Brooks Firetracker FT128 CIE - OWS Volume Adjustment; Auxiliary Audio Inputs; Table 8 OWS 250 W Amplifier Specifications; Table 9 Connection of the Audio Amplifier 60 W, 120 W and 250 W

Technical / Programming Manual
FT128 Rev 2.2
44
Table 8 OWS 250W amplifier specifications
Function
Rating
Voltage input range
20 – 32 VDC
Fuse rating
15 A (automotive blade fuse)
Low voltage shutdown
19 V (approx.)
Audio input impedance
10 kΩ
Output load
1 Ω
Amplifier Quiescent Current
38
40 mA
Total OWS quiescent current
38
119 mA
Total OWS active current – full load
38
10 A
Table 9 Connection of the Audio Amplifier 60W, 120W and 250W
Designator
Type
No.
Label
Pin
Description
CON1
Screw
terminal
1
24Vdc
+
Power input. 19V - 32V, 2.8A (60W), 5.2A
(120W), 10A (250W)
38
2
-
CON2
Screw
terminal
1
AUDIO
IN
+
Audio input <=1 V
RMS
. Input impedance:
10KΩ.
2
-
3
STDBY
Audio amplifier enable/disable input, logic
5V, <= 5mA. It is to minimize the unit power
consumption.
The amplifier output will be disabled when
the input is high.
CON3
Screw
terminal
1
AUDIO
OUTPUT
+
Audio output to the transformer secondary
side on the main control board. 16V
RMS
to the
associated different transformer.
2
-
5.4.3 OWS Volume Adjustment
All volume adjustments are made on the Audio Amplifier Module via the trimpot VR1 only.
This volume adjustment is given a reference designator, VR1 and named “VOLUME” on all
amplifier boards. This trimpot, VR1, is shown in both Figure 17 page 42 and Figure 19 page
43. Do not use VR2 for adjusting the volume at any time, VR2 is only used for factory
calibration purposes.
The following procedures describe how to adjust the volume.
1. Manually turn on the evacuation tone.
2. Adjust the trimpot clockwise a little at a time to increase the volume on the audio
amplifier.
3. Then test or measure if the required audio level is met.
4. Repeat 1 to 3 as necessary.
5.4.4 Auxiliary Audio inputs
The OWS provides an auxiliary audio input controlled by a supervised auxiliary enable
input. The auxiliary audio input can be connected to a background music source and
enabled via the auxiliary input. The auxiliary inputs are also used to connect the Brooks
remote desktop microphones. When the CIE is in quiescent conditions and the auxiliary
enable input is activated, the auxiliary audio is activated and remote PA announcement or
background music will be broadcasted across the speakers.