Installation manual

SAFEPATH Manual Sheet 70 of 78
Rev. C April 1999
Self Amplified Speaker Control/Signal Circuit Module, (SACM-4)
The self amplified speaker control/signal circuit module, (SACM-4) provides audio output for the SAFEPATH system. The circuit
module has a -5 dBm, 15 ohm audio output, a 24VDC, 2A speaker amplifier power output, and a 24VDC, 2A strobe output. The
circuit module contains a linear amplifier and supervision circuitry.
The circuit module supervises the strobe field wiring, the speaker amplifier audio field wiring, the speaker amplifier power field
wiring, and the amplifier. The strobe 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
strobes. The speaker amplifier audio 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 state. The amplifier is supervised by monitoring the amplifier output for
audio. The state of each of the four supervision features is indicated via four indicators on the printed circuit board. See Figure 35
for indicator locations.
There are three fuses on the printed circuit board, F1 and F2, and F3. Fuse F1 is the fuse for the strobe power. F2 is the fuse for
the speaker amplifier power. F3 is the main fuse for the entire board. See Figure 35 for fuse locations.
Fuse
Rating
F1 3A
F2 3A
F3 6A
Nominal Specifications:
Rated Output @ 1kHz 500m Vrms, 15 ohm load
Input Sensitivity 1Vrms
S/N Ratio -75dB
Frequency Response 275Hz to 4kHz
Input Voltage 24VDC
Supply Current (Idle) @ 24VDC 50mA
Supply Current (Full Load) @ 24VDC 135mA
Operating Temperature Range 0 to 49 Degrees C (32-120 Degrees F)
Humidity Range 0 to 85%, Non-condensing