Instruction manual

9-13
Section 9-7 - Supervised Audio Line Level Module (SALL-15S)
Wheelock, Inc. Part Number: 105497
The Supervised Audio Line Level Module (SALL-15S) provides audio output for the SAFEPATH

system.
The circuit module has a 0.5Vrms, 15 ohm audio NAC circuit, a 24VDC, 2A speaker amplifier power
output, and a 24VDC, 2A strobe NAC Circuit. The circuit module contains a linear amplifier and
supervision circuitry.
The module supervises the strobe NAC circuit field wiring, the speaker amplifier audio field wiring, the
speaker amplifier power NAC circuit field wiring, and the amplifier. The strobe NAC circuit field wiring and
the speaker amplifier power wiring are supervised with a reverse polarity technique, which applies a DC
voltage with one polarity to supervise the wiring and then reverses the polarity to energize the strobe NAC
circuit. The speaker amplifier audio NAC circuit field wiring is supervised with a DC current, which is
removed when audio is being played. Both field-wiring circuits are only supervised in the standby
condition. The amplifier is supervised by monitoring the amplifier output for audio. The state of each of
the four supervision features is indicated via four LEDs on the printed circuit board. See Figure 9-7 on
Page 9-14 for LED locations.
There are three fuses on the printed circuit board, F1 and F2, and F3. Fuse F1 is the fuse for the strobe
NAC circuit. F2 is the fuse for the speaker amplifier power. F3 is the main fuse for the entire board. See
Figure 9-7 on Page 9-14 for fuse locations.
Fuse
Rating
F1 3A
F2 3A
F3 6A
Nominal Specifications:
Rated Output at 1kHz 500m Vrms, 30 ohm load
Input Sensitivity 1Vrms
S/N Ratio -75dB
Frequency Response 275Hz to 4kHz
Input Voltage 24VDC
Supply Current (Idle) at 24VDC 50mA
Supply Current (Full Load) at 24VDC 135mA
Operating Temperature Range 0 to 49 Degrees C (32-120 Degrees F)
Humidity Range 0 to 85%, Non-condensing