Pub. 42004-139D
700 Series
Page/Party® Systems
Confidentiality Notice
This manual is provided solely as an operational, installation, and maintenance guide and contains
sensitive business and technical information that is confidential and proprietary to GAI-Tronics. GAITronics retains all intellectual property and other rights in or to the information contained herein, and
such information may only be used in connection with the operation of your GAI-Tronics product or
system. This manual may not be disclosed in any form, in whole or in part, directly or indirectly, to any
third party.
General Information
The GAI-Tronics Page/Party® System is a modular industrial communication system incorporating from
two to possibly hundreds of stations. Available in several forms, each station includes a handset, two
amplifiers (one for the handset and the other to drive one or more paging speakers), associated controls,
and a paging speaker (usually mounted separately). All stations are wired in parallel and additional
stations may be added at any time.
A GAI-Tronics Page/Party® System layout should be planned in advance of installation. Select handset
station locations carefully, taking convenience, accessibility, and personal safety into account. The
quantity and location of paging speakers must be carefully considered, particularly in areas of high
ambient noise or reverberation. The speaker amplifier built into each station drives one horn-loaded page
speaker. If additional paging speakers are needed, separate speaker amplifiers can be added to the
system. In quiet areas, such as offices, several paging speakers can be connected to a single station.
Please refer to Pub. 42004-135, Speaker Installation, or consult with a GAI-Tronics sales representative
for additional system planning information.
All units are wired in parallel. Good planning will minimize the cable required for each installation.
GAI-Tronics Corporation can supply multi-conductor cable designed especially for this application. The
number, size and color-coding of conductors are listed in the accompanying system connection diagrams.
Standard cable has 600-volt insulation and is UL-rated for power cable tray use. Additionally, for ease of
installation GAI-Tronics’ cable is color-coded to match the termination points in our enclosures. The
maximum standard cable length is 5250 feet (1600m) from the Line Balance Assembly systems. For nonstandard cable, please contact a GAI-Tronics representative.
The cable described above includes conductors to provide ac operating power to each station. All stations
operate from a common source, enhancing reliability, particularly if no other ac load is placed on the
circuit breaker or branch line feeding the system. This configuration also allows easy transfer to an
emergency power source in the event of power failure. However, if preferred, each station may be
individually powered from a nearby nominal 115 volt, 50 or 60 Hz single phase outlet.
GAI-Tronics Corporation P.O. Box 1060, Reading, PA 19607-1060 USA
610-777-1374 „ 800-492-1212 „ Fax: 610-796-5954
GAI-Tronics 700 Series Page/Party Systems
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Installation Procedure
Step 1 — Electrical Noise Considerations
When planning your system, consider the following suggestions to avoid electrical noise caused by slip
rings and silicon control rectifier (SCR) power supplies.
Slip Rings - Use a radio frequency (RF) alternative and avoid using slip rings as audio conductors. Slip
rings are a source of electrical noise and are not reliable.
SCR Power Supplies - If the Page/Party® system will be installed in areas where SCR power supplies
are used to power motors or other heavy equipment, consider using one or all of the following four
recommendations to reduce electrical noise.
Separation—Locate the Page/Party® system cables as far as possible from the SCR power supply
input or output cables. Electrical coupling between cables is reduced by the square of the distance
between the cables.
Shielding—Use shielded (armored) system cables if the cable must be run in the same bundle or cable
tray with the SCR power supply cables. Shielded cables reduce capacitive coupling between SCR
power supply cables and Page/Party® audio cables.
Isolation—Two methods of power source isolation can be used to avoid electrical noise:
A. Use a low capacitance (primary to secondary) isolation transformer between the Page/Party® system
and the ac supply to the SCRs. This electrically isolates the Page/Party® system’s ac power from the
noise generated by the SCR on the ac power feed. Also use an isolation transformer to isolate the
Page/Party® ac power from an ungrounded ac power source. Note: The neutral side of the
transformer output must be grounded in all instances.
The size of the isolation transformer should be based on the number of amplifiers used in the system.
If ten or less amplifiers are used in the system, a 500 VA transformer is sufficient. If 11 to 20
amplifiers are used in the system, select a 1000 VA transformer. For systems with more than 20
amplifiers, the transformer should be sized to accommodate a load of 50 VA per amplifier.
B. A battery powered 24 V Page/Party® system can be used as an alternative to the standard 120 V ac
system. In this instance, the battery/battery charger provides isolation from the SCR noise on ac
power systems. Cable shielding and separation as mentioned above still apply.
NOTE: Avoid battery chargers that utilize SCRs in their design.
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Step 2 — Mounting of Station and Speaker Amplifier Enclosure
Each Page/Party® system station includes a plug-in amplifier, that mates with a fabricated steel, cast
aluminum, or molded reinforced non-metallic enclosure. Each enclosure provides a terminal strip for
connecting inter-station cable. Enclosures are packed separately from the plug-in amplifiers at the
factory, allowing the amplifiers to remain protected while the enclosures are installed and wired —
particularly important during system installation in areas under construction.
The 16-gauge steel enclosures do not provide any openings for conduits or cables because the location of
these will vary with each installation. Drill or punch the necessary openings before mounting the
enclosure. Locate the openings either along the top or bottom of the enclosure and near the rear surface.
Avoid the top center because of possible interference with the plug-in amplifier receptacle. A drill
template is supplied with each enclosure.
Cast aluminum enclosures are drilled and tapped on the top and bottom for specially-designed hub plates.
Unless special arrangements are made, the enclosures include plates for single 1¼-inch conduit. Plates
for single ½-inch or 1½-inch, or dual inch are available. The molded enclosures are supplied without any
conduit openings. Sealed threaded hubs, such as Myers “Scru-tite”, are recommended. A drill template is
supplied with each enclosure.
Use caution when drilling holes to avoid damaging internal electrical components and wiring.
Suggested mounting height for all station enclosures is 54 inches (137 cm). Subsets used with remote
subset amplifiers are supplied with 8-foot (244 cm) cables. Enclosures for remote subset amplifiers must
be mounted within reach of the 8-foot cable. Desktop or desk-edge stations enclosures are often mounted
in the knee-well of the desk.
Step 3 — Mounting of Line Balance Assembly
Each GAI-Tronics Page/Party® system requires one line balance assembly. Its function is to properly
load the page and party line circuits. When using GAI-Tronics standard cable, select a location that is:
near the electrical center of the system
adjacent to an indoor station in a relatively quiet area
no more than 5250 feet (1600m) from the most distant station
For larger systems or when using other types of cable, contact a GAI-Tronics representative for further
information. The line balance assembly has one electrical adjustment that must be made while using a
station (see below). The following is the preferred method for mounting the line balance assembly:
1. Suspend the assembly from the lower side of the indoor wall station using a 1-inch conduit nipple
(not supplied).
2. Connect one twisted pair wire for the page circuit and another for each of the party lines between the
terminal blocks of the line balance assembly and the associated indoor wall station.
3. Make the wiring connections between the 305 Series Line Balance Assembly and the Model 702 and
703 Indoor Wall Station enclosures in accordance with the wiring diagrams at the end of this
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GAI-Tronics 700 Series Page/Party Systems
Step 4 — Installation of Inter-station Conduit and Cable
Inter-station cables are generally installed in cable trays or conduit. To assist in determining the conduit
sizes required, the outside diameters of the GAI-Tronics Corporation cables discussed in this publication
are listed below. Size and installation of conduit and cable must meet the requirements of applicable
electrical codes.
0.60 in. (15.1mm)
0.68 in. (17.2mm)
A ground conductor, with green/yellow insulation, should be included with cable in any area where no
conduit or non-metallic conduit is used. Non-metallic enclosures used with metallic conduit and cable
without a ground conductor require a bond between the conduit(s) and the ground terminal (point 3)
within the enclosure.
When using GAI-Tronics cable, attach wire lugs to each conductor and connect to the terminal in
accordance with either the color code shown on the applicable accompanying diagram or with special
drawings provided for this purpose.
Exception: Some cables have an orange “spare” conductor. Unless otherwise instructed, this
should be taped and not connected to the terminal strip(s) in the enclosures.
GAI-Tronics cable is considered to be a Class 1 cable (maximum voltage is less than 600 V). In a cable
tray, Class 1 cable may only be grouped with other Class 1 cables. Long runs of GAI-Tronics cable in
proximity to 600-volt cable may cause an undesirable amount of hum being induced onto the Page/Party®
system’s signaling lines. To reduce undesired hum, it is recommended that runs of cable over ½ mile be
separated from 600-volt cable by a minimum of 12 inches.
Step 5 — Installation of Amplifiers and Subsets
One of the many features of GAI-Tronics Page/Party® system equipment is automatic speaker muting.
When the push-to-page switch is pressed at a particular station, the paging speaker connected to that
station is silenced, preventing acoustic feedback to the handset microphone. However, while the handset
is in use for the party line conversations, the paging speaker is still “live” to paging calls from other
For cases where the muting feature is not necessary or may be a disadvantage, it can be defeated as
outlined below:
1. Locate lugged violet wire attached to terminal point 7 (Mute) on the terminal block within the
enclosure for station to be modified.
2. Transfer lugged violet wire to terminal point 8 (Page L1).
After making any necessary muting changes, unpack and install the amplifier for each station. Also,
unpack remote subsets (for desktop, desk-edge or panel-mount stations) and plug each into the bottom
sides of the amplifier enclosure.
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Step 6 — Checkout and Adjustment
Test all field wiring connections (page line, party line(s), mute, ac power and speaker) between stations,
and complete the line balance assembly installation before checkout begins. Ensure that all handsets are
1. Apply ac power, and check the station next to the line balance assembly.
2. Press the “push-to-page” switch (in the handset handle on some stations) and speak directly into the
microphone of the handset. The broadcast should be heard at all paging speakers in the system except
those associated with the station under test. If working properly, very little or none of your own voice
(sidetone) is heard from the handset earpiece. If the line balance assembly is not connected properly,
there will be a high level of sidetone, perhaps enough to cause feedback. Adjust the line balance
assembly to optimize sidetone rejection on the page line. If the system is complete when the first
station is checked, adjust the line balance assembly as noted below. Do not adjust station
(amplifier) controls until the line balance assembly is adjusted.
3. Release the push-to-page switch and check the party line(s) sidetone level by speaking into the
microphone of the handset. If working properly, very little or none of your own voice is heard from
the handset earpiece. This sidetone rejection will only occur if the line balance assembly is properly
connected because it contains a fixed resistor load for each party line. In addition, no party line
adjustments are provided. Check party line operation by conversing between two or more stations.
Adjustment of the Line Balance Assembly
To set the control for proper page circuit loading:
1. Remove the line balance assembly cover to expose the line balance control.
2. Lift the handset from the adjacent handset hook and press the push-to-page button.
3. From the normal speaking distance (approximately ½-inch), blow steadily into the handset
microphone and adjust the control to minimize receiver sidetone. This adjustment needs to be made
only at the initial installation of the system. However, if in the future more than 10 speaker amplifiers
are added or deleted, repeat adjustment of page circuit loading.
4. After final adjustment, replace and secure the cover with the four mounting screws to discourage
tampering by unauthorized personnel and prevent entry of contaminants.
Each amplifier has a paging speaker volume control. It is accessible from the front panel with a
screwdriver, but is concealed behind the metal nameplate. To reach it, simply loosen (do not remove) the
two nameplate screws and pivot the nameplate around the left screw. This control is adjusted at the
factory so that a moderate page level produces 4 watts of output power.
Each handset/speaker station amplifier has two additional internal controls: receiver volume control and
receiver sidetone control, both accessible using a screwdriver through the holes in the chassis. A third
hole allows similar access from the rear of the paging speaker volume control. Both controls are
factory-adjusted for optimum results in most industrial applications. Do not readjust these controls to
solve system problems until other possible faults are checked, such as a missing, defective, or improperly
connected line balance assembly. There is very little drop in receiver (handset earpiece) volume level due
to system cable losses. Generally, the only reason to reset the receiver volume control is to compensate
for extremely high ambient noise levels (up to 110 dB) or to meet particular personnel needs.
At stations with cable lengths of 3,000 feet (1 km) or more from the line balance assembly, receiver
sidetone rejection is noticeably affected by cable impedance. Use the receiver sidetone control to
compensate for this by rotating the control clockwise approximately 60 degrees for 3,000 feet (1 km) of
cable length.
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Step 7 — Troubleshooting the System
Hum or Buzz
Hum or buzz on the page circuit (or one or more party circuits) is usually due to either a short circuit of
one of the two conductors for each circuit to ground or unbalanced leakage to ground. As long as both
conductors are twisted pairs and there are no significant leakage paths or short circuits to ground, any
included voltages are the same on both conductors and do not appear across the line.
To correct the problem, locate the source of the ground. Using an ohmmeter, check various junction
points of the system wiring to determine in which direction the ground can be located. Locate the ground
by going from one junction point to another and disconnecting the affected circuit. The fault could be
within a plug-in amplifier. However, most ground circuits occur in improper terminations or are caused
by small strands protruding from an improperly lugged wire.
Another source of grounds or near-grounded circuits is junction boxes filled or partially-filled with water.
In many cases, there are deposits in the boxes, which, when combined with water, produce conductive or
corrosive solutions. These deposits cause leakage between circuits and can corrode the wire and
Isolation of field wiring may be necessary for test purposes. If such isolation removes the line balance
assembly from the operating portion of the system, connect a 33-ohm, 0.5-watt resistor across L1 and L2
of the Page/Party® line circuits. Remove these resistors after completion of the tests.
Feedback or Distortion on the System
Each page and party circuit must be loaded to the optimum 33 ohms using the line balance assembly. If
the line balance is not connected, or is defective, the system will have excessive gain and will break into
feedback quite easily. Speech will also be distorted, and there will be a high level of sidetone in the
handset receiver.
Each party line is terminated with fixed 33-ohm resistor in the line balance assembly. However, an
adjustable control is provided for the page line to compensate for the number of speaker amplifiers
connected to the system. Improper adjustment will affect gain and increase the level of sidetone. Please
refer to specific instructions above for adjusting the line balance assembly.
Very Low Audio Level on One or More Lines at all Stations
It is possible for the system, or part of the system, to function with a dead short across the page or party
circuits. If this occurs, the level of the system will be very low, decreasing to minimum level in the
vicinity of the short circuit. Locate the short circuit in the same manner as locating a ground, by checking
junction points with an ohmmeter.
Cross Talk
Cross talk, or interference, is generally caused by accidental crossing of circuits in a junction box. To
check for this condition, measure resistance between circuits of the interfering channels. The resistance
should be infinite or a very high value. Leakage or shorts to ground in two or more circuits can result in
cross talk on those circuits.
In a multi-party line system, it is possible to have a small amount of cross talk between channels if line
balance resistors are opened or not connected. This condition can be detected by the presence of high
sidetone in the handset.
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Static Charges
In many normal installations, a static ac voltage may be read from the conductors of the page and party
line circuits to ground. In many cases this voltage may be as high as 50 volts or more. This voltage is
induced into the circuits by capacitance to the ac power circuit (generally carried in the same cable, and
also from power cables paralleling communication cables). This voltage is inconsequential and can be
ignored. Problems would only occur if one side of the page or party circuit becomes grounded.
Audio Voltage
In a properly operating system, audio voltage read across any of the page or party circuits (L1 or L2) is
0.5 to 0.75 volts ac on peaks when an audio signal is present: i.e., someone speaking into a handset. The
voltage is proportional to the loudness of the person’s voice using the handset.
One Inoperative Station in a Working System
Except for a wiring error, an inoperative station indicates a defect in the amplifier at the station. This is
checked quickly by installing a spare amplifier or exchanging amplifiers with a properly operating station.
Special Note Regarding Installation
GAI-Tronics Corporation Page/Party® system equipment does not, in normal operation, produce arcs,
sparks or heat that would ignite industrial gases or dusts. Many standard GAI-Tonics products are
approved by Factory Mutual (USA) and certified by CSA (Canada) for intended use in specified Division
2 areas if properly installed and maintained.
Proper installation is defined as (1) mounting and wiring per factory directions without unauthorized
modification and (2) following all requirements of the U.S. National Electric Code (NFPA - 70) or the
Canadian Electric Code (CSA Standard C22.1). Installers must be familiar with these codes and consult
them as required. The most applicable parts of the N.E.C. code are in articles 500-503. The most
applicable parts of the Canadian code are in Section 18. Some, but not all, significant points are:
1. Conduits in a Class I, Division 2 area to or from a non-hazardous area or an adjacent Class I, Division
1 area must have approved seals in the boundary.
2. Conduits or raceways in a Class II, Division 2 or Class III area must have dust seals at entrances to
dust-tight equipment and at boundaries to other areas unless such conduits or raceways are also dusttight.
3. Explosion-proof (Division 1) equipment may be installed in a Division 2 area but must have the same
conduit and cable seals as if installed in the corresponding Division 1 area.
4. Sealing of multi-conductor cables or conduits containing multi-conductor cables in Class I, Division 1
or 2 areas must be around each conductor of the cable - except where type MI cable is used.
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Safe Power Connection/Disconnection
In order to satisfy Division 2 requirements, equipment must not create arcs or sparks during normal
operation, when completely installed and powered. Installing or removing an amplifier or plugging in a
live enclosure is not normal operation and can create arcs. To guarantee safety, adhere to the following
cautionary note:
Do not insert or remove equipment from live enclosures, unless the area is known to be nonhazardous at the time.
A separate power disconnect is highly recommenced. It can be installed and safely used in either of two
1. An explosion-proof disconnect switch can be located in the Division 2 area.
2. An ordinary disconnect switch can be located in a non-hazardous area (outside the Division 2 area).
Either method will allow the use of the switch at all times. Connect field wiring as detailed in
instructions for the same equipment mounted in non-hazardous areas.
Power Distribution Recommmendations
The ac input current for a 12-watt 700 Series Station (Handset/Speaker Amplifier or Speaker Amplifier)
is 0.46 amperes RMS at full power output (50 VA/27 watts) with 120 V ac line voltage. The 14 AWG
wire used for power distribution in standard GAI-Tronics cable is rated at 15 amperes. This limits the
number of speaker amp stations per ac feed to 32 units or less. System larger than 32 stations will require
breaking the ac power feed into different branches.
Voltage drop must also be taken into consideration for long cable runs. The minimum operating voltage
for a GAI-Tronics station is 90V ac and the resistance of 14 AWG cable is 26.8 ohms per loop mile.
Contact your nearest GAI-Tronics representative it you require assistance with system layout.
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