ACR Electronics EM-1A User Manual

PRODUCT

EM-1A, EM-1D™

SUPPORT

Product No. 2204, 2208

FAA PMA Approved under A3-06-1402-

MANUAL

Y1-03-0014

(25-60-01)

Overhaul Manual

with Illustrated Parts List

Rev. R

Portable Safety Megaphone

ACR Electronics, Inc.

5757 Ravenswood Road

Fort Lauderdale, Fl 33312

[phone] • Fax [phone]

www.acrelectronics.com

Email: [e-mail]

A Chelton Group company

TABLE OF CONTENTS

SECTION TITLE PAGE

1.0 Description 1

2.0 Technical Data 1

3.0 Operation 2

4.0 Cleaning 4

5.0 Battery Replacement 4

6.0 Testing 4

7.0 Trouble Shooting 5

8.0 Disassembly 6

9.0 Inspection Check 6

10.0 Repair 6

11.0 Assembly 7

12.0 Parts List 9

ILLUSTRATION

Figure 1 Block Diagram 3
ACR/EM-1A & EM-1D
Portable Safety Megaphone

Figure 2 Illustrated Parts List 8
ACR/EM-1A & EM-1D
Portable Safety Megaphone

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Y1-03-0014 Rev. R

1.0 DESCRIPTION

1.1 The ACR/EM-1A, 1D is a battery operated solid state megaphone

specifically developed for use in enclosed areas such as in the interior of
an aircraft or ship cabin. It has been designed to minimize regenerative
acoustic feedback that results in whistling and other oscillations of this
nature. It has a 90° sound projection angle to direct the sound to persons
in its immediate vicinity, as well as in the rear sections of any aircraft.
The amplifier frequency band-pass has been selected to produce a crisp,
clear reproduction of voice signals. The operating power level is also
sufficient to provide adequate sound under high ambient noise level
conditions without being over-powering. Specific attention has been
given to the physical size so that it can be used effectively in a crowded
environment.

The EM-1A & EM-1D are the same except for installed options:

MODEL MANUAL GAIN ALARM ACTUATOR BATTERY MONITOR

Visual Audible

OPTIONS MATRIX

EM-1A Yes Yes Yes No
EM-1D Yes No Yes Yes

1.2 The integrated circuit amplifier only uses a small current when turned
“ON”. Large currents necessary to drive the speaker are utilized only on
voice peaks. This extends the life of the batteries so that several hours of
operation may be expected when used normally in an intermittent manner.
Batteries should be replaced periodically as recommended by the
manufacturer. (See section 5.0) A simplified block diagram of the
megaphone is shown in Figure 1.

2.0 TECHNICAL DATA

Dimensions 5.5” max diameter bell, 11.5” max long

Weight 2.3 lbs., including batteries

Materials Horn, handle – Anodized Aluminum
Housing – Aluminum

Attachment Neck strap at top of unit

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Y1-03-0014 Rev. R

Gain Control* Thumb operated

Amplifier Integrated circuit, 2 watts power output

Speaker Re-entrant horn and driver type;
input power five (5) watts;
90° dispersion angle

Microphone High Sensitivity

Batteries Six (6) standard 1½ volt “AA” cells

Power Drain 25 milliamps static current
550 milliamps maximum current

Frequency Response 500 to 3500 Hz

Anti-Removal Alarm* Warbling tone 500 – 1200 Hz

Alarm Actuator* Plug pin, retained by nylon cord

Battery Test Circuits Visual Flashing Green LED*
Acoustical Beep*

*Optional feature (see options matrix)

3.0 OPERATION

3.1 A siren, incorporated into the megaphone, is automatically activated by
unplugging the alarm plug pin.*

Note: A long lanyard with an alarm plug pin is supplied with the
megaphone for use as an anti-theft alarm (optional).

3.2 Squeezing the handle automatically stops the siren, and the megaphone is
ready for use. Re-insert the alarm pin so that alarm will not be reactivated
when pressure on the handle is removed.

3.3 Hold the megaphone in one hand. Place mouth almost in contact with the
microphone mouthpiece at the rear of the assembly. Squeeze the handle,
which will flex slightly, turning the megaphone “ON” and speak slowly
with loud, crisp, clear tones.

Megaphones without the optional gain control knob are preset to a

standard level via control under access hole plug.

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Y1-03-0014 Rev. R