Technical data

Chapter 4: Installation

SP40S Multi-Function Facility Communication System Manual, Revision L

4.4.10 Setting Adjustable Audio BGM Sources

NOTE: Use a good multi-meter that provides true RMS readings in the AC voltage scale and calculates the

results through average sampling. Some multi-meters can select instant or average sampling readings. Always

do this adjustment in the “averaging” mode. Most digital multi-meters use the average sampling method in the

“AC Volts RMS” setting.

1. Ensure that power is disconnected from the SP40S panel.

2. Set the Audio Source volume control to the minimum setting.

3. Connect the Audio Source output to the BGM input terminals (TB5) on the panel.

4. Set the multi-meter to the AC Volts scale, which is capable of reading 300mV RMS.

5. Connect the multi-meter across the BGM terminals on the panel.

6. Adjust the output control of the audio source to obtain a reading of 300mV RMS on the multi-meter.

7. Secure the output control of the audio source so that it cannot be changed inadvertently.

8. Disconnect the multi-meter. The output of the Audio Source is now correctly set for the SP40S BGM

input.