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TABLE 8 − − SPEAKER CONNECTIONS
AUDIO PA
SPEAKER
BOARD
Select
#1 *
Unselect #1
#1 *
Unselect #2
#2 *
Unselect #3
#2 *
* Audio PA Board #1 is the board in the slot adjacent to the
Audio Matrix Board. Audio PA Board #2 is the board in the
far right-hand slot as viewed from the back of the Audio
Tower.
CAUTION
THE
SPEAKER
CONNECTED TO GROUND. Connecting a
speaker lead to ground will short-circuit the
speaker power amplifier and reduce output power
considerably. Speaker damage may also occur.
These terminals are intentionally not labeled with
polarity to help prevent any of the terminals from
being connected to ground or to another amplifier.
Recorder Outputs (if used)
To provide call-check recorder support, select and
unselect audio outputs are available from the Audio Tower.
These 600-ohm outputs appear at the top terminal block on
the I/O Board. Unselect audio appears on the two terminals
labeled "UNSELECT RECORDER" and select audio
appears
on
the
two
RECORDER". Interconnect the outputs to call-check
recorders as required. These outputs are not isolated from
ground through isolation transformers and the two ground
terminals are common. See the specifications page in LBI-
39062 for audio signal output level specifications.
(TOP)
UNSELECT
AUDIO OUTPUT
UNSELECT
AUDIO GROUND
SELECT AUDIO
OUTPUT
SELECT AUDIO
GROUND
Figure 10 − − I/O Board Recorder Terminal Block
Pin-Out
TERMINAL
SCREW
BLOCK
TER-
LABELING
MINALS
SPKR A
upper two
SPKR B
lower two
SPKR A
upper two
SPKR B
lower two
CAUTION
LEADS
CANNOT
BE
terminals
labeled
"SELECT
UNSELECT
RECORDER
SELECT
RECORDER
Pager Input (if used)
Pager connections are also located on a terminal block
on the I/O Board. A 600-ohm audio input and a PTT (page
enable) input are included. The terminals are labeled
"PAGE INPUT" and "PAGE PTT" respectively.
Pager audio on "PAGE INPUT" is switched in when
"PAGE PTT" becomes active. "PAGE PTT" is active
when its two terminals are shorted together by a relay
contact (or equivalent) in the pager. During a page, no other
audio signals are applied to the Line A output. Also, the
paging signal is sent to the headsets and speakers
approximately 16 dB lower than other audio signal levels.
Connect the pager to the terminal block in accordance
with the manufacturer's instructions. As shown in Figure 11,
the two (2) upper terminals on the terminal block are the
"PAGE INPUT" connections and the two lower terminals
are the "PAGE PTT" connections. These inputs are not
isolated from ground and the ground terminals are common.
See the specifications page in LBI-39062 for audio signal
input level specifications.
PAGER AUDIO
INPUT
PAGER AUDIO
GROUND
PAGER PTT
INPUT
PAGER PTT
GROUND
Figure 11 − − I/O Board Pager Terminal Block Pin-Out
Relay Outputs (if used)
Form-A relay contacts (SPST normally-open) are
available from the Audio Tower for external device control.
All relay contact connections are made at the screw-terminal
type terminal blocks on the I/O Board and Audio PA
Board(s). See Table 9 for details. All relay connections are
isolated from ground.
"RELAY 1" contacts at the I/O Board close when the
console is keyed (PTTed). Audio PA Board #1 "RELAY 1"
contacts toggle open/closed at an <Alt><F9> keystroke from
the Dispatch Keyboard and the RELAY 2 contacts close
(momentarily action) while <Alt><F10> is depressed at the
Dispatch Keyboard. The other relays are not supported by
software.
LBI-39055
(TOP)
PAGE
INPUT
PAGE
PTT
15
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