Specifications
LBI-39062
8
• five (5) simulselect keys
• eleven (11) patch keys
• five (5) telephone/intercom keys
• ten (10) function keys and an escape key
AUDIO TOWER
The Audio Tower contains all of the audio interface
and audio routing circuitry for the C3 Maestro console
system. This unit is interfaced to the PC by the Logic Board
and the 37-conductor interconnect cable between the two
units.
Case Assembly
The Audio Tower's case provides housing for all major
components within the unit. As shown in the Mechanical
Parts drawing in this manual (page 15), the case assembly
consists of a frame support assembly, a card cage assembly,
side panels, front and rear door assemblies, and other
miscellaneous items. A lock is included on the rear door to
prevent access by unauthorized persons.
All cables are routed out of the bottom of the case
through the cut-out in the bottom of the rear door. If
necessary, some or all of the cables can be routed under the
case's stand and out to the front of the Audio Tower. For
example, it may be advantageous to route a microphone
cable in this manner.
Power Supply
As shown in the Mechanical Parts drawing, the power
supply is mounted in the bottom of the case near the front
end of the Audio Tower. This power supply converts ac line
power to regulated 15 Vdc power. It is a non-serviceable
unit.
Fifteen volts dc power is applied to all boards within
the Audio Tower by the supply's output cables and the
Backplane. The ac power on/off switch is located near the
bottom of the rear vertical panel just above the ac power
cord connector.
Backplane And Spreader Boards
The Backplane and Spreader Boards are installed in
the case assembly. The "Backplane" actually mounts on
rails near the Audio Tower's front-end. The Spreader Board
mounts on the rear vertical panel.
The Backplane provides signal interconnections
between the slide-in boards installed in the Audio Tower.
These boards include the Audio Matrix Board, the Audio
PA Board(s) and the I/O Board. The Backplane also
furnishes 15 Vdc interconnections from the power supply to
these boards.
In a C3 Maestro console system equipped with multiple
unselect speakers, two (2) Audio PA Boards are required.
Essentially, the Spreader Board's earns its name in a
console system of this type because it expands or "spreads"
volume control wiper connections from the Volume
Controller Box to both Audio PA Boards within the Audio
Tower. Basically, it is a "Y" cable adapter. The Spreader
Board also has an LED ac power indicator and current-
limited auxiliary 15 Vdc connections for external
equipment. The aux. 15 Vdc connections are available at
the removable screw-terminal type terminal block. This
terminal block is located on the rear vertical panel adjacent
to the ac on/off power switch.
Audio PA Board(s)
Primary circuits on the Audio PA Board in the Audio
Tower include two 4-wire 600-ohm balanced line audio
coupling circuits and two audio power amplifier circuits.
The balanced line audio coupling circuits provide audio
interfacing to and from the Console Interface Module
(CIM) within the CEC/IMC. The audio power amplifier
circuits drive the consoles speakers. The board also
contains two relay output circuits and two optically-coupled
digital inputs. From top to bottom, the connectors on the
board's panel provide:
• select and unselect speaker audio outputs (Speaker
A and B respectively; terminal block connector)
• speaker volume control connections from Volume
Controller Box via Spreader Board and associated
cables (DB-9 subminiature connector)
• relay Form-A contact outputs (terminal block
connector)
• Line A balanced line audio input and output
(modular jack)
• Line B balanced line audio input and output
(modular jack)
• digital inputs (terminal block connector; these
inputs not supported)
NOTE
In the dispatch environment, "select" audio is
audio received from the dispatcher's primary or
"selected" entity (group, individual, conventional
channel, etc.) and "unselect" audio is audio
received from all other entities which are currently
programmed into communication modules.