23-71-00
 ALL  ú ú 09 Page 2 ú Dec 20/95
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
C75500
A
757
MAINTENANCE MANUAL

UNDERWATER LOCATOR BEACON (ULB)

TAPE BASED MODEL A100A
SOLID STATE MODEL
TAPE BASED MODEL A100
Voice Recorder System -Component Location Figure 1 (Sheet 2)
D05011
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 LORAL/FAIRCHILD VOICE RECORDER ú 23-71-00
 ú ú 08 Page 3 ú Dec 20/95
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A

(3)

(4)

757
MAINTENANCE MANUAL

 (a)  
The recording tape is 308 feet long, 1/4 inch wide in a continuous endless loop. The four track tape runs at 1 7/8 IPS providing 30 minutes of recording time.

AIRPLANES WITH LORAL/FAIRCHILD SOLID STATE VOICE RECORDER;
 The unit contains the printed wiring assemblies; aircraft interface,
 audio processor, and the store processor. The interface card
 connects the airplane wiring to the voice recorder. The audio
 processor card accepts the four channels of data and converts this
 data to digital data which is stored into the solid state memory.
 The store processor card encodes the data and supplies it to the
 crash protected store memory.

 (a)  
The voice recorder provides storage for 30 minutes of consecutive recording into the crash protected memory.

 (b)  
A headset inserted into the headphone jack on the front panel will monitor all channels slightly delayed after they are recorded.

AIRPLANES WITH LORAL/FAIRCHILD TAPE BASED VOICE RECORDER; The Model A100A recorder front panel contains a headphone jack and a underwater locator beacon (ULB). The Model A100 recorder front panel contains a headphone jack, test meter, five test pushbuttons and a underwater locator beacon (ULB). The monitor jack provides a slightly delayed means of monitoring all four tracks being recorded. The ULB is attached to the front panel and is a self-contained device. The ULB will emit a 37.5-kHz signal when the water activated switch is closed. The ULB contains a dated label to indicate when the battery requires replacement.

 (a)  
FOR VOICE RECORDER MODEL A100 ONLY; Pushbuttons 1 thru 4 are used to test the recording channels separately. The fifth pushbutton is used to test all four channels in sequence. A 600 Hz tone is supplied to the MONITOR jack while each of the channel pushbuttons is pushed. If the recorder is operating properly, the meter indicates in the the green area. If the ALL pushbutton is pushed, the 600 Hz tone and the meter indications are available for 0.8 seconds at a time as the test module ring counter samples each channel in turn. All four channels are sampled in about 5 seconds. The test stops whenever the test pushbutton is released.

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 23-71-00
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A

757
MAINTENANCE MANUAL

 (5)  The front panel contains a TEST switch, headphone jack, STATUS light (green) and a underwater locator beacon (ULB).
 3. Operation (Fig. 2)
_________
 A. Functional Description
______________________
 (1)  
The voice recorder automatically records the latest 30 minutes of communications and conversations in the flight compartment. Channels 1 thru 3 of the voice recorder receive inputs from the first observer's, the first officer's, and the captain's audio selector panels, respectively. The area microphone on the voice recorder control panel provides the input to channel No. 4.

 (2)  
The voice recorder is powered directly from the 115 VAC right bus. The power supply in the voice recorder supplies +30 VDC used within the recorder and +18 VDC used in the voice recorder control panel.

 (3)  
AIRPLANES WITH LORAL/FAIRCHILD TAPE BASED VOICE RECORDER; The four track endless tape runs at 1 7/8 IPS on a single-sided reel. The 1/4 inch wide tape is 308 feet long providing 30 minutes of recording time. The tape comes off the reel in a continuous loop, first passing the erase head, then the four record heads, then the play head and then back onto the reel.
　
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