Description (AMM 23-31-00)

 

A- The passenger address amplifier provides high-quality audio power to the speaker system of the airplane. It includes microphone inputs for use by the pilot and cabin attendants.           

 

B- It has two balanced inputs for use by the tape reproducer for prerecorded announcements or boarding music.

 

C- The amplifier has high, high/low, and low chimes for use by the pilot and passengers.            

 

D- The amplifier is a shelf-mounted unit located on the E2 main equipment center that weighs approximately 6 pounds.           

 

E- AIRPLANES WITH COLLINS 346D-2B AMPLIFIER; Refer to the data that follows:

(1) The amplifier unit consists of a wraparound aluminum chassis with an attached front panel, two electrical subassemblies, and dust cover. 

 

(2) A three-position rotary switch and three red LED's are located on the front panel.                

 

(3) The center position of the switch is for normal operation with the LED's connected across the output load.                

 

(4)The spring-loaded CAL position allows the unit to be tested for optimum output.               

 

(5)The TEST position supplies a tone for checking the speakers.                

 

(6) An access hole is provided on the front panel for adjustment of the master gain control. All other controls are accessible with the dust cover removed.           

 

F- AIRPLANES WITH COLLINS PAU700 AMPLIFIER; Refer to the data that follows:               

(1) The PA amplifier front panel has a three-character LED for test meter readouts.

 

(2) A four-position function switch is spring-loaded from LOAD back to TONE and from LEVEL back to OPERATE.               

 

(3) The LED is off when the TONE and OPERATE positions are selected.                

 

(4) In the LOAD position, the amplifier measures the magnitude of the load impedance at 587 Hz.               

 

(5) In the TONE position, a 587 Hz test tone is broadcast over the speakers.               

 

(6) In the LEVEL position, the switch measures main power amplifier output at 587 Hz into an internal load with the speakers disconnected as a reference for setting the gain controls. 

              

(6) Normal operation of the PA amplifier requires the switch to be in the OPERATE position.                 

 

(7) Cooling air is from the equipment cooling system via inlet and exhaust ports at the bottom and top of the unit, respectively.                

 

(8) The master gain control adjusment is halfway up the front of the panel.