Bogen Communications AFDS2
Automatic Failure Detector/Substitutor

The Bogen Model AFDS-2 Automatic Failure Detector and Substitutor provides continuous electronic supervision of the main and standby power amplifiers in a sound system, and substitutes the standby power amplifier should the main power amplifier’s output drop by as little as 2dB.  The changeover is almost instantaneous with virtually no loss of signal, thereby assuring uninterrupted performance.This device is a critical, highly desirable component in systems with a dedicated emergency announcement amplifier.

The device pulses a 40kHz frequency into the inputs of the main and standby power amplifiers and continuously analyzes their output. If the 40kHz level from either amplifier should fall below 2dB*, a fault alert tone will sound, indicating a failure.  Front-panel-mounted LEDs indicate which (main or standby) amplifier has failed. The fault alert tone may be silenced by momentarily pressing the SILENCE button; however, the LED will stay on for the duration of the malfunction and the SILENCE button will automatically reset when the failure is corrected.

The unit operates with 25V or 70V constant-voltage systems, balanced or unbalanced. In a balanced system, two accessory input isolation transformers (TL100) are required. In applications where the preamplifier is located away from the amplifier, the AFDS-2 input can be converted to 600 ohms with an accessory WMT-1A Line- Matching Transformer.

Rear-panel screwdriver-adjustable controls are provided for setting the oscillator level and thedetector levels and sensitivities. All connections are made at screw terminals or phono jacks also located at the rear panel.

The unit operates from a line voltage of 120VAC, 60Hz or from a 12VDC source. It has a standard 19-inch panel 3-1/2 inches high (48.26cm x 8.89cm), making it suitable for either rack mounting or cabinet installation.The front panel is made of #16 gauge cold-rolled steel, finished in black enamel.