User manual ACR ELECTRONICS EM-1A MEGAPHONE

[. . . ] 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 Weight Materials 5. 5" max diameter bell, 11. 5" max long 2. 3 lbs. , including batteries Horn, handle ­ Anodized Aluminum Housing ­ Aluminum Neck strap at top of unit Attachment 2 Y1-03-0014 Rev. [. . . ] CAUTION: Observe polarity of cells carefully before replacement. 5. 2 5. 3 6. 0 TESTING Note: The megaphone consists of three major assemblies; the microphone and mouthpiece assembly, the megaphone sub-assembly, and the horn and speaker assembly. To locate a defect, follow the procedure outlined below: 6. 1 6. 2 Squeeze the handle. If a clicking sound is heard, the speaker is operating. Remove the pin that activates the siren. If the alarm is of normal amplitude and sound character, the amplifier and siren circuitry are functioning properly. If the amplification is low, check the batteries and 5 Y1-03-0014 Rev. If the sound character is abnormal, check the batteries and then the siren circuitry. * 6. 3 If no sound is heard, remove the microphone and mouthpiece assembly and the batteries. Check that both the microphone and battery contacts are clean. If not, clean with a mild, non-abrasive cleaner such as alcohol. Test amplifier and speaker assembly by replacing the microphone with a spare microphone assembly. If no sound can be produced after microphone replacement, it may be assumed that the amplifier or speaker assembly is defective. To test the speaker, disassemble the speaker. Disconnect one wire and apply 1 ½ volts intermittently across the speaker. If no clicks are heard, the speaker is defective. * Optional Feature (see options Matrix) 6. 4 6. 5 7. 0 7. 1 TROUBLESHOOTING Testing procedure for locating defects is given in paragraph 6. 0. Possible faults and corrections are summarized below for ready reference. POSSIBLE CAUSE Exhausted batteries, defective microphone, speaker or amplifier assembly Exhausted batteries, defective siren circuitry or defective amplifier Exhausted batteries or wrong polarity of battery series Defective speaker TROUBLE No sound from speaker when handle is squeezed (Step 6. 1) CORRECTION Replace defective component No siren when alarm pin is pulled (Step 6. 2)* Replace defective component Sound is abnormally low or distorted Speaker does not respond to Step 6. 5 Check proper insertion of batteries or replace batteries. Replace speaker *Optional Feature (see options Matrix) 6 Y1-03-0014 Rev. R 8. 0 DISASSEMBLY (see Figure 2) 8. 1 Megaphone should be disassembled for repair or replacement of components only. 8. 1. 1 Remove microphone and mouthpiece assembly (2) by removing the three set screws (3). Remove battery cells (4) from the three tubes by tilting megaphone to allow cells to drop out into the hand. Unplug alarm plug pin (5) from side of housing. * Remove volume control knob (6) (pulls off). [. . . ] CAUTION: Observe polarity of batteries during installation procedure (see instructions at battery tube openings of the megaphone). 11. 1. 8 Replace microphone and mouthpiece assembly (2). Align keyway, and secure with the three setscrews (3). 11. 1. 9 Steps 11. 1. 1 through 11. 1. 8 complete the assembly of the megaphone. [. . . ]