(g)  
When a failure is detected, the output of the fault gate is a logic 1. This sends a maintenance flag discrete signal to the BITE LED on the front panel and to the DFDAU.

 (5)  
GUN 206-999; The functions of the DFDR are as follows:

 (a)  
The DFDR receives 115V ac power from the FLIGHT RECORDER AC circuit breaker through either the manual or automatic switching network. The DFDR contains a regulated power supply that generates the necessary operating voltages.

 (b)  
The store management section of the recorder, controls the operation of the recorder and is responsible for addressing and monitoring the solid state memory. The store management section controls the recorder operation through the use of a microprocessor which addresses recorder components via an 8 bit parallel address/data path and the data acquisition bus.

 (c)  
The purpose of the flash storage interface wiring assemble is to provide an interface between store data assemble and the protected solid state memory assemble. The flash storage interface uses a programmable logic cell array to condition the data as it is transferred between the store data assemble and the crash survivable store unit.

 (d)  
The playback data is routed to the DFDR front panel connector and to the DFDAU for output to a flight deck test connector. This enables the transfer of the recorded data to a portable copy recorder for ground processing.

 (6)  
Underwater Locator Beacon

 (a)  The underwater locator beacon is powered by a self contained battery. The ULB is activated when its water switch is immersed in water. The water switch is part of a low-current trigger circuit that turns on the oscillator circuit. The oscillator output drives a transducer that is mechanically coupled to the units case, radiating 37 kHz acoustic energy into the surrounding water. It sends out acoustic rf pulses when it is immersed in water up to 20,000 feet. It has a detection range of 2,000 to 4,000 yards.
 
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 (7)  System Functional Test
 (a)  A system self-test may be performed by momentarily setting the ON-NORM-TEST switch on the FDEP or the FRCP to the TEST position. On the FDEP, the SYSTEM, DFDAU, DFDR, and FDEP lights will extinguish if no fault is detected. On the FRCP, the OFF light will also extinguish if no fault is detected.
 
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757 MAINTENANCE MANUAL
 FLIGHT DATA RECORDER SYSTEM - DESCRIPTION AND OPERATION
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 1.  General (Fig. 1)_______
　
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