User manual ASL INTERCOM PS 278

[. . . ] PRO SERIES USER MANUAL FOR THE PS 278 DUAL CHANNEL MASTER STATION CONTENTS 1. 0 2. 0 3. 0 4. 0 5. 0 6. 0 7. 0 8. 0 9. 0 10. 0 11. 0 12. 0 GENERAL DESCRIPTION . 10 User Manual PS 278 / Issue 2 © 1996 ASL Intercom, Utrecht, Holland. 1. 0 GENERAL DESCRIPTION The unique ASL CALL system provides both a flashing red LED and a very distinctive and characteristic sound signal. Only a slight touch of the CALL button will make the LED flash, whilst holding the button for two seconds will activate the call sound signal. In case the sound signal is undesirable, all buzzers can be muted with the front panel 'all buzzers on/off' button. [. . . ] - switch off the microphone of all connected (speaker!) stations. - switch on the microphone of the required channel. - turn up the volume of the required channel. - adjust the listen level by turning the sidetone trimmer. The operating area is between fully clockwise and minimum level. Adjusting the sidetone does not affect the level of your voice as it is heard by other stations. 12 TALK buttons These buttons allow you to talk to each channel separately or simultaneously. The large green LED indicates if the talk function is activated. Latched switching: When a TALK button is momentarily pressed, the microphone will be switched on for the chosen channel and is electronically latched. When pressed again, the microphone will be switched off. Momentary switching: When a TALK button is pressed and held, the microphone will be switched on, and when released, will be switched off. 13 CALL A & B buttons These push buttons activate the CALL system. A momentary push will send a CALL signal to all stations connected to that intercom channel and the CALL LEDS will start flashing. Press and hold the buttons for 2 seconds will activate the call buzzer, if not muted. After the CALL button is released the LEDS will continue to flash for a further 2 seconds. 14 HEADSET connector A XLR-4 type connector for the connection of the local headset. This must have a can impedance of 200 ohms (or greater), or each 400 ohms minimum when in parallel. The mic may be of the dynamic or electret type. phones The wiring is such that both headset cans are connected in parallel and receive the same signal. The two headphone amplifiers run in a bridged mode. As an option, a XLR-6 type connector can be fitted to give a binaural headset configuration where a different signal will appear on each can. In this mode the internal headphone amplifiers are not bridged. See section 7. 1 Internal Jumpers and Controls. User Manual PS 278 / Issue 2 © 1996 ASL Intercom, Utrecht, Holland. 5 6. 0 REAR PANEL CONTROLS & CONNECTORS 15 A & B LINE connectors These XLR-3 type connectors are for connecting the remote-stations, via standard microphone cable. [. . . ] This principle has three advantages: - the use of a single audio line allows several stations to talk and listen simultaneously. - due to the high bridging impedance offered by each station, the number of stations 'on line' has no influence on the level of the communications signal. - power and audio to the intercom stations use the same cable. The Call signal is also sent as a current on the audio line. [. . . ]