Positron Teleline 751221 Operating and installation instructions

Standalone Telephone Unit, 751221
Description and Installation

DOCUMENT CONTROL INFORMATION
Document Part Number: 7501-24-52, Rev 9
Document Issue Number: 9
Publication Date: January 07, 2003
Document ID: o02i1000.fm
CONFIDENTIALITY NOTICE
The information contained in this document is the property of Positron Inc. Except as specifically
authorized in writing by Positron Inc., the holder of this document: 1) shall keep all information
contained herein confidential and shall protect same in whole or in part from the disclosure and
dissemination to all third parties, and 2) shall use same for operating and maintenance purposes only.
DISCLAIMER NOTICE
Although Positron Inc. has made every effort to ensure the accuracy of the information contained
herein, this document is subject to change without notice.
TECHNICAL CUSTOMER SUPPORT
Should a problem arise, contact your customer support department. If the problem cannot be resolved
by your support department or if you have any questions, contact Positron’s Technical Customer
Support department at 1-888-577-5254.
© 2003 Positron Inc.
Teleline Isolator is a registered trademark of Positron Inc.
Product names, other than Positron’s, mentioned herein may be trademarks and/or registered trademarks
of their respective companies.

Contents i
o02i1000TOC.fm
1. The Standalone Telephone Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2. Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Hardware Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Technical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6. Battery Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7. Service and Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

(22 pages) Standalone Telephone Unit 1
751221
o02i1001.fm
1. The Standalone Telephone Unit
The Standalone Telephone Unit, model 751221, provides high voltage isolation
between a telephone line and the drop side of one loop start telephone circuit
(telephone, dial-up modem, or loop start private branch exchange (PBX)).
The unit consists of an isolator card and a power supply mounted inside a small
compact enclosure. The enclosure is molded from fiberglass, making it a
lightweight, flame retardant product of high dielectric strength. Its fiberglass
body limits the possibility of many kinds of infiltration while providing reliable
isolation from external ground potentials.
Its features include the following:
•The unit can operate from either 120 V ac or -24 to 130 V dc. It is not
polarity sensitive, although the live wire should be connected to the fused
terminal.
•The unit’s power supply provides a -24 V dc feed to the telephone on the
subscriber side of the card. In the event of a power outage, communications
are maintained by the onboard battery.
•The Central Office (CO) side circuit components are powered from the
battery feed.
•The unit’s sinusoidal ringing generator can ring up to five standard 500 type
sets and track the CO side frequency, which enables selective ringing.
•The unit withstands 600V power cross (as per UL1950) with automatic
restoration of service after a fault.
•The enclosure resists the infiltration of dust, mist, and water from sprinklers
and operates from 0°C to 50°C.
•The unit’s operating temperature range may be extended to -20°C to +65°C
by removing the battery completely. (Since this would result in no internal
backup power, an external 48 V or 130 V dc supply with battery backup
would be the preferred power source in such a case.)
For a view of the Standalone Telephone Unit enclosure, refer to Figure 1.
For a view of the Standalone Telephone Unit, cover open, refer to Figure 2.

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2 Standalone Telephone Unit
Figure 1 Model 751221 Cover Closed
FRONT VIEW
11-5/16"
13-1/2"
DANGER
- DO NOT OPEN THIS COVER
UNLESS THE PROPER SAFETY
PRECAUTIONS ARE TAKEN
- THIS COVER MUST ALWAYS BE
CLOSED AS IT PROVIDES
THE NECESSARY SPECIAL
SAFETY INSULATION TO
PROTECT PERSONNEL FROM
DANGEROUS VOLTAGES
PRESENT DURING GROUND
FAULT CONDITIONS
CABINET USE RUBBER GLOVES
AND INSULATED CARPET
- WHEN WORKING IN THE
POSITRON
GROUND
LUG
SIDE VIEW 5- 9/16"

Standalone Telephone Unit 3
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Figure 2 Model 751221 Cover Open (Only Major Components
Shown)
MAIN
BOARD
OPTO-
ISOLATORS
TB2
TB1
J4
R
T
R
RMT GND
TB1
T
1
2
3
F1
(2A,250V)
GND
-24V
POWER SUPPLY
GND LUG
Power In (green LED)
Power Out (yellow LED)
Low Battery (red LED)
RETAINING CLAMP
+
-
F2
(6A, 32V)
BATTERY
+
-
ISOLATION
GAP
5¼
POWER
SUPPLY
OUTPUT
CONNECTOR

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4 Standalone Telephone Unit
2. Applications
The applications of the Standalone Telephone Unit include the following:
•Loop start plain old telephone service (POTS)
•Dial-up “smart”modems (up to 19200 baud)
•Fax lines (up to19200 baud)
•Loop start PBX
•Dial-up remote meter reading
For an illustration of the unit’s applications, refer to Figure 3.
Figure 3 High Voltage Interface Applications
Standalone Telephone
Unit
Model 751221
Communications Cable
300 Volt
Point
300 Volt
Point
300 Volt
Point
Zone of Influence
Metal
Conduit
PVC
Conduit
Lightning
Arrestor
CENTRAL OFFICE
HIGH VOLTAGE INTERFACE
SUBSTATION
Telephone,
Fax or
Modem

Standalone Telephone Unit 5
751221
3. Hardware Description
The Standalone Telephone Unit contains the Fiberline Telephone card. This card
is comprised of two sides. The Station side is located on the upper portion of the
card and the CO side is located on the lower portion of the card. The Station side
is separated from the CO side by the opto-isolators, which create a 5¼inch
isolation gap. For the Fiberline Telephone card block diagram, refer to Figure 4.
Figure 4 Block Diagram
STATION SIDE
POWER
FUSE
SUPPLY
CO SIDE
HYBRID VOICE
CIRCUIT
SWITCH
OFF-HOOK
ON-HOOK/
RING
DETECTOR
120 V ac or -24 to 130 V dc
-24 V dc
RECEIVE
ANALOG
OPTO-
DIGITAL
OPTO-
ISOLATOR ISOLATOR ISOLATOR ISOLATOR
DIGITAL
GAP
MAIN ISOLATOR
PCB
FUSE
POWER
SUPPLY
FUSE
BIAS CIRCUIT
HYBRID VOICE
CIRCUIT
OFF-HOOK
DETECTOR
RING
GENERATOR
TRANSMIT
ISOLATION
OPTO-
OPTO-
ANALOG

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6 Standalone Telephone Unit
Hybrid Voice Circuits
The Hybrid Voice Circuits located on both the Station and CO sides of the card
form a two-wire to four-wire to two-wire configuration that permits the
separation of Transmit (TX) and Receive (RX) signals. These circuits also
perform an impedance matching function such that the Station side impedance is
reflected to the CO side. This renders the card effectively transparent for
communication purposes.
Ring Detector
The Ring Detector is a bandpass filter centered about 20 Hz. It detects ringing
signals and sends 40 Hz pulses to the ring generator on the Station side, via a
digital opto-coupler.
Digital Opto-Isolators
Each Digital Opto-Isolator consists of a light emitting diode (LED) and a
phototransistor pair, connected with a plastic fiber optic cable for isolation. They
provide digital signal transmission across the isolation gap.
Transmit and Receive Analog Opto-Isolators
The Transmit and Receive Analog Opto-Isolator employs feedback circuitry to
“linearize”the behavior of its LED/photodiode pairs, thus providing for
undistorted lightwave analog signal transmission across the air gap. Feedback
also makes it possible to compensate for the aging of the LEDs, ensuring that the
performance of the unit does not degrade over time.
Ring Generator
The Ring Generator receives 40 Hz pulses from the CO side and regenerates a
ringing signal at the same frequency and synchronism as the CO side.
On-hook/Off-hook Switch
The On-hook/off-hook Switch is a metal oxide semiconductor field effect
transistor (MOSFET) current limiting circuit that is turned on by the off-hook
signal. When switched on, it permits modulation of the hybrid voice circuits.
Off-hook Detector
The Off-hook Detector transmits a signal to the CO side to go off-hook when the
telephone is lifted.

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751221
Main Isolator Bias Circuit
The Main Isolator Bias Circuit generates the off-hook and ring trip signals, and
feeds a -24 V dc (on-hook potential) bias to the Station side telephones.
Power Supply PCB
The Power Supply PCB accepts either 120 V ac or -24 to 130V dc, and provides
-24 V dc to the Station side circuitry. It also keeps the onboard battery backup
charged.
Fuse F1 and F2
Fuse F1 limits the power supply’s input current in case of input power
overvoltage or power supply circuit failure. Fuse F2 protects the power supply
circuitry if the battery is reversed when connected. For the location of F2, refer to
Figure 2.

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8 Standalone Telephone Unit
4. Technical Specifications
For a listing of the unit’s electrical specifications, refer to Table 1. For a listing of
the unit’s physical specifications, refer to Table 2.
Table 1 Electrical Specifications (measured at 77°F or 25°C,
50% R.H)
Parameter Specifications
ISOLATION DATA:
Isolation resistance 100 000 MΩ
Metallic surge 3 kV maximum
Insulation voltage 50 kVrms (70 kV peak)
ON-HOOK
Ringing generator voltage > to 84 Vrms with 5 ringers (type 500) at 20
Hz
CO side input ringing detection 50 V to 105 Vrms, 17 to 30 Hz
Terminal resistance (CO side) >5 MΩat ± 100 V dc
Metallic impedance (CO side) >17 kΩat 20 Hz; >82 kΩfrom 200 Hz to 3.2
kHz
OFF-HOOK (40 mA dc)
Minimum loop current (CO) 20 mAdc
Maximum loop current (CO) Current limiting at 110 mAdc
Minimum loop current (station) Will detect off-hook down to 20 mA
Maximum loop current (station) Current limiting at 60 mAdc
Maximum loop resistance
(station, 20 mA dc)
850 Ωmaximum, including telephone
Longitudinal balance (CO side) >80 dB @ 60 Hz; >56 dB @ 4 kHz
Dial pulse distortion <1%, measured at 14 mA threshold (output
duty cycle w.r.t. input duty cycle)

Standalone Telephone Unit 9
751221
NOISE (Off-hook, 40 mA dc)
Impulse noise (both sides) Less than 1 count in 30 minutes above 48
dBrnCz
Phase jitter < 0.5°, 300 to 3400 Hz
Common mode rejection ratio (from CO to
Station side, terminated in 600 or 900Ω)
>80 dB, 300 to 3400 Hz
Noise (2 Hz to 100 Hz) -60 dBm
Message circuit noise (quiet termination) <5 dBrnC
S/N ratio (C message filter) 50 dB at 0 dBm
SIGNAL
Echo return loss (either side, opposite side
terminated in 600 or 900Ω)
Better than 21 dB
Singing return loss (either side, opposite
side terminated in 600 or 900Ω)
Better than 13 dB
Insertion loss (at 0 dBm) < 0.35 dB @ 1000 Hz
Frequency response (300 to 3400 Hz) ± 0.2 dB relative to 1000 Hz
Flatness 1.0 dB max from 100 to 10 kHz
Rolloff 12 dB / octave from 30 kHz
POWER SUPPLY
Input voltage 120 V ac or -24 to 130 V dc (not polarity
sensitive)
Input current with maximum Load at:
-24 V dc
48 V dc
130 V dc
120 V ac
600 mA
300 mA
125 mA
150 mA rms
Parameter Specifications

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10 Standalone Telephone Unit
Table 2 Physical Specifications
BATTERY TIME AVAILABLE (with new, fully charged battery)
On-hook (idle)
or: ringing (1 ringer)
or: off-hook
17 hours minimum
5.5 hours minimum
5.5 hours minimum
Composite specification 10 hrs idle + 2 hrs off-hook + 20 minute
ringings
BATTERY SERVICE LIFE 4 years (minimum)
BATTERY REPLACEMENT Sonnenschein 12V/1.2 Ah A212/1.2S
Parameter Specifications
Operating temperature range with battery +32°F to +122°F (0°C to + 50°C)
Operating temperature range without battery -4°F to +131°F (-20°C to + 55°C)
Height 13-1/2”(34.29 cm)
Width 11-5/16”(28.734 cm)
Depth 5-9/16”(14.129 cm)
Weight 8.648 lbs (3.922 kg)
Parameter Specifications

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5. Installation
The Standalone Telephone Unit is used when the number of lines to be isolated
does not justify the installation of a shelf. It will isolate one telephone circuit and
is powered from an AC or DC source.
To view the Standalone Two-wire Telephone Units’wiring connections, refer to
Figure 5.
Figure 5 Standalone Two-wire Telephone Unit
Power & Ground Connections
POWER
120 V ac
24-130 V dc
TB1-1
Neutral
V dc
TB1-2
Ground
Ground
TB1-3
Live
V dc
-
+
TB1
TB2
J4
Ring
Tip
Ground
Live
Neutral
Station Side
Main Board
Power
Supply
Board
Station
Side
Standby Battery
(in the advent
of Station side
power failure)
CO
Side
Battery
3
2
1
CO Side Main Board
TB1
RMT GND
Ring
Tip
To
Central
Office
Station
Ground
To Station
Side
Telephone
Station Side
Power and Ground
Connections
External Ground
Lug Connection
(to station ground)

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12 Standalone Telephone Unit
Note
1. This unit can be powered by 120 V ac or a DC voltage source of
24 V dc to 130 V dc (maximum of 150 V dc).
2. The input power is not polarity sensitive.
3. The power connections are made at TB1 on the power supply board
(see Power & Ground Connections in the figure).
4. J4 connects the -24 V dc output of the power supply to the Station
side main board.
5. This unit contains an internal standby battery, which may be
removed if this internal backup power supply is not required.
6. The station ground must be connected to the unit by either TB1
terminal 2 of the power supply board or the external ground lug
connection. It must not be connected to both to avoid inductive
loop.
7. Both TB1 terminal 2 and the external ground lug connection may
be used to provide a common ground, as long as ground loop
limitations are recognized. (GND LUG is the preferred way of
grounding).
8. The Tip and Ring of the Station side are connected to TB2.
9. The loop voltage supplied to the Station side telephone is 24 V dc.
10. The Tip and Ring of the CO side are connected to TB1 of the CO
side main board.
11. The RMT GND on the CO side is shown as a reference only and is
not normally connected.
12. Do not connect the incoming cable shield to the RMT GND.
13. The unit is usually mounted with the Station side up, but may be
mounted in any position.

Standalone Telephone Unit 13
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Caution
•Stand on a thick rubber mat and wear rubber gloves during the
installation procedure. It is preferable to perform these procedures on a
clear dry day when a Ground Potential Rise (GPR) or transients are less
likely to occur.
•This card utilizes CMOS circuitry that can be damaged by static
electricity. Observe normal CMOS handling procedures to avoid static
discharge. Manipulate the card exclusively by the faceplate to prevent
any damage to the card and to limit the possibility of electric shock.
When moving the card, carry it in an ESD safe container or the antistatic
bag, provided with the card. Failure to follow ESD precautions may
void the warranty. For further information concerning ESD precautions,
contact Positron’s Customer Support department.
•Power should only be applied after all wiring is completed. The station
and CO cables should be kept at least six inches apart upon wiring in
order to prevent an electric arc between the two in the event of damage
to, or degradation of, their insulation.
1. Verify that you have the following customer provided tools and hardware
which are required to install the unit:
•Station cable
•Center punch
•Electric drill with a 5/32”diameter bit
•7/16”hex wrench
•1/8”and 1/4”common blade screw drivers
•1”thick plywood backboard with appropriate mounting hardware
•Digital voltmeter
•Cable clamps and mounting hardware for routing cables exterior to the unit
(quantity determined by the cable lengths involved).
2. Unpack the Standalone Telephone Unit and its installation hardware from
its protective box.
3. Check the contents of your Standalone Telephone Unit kit. For a listing of
the items included in the kit, refer to Table 3.

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14 Standalone Telephone Unit
Table 3 Model 751221 Kit Contents
4. Remove the cover of the unit by unfastening the four screws located at each
corner.
5. Confirm that the unit is a Standalone Telephone Unit by identifying the
name located inside the cover and the model number on a metallic label on
the top of the right-hand portion of the unit.
Items Included Qty Part Numbers
Standalone Telephone Unit 1 244-751221-401
Description and Installation document 1 7501-24-52
One-card Shelf accessory kit 1 7501-22-02
6’power cable (3-conductor) 1 207-990000-020
10’insulated cable (12-conductor) 1 207-990000-138
Connector cord grip (1/2”hub) 1 230-990400-036
Connector cord grip (1/2”hub) 1 230-990400-037
Connector cord grip (1/2”hub) 1 230-990400-038
Instruction sheet, strain relief 1 241-010016-001
Fuse (2 A, 250 V) 1 248-990000-008
Terminal block (0.2”) 1 666-990000-071
Terminal block (0.2”) 1 666-990000-086
Nylon cable fastener (3/4”diameter) 5 706-990000-010
Hex nut 1/2-14NPT 3 714-990000-005
Screw, pan (6-32 X 3/8) 2 724-020001-015
Hex screw with washer (#14A) 4 724-990000-011
Screw, pan (6-32 X 3/8) 2 724-990000-073
Washer (#6) 2 738-990010-003
Instruction sheet, One-card Shelf 1 7501-18-113

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6. The power supply board is not fastened to the main isolation card prior to
shipment and, therefore, requires installation first. Unfasten the cover of the
unit and proceed as follows:
?Remove the screws from the tops of the spacers mounted on the Station side
circuit board.
?Position the power supply board onto the spacers and align the board holes
with the spacers.
?Secure using the four screws with the nylon screw going on the spacer in
the isolation gap.
7. Fasten the 1”thick plywood backboard to the wall.
?Mount the enclosure onto it using the four screws supplied.
Note
The Station (subscriber) side of the enclosure may be identified by two
access holes, one for the telephone cable and the other for the power cable.
The CO (remote) side has only one hole for the telephone cable entry. The
orientation of the unit does not matter.
8. Plug the power supply’s output connector into receptacle J4 of the main
isolation card.
To locate J4 and the output of the power supply, refer to Figure 2.
9. The strain reliefs supplied each have a cable entry diameter appropriate to
one of the three cables employed in this installation. The CO cable strain
relief is the largest, accommodating a cable diameter from 0.375”to 0.570”.
The power cable strain relief accommodates a cable diameter from 0.250”
to 0.570”, and the station cable strain relief accepts a cable diameter from
0.125”to 0.275”. All measurements are the outside cable diameters.
?Slide the strain reliefs supplied onto the CO, station, and power cables and
affix them to the unit.
?Route the power cable and the two telephone cables, allowing a length of
five inches per cable for the internal connections to the terminal blocks. Cut
the excess wire once the exact internal length is established, and tighten the
strain reliefs.

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16 Standalone Telephone Unit
?Strip back the outer jacket of each cable one inch. Strip the inner insulating
jacket of each conductor 1/8”. Connect these stripped conductors to the
designated terminal locations. For a listing of the terminal block
connections, refer to Table 4.
Table 4 Terminal Block Connections
?Bundle the cable conductors using the tie wraps supplied.
?Connect the ground lug to station ground by using a #6 AWG stranded wire.
10. The unit is shipped with both leads of the battery disconnected to prevent
discharge.
?Reconnect these leads to their respective battery terminals: red to “+”,black
to “-”.
To locate F2, refer to Figure 2.
11. Fuse F2 protects the power supply card against improper connection of the
battery leads.
?Should the fuse blow, correct the wiring error and replace the fuse.
12. Apply power to the unit, and use a digital voltmeter to measure the voltage
across the terminals of TB1 on the power supply card. The voltage should
correspond to the source voltage to within 1%.
Cable Signal Color Coding Connector
Position
Station Tip
Ring
Customer determined
Customer determined
TB2-T
TB2-R
CO Tip
Ring
Remote Ground
Any of the available
12 conductors
TB1-T (CO side)
TB1-R (CO side)
TB1-RMTGND (CO
side)
Power Live
Neutral
Ground1
Black
White
Green
TB1-3 (Station side)
TB1-1 (Station side)
TB1-2 (Station side)
1 The ground lug is the preferred way of grounding the unit. Use ground of power cable only if no
local ground is available. If ground lug is used, cut the green wire of the power cable.