Revision History of this practice.
Revision 02—January 12, 1998
A) Update Format

Section 363-704-102-02 January 12, 1998 Revision 02
ii PairGain Engineering - Plant Series PG-Flex FLC-704 List 2
TABLE OF CONTENTS
A. PRODUCT OVERVIEW................................................................................................................1
1. Description and Features....................................................................................................1
2. Front Panel........................................................................................................................2
3. Specifications....................................................................................................................3
B. FUNCTIONAL DESCRIPTION......................................................................................................4
4. Applications ......................................................................................................................4
5. Operational Capabilities ....................................................................................................6
C. INSTALLATION AND TEST.........................................................................................................7
6. Unpacking.........................................................................................................................7
7. Turn-Up and Testing..........................................................................................................7
8. Troubleshooting.................................................................................................................7
D. TECHNICAL SUPPORT.................................................................................................................9
9. Technical Support..............................................................................................................9
E. CERTIFICATION AND WARRANTY..........................................................................................9
10. Certification.....................................................................................................................9
11. Warranty.........................................................................................................................10
F. ABBREVIATIONS.........................................................................................................................10
12. Abbreviations .................................................................................................................10
USING THIS TECHNICAL PRACTICE
Two types of messages, identified by icons, appear in the text:
A note informs you of special circumstances.
Cautions indicate the possibility of damage to equipment or the possibility of
personal injury.
Copyright 1998 PairGain Technologies, Inc.
PairGain is a registered trademark, and PG-Flex is a trademark of PairGain Technologies, Inc.
Information contained in this document is Company Private to PairGain Technologies and shall not be modified, used, copied,
reproduced, or disclosed in whole or in part without the written consent of PairGain.
Other product names mentioned in this practice are used for identification purposes only and may be trademarks and/or registered
trademarks of their respective companies.

Revision 02 January 12, 1998 Section 363-704-102-02
PG-Flex FLC-704 List 2 PairGain Engineering - Plant Series Page 1
A. PRODUCT OVERVIEW
1. Description and Features
1.1 The PairGain® PG-Flex
 FLC-704 List 2 Channel Unit provides eight Plain Old Telephone Service
(POTS) interfaces between the Central Office and the PG-Flex, and uses A-Law pulse code
modulation (PCM) encoding. The Model FLC-704 Channel Unit includes green status LEDs for
each line indicating idle, ringing, and off-hook conditions, as well as a red LED indicating a fault
condition. The channel unit provides metallic test access to the subscriber line connection through
an optional metallic bypass pair.
1.2 Features of the PG-Flex FLC-704 COT Channel Unit:
• eight POTS subscriber interfaces
• 64 kbps A-Law PCM encoding
• metering tones (12 kHz, 16 kHz)
• front panel ACTIVE LEDs indicate idle, ringing, metallic test access, and off-hook for each
channel
• front panel FAULT LED indicator simplifies troubleshooting

Section 363-704-102-02 January 12, 1998 Revision 02
Page 2 PairGain Engineering - Plant Series PG-Flex FLC-704 List 2
2. Front Panel
2.1 Figure 1 shows the FLC-704 front panel. Table 1 lists the different states and indications for the
FLC-704 Channel Unit front panel LEDs.
Figure 1. FLC-704 Front Panel
Table 1. FLC-704 Front Panel LEDs
LED LED State Indicates
Solid green Channel is off hook.
ACTIVE Fast flashing green Channel is in test access mode.
(1 through 8) Slow flashing green Channel is ringing.
Off Channel is on hook.
FAULT Red Fault detected b
y
the unit. Refer to
Table 3 for troubleshootin
g
procedures.
Off No faults detected.

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PG-Flex FLC-704 List 2 PairGain Engineering - Plant Series Page 3
3. Specifications
Electrical Characteristics
Analog Impedance ......................................600 Ω
Loop Resistance..........................................100 Ω,(CO switch to COT)
End-to-End Loss .........................................-2.5 dB ±1.0
DC Off-Hook Current .................................30 mA
Channel Signature
Tip-Ring...............................................475 kΩ, 1%
Tip-Ground ..........................................332 kΩ, 1%
Ring-Ground ........................................(open)
COT 20 Hz Input Impedance.......................0.5 REN
Environmental
Operating Elevation ....................................-200 ft. to 13,000 ft (-60 m to 4,000 m)
Temperature and Humidity .........................-40° F to +150° F (-40° C to +65° C)
5% to 95% (non condensing)
Physical
Weight ........................................................0.8 lb (0.4 kg)
Dimensions
Height..................................................6.75 in. (17.2 cm)
Width...................................................1.00 in. (2.5 cm)
Depth...................................................10.50 in. (26.7 cm)

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Page 4 PairGain Engineering - Plant Series PG-Flex FLC-704 List 2
B. FUNCTIONAL DESCRIPTION
4. Applications
4.1 PG-Flex is a small capacity universal subscriber carrier system that can support up to 32 DS0
subscriber channels, including POTS and ISDN services. The system is based on HDSL transmission
technology and is remotely powered from the Central Office (CO). Using two 24 gauge (0.5mm)
unconditioned copper pairs, the remote terminal may be located up to 10.7 kft (3.3 km) from the
Central Office Terminal (COT). Standard 19- or 23-inch shelves contain multiple systems; circuit
cards may be hot-swapped without affecting other systems installed in the shelf. POTS channel units
use 64-kbps A-Law pulse coded modulation (PCM) encoding to allow Group 3 facsimile or high-
speed modem operation on all channels.
4.2 System Flex Configuration. Figure 2 shows a typical PG-Flex system that consists of:
• COT. Two complete systems may be installed in a 19-inch COT Shelf and four complete
systems may be installed in a 23-inch COT Shelf. Each system requires one COT Line Unit and
up to three (23-inch shelf) or six (19-inch shelf) Channel Units. A common Alarm Unit or Pair
Gain Test Controller Interface Unit in each shelf provides an interface for maintenance alarm
relays and metallic access to the remote subscriber lines.
• RT. The RT Enclosure provides a weatherproof housing for the PG-Flex remote electronics and
subscriber terminations. The enclosure accepts one common RT Line Unit and up to four
Channel Units. The RT communicates with, and is line-powered from, the COT over two pairs of
19 AWG to 26 AWG (0.9 mm to 0.4 mm) twisted-pair telephone wire. Each pair carries both
power and HDSL signaling.
Figure 2. Typical PG-Flex Configuration.

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PG-Flex FLC-704 List 2 PairGain Engineering - Plant Series Page 5
4.3 HDSL Transmission. PG-Flex utilizes HDSL transmission technology between the COT and RT
and provides up to 32 DS0s, plus signaling, over two copper pairs without the need for repeaters,
loop conditioning, or pair selection. Adaptive equalization, scrambling, and a four-level 2B1Q line
coding scheme increase range and minimize crosstalk.
4.4 The line interface is a two-pair, 1110-kbps full-duplex 2B1Q transmission format. The dual HDSL
lines provide 32 64-kbps channels with signaling, and an embedded operations channel for
management control. The signal characteristics on the carrier pairs comply with TR-NWT-001210,
Generic Requirements for High-bit-rate Digital Subscriber Line (HDSL) Systems.
4.5 For the system configuration depicted in Figure 2, the maximum distance between the COT and the
RT is 10.7 kft (3.3 km), assuming the HDSL lines are 24 gauge (0.5 mm). Table 2 shows the
maximum distance between the COT and RT for various gauge wire. Due to the nature of HDSL
transmission technology, the HDSL lines do not require any special conditioning and may include
unterminated bridge taps, but cannot include load coils.
Table 2. PG-Flex Distances
Loop Length
Wire Gauge 16/32 Channel System Resistance @ 28 ° C
26 AWG (0.4 mm) 8.1 kft (2.5 km) 686 Ω
24 AWG (0.5 mm) 10.7 kft (3.3 km) 569 Ω
22 AWG (0.6 mm) 13.7 kft (4.2 km) 457 Ω
19 AWG (0.9 mm) 19.4 kft (5.9 km) 322 Ω
4.6 Subscriber Drop Testing. For subscriber drop testing from the CO, PG-Flex is able to select and
connect any subscriber drop to a metallic test pair at the RT. PG-Flex extends this connection back
to the COT where technicians can switch it onto a test access bus, or to the corresponding subscriber
line on the COT channel card.
4.7 Metallic access is performed by momentarily placing +116 Vdc (from the CO) on the subscriber’s
Tip lead. (The Ring lead should be between GND and the Tip value.) Depending on the PG-Flex
system configuration, the selected subscriber drop (assuming a working metallic bypass pair)
connects to the corresponding COT subscriber line.
4.8 The metallic connection drops when -116 Vdc is momentarily applied to the subscriber’s COT Tip.
4.9 Metallic access may also be activated through and ASCII terminal connected to the RS-232 Craft
Maintenance port located on the front of the FLL-716 line unit or through the FAU-728 or FPI-729
units.

Section 363-704-102-02 January 12, 1998 Revision 02
Page 6 PairGain Engineering - Plant Series PG-Flex FLC-704 List 2
5. Operational Capabilities
5.1 The FLC-704 Channel Unit provides eight POTS interfaces to the CO switch. The unit performs the
interface function between the analog POTS circuit and the internal digital PCM bus. In addition,
each channel unit:
• converts analog signals to 64 kbps A-Law PCM digital format
• detects ringing voltage
• detects loop current feed
• detects forward disconnect
• detects a subscriber test access signal
• detects metering tones
• provides loop closure
5.2 A block diagram of the FLC-704 Channel Unit is shown in Figure 3. One 8-Channel COT Channel
Unit supports eight POTS interfaces.
5.3 A status LED is associated with each line to indicate whether the line is off-hook, idle, ringing, or
being tested. A common fault LED indicates a general fault has been detected on the card and it
should be replaced.
5.4 Test access connections to a specific line circuit are made through the maintenance terminal or by
the CO switch applying the appropriate voltages on the subscriber line (paragraphs 4.6 through 4.9).
Figure 3. FLC-704 Block Diagram

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PG-Flex FLC-704 List 2 PairGain Engineering - Plant Series Page 7
C. INSTALLATION AND TEST
6. Unpacking
6.1 Upon receipt of the equipment, proceed as follows:
1Unpack each container and visually inspect it for signs of damage. If the equipment has been
damaged in transit, immediately report the extent of damage to the transportation company and
to PairGain. Order replacement equipment if necessary.
2Check the contents versus the packing list to ensure complete and accurate shipment. If the
shipment is short or irregular, contact PairGain as described in Section 9. If you must store the
equipment for a prolonged period, store the equipment in its original container.
7. Turn-Up and Testing
7.1 Install COT Channel Units
1Insert each FLC-704 Channel Unit into the COT shelf.
All LEDs on the Channel Unit will turn on for approximately 1/2 second, then scan from top to
bottom, then flash all on, then off.
2After the system has powered up, established HDSL synchronized communications, and no calls
are in progress, verify that the Channel Unit front panel indicators ACTIVE 1 through
ACTIVE 8 and FAULT LEDs are all off.
7.2 Test Subscriber Circuits. Test each subscriber circuit by placing and receiving calls; ACTIVE 1
through 8 LEDs track call progress.
8. Troubleshooting
8.1 Table 3 on page 8 provides troubleshooting procedures based on indications displayed by the front
panel indicators of FLC-704 Channel Unit.

Section 363-704-102-02 January 12, 1998 Revision 02
Page 8 PairGain Engineering - Plant Series PG-Flex FLC-704 List 2
Table 3. FLC-704 Channel Unit Troubleshooting
Indication Problem Action
FAULT LED
ON The FLC-704 processor has detected a fault. Remove and re-insert the Channel Unit. If the FAULT LED does not extinguish, replace the Channel Unit.
Troubleshooting based on customer-originated trouble reports
No Dial tone,
Can’t Dial
• fault
y
RT or COT
Channel Unit
• facility short/open
• CO switch problem
1Lift the subscriber
p
air at the network interface. If dial tone is
p
resent
and
y
ou can
p
lace a call, refer the
p
roblem to the customer
p
er local
practice.
2If
y
ou cannot hear dial tone or cannot
p
lace a call at the network
interface (with the subscriber
p
air lifted), check for dial tone at the RT.
If dial tone is
p
resent, check the
p
air between the RT and the network
interface. If no dial tone is present, replace the RT Channel Unit.
3If the
p
roblem still exists, re-insert the ori
g
inal RT Channel Unit and
replace the COT Channel Unit. Test for operation.
4If the problem still exists, refer the problem to the CO switch.
Phone Doesn’t
Ring
•hi
g
h-resistance
subscriber line short
• fault
y
RT or CO
Channel Unit
• loop length too long
1Lift the subscriber
p
air at the network interface. If rin
g
in
g
is
p
resent,
refer the problem to the customer per local practice.
2If rin
g
in
g
is not
p
resent, check for rin
g
in
g
at the RT. If rin
g
in
g
is
p
resent, check the
p
air between the RT and the network interface. If no
rin
g
in
g
is
p
resent, re
p
lace the RT Channel Unit. If rin
g
in
g
is still not
p
resent, check a circuit on another Channel Unit. If rin
g
in
g
is still not
present, replace the Line Unit.
3If rin
g
in
g
is still not
p
resent at the RT, re-insert the ori
g
inal Channel
Unit and Line Unit. Test for ringing at the COT.
4Test for rin
g
in
g
into the COT from the CO switch. If no rin
g
in
g
is
p
resent, refer the trouble to the CO switch. If rin
g
in
g
is
p
resent, re
p
lace
the COT Channel Unit. Test a
g
ain for rin
g
in
g
at the network interface.
If rin
g
in
g
is still not
p
resent, contact PairGain technical assistance
p
er
section 9.
5Verif
y
the resistance of the co
pp
er loo
p
between the RT Enclosure and
the network interface is less than 530 Ω.
Phone doesn’t
stop ringing
• fault
y
subscriber
instrument
• faulty RT Channel Unit
• loop length too long
1Test for rin
g
tri
p
at the network interface. If the rin
g
in
g
is tri
pp
ed, refer
the trouble to the customer per local practice.
2If the rin
g
in
g
is not tri
pp
ed, test for tri
pp
in
g
at the RT. If rin
g
tri
p
does
occur, check the loo
p
for excessive len
g
th. If rin
g
tri
p
does not occur,
re
p
lace the RT Channel Unit. If rin
g
tri
p
still does not occur, contact
PairGain technical assistance per section 9.
3Verif
y
the resistance of the co
pp
er loo
p
between the RT Enclosure and
the network interface is less than 530 Ω.
Can’t Hear,
Can’t Be
Heard
• subscriber problem
• fault
y
RT or COT
Channel Unit
1Lift the subscriber line at the network interface and check the si
g
nal
level. If correct, refer trouble to the customer per local practice.
2If the level is too low, check the level at the RT. If the level is correct
at the RT, check the
p
air between the RT and the network interface. If
the level is too low at the RT, replace the RT Channel Unit.
3If the level is still too low, re-insert the original RT Channel Unit.
4Check the level at the COT comin
g
from the CO switch. If it is correct,
re
p
lace the COT Channel Unit. If it is not correct, refer the
p
roblem to
the CO regarding the switch.
5If the level is still not correct, re-insert the ori
g
inal COT Channel Unit.
Contact PairGain technical assistance per section 9.

Revision 02 January 12, 1998 Section 363-704-102-02
PG-Flex FLC-704 List 2 PairGain Engineering - Plant Series Page 9
D. TECHNICAL SUPPORT
9. Technical Support
9.1 PairGain Technical Assistance is available 24-hours-a-day, 7-days-a-week by contacting PairGain
Customer Service Engineering group at:
Telephone: [phone] or [phone]
Fax: [phone]
9.2 During normal business hours (8:00 AM to 5:00 PM, Pacific Time, Monday - Friday, excluding
holidays), technical assistance calls are normally answered directly by a Customer Service Engineer.
At other times, a request for technical assistance is handled by an on-duty Customer Service
Engineer through a callback process. This process normally results in a callback within 30 minutes
of initiating the request.
9.3 In addition, PairGain maintains a computer bulletin board system for obtaining current information
on PairGain products, product troubleshooting tips and aids, accessing helpful utilities, and for
posting requests or questions. This system is available 24-hours-a-day by calling [phone].
Transmission speeds up to 28.8 kbps are supported with a character format of 8-N-1.
E. CERTIFICATION AND WARRANTY
10. Certification
10.1 FCC Compliance. The FLC-704 List 2 Channel Unit complies with the limits for Class A digital
devices pursuant to Part 15 of the FCC rules. These limits are designed to provide reasonable
protection against harmful interference when the equipment is operated in a commercial
environment. This equipment generates, uses and can radiate radio frequency energy and, if not
installed and used in accordance with the instruction manual, may cause harmful interference to
radio communications. Operation of this equipment in a residential area is likely to cause harmful
interference in which case the user will be required to correct the interference at his own expense.
10.2 Refer to the installation section of the appropriate instruction manual for the unit you are installing to
get information on:
•cabling
•proper connections
•grounding
•line power
10.3 All wiring external to the product(s) should follow the provisions of the current edition of the
National Electrical Code.

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Page 10 PairGain Engineering - Plant Series PG-Flex FLC-704 List 2
11. Warranty
11.1 PairGain Technologies warrants this product to be free of defects and to be fully functional for a
period of 5 years from the date of original shipment, given proper customer installation and regular
maintenance. PairGain will repair or replace any unit without cost during this period if the unit is
found to be defective for any reason other than abuse or improper use or installation.
11.2 This module should not be field repaired. If it fails, replace it with another unit and return the faulty
unit to PairGain for repair. Any modifications of the unit by anyone other than an authorized
PairGain representative will void the warranty.
11.3 If a unit needs repair, call PairGain for a Return Material Authorization (RMA) number and return
the defective unit, freight prepaid, along with a brief description of the problem, to:
PairGain Repair Center
14352 Franklin Avenue
Tustin, CA 92780-7013
FAX: [phone]
Phone: [phone] or [phone]
11.4 PairGain will continue to repair faulty modules beyond the warranty program at a nominal charge.
Contact your PairGain sales representative for details and pricing.
F. ABBREVIATIONS
12. Abbreviations
2B1Q 2 binary bits encoded in one quaternary symbol
CLASS Custom Local Area Signaling Services
CO Central Office
COT Central Office Terminal
DS0 Digital Signal Level Zero (64 kb/s)
DTMF Dual Tone Multi Frequency
HDSL High-bit-rate Digital Subscriber Line
MLT Mechanized Loop Testing
PBX Private Branch Exchange
PCM Pulse Code Modulation
PGTC Pair Gain Test Controller
POTS Plain Old Telephone Service
RMA Return Material Authorization
RT Remote Terminal

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PG-Flex FLC-704 List 2 PairGain Engineering - Plant Series Page 11