Guardian Telecom TBA Series Guide

Talk Back Intercom System
Model TBA
Installation & Operation
P007143 Rev. D 150824 8/24/2015 11:32 AM
Ph: 403.258.3100 \ email:[e-mail] \ www.guardiantelecom.com

Guardian Telecom Inc. Installation & Operation
TBA Models
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Contents
1.Purpose...............................................................................................4
2.Scope..................................................................................................4
3.Identification of equipment..................................................................4
3.1.TBA Model Numbering ..............................................................4
3.2.TBA Front Panel........................................................................5
3.3.TBA Rear Panel.........................................................................5
3.4.TBA Enclosure Inside................................................................6
4.System Overview................................................................................7
4.1.Central Station...........................................................................7
4.2.Monitored Station.......................................................................7
4.3.Stations #1, #2 and #3...............................................................7
4.4.PTT Actions...............................................................................8
4.5.Alert or Go-Ahead Tone.............................................................8
4.6.Applications on Drilling Rigs......................................................8
4.7.Applications on Shipboard.........................................................8
5.Application Restrictions.......................................................................8
6.Installation Instructions........................................................................9
6.1.TBA Enclosure...........................................................................9
6.2.AC Supply..................................................................................9
6.2.1.230 VAC operation.............................................................9
6.2.2.DC Supply Options.............................................................9
6.3.Push to Talk Switches .............................................................10
6.4.Microphone..............................................................................10
6.5.Speaker ...................................................................................10
7.TBA Configurations except for TBA-33.............................................11
8.TBA-33 Configuration........................................................................13
9.Installation Adjustments....................................................................19
9.1.Initial Settings ..........................................................................19
9.2.Powering ON the TBA .............................................................20
9.3.Monitored Station Microphone Volume Adjustment.................20
9.4.Central Station Microphone Volume Adjustment.....................20
9.5.Ringer Volume Adjustment......................................................20
9.6.Central Station Speaker Volume .............................................20
9.7.Station #1 Speaker Volume.....................................................20
9.8.Station #2 Speaker Volume.....................................................20
9.9.Station #3 Speaker Volume.....................................................20
9.10.Optional Hum Cancellation......................................................20
9.11.Optional ringing from PTTs......................................................21
9.12.Replace the TBA enclosure top panel.....................................21
10.Locations of adjustments for the TBA...............................................21
10.1.Audio transformer tap adjustments..........................................21
11.Product Specifications.......................................................................22

Guardian Telecom Inc. Installation & Operation
TBA Models
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12.Replacement Parts............................................................................23
13.Warranty............................................................................................24
14.Disclaimer .........................................................................................24
15.Warning.............................................................................................24
16.Service Telephone Number 1-800-363-8010...................................24
17.Feedback ..........................................................................................24
18.Guardian Product Return..................................................................25
Figures
Figure 1 - Table of TBA Models.................................................................4
Figure 2 – TBA-41 Front Panel..................................................................5
Figure 3 – TBA-41 Rear Panel...................................................................5
Figure 4 - TBA Enclosure Inside Front.......................................................6
Figure 5 - TBA Enclosure Inside Rear .......................................................6
Figure 6 - TBA External Audio Connections ............................................11
Figure 7 - TBA Internal Audio Connections..............................................12
Figure 8 - TBA-33 Internal Audio Connections to 2011 ...........................13
Figure 9 - TBA-33 Internal Transformer Wiring Pre 2011........................14
Figure 10 - TBA-33 Internal Audio Connections Starting 2012................15
Figure 11 - TBA-33 Internal Transformer Connections............................16
Figure 12 - Station Connector Wiring.......................................................17
Figure 13 - Central Station Microphone Wiring........................................17
Figure 14 - Central Station Speaker Wiring .............................................18
Figure 15 - Adjustment Locations ............................................................21
Package Contents
(1) TBA Talk Back Amplifier
(1) Loudspeaker
Additional Loudspeakers (optional – up to four)
(1) Optional Central Station Microphone (except for model TBA-22)
(1) Installation & Operation Manual
Acronyms:
TBA Talk Back Amplifier
PWB Printed Wiring Board
PWBA Printed Wiring Board Assembly
AC Alternating Current
DC Direct Current
KHz Thousand Hertz
Hz Cycles per second

Guardian Telecom Inc. Installation & Operation
TBA Models
1. Purpose
This document is provided to assist in the electrical installation and operation of a Talk Back Amplifier
(TBA) as produced by Guardian Telecom Inc.
2. Scope
The installation information will consist of connections to the TBA unit in the enclosure. The
connections to external speakers and microphones are covered in their respective manuals.
The operation information will consist of adjustment of potentiometers and power supply requirements
for the TBA unit.
Some information for the speaker and microphone sensitivity that relates to the TBA operation will be
given to assist in the selection and installation of TBA peripherals.
3. Identification of equipment
There are several models of Guardian Talk Back Amplifiers (TBA). The Printed Wiring Board Assembly
(PWBA) in the TBA will support up to five speaker outputs; therefore the listing of equipment goes from
five speaker outputs to two speaker outputs.
3.1. TBA Model Numbering
The table below uses “CEN” for Central Station, “MON” for Monitored Station and #1 to #3 for
Stations #1 to #3. The “X” in a square indicates that the speaker amplifier is populated on the
PWBA. The “L” indicates low impedance and the “H” indicates high impedance.
Figure 1 - Table of TBA Models
Note: The Central Station input for the microphone on TBA-33 is modified to have an impedance of
near 1K Ohm when the PTT is not pressed. See the section titled “Microphone” for further information.
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Guardian Telecom Inc. Installation & Operation
TBA Models
3.2. TBA Front Panel
The TBA Front Panel of the enclosure has from two to five volume controls and a power indicator.
The power indicator shows the presence of AC power, and is a green illumination if AC is present.
The volume controls are labeled for the Station being controlled. Clockwise rotation gives more
volume, the volume controls have numbers from1 to 10 to assist in setting repeatability.
Figure 2 – TBA-41 Front Panel
3.3. TBA Rear Panel
The TBA Rear Panel of the enclosure has from two to five cable entries, an AC power connector,
an AC fuse and a Power ON/OFF switch.
The AC power connector is a standard connector for AC supplies. The AC fuse is a 1 amp slow
blow 250 volt fuse of 1.25” long and 0.25” diameter.
Buss fuse type MDL 1A is supplied with the TBA.
The POWER ON/OFF switch is a rocker switch; pushing the switch upwards turns on the TBA.
Figure 3 – TBA-41 Rear Panel
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Guardian Telecom Inc. Installation & Operation
TBA Models
3.4. TBA Enclosure Inside
The photos below show the TBA-50 with the top cover removed.
Figure 4 - TBA Enclosure Inside Front
Figure 5 - TBA Enclosure Inside Rear
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TBA Models
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4. System Overview
The Talk Back Amplifier (TBA) is so named because of the ability for the user to talk back to the
speakers instead of using a separate microphone to talk back.
The model TBA is an intercom system designed for use in situations where frequent communications
between two or more stations are required.
The TBA system utilizes speakers in two modes:
as a speaker output to broadcast audio messages from other stations
as an audio microphone to pick up audio messages.
4.1. Central Station
The Central Station speaker normally outputs audio coming from the Monitored Station.
The audio from the Monitored Station or Stations #1, #2 or #3 with their PTT depressed, will be
output on the Central Station speaker.
To output audio the Central Station user presses the Press to Talk (PTT) switch. The Central
Station PTT switch is normally mounted on the microphone housing, but it may be a foot switch.
The Central station is different from the other stations in that it has a separate microphone input as
well as a speaker output. The Central Station speaker also has a low level “sidetone” audio from
the speaker to allow the user to hear that the Central Station audio output is working.
The Central Station console consists of a (goose neck) dynamic microphone and a hand switch or
pedal switch for PTT. The Central Station has the highest priority in using PTT. When the Central
Station PTT switch is engaged (depressed) the TBA puts a low level audio onto the Central Station
speaker. This low level is to prevent acoustical feedback. The other speakers in the system are set
to the speaker mode and output audio coming from the Central Station.
4.2. Monitored Station
The Monitored Station is different from the other stations in that it will continuously send the audio
heard at its speaker to the other stations when no Press to Talk (PTT) switch in the TBA is
depressed. The Central Station and up to three stations normally output audio coming from the
Monitored Station to their speakers.
The PTT switch on the Monitored Station is used only as a “Ringing” or Alert Tone activation.
Pressing the Monitored Station PTT will stop the audio output from the Monitored Station and put a
“Ringing” tone onto the Central Station, Monitored Station and the other stations’ speakers.
The Monitored Station speaker will output the audio coming from another station if the other station
presses a PTT switch. When the Monitored Station speaker is outputting audio it does not send
audio to the other stations. The Monitored Station speaker will change from a microphone input
into a speaker output when the Central Station or another station has the PTT switch pressed.
4.3. Stations #1, #2 and #3
The Stations #1, #2 and #3 have a speaker and a PTT switch. The audio from the Monitored
Station or any other station with a PTT depressed will be output on that station’s speaker. When
the station’s PTT switch is depressed the station will output audio to the other stations. When the
speaker is outputting audio it does not receive audio from the other stations.

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TBA Models
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4.4. PTT Actions
The Central Station Push to Talk (PTT) switch has the highest priority in using PTT.
When the PTT is pressed on the Monitored or Stations #1, #2 or #3 the stations are a first-come
first-served basis for PTT.
When the PTT switch on the Monitored Station is pressed the other speakers on the system will
output a “ringing” tone for as long as the PTT is pressed.
When the PTT switch on the Central Station, Stations #1, #2 or #3 is pressed the system will use
the speaker on that station to generate audio for the other station speakers.
4.5. Alert or Go-Ahead Tone
The Talk Back Amplifier (TBA) has a tone generator that sounds similar to a telephone ringing.
This dual tone (“Ringing”) is generated for two purposes:
Alert
Go-Ahead
The Alert Tone or “Ringing” is caused by the Monitored Station pushing the Push to Talk (PTT)
switch.
The Go-Ahead short “Ringing” is a 0.1 second long sound burst that indicates to the users that a
PTT switch has just been released on the Central Station or Station #1, #2 or #3. This Go-Ahead
indicates that the other station has ceased pressing the PTT switch and that normal operation can
be resumed. When this post announcement short “Ringing” tone is heard it confirms to the listener
that the system is in the receive mode.
Jumper JP1 on the Printed Circuit Board Assembly (PCBA) is a switch to allow the injection of the
post PTT Go-Ahead or short “Ringing” tone. Moving JP1 to the bottom set of terminals will disable
the Go-Ahead or short “Ringing” tone.
4.6. Applications on Drilling Rigs
In drilling rig applications the TBA normally consists of:
Central Station at the doghouse with a speaker and microphone
Monitored Station at the monkey board
Station #1, #2 and #3 as needed.
The monkey board or racking board for the derrick man is up on the drilling rig tower, and the
derrick man’s instructions to the dog house (driller’s communication shack) should be continuously
monitored.
4.7. Applications on Shipboard
Audio monitoring of the wheelhouse or control station can be used to inform the engine room and other
stations of the actions needed to be performed. In this way commands for ship operation can be
communicated without delay by the ship operator simply speaking.
The telephone intercom on board the ship is connected to a special impedance of the Central Station
made for the 600 Ohm telephone system. A PTT from the telephone line is used to activate the output
to the talk back speakers both FORE and AFT. After the PTT the FORE and AFT can reply back to the
telephone system by talking to the speakers. The period for the FORE and AFT stations to talk back
after a PTT is received from the telephone interface is selected by a jumper on Monitored Station PTT
for 1 minute, or a jumper on Station #1 PTT for 10 minutes.
5. Application Restrictions
The Talk Back Amplifier (TBA) enclosure is not approved for use in hazardous areas.
The Central Station console microphone (as supplied) is not approved for use in hazardous areas. A
microphone may be used in hazardous areas if it is connected through an approved intrinsically safe
barrier.

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TBA Models
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The Push to Talk (PTT) switches may be of a suitable rating for use in hazardous areas, or connected
through an approved intrinsically safe barrier.
Any application of equipment into a hazardous area must be approved by the appropriate authority.
The speakers used may be of a suitable rating for use in hazardous areas. The speakers used with the
system may or may not be approved, check the labels on the speakers for ratings.
Follow all local codes and requirements when installing the TBA Intercom System.
The TBA does not have a weatherproof or drip-proof rating, and is not protected for prolonged
exposure to high humidity and salt fog.
6. Installation Instructions
The Talk Back Amplifier (TBA) is an audio amplifier that has been designed to operate in a commercial
setting. In order to obtain the best results, use shielded cable and follow the instructions below.
6.1. TBA Enclosure
The TBA enclosure houses the Printed Wiring Board Assembly (PWBA) within a steel enclosure
that has a removable top cover. A wiring diagram is on the inside of the cover. The enclosure may
be placed on a flat surface, mounted in an equipment rack or otherwise securely mounted.
The TBA enclosure can dissipate up to 110 watts with all of the speaker amplifiers outputting
maximum energy. There must be adequate heat conduction so that the enclosure does not exceed
20 deg above ambient with 110 watts dissipation. An air flow caused by convection with a 1 inch
gap to surrounding side walls is normally adequate. If in doubt, test the temperature rise using a
heater of 100 watts in the case and measure the resultant temperature after 1 hour.
The TBA enclosure top panel may be removed by unfastening the six screws. Once the top panel
has been removed, access to 120 volts AC is provided; therefore the service personnel should be
qualified to work with electrical equipment.
The TBA amplifier enclosure is painted and uses stainless steel hardware internally. The
components within the enclosure are not waterproof or corrosion resistant so the enclosure should
not be used in a corrosive or contaminated environment.
6.2. AC Supply
The Talk Back Amplifier uses 120 VAC at 60 Hz with a maximum of 1 amp continuous current for
energy supply. Note that the inrush current may be up to 10 amps for a fraction of a second.
There is an inrush surge reduction circuit that reduces the capacitive charging surge on power-on.
This circuit can be evaluated for inrush surge reduction if there is a problem with the external 120
volt power current surge capability.
6.2.1. 230 VAC operation
A 230 VAC to 24 VAC transformer can be special ordered for the TBA. The input voltage
labeling and serial number label must be changed or marked to indicate this change. The front
panel Power ON indicator must also be changed for 230 VAC operation.
6.2.2. DC Supply Options
The use of a separate DC supply for 27 to 35 volts (0.5 amps maximum) is possible to replace
the internal supply of the TBA logic and preamplifier sections for supply to J22 pins 1 and 3.
The negative ground connection is available at J22 pin 3 and positive is attached to J22 pin 1.
The use of a separate 30 to 70 volt supply (10 amps maximum) can be applied separately for
the audio power amplifiers if the jumper on J22 pin 1 to 2 is removed. The negative ground
connection is available at J22 pin 3. If this option is used, the internal transformer for 8 to 325
Ohms is to be removed and the amplifier will drive the 70 volt line directly.
Note that the DC supply generated within the TBA is “floating” with respect to the chassis
ground. Verify that the negative at J22 pin 3 (PWBA ground) has a low voltage and low audio
frequency noise with respect to chassis ground if there is noise present on the Talk Back
Amplifier system.

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TBA Models
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6.3. Push to Talk Switches
The Talk Back Amplifier has a 24 volt resistive connection to Push to Talk (PTT) switches.
The use of gold or silver plated switch contacts within an environmentally sealed housing is
recommended for long term reliability.
The switches will conduct about 0.5 milliamp when pressed, and have 24 volts across the terminals
when not pressed.
Each of these connections should be evaluated separately for safety.
6.4. Microphone
For all of the models except the TBA-33 the microphone input is terminated with a low impedance
of less than 10 Ohms at 1 KHz when the Central Station PTT is not pressed.
The TBA-33 has a 1K Ohm impedance across its terminals when the Central Station PTT is not
pressed. There is no DC supply or bias applied to the microphone line pair as the microphone input
is optimized for a dynamic microphone.
The level on the microphone is -80 dB reference 1 volt per bar (0.1 millivolt per bar). This is 0.1
millivolt from 150 Ohms series impedance with a 94 dB SPL activation. EIA sensitivity is -152 dB.
The Telex 785L is one microphone type that meets this specification.
The connection to the microphone is a two wire shielded cable, with the shield terminated at the
TBA enclosure only.
Ensure the microphone cable is not routed near a source of interference such as a generator, high
voltage cable or AC supply transformer.
Each of these connections should be evaluated separately for safety.
6.5. Speaker
The Talk Back Amplifier has a 10 watt at 325 ohm audio output to the speakers. This is also known
as a 70 volt intercom system.
The speakers used should be transformer coupled to the acoustic transducer. The acoustic
transducer may be a cone type speaker or a compression driver with an expansion cone. The
compression driver type of speaker is about 6 dB more efficient than a cone speaker for sound
input to electrical output when it used as a microphone.
The speaker on the Monitored Station and Stations #1, #2 and #3 are used as audio input devices.
The level of audio from these speakers is near 1 millivolt for 94 dB SPL at 1 foot from the front of
the speakers. Different types of speakers will have different sensitivities and the user must
evaluate the performance of the speaker when at the location.
The transformer on the speaker is capable of picking up surrounding magnetic fields, especially
from a 60 Hz transformer nearby. Ensure that the speakers and transformers are separated from
AC supply transformers and other sources of magnetic fields.
The connection to the speaker is a two wire shielded cable, with the shield terminated at the TBA
enclosure only.
Ensure the speaker cable is not routed near a source of interference such as a generator, high
voltage cable or AC supply transformer.
Each of these connections should be evaluated separately for safety.

Guardian Telecom Inc. Installation & Operation
TBA Models
7. TBA Configurations except for TBA-33
The external and internal connections for the TBA’s audio connections are shown in block form below.
Note that the connections of Stn #1, #2 and #3 are the same as for the Monitored (Mon) station.
Stations #1, #2 and #3 are connected in the same manner as the Monitored Station shown below.
Figure 6 - TBA External Audio Connections
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Guardian Telecom Inc. Installation & Operation
TBA Models
The 8 Ohm to 325 Ohm transformer is called a “70 volt transformer”, and it connects between the
output amplifier and the speaker. Stations #1, #2 and #3 are connected in the same manner as the
Monitored Station shown below.
Figure 7 - TBA Internal Audio Connections
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Guardian Telecom Inc. Installation & Operation
TBA Models
8. TBA-33 Configuration
The connections for the TBA-33 PWBAs before 2012 are shown below. The 8 Ohm to 325 Ohm
transformer is called a “70 volt transformer”, and it connects between the output amplifier and the
speaker.
Figure 8 - TBA-33 Internal Audio Connections Pre 2012
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Guardian Telecom Inc. Installation & Operation
TBA Models
Figure 9 - TBA-33 Internal Transformer Connections Pre 2012
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Guardian Telecom Inc. Installation & Operation
TBA Models
The connections for the TBA-33 PWBAs starting in 2012 are shown below. Note that the value of R161
is 10 K Ohm and R166 is 1.0 K Ohm to reduce the input gain to telephone line levels. The transformer
on the Central Station output is a 600 to 10K Ohm transformer to raise the impedance from 8 Ohms to
150 Ohms in order to be closer to the impedance of a microphone input to a telephone line adaptor
module.
Figure 10 - TBA-33 Internal Audio Connections Starting 2012
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Guardian Telecom Inc. Installation & Operation
TBA Models
Figure 11 - TBA-33 Internal Transformer Connections Starting 2012
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Guardian Telecom Inc. Installation & Operation
TBA Models
Figure 12 - Station Connector Wiring
Figure 13 - Central Station Microphone Wiring
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Guardian Telecom Inc. Installation & Operation
TBA Models
Figure 14 - Central Station Speaker Wiring
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TBA Models
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9. Installation Adjustments
The speaker outputs levels are each individually adjustable.
The gain for the Central Station microphone is adjustable.
The gain for the Monitored Station, Station #1, #2, and #3 are on one adjustment.
Remove the TBA enclosure top panel by unfastening the six screws; retain the screws and panel.
Once the top panel has been removed, access to 120 volts AC is provided; therefore the service
personnel should be qualified to work with electrical equipment.
9.1. Initial Settings
These settings are to be done before powering the TBA “on” for the first time. If previous
adjustments have been made, note the front panel adjustment positions or mark them on the
internal PWBA potentiometers.
Refer to Figure 15 - Adjustment Locations for the locations of the following adjustments.
Adjust these potentiometers to the 50% rotation point:
Central Station Volume (R11)
Monitored Station Volume (R141)
Station #1 Volume (R47)
Station #2 Volume (R79)
Station #3 Volume (R110)
Central Station Volume (Microphone – R183)
Stations 1 to 3 and Monitored Station Volume (Microphone – R184)
Ring Volume (R186)
As well the following settings are to be done.
Adjust Central Station Attenuation (R12) to fully counterclockwise
JP1 to “Ring Enable”
JP2 to “nearest pair to R180
J21 jumper on 1 to 2 (CENTRAL RELAY)
J21 jumper on 5 to 6 (MONITORED RELAY)
J21 jumper on 9 to 10 (STN #1 RELAY)
J21 jumper on 13 to 14 (STN #2 RELAY)
J21 jumper on 17 to 18 (STN #3 RELAY)
Verify the jumpers on J21 are only those shown above unless special instructions are given
for “RINGING” settings.

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TBA Models
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9.2. Powering ON the TBA
Turn the AC power switch on the back panel to “ON”.
Verify that the “Go-Ahead” tone is heard briefly on all of the speakers attached.
9.3. Monitored Station Microphone Volume Adjustment
Monitored Station Volume (Microphone – R184) adjustment is done while listening to the output of
the audio on the speaker for another station. With a sound source that is expected to be near the
maximum level adjust R184 so that the sound is just starting to be distorted.
Alternatively adjust R184 so the signal on J15 pin 1 is at 0.1 volts RMS with a normal voice level.
Alternatively adjust R184 so that it is at 25% of the rotation clockwise.
9.4. Central Station Microphone Volume Adjustment
Press the Central Station PTT switch. Adjust the Central Station Volume (Microphone – R183).
Adjustment is done while listening to the output of the audio on the speaker for another station.
With a sound source that is expected to be near the maximum level adjust R183 so that the sound
is just starting to be distorted.
Alternatively adjust R183 so the signal on J15 pin 1 is at 0.1 volts RMS with a normal voice.
Alternatively adjust R183 so that it is at 50% of the rotation clockwise.
9.5. Ringer Volume Adjustment
Press the Monitored Station PTT switch. Adjust the Ring Volume (R186) to have a ringing signal
that is loud enough but does not distort.
Alternatively adjust R186 so the signal on J15 pin 1 is at 0.2 volts RMS.
Alternatively adjust R186 so that it is at 50% of the rotation clockwise.
9.6. Central Station Speaker Volume
Adjust Central Station Volume (R11) so that the voice from the Monitored Station is at a
comfortable level for the Central Station operator.
9.7. Station #1 Speaker Volume
Adjust Station #1 Volume (R47) so that the voice from the Monitored Station is at a comfortable
level for the Station #1 operator.
9.8. Station #2 Speaker Volume
Adjust Station #2 (R79) so that the voice from the Monitored Station is at a comfortable level for the
Central Station operator.
9.9. Station #3 Speaker Volume
Adjust Station #3 Volume (R110) so that the voice from the Monitored Station is at a comfortable
level for the Station #3 operator.
9.10. Optional Hum Cancellation
The jumper on JP2 should be removed and replaced. If the sound level of the background noise or
hum changes with this action, replace JP2 jumper to the location nearest R180. If the sound does
not change replace JP2 jumper to the location away from R180 and do not adjust R179.
Adjust R179 for the minimum noise from a station speaker. This is a subjective adjustment.