Audio international PA-7500A User manual

7300 Industry Drive, North Little Rock, AR 72117
Phone: [phone] Fax: [phone]
www.audiointl.com
Installation Manual
PA-7500A
Cabin Audio Amplifier
Document # 540056A

Audio International, Inc. PA-7500A Installation
Document # 540056A, Rev. A, 7/2000 Page 1 of 11
Document Revision History
Rev. Level Date Description
IR 10/1997 Initial Release
A 7/2000 ECN #5237
Reference Documents
Document # Description
520754 Rev A PA-7500A Outline Drawing
Service Bulletin List
Service
Bulletin # Subject Manual Revision Revision Date
Table of Illustrations
Illustration # Description Page #
2.2 Block Diagram – Typical Application 5
6.0 Reference Drawings 11
PROPRIETARY INFORMATION NOTICE: Despite any other copyright notice, this document and
information disclosed herein contains confidential, proprietary designs owned by Audio International, Inc.
Neither this document nor the data contained herein shall be reproduced, used, or disclosed to anyone
without the written authorization of Audio International, Inc.

Audio International, Inc. PA-7500A Installation
Document # 540056A, Rev. A, 7/2000 Page 2 of 11
Table of Contents
Section Description Page
1.0 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Purpose of the Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Operational Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Optional Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.0 Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Block Diagram – Typical Application. . . . . . . . . . . . . . . . . . . . . 4
3.0 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1 Prior to Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2 Unpacking and Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.3
Cautions &Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.4 Wiring Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.5 Physical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.6 Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.7 Mating Connector Information . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.8 Pinout Assignments and Descriptions . . . . . . . . . . . . . . . . . . 8
3.9 Post-Installation Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.0 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1 General Troubleshooting Procedures . . . . . . . . . . . . . . . . . . . . 10
4.2 Troubleshooting Chart . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 10
5.0 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.0 Reference Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Audio International, Inc. PA-7500A Installation
Document # 540056A, Rev. A, 7/2000 Page 3 of 11
PA-7500A
Cabin Audio Amplifier
1.0 General Information
1.1 Introduction
This manual contains information for the proper installation of the Audio
International, Inc. (AI) Cabin Audio Amplifier, Model No: PA-7500A. Also
included are physical and electrical characteristics of the unit.
1.2 Purpose of the Equipment
The PA-7500A is a class ‘D’, 300 watt, dual stereo power amplifier that
takes low audio signal and magnifies it. This audio amplifier delivers high
performance, excellent frequency response, and clear sound quality. The
unit has a small footprint and generates little heat yet produces dual
output, high-powered, high fidelity sound.
The unit has four (4) channel outputs, 75 watts peak output per channel.
A 135 Hz crossover is incorporated within the unit. Provisions are included
for PA audio override input. The unit is designed to interface with AI’s
proprietary RS-485 serial data bus allowing the entertainment switch
panels to communicate with the audio amplifier.
1.3 Operational Features
Listed below are key features of the PA-7500A:
q Solid state circuitry
q Small footprint
q Minimal heat generation
q Dual output, high-power, high fidelity sound
q Four (4) channel outputs, 75 watts peak output per channel
q Electric crossover –135 Hz range
q PA override input
q Automatic speaker turn ‘ON’and PA audio level setting when PA
interface is activated
q Lightweight, compact
q Specially designed to meet aircraft standards

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1.4 Optional Equipment
Audio International, Inc. offers a complete line of speaker systems to
enhance any aircraft entertainment system. Contact your AI
representative for details.
2.0 Application
2.1 Introduction
The PA-7500A will produce stereo audio output for the entertainment
system and monaural audio for page / chime. Each amplifier is designed
to interface with AI’s proprietary RS-485 serial data bus allowing all
entertainment switch panels to communicate with the audio amplifier.
The unit has the capability of producing four (4) channels, 75 watts RMS
peak output. Output impedance 4-ohms per channel; input impedance
10-k briefer, 1 VRMS nominal. Emergency input power is provided for PA
override capabilities. Electric crossover low range 20 –135 Hz, high
range 135Hz –20 kHz.
2.2 Block Diagram –Typical Application

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3.0 Installation
3.1 Prior to Installation
3.1.1 During the design and layout of the aircraft cabin, careful
consideration of the location of this module is necessary. Some of
the items to be considered include:
• Space
• Available power supply
• Environmental conditions (temperature, humidity, etc.)
• Length of cable runs
3.1.2 The PA-7500A shall be installed to conform to the standards
designated by the customer, installing agency, and existing
conditions as to the unit location and type of installation.
3.1.3 Mounting screws are required to secure the unit. Refer to
Section 6.0, Reference Drawings, for mounting hole diameters and
configuration.
3.1.4 The unit must be located as close to source equipment as possible.
Long low-level runs may introduce noise into the audio signal.
3.2 Unpacking and Inspection
Carefully open the packaging and remove the unit. Verify that all
components have been included in the package per the packing list.
Inspect the unit for damage. Retain the packing materials and packing
list.
If damage has occurred during shipping, a claim must be filed with AI
within 24 hours and a “Return Request Authorization Number”must be
obtained from AI. Refer to the front cover of this manual for address and
telephone number of Audio International. Repackage the unit in its
original packaging materials and return it to AI following instructions given
by the AI representative. If no return is necessary, retain the packing
materials for storage or reshipment if necessary.

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3.3 Cautions and Warnings
3.3.1 It is important to do a pin-to-pin power and ground check on all
connectors. Ensure that power and ground are applied only where
specified. Damage to the unit may result if power or ground is
applied to the wrong points.
3.3.2 DO NOT connect or disconnect the module while power is applied.
3.3.3 DO NOT remove any factory-installed screws. Damage to the units
may result and void any warranties.
3.3.4 ESD (Electro Static Discharge) guidelines shall be followed.
3.4 Wiring Requirements
3.4.1 Introduction
The installing agency must supply and fabricate all external cables
and mating connectors. The length and routing of external cables
must be carefully studied and planned before attempting installation
of the equipment. Allow adequate space for installation of cable
and connectors. Avoid sharp bends and placing cables near
aircraft control cables. Maintain a MINIMUM clearance of three (3)
inches from any control cable. If wiring is run parallel to
combustible fluid or oxygen lines, maintain a separation of six (6)
inches between the lines.
3.4.2 Power Wires
All power and ground wires shall be 18 AWG, MINIMUM. Power
ground wires shall be grounded within twelve inches of the unit. All
wires shall be in accordance with MIL-W-22759 or equivalent.
Protect power wires with circuit breakers or fuses located close to
the electrical power source bus.
3.4.3 Audio Lines
All audio input and output cables shall be 20 AWG, MINIMUM (16
to 18 preferred). All audio lines require twisted, shielded cable with
the cable shields grounded at the source. Twisted shielded cable
must be in accordance with MIL-DTL-27500 or equivalent.

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3.4.4 AI Proprietary RS-485 Data Bus
The PA-7500A is designed to interface with other AI equipment via
AI’s proprietary RS-485 serial data bus. This is a bi-directional data
bus that allows multiple units to be connected simultaneously.
The data bus is to be implemented using a twisted shielded pair
cable in accordance with MIL-DTL-27500 or equivalent. The wire
size for the conductors in this cable is to be 22 AWG,MINIMUM.
The shield is to be connected wherever a shield pin is provided.
Shield terminations are to be made as close to the connector pin as
possible. In the event shield pins are not provided, the data bus
shield must be terminated per AI’s proprietary RS-485 specification.
All modules on AI’s proprietary RS-485 data bus shall be connected
in a “daisy-chain”configuration. AI’s proprietary RS-485 serial data
bus specification is available upon request.
3.5 Physical Characteristics
3.5.1 Refer to Section 5.0 for unit dimensions.
3.5.2 Refer to Section 6.0 for attachment points.
3.5.3 When mounting the unit, allow sufficient space for mating
connectors.
3.6 Electrical Characteristics
3.6.1 Refer to Section 5.0 for electrical specifications.
3.6.2 P1 is a 25-pin connector. The signals interfaced through P1 are left
/ right speaker, +28 VDC emergency power and woofer outputs.
Power requirement is +28 VDC at continuous power output at 12
amps (15 amp breaker –4 channel). Emergency power input is
provided for cabin page and chime functions in case of power
failure.
3.6.3 P2 is a 37-pin connector. The signals interfaced through P2 are PA
/ chime, briefer, stereo left and right (high and low), data bus
control, and +28 VDC power. When the briefer key input is
activated, all entertainment audio will be muted. The PA key input
has the highest priority and will override all briefer and
entertainment audio inputs. When the PA source is keyed, all other
audio will be muted. Chime inputs will operate simultaneously with
the briefer.
.

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3.7 Mating Connector Information
All wiring harnesses to the unit are supplied and fabricated by the
installing agency. P1 mating connector is SD25F10HVL0. P2 mating
connector is SD27F10HVL0.
3.8 Pinout Assignment and Descriptions
P1 P2
Pin # Description Pin # Description
1 Left Speaker 1 –High 1 No Connection
2 Left Speaker 2 –High 2 PA MIC +
3 Left Speaker 1 –Low 3 Wgt-On-Wheels Input (Ground)
4 Left Speaker 2 –Low 4 Briefer +
5 Woofer 1 –Low 5 No Connection
6 + 28 VDC 6 Left In +
7 + 28 VDC 7 Left In -
8 + 28 VDC 8 Right In +
9 Woofer 2 –Low 9 Right In -
10 Right Speaker 1 –Low 10 Data Bus Shield
11 Right Speaker 2 –Low 11 +28 VDC (Adj)
12 Right Speaker 1 –High 12 Data Bus Ground (Adj)
13 Right Speaker 2 –High 13 Data Bus SER + (Adj)
14 Woofer 1 –High 14 Data Bus SER –(Adj)
15 Emergency Bus +28 VDC In 15 No Connection
16 + 28 VDC 16 No Connection
17 + 28 VDC 17 No Connection
18 Ground 18 No Connection
19 Ground 19 No Connection
20 Ground 20 PA MIC -
21 Ground 21 No Connection
22 Chassis Ground 22 Briefer -
23 Ground 23 No Connection
24 Ground 24 PA MIC Key
25 Woofer 2 –High 25 Briefer Key
26 + PA Output
27 - PA Output
28 PA Key Out
29 Data Bus SER Data +
30 Data Bus SER Data -
31 Chime In (+28 VDC)
32 TT Chime In (+28 VDC)
33 Call In (GND)
34 Hook In (GND)
35 PA Sidetone +
36 High Tone
37 Low Tone

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3.9 Post-Installation Test
3.9.1 With aircraft power ‘ON’, test the cabin audio amplifier. Any unit
providing audio that is connected to the RS-485 data bus may be
used to test proper operation the unit.
3.9.2 While an audio unit is sending audio signals through the amplifier,
key and speak into a microphone to ensure that the page / chime
overrides the entertainment audio. Ensure all microphones are
tested. Verify that the briefer audio can be heard through the
speakers.
3.9.3 Verify that the selected material may be heard through the
headphone and/or speaker system. Activate the PA key. Verify PA
overrides the headphone and/or speaker system.
3.9.4 Remove power from the amplifier and verify that the +28 VDC
emergency power is supplied to the amplifier. Verify that the
subwoofers are disabled while emergency power is applied.
Ensure that PA audio can be heard in the speaker system from all
respective microphones.
3.9.5 Audio level adjustments are accomplished via AI’s proprietary
RS-485 data bus. Contact Audio International, Inc. for setup
requirements.

Audio International, Inc. PA-7500A Installation
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4.0 Troubleshooting Guide
4.1 General Troubleshooting Procedures
Many problems can be isolated with the following general techniques:
• To verify power to the unit, recheck +28 VDC power is applied to the
proper pins on the unit. Use a voltmeter to verify correct level.
• Reset by removing power from the unit for at least one (1) minute and
reapply power. Verify the problem still exists.
• Recheck all connections to the unit for security. Check all harness
runs for possible pinching. Recheck all pinouts for application
accuracy.
4.2 Troubleshooting Chart
Problem Possible Cause Solution
No sound Unit improperly installed Verify +28 VDC power and audio
input is present
No audio material in
source unit Insert audio material in source unit
Poor audio
quality Audio controls are not adjusted properly Contact AI
5.0 Specifications
Physical Specifications
Housing Aluminum
Dimensions
(l x w x h) 9.3" x 4.9" x 2.0" 23.62cm x 12.45cm x 5.0cm
Weight 2.7 lb / 1.22 kg
Electrical Specifications
Power + 28 VDC at continuous power output
@ 12 amps,
3.5 amps MINIMUM, 17.5 amps MAXIMUM
Emergency Power + 28 VDC Page / Chime
Data Bus Type AI Proprietary RS-485
Electric Crossover Low Range: 20 Hz to 135 kHz
High Range: 135 Hz to 20 kHz
Channel Output Power 4-Channel, 75 watts peak output
Input Impedance 10-k briefer, 1 VRMS (NOMINAL)
Output Impedance 4-ohms per channel

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6.0 Reference Drawings
The following diagrams show the unit dimensions and connector locations for the
PA-7500A. All dimensions are shown in inches.