User manual ASL INTERCOM PS 19A

[. . . ] On the front panel are Volume (listen level) controls for the PGM and the communications signals and a Talk and a Call button with LED indicators. Special attention has been paid to the intelligibility of speech. By applying low noise/high speed opamps, a speech presence filter and a specially developed high power bridged headphone amplifier, communication is very comfortable even in environments with a very high background noise level. 2. 0 UNPACKING After unpacking the unit please inspect for any physical damage and retain the shipping carton and relevant packing materials for use should the unit need returning. If any damage has occured, please notify your dealer immediately so that a written claim can be initiated. [. . . ] - adjust 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. BUZZER VOLUME trimmer This trimmer adjusts the volume of the internal buzzer, which is located behind the front panel. The buzzer is activated if you press the CALL button of the PS 19A or a CALL button of any other station (on the channel to which the PS 19A is connected), for longer than 2 seconds and the buzzers are not muted (on the master station or power supply). 9 7. 0 INTERNAL CONTROLS MIC GAIN The mic gain can be adjusted internally by a trimmer, located on the lower PCB. PGM LINE/MIC LEVEL selection Two jumpers inside the PS19A determine the selection between MIC and Line level for the PGM input. Open the PS19A by removing the four screws on the underside. Remove the screws which fasten the upper PCBboard. Remove the upper PCB-board by lifting it up. On the upper PCB board you see two jumpers. Jumper position for PGM input 1-2 Line level 2-3 Mic level 6 User Manual PS 19A / Issue 1 © 1994 ASL Intercom, Utrecht, Holland. 8. 0 CABLING For the PRO Series Intercom system the interconnecting cables are of the shielded two-conductor microphone cable type and the intercom line connectors are of the XLR-3 type. Audio and Call signals are on XLR pin 3, DC power is on XLR pin 2. XLR pin 1 is connected to the shield of the cable which functions as the common return for audio and power. Since the audio signal is transferred in an unbalanced way, certain rules have to be obeyed when installing the cables of an intercom network. This is to avoid earth loops and to minimize power loss and the possible effect of electromagnetic fields. These rules are: ¼ Use high quality (multipair) cable. For interconnecting user stations, power supplies and accessories in an ASL Intercom network, use high quality shielded two-conductor (minimum 2x 0. 30 mm2) microphone cable only. In case of a multi channel intercom network, use high quality microphone 'multipair' cable only, each pair consisting of two conductors (minimum 2x 0. 15 mm2) with separate shield. Multipair cable should also have an overall shield. Use flexible single and multipair microphone cable instead of cable with solid cores, especially when the cable is subjected to bending during operation or installation. The screen of each separate microphone cable and/or the screen of each single pair in a multipair cable, should be connected to pin 1 of each XLR-3 connector. Do not connect this cable screen to the metal housing of the connector or to metal wall boxes (outlets). [. . . ] Users of the system are connected via a 'party line'. Master stations (with built-in power supply), beltpacks, speaker stations and power supplies are interconnected via standard microphone cable. One wire is used as an audio line, one as a power line and the screen of the cable functions as earth/return. Current drive is used for signal transfer. [. . . ]