7. Operation (Fig. 2)
A. The passenger address system may be used to communicate with anyone in the passenger compartment. Announcements, sign posted chimes, and music are heard by the passengers over the PSU speakers and lavatory speakers. The crew call chimes are also heard over the attendant's speakers.
B. Music and all announcements are amplified by the PA amplifier. Switching in the amplifier assigns a priority to each input which causes any higher priority input to interrupt any lower priority input. In descending order the priorities are (1) pilot's announcements, (2) attendant's announcements, and (3) prerecorded announcements.
C. A control signal from a PTT switch enables voice audio to be amplified. Sidetone is returned to the pilots through the interphone system. A flight/ground level signal from the oil pressure indicating system establishes the audio level to the speakers. When the airplane is on the ground and engines not running, the level of speaker audio is reduced from that of flight conditions by 6 db.
D. On GUN/XIA B-2501-B-2505, B-2511, B-2512, and B-2514-B-2516, music from the music reproducer is sent to the amplifier when the music switch-volume control on the forward attendant's panel is turned on and adjusted.
E. On GUN/XIA B-2509 and B-2510, the tape reproducer is operated from the MUSIC control on the fwd attendant panel. Rotating the MUSIC control clockwise from the OFF position powers the capstan drive within the tape reproducer. The MUSIC control also controls the boarding music volume and provides the PTT 4 (priority 4) input to the PA amplifier.
(1)
The tape reproducer boarding music magazine is an endless tape containing four one-hour tracks of entertainment audio. The track selection switch on the tape reproducer front panel controls which track provides audio to the PA amplifier. The track selection will automatically sequence whenever the switch is in the A position. In the numbered positions the audio output will be from only a single track. The track selection switch is set to the A position for normal system operation.
(2)
Three prerecorded announcement tapes are provided in the tape reproducer. These tapes are designated A, B, and C. Each tape can hold 8 messages. They are designated 1 thru 8.
(3)
The prerecorded announcement control panel is located on the forward lavatory wall above the attendant seat. The attendant can select a prerecorded message on any tape by pushing the appropriate lettered pushbutton on the control panel and then selecting a prerecorded message on that tape by depressing the appropriate numbered pushbutton. The rows of pushbuttons are interlocked so that only one lettered and one numbered pushbutton may be depressed at a time.
(4)
A wait indicator light on the control panel will illuminate until the selected announcement has cued to the selected message.
(5)
After the wait indicator light has gone out, the message may be played on the PA system by depressing the ANN (announcement) pushbutton. The announcement will then play unless muted by an announcement of higher priority. Another announcement may be selected for the next playback after the first announcement is in the playback mode.
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：737 AMM 飞机维护手册 通讯 COMMUNICATIONS(25)
