(b)  
P6 Load Control Center - Right
 1) ELEX PANEL
 2) SELCAL-2

 S 024-017
 (2)  Remove the Control Panel:
 (a)  
Loosen the fasteners on the control panel.

 (b)  
Pull the control panel out.

 (c)  
Disconnect the electrical connector.

 TASK 23-28-21-424-007
 3.  SELCAL Control Panel Installation_________________________________
 A.  References
 (1)  23-28-00/501, SELCAL System Adjustment/Test
 B.  Access
 (1)  Location Zone
 101/102 Control Cabin

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A
737-300/400/500MAINTENANCE MANUAL
 C. Procedure
 S 424-015
 (1)  Install the Control panel:
 (a)  
Connect the electrical connector to the control panel.

 (b)  
Attach the panel with the fasteners.

 S 864-020
 (2)  
Remove the DO-NOT-CLOSE tags and close these circuit breakers:

 (a)  
P18 Load Control Center - Left
 1) SELCAL-1

 (b)  
P6 Load Control Center - Right
 1) ELEX PANEL
 2) SELCAL-2

 (3)
Do this task: "SELCAL System Test", (Ref 23-28-00/501).

 S 714-012
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
 PASSENGER ADDRESS SYSTEM - DESCRIPTION AND OPERATION
____________________________________________________
 1.  General_______
 A.  The passenger address (PA) system provides voice announcements, boarding music and chime signals to the passengers.
 B.  AIRPLANES WITH A TAPE REPRODUCER ON THE FORWARD LAVATORY WALL; The PA system also provides boarding music and prerecorded announcements.
 C.  AIRPLANES WITH A TAPE REPRODUCER IN THE ELECTRONIC EQUIPMENT BAY; The PA system also provides boarding music.
 D.  The passenger address system consists of a PA amplifier, tape reproducer (when installed), and loudspeakers. The speakers are located in the PSU, lavatory, and attendant areas.
 E.  Power to the system is provided by 115v ac and 28v dc circuit breakers on panel P6.
 2.  Passenger Address Amplifier___________________________
 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.

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