TC Communications TC8619 User manual

TC8619
4 Channel
Ethernet-over-T1/E1
Multiplexer
User Manual
MNL-86190-01-01

2 TC8619 Rev 1.1 User Manual
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Copyright © 2022 by TC Communications. Products described in this publication are protected
by one or more U.S. and foreign patents.
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Record of Revisions
Revision Date Description of Changes
1.1 07/07/2022 Initial Release of TC8619.
TC Communications
17881 Cartwright Road
Irvine, California U.S.A. 92614
Tel. [phone]
Fax [phone]
E-Mail: [email protected]
Website: tccomm.com

TC8619 Rev 1.1 User Manual 3
Guide to Alert Symbols
These alert symbols are used in Caution, Warning, and Danger notes.
Symbol Meaning
Pinching or crushing hazard
Electrical hazard.
Equipment alert: be careful of
damage from static electricity
General alert: used for all
other hazardous conditions
(referring to people, not
equipment).

TABLE OF CONTENTS
TOC-1 TC8619 Rev 1.1User Manual
1Introduction
1.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.2 Product Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.2.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
1.2.2 Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
1.3 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
2 Installation
2.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.2 Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.3 Equipment Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.4 Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2.5 Dry Contact Alarm Relay (DCAR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2.6 System Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2.7 System Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
2.7.1 Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
2.7.2 Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
3 Quick Start Guide
3.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.2 Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
4 Tutorial
4.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.2 Latched Alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.2.1 Latched Alarm Clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
4.3 T1/E1 Local Loopback Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
5 Troubleshooting
5.1 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.2 All LEDs are OFF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.3 Alarm LED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Appendix A 19” Rack Mount Card Cage
A.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
A.2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
A.3 Chassis Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
Appendix B Push Button & LED Functions
B.1 CLEAR ERROR Button Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1
B.1.1 CLEAR ERROR Push Button Functions. . . . . . . . . . . . . . . . . . . . . . B-1
B.2 LED Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1
B.3 CSU Loop Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2
Appendix C Return Policy
C.1 Return Policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1
C.1.1 Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1
C.1.2 Limitation of Liability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

TC8619 Rev 1.1User Manual 1-1
Chapter 1 Introduction
1.1 General Information
This manual is intended to describe the features and functionality in addition to
aiding in the planning, configuring, commissioning and maintaining of the TC8619
Ethernet-over-T1/E1 multiplexer.
1.2 Product Description
The TC8619 is a 4 Channel Ethernet-over-T1/E1 multiplexer with built-in power
redundancy.
TC8619 can support either T1 or E1 upon the order.
Extensive diagnostics include DIP switches for T1/E1 Loopback and other
application configuration switches. Each unit also provides multiple LEDs for
Alarm, Power, Vcc, T1/E1 Status, and Link and Duplex LEDs for each channel.
The built-in sync mechanism verifies both device and T1/E1 link operation. No
other test equipment is required for link and device verification.
The TC8619 is compatible with standard 100ΩT1 for copper line lengths up to
6000ft and up to 2.5km for 75Ω/ 120ΩE1 (copper line length is the distance
between the TC8619 and the T1/E1 cross-connect). The T1/E1 uses an RJ-48
connector and the Ethernet channels use RJ-48 connectors. Optional BNC adapter
cable is available for 75 Ohm E1. Power is 12VDC standard or optional 24VDC,
-48VDC, 125VDC, or 115/230VAC with an external power cube. Optionally, a high
temperature version (-20°C to 70°C) and extreme temperature version (-40°C to
80°C) are also available.
*Note: Check factory for availability

Chapter 1 Introduction Product Description
1-2 TC8619 Rev 1.1User Manual
Figure 1-1 TC8619 Front and Rear Panels
1.2.1 Features
• 10/100 Base-T Ethernet with IEEE 802.1p support
• T1 Features:
• ESF Framing
• Supports Line Length up to 3000ft (T1)*
• E1 Features:
• PCM31C Framing
• Supports Line Length up to 2.5km
• Very Low Latency ~ 600μs
• LEDs for Link (L) and Duplex (D) (to monitor Ethernet status)
• LEDs for "SYNC", "AMI", "BPV", "LOS", "AIS", "RAI", "CRC" (to monitor
each T1/E1 channel status)
• LEDs for "PWR A," "PWR B," "Vcc," & "ALM" (to monitor each unit's
power supply and alarm condition status)
• Built-in Power Redundancy
• Diagnostic DIP Switches for T1/E1 Loopback test.
• Rack Mount or Stand Alone
*Note: For line lengths beyond 655ft additional testing is required.
1.2.2 Applications
The TC8619 offers an inexpensive, plug and play method for connecting Ethernet
devices over existing T1/E1 links. Popular applications include:

Chapter 1 Introduction Product Description
TC8619 Rev 1.1User Manual 1-3
• Bridging Ethernet LANs over Existing T1/E1 Telecom Network
• Extending Ethernet Networks by Utilizing TDM Telecom Infrastructure (i.e.
T1/E1 Landline, or T1/E1s/PDH/SDH Microwave Carrying T1/E1)
• Demarcation Between the Carrier’s and Customer’s Networks
• Bonded Transparent LAN Service
Figure 1-2 Typical Application using TC8619 Ethernet-over-T1/E1
Multiplexer
T1/E1
Ethernet
TC8619
IP Based
Voter
TC8619
IP Based
Repeater/Receiver
Ethernet

Chapter 1 Introduction Specifications
1-4 TC8619 Rev 1.1User Manual
1.3 Specifications
Ethernet Capacity
Channels 4 ports - 10/100 Base-T Ethernet Channels
Electrical
Ethernet Connectors RJ-48F
T1/E1 Connector RJ-48F
System
Bit Error Rate 1 in 109or better
Unit Status Indicators PWR A, PWR B, Vcc
T1/E1 Status Indicators ALARM, SYNC, AMI, BPV, LOS, AIS, RAI,
CRC, RMT
Ethernet Status Indicators Link (L) and Duplex (D)
Diagnostic Functions T1/E1 Loopback
Power Source
Standard 12VDC @300mA
Optional 24VDC, -48VDC, 125VDC, or 115/230VAC
with an external power cube
Temperature
Operating -10°C to 50°C
Optional Hi-Temp Version -20°C to 70°C
Optional Extreme-Temp Version -40°C to 80°C
Storage -40°C to 90°C
Humidity 95% non-condensing

Chapter 1 Introduction Specifications
TC8619 Rev 1.1User Manual 1-5
Physical (Standalone Unit)
Height (3.53 cm) 1.40"
Width (18.14 cm) 7.20"
Depth (24.89 cm) 9.80"
Weight (0.9 Kg) 2.0 lbs.
Physical (Rack mount 1U “Pizza Box” with two cards)
Height (4.45 cm) 1.75"
Width (48.26 cm) 19.0"
Depth (22.86 cm) 9.0"
Weight (1.86 Kg) 4.1 lbs.

TC8619 Rev 1.1User Manual 2-1
Chapter 2 Installation
2.1 General Information
The installation section describes how to:
• Unpack the unit
• Ensure an optimum site location
• Install the power supply and dry contact connection
2.2 Unpacking
Before unpacking any equipment:
• Inspect all shipping containers for evidence of external damage caused during
transportation
• Inspect for damage after it is removed from the containers
2.3 Equipment Location
The TC8619 should be located in an area that provides adequate light, work space
and ventilation.
IMPORTANT Any claims concerning shipping damage should be made directly to
the pertinent shipping agencies. Any discrepancies should be
reported immediately to the Customer Service Department at TC
Communications, Inc. at [phone].
Important Avoid locating it next to any equipment that may produce electrical
interference or strong magnetic fields, such as elevator shafts or
heavy duty power supplies.
As with any electronic equipment, keep the unit from excessive
moisture, heat, vibration and freezing temperatures.

Chapter 2 Installation Power Supply
TC8619 Rev 1.1User Manual 2-2
2.4 Power Supply
The TC8619 can be powered by external DC power.
Available power options are 12 VDC, 24 VDC, -48 VDC,
and 125 VDC. There are two terminal block connectors
labeled "PWR A" and "PWR B" only one is required to
power up the unit. Since each TC8619 card is equipped
with a power redundancy capability, the power LEDs on the
front panel will light according to which power jack (A or
B) is connected. Both LEDs will light when power redundancy is utilized.
2.5 Dry Contact Alarm Relay (DCAR)
A terminal block connector at the rear panel provides for the Dry Contact Alarm
Relay. This relay can be used in NO (Normal Open) or NC (Normal Close)
configuration.
When used in NO (Normal Open) configuration, the relay will close if the unit loses
power completely or the Alarm is on. The relay remains open during normal
operation.
When used in NC (Normal Close) configuration, the relay will open if the unit loses
power completely or the Alarm is on. The relay remains close during normal
operation.
2.6 System Start Up
Apply the power by plugging the power plug into a power jack (both PWR A &
PWR B for dual power units).
After power is applied, all LEDs (except PWR & VCC LEDs) will flash
momentarily and the following LED status should be observed from the front and
back panels:
1. The Power "A" and/or "B" and VCC LEDs should be lit.
Note: TC8619 cards installed in the 1U rack chassis will not show the
PWR A LED in the “On” lit state and will be Off. This is normal and the
power to the card will be monitored by the VCC LED being “On” lit.
2. The "ALM" and "SYNC" LEDs on the front panel will be flashing indicating
that the T1/E1 connection is not established. This is normal when the T1/E1
connection has not been established.
Important Read and only connect a supply voltage that corresponds to the
type plate of your device. Make sure that the contact load capacity
of the signal contact is not exceeded.

Chapter 2 Installation System Configuration
2-3 TC8619 Rev 1.1User Manual
2.7 System Configuration
The TC8619 has been pre-tested and set per factory specifications.
2.7.1 Front Panel
RJ48F connectors are provided on the front panel for Ethernet connections.
Figure 2-1 TC8619 Front Panel LED Definitions
T1/E1 Status
ALM (Alarm) LED
xSolid: Latched alarm condition.
xFlash: Unit detects errors or is in loopback mode.
xOff: Normal condition.
RAI (Remote Alarm Indicator) LED
xBlink: Latched RAI indication.
xFlash: Unit detected RAI (Yellow Alarm).
xOff: Normal condition.
AIS (Alarm Indication Signal) LED
xBlink: Latched AIS indication.
xFlash: Unit detected AIS (Blue Alarm).
xOff: Normal condition.
LOS (Loss of Signal) LED
xSolid: Valid T1/E1 signal is detected.
xFlash: No T1/E1 signal is detected.
LB (T1/E1 Loopback) LED
xFlash: Local loopback is enabled or received
CSU loop-up code.
xOff: Normal condition.
BPV (Bipolar Violations) LED
xBlink: Latched BPV error indication.
xFlash: Unit detected bipolar violations.
xOff: Normal condition.
CRC (T1/E1 CRC Error) LED
xBlink: Latched CRC error indication.
xFlash: Unit detected CRC error.
xOff: Normal condition.
SYNC (Loss of Frame) LED
xSolid: T1/E1 sync. (Normal condition)
xBlink: Latched T1/E1 sync loss indication.
xFlash: Unit detected T1/E1 sync loss.
Ethernet Port Status
D (Duplex) LED
xOn: Full Duplex.
xOff: Half Duplex.
L (Link / Activity) LED
xOn: Link Up.
xFlash: Activity Detected
xOff: Link Down
PWR (Power) A LED
PWR (Power) B LED
xOn: Power supplied is good.
xOff: Power supply failed, or card fuse is
burned.
Vcc LED (Voltage) LED
xOn: 5V DC is good.
xOff: No 5V DC is supplied to this card.
CLEAR ERROR (T1/E1) Button
xPress and Hold (> 3 secs) to clear latched T1/E1
error.

Chapter 2 Installation System Configuration
TC8619 Rev 1.1User Manual 2-4
2.7.2 Rear Panel
Figure 2-2 TC8619 Rear Panel LED Definitions
ALM (Alarm) LED
xSolid: Latched alarm condition.
xFlash: Unit detects errors or is in loopback
mode.
xOff: Normal condition.
RAI (Remote Alarm Indicator) LED
xFlash: Unit detected RAI (Yellow Alarm).
xOff: Normal condition.
AIS (Alarm Indication Signal) LED
xFlash: Unit detected AIS (Blue Alarm).
xOff: Normal condition.
LOS (Loss of Signal) LED
xSolid: Valid T1/E1 signal is detected.
xFlash: No T1/E1 signal is detected.
Dipswitch Configurations
SW1: LOCLB (Local Loopback)
xDown (On): Enable T1/E1 loopback.
xUp (Off): Normal.
SW2: WRR (Weighted Round Robin Scheduling)
xDown (On): Weighted Round Robin Scheduling
xUp (Off): Strict Priority Scheduling
SW3: INT CLK (Internal Clock)
xDown (On): Enable internal timing mode.
xUp (Off): Enable RX loop timing mode.
SW4: B8ZS / HDB3 (Line Code)
xDown (On): B8ZS (T1) / HDB3 (E1)
xUp (Off): AMI
SW5: DIS ALM (Disable Alarm)
xDown (On): Disable alarm buzzer and dry contact.
xUp (Off): Normal.
SW6, SW7, SW8: L1, L2, L3 (Line Build-Out)
L1 L2 L3 T1
Up Up Up 0 – 133 feet
Down Up Up 133 – 266 feet
Up Down Up 267 – 399 feet
Down Down Up 400 – 533 feet
Up Up Down 534 – 655 feet
Down Up Down -7.5dB CSU
Up Down Down -15dB CSU
Down Down Down -22.5dB CSU
L1 L2 L3 E1
Up Up Up 75 ohm Normal
Down Up Up 120 ohm Normal
Up Up Down 75 ohm High Loss
Down Up Down 120 ohm High Loss
Alarm Relay
NO (Normal Open)
xOpen: When power is on, and alarm is off.
xClose: When power is off, or alarm is on.
NC (Normal Close)
xClose: When power is on, and alarm is off.
xOpen: When power is off, or alarm is on.

Chapter 2 Installation System Configuration
2-5 TC8619 Rev 1.1User Manual
2.7.2.1 Rear Panel (T1/E1 RJ-48F Connector & Pin Assignments)
An RJ-48F female connector is provided on the rear panel for the connection of the
T1/E1 wire pairs. When viewing the RJ-48F connector, the left pair (Pin # 1 & 2) of
the RJ-48F connector are for T1/E1 signal going into the TC8619 (receive), while
the right pair (Pin # 4 & 5) of the RJ-48F connector are for the transmit signal
coming out of the unit.
Figure 2-3 TC8619 Rear Panel T1/E1 Connector & Pin Assignment
Note 1: The T1/E1 signal use the same
pin connections on the RJ-48 female connector.

Chapter 2 Installation System Configuration
TC8619 Rev 1.1User Manual 2-6
2.7.2.2 Rear Panel DIP Switch Functions
Figure 2-4 Rear Panel DIP Switch
The DIP switch functions on the TC8619 are described below. To activate the
function, set the appropriate switch to the On (Down) position.
•LOCLB: Local T1/E1 Loopback. This switch (SW1) initiates the Local T1/E1
Loopback function.
•WRR: Weighted Round Robin Priority Scheduling. This switch (SW2) is
used to configure the Ethernet priority scheduling mode. "On" for weighted
round robin priority scheduling. "Off" for strict priority scheduling.
•INT CLK: Internal Clock. This switch (SW3) is used to setup the T1/E1
timing mode. "On" for internal timing mode. "Off " for Rx loop timing mode.
•B8ZS/HDB3: This switch (SW4) is used to setup the T1/E1 Line Code. "On"
for B8ZS (T1) or HDB3 (E1). "Off" for AMI.
•DIS ALM: This switch (SW5) is used to disable the audio buzzer and dry
contact alarm relay. “On” (down) position disables the buzzer and relay. “Off”
enables the buzzer and relay. "DIS ALM" dip switch should be in “Off” under
normal condition.
•L1, L2, L3: These switches (SW6, SW7, & SW8) are used to set the T1/E1
cross-connect distance (copper line build-out).
For example, in a T1/E1 application, this is the length of twisted pair cable
connecting the TC8619 to the user's equipment, which may be a CSU or DSU. See
Table 2-1.
Table 2-1: Copper Line Length Setup Table
NOTE Power cycle is required when changing priority scheduling
T1 Settings
L3 L2 L1 Application Line Length
Off Off Off DSX-1 (0 to 133 feet) / 0 dB CSU
Off Off On DSX-1 (133 to 266 feet)
Off On Off DSX-1 (266 to 400 feet)
Off On On DSX-1 (400 to 533 feet)
On Off Off DSX-1 (533 to 655 feet)

Chapter 2 Installation System Configuration
2-7 TC8619 Rev 1.1User Manual
Table 2-2: E1 Termination Setup Table
On Off On -7.5 dB CSU
On On Off -15 dB CSU
On On On -22.5 dB CSU
E1 Settings
L1 L2 L3 Application Termination
Up Up Up 75 Ohm Normal
Down Up Up 120 Ohm Normal
Up Up Down 75 Ohm High Loss
Down Up Down 120 Ohm High Loss
T1 Settings

TC8619 Rev 1.1User Manual 3-1
Chapter 3 Quick Start Guide
3.1 Introduction
The TC8619 is designed for quick and easy installation. First, configure the unit for
your specific application by setting the Line Code, and Line Length DIP switches.
Once configured, you can connect the Ethernet, T1/E1 signal source and power.
3.2 Setup
1. Set the appropriate Line Code for your application with the rear panel DIP
switch SW4. "On" for B8ZS (T1) or HDB3 (E1). "Off" for AMI.
2. For T1/E1 applications, set the appropriate T1/E1 Line Length with the rear
panel DIP switch SW6, SW7, & SW8. It is set to "0-133 feet" by default.
3. Set the appropriate T1/E1 timing mode with rear panel DIP switch SW3. There
should be one and only one clock source throughout the entire T1/E1 network.
If two TC8619 units are connected back to back, one unit should set to
“Internal” timing mode, and the other unit should set to “RX Loop” timing
mode.
4. Verify the Ethernet pin connections as well as the T1/E1 pin connections. After
that, connect the two TC8619 units with a T1/E1 cable.
5. Connect the Ethernet signal source to the TC8619 Port 1 RJ-48 connector.
6. Verify the corresponding channel's Ethernet Link LED is solidly lit to indicate
that data is being received. If the Link LED does not light up solidly on a
particular channel, it usually indicates incorrect connections at the Ethernet
port.

TC8619 Rev 1.1User Manual 4-1
Chapter 4 Tutorial
4.1 Introduction
It is highly recommended to conduct bench tests before actual installation. Bench
testing allows the user to become familiar with all the functions and features of the
TC8619 in a controlled environment. Knowledge of these functions and features
will ease installation and troubleshooting efforts later on.
Loopback tests assist troubleshooting by helping in pinpointing the source of errors
The TC8619 is a sophisticated product designed with multiple advanced
technologies. Loopback tests have been implemented to test independent
components of it.
4.2 Latched Alarm
The front panel "ALM", "BPV", "CRC" and "SYNC" LEDs can display both
current and latched error conditions.
For example, if the "ALM" LED is on, and "SYNC" LED blinks twice, it indicates
that there are two "T1/E1 sync loss" after the last alarm reset.
To reset the alarm, press and hold the "CLEAR ERROR" button for 3 seconds until
the "ALM", "BPV", "CRC", and "SYNC" LEDs are flashing. The alarm will reset
after the "CLEAR ERROR" button is released.
See the table below for latched alarm definitions.
Table 4-1 Latched Alarm Definitions
LED Normal Current Error Latched Error Note
ALM Off Flashing
Continuously
On
BPV Off Flashing
Continuously
Blink The number of blinks
indicates the number of
times the error condition
happens. (Max. 3 Blinks)
CRC Off Flashing
Continuously
Blink The number of blinks
indicates the number of
times the error condition
happens. (Max. 3 Blinks)
SYNC On Flashing
Continuously
Blink The number of blinks
indicates the number of
times the error condition
happens. (Max. 3 Blinks)

Chapter 4 Tutorial Latched Alarm
TC8619 Rev 1.1 User Manual 4-2
4.2.1 Latched Alarm Clearing
Latched alarm is cleared automatically after 10 seconds by default. This default
setting can be changed using unit's internal dipswitch SW2-3 and SW2-4.
*Please contact TC Communications technical support before opening the unit to
access the internal dipswitch.
Table 4-1: Latched Alarm Clear Times
SW2-3 SW2-4 Latched Alarm Auto Clear
Time Usage
OFF OFF 10 seconds (Default) Use for general T1/E1 line stability
monitoring.
Any specific T1/E1 error will be
shown on the T1/E1 status LEDs:
BPV, CRC, RAI, AIS, and SYNC.
ON OFF 1 hour This is useful for verifying T1/E1 line
condition after initial setup or T1/E1
setting changes.
User does not need to wait at the
unit location and can check back
within an hour to verify the T1/E1
line stability.
OFF ON 24 hours This is useful for verifying T1/E1 line
condition during off office hours.
(Example: Overnight)
The unit will log T1/E1 errors for the
past 24 hours.
ON ON 48 hours This is useful for verifying T1/E1 line
condition during off office hours.
(Example: Over the weekends)
The unit will log T1/E1 errors for the
past 48 hours.

Chapter 4 Tutorial T1/E1 Local Loopback Test
4-3 TC8619 Rev 1.1 User Manual
4.3 T1/E1 Local Loopback Test
A T1/E1 Local loopback is used to test T1/E1 wiring and T1/E1 transceiver
functionality. It can be enabled by pushing both rear panel DIP switches SW1 to the
“On” (down) position. The diagram below shows the T1/E1 signal flow and related
loopback path.
1. The “ALM” LED should be flashing indicating the unit is in T1/E1 Loopback
mode.
2. The “LOS” LED should be off indicating that a valid T1/E1 signal is being
received. If the “LOS” LED is flashing it means that the TC8619 is not
receiving a valid T1/E1 or the T1/E1 cable is in question. Please reference
Figure 2-3, TC8619 Rear Panel T1/E1 Connector & Pin Assignment, on
page 2-5 for T1/E1 pinouts.
3. The T1/E1 signal should be looped back to the Carrier/Service Provider or T1/
E1 tester. Please make sure a valid T1/E1 signal is being received.
4. Upon successful completion of this test, please return dip switches
SW1(LOCLB) to the Up (Off) position for normal operation of the TC8619
unit(s).
Figure 4-1 T1/E1 Loopback Test