DESCRIPTION
The Bogen Model AFDS2,Automatic Failure Detector and Substitutor, is an electronic unit which continuously supervises the
operation of the main and standby power amplifiers in a sound system. Should the main amplifier’s output level drop by as
little as 2 dB, the AFDS2 substitutes the standby power amplifier.The changeover is nearly instantaneous with virtually no loss
of signal.
The AFDS2 injects a set level of a supersonic frequency (40 kHz) into the inputs of the main and standby power amplifiers
and continuously samples their outputs. If the 40 kHz level from either amplifier should fall below 2 dB*, a fault alert tone
will sound, indicating a failure. Front panel-mounted LEDs indicate whether the main amplifier or the standby amplifier failed.
The fault alert tone may be silenced by momentarily pressing the Silence button; however, the LED will stay on for the dura-
tion of the malfunction.
The AFDS2 may be used in either 25V or 70V systems. Booster output may be balanced or unbalanced; but, in a balanced sys-
tem, two accessory input isolation transformers (Model TL
1
00) are required.
The AFDS2 input impedance from the audio source is
1
0,000 ohms. In applications where the pre-amplifier is located away
from the amplifier, the AFDS2 input can be converted to 600 ohms with the accessory WMT
1
A Line-Matching Transformer.
Screwdriver-adjustable controls for setting the oscillator level and the detector sensitivities are provided on the rear panel.
The AFDS2 operates from a
1
20V AC/60 Hz or
1
2V DC source. Line power consumption is
1
5W. All connections are made
at screw terminals and RCA connectors on the rear chassis.The unit has a standard
1
9-inch wide panel, is 3
1
/2-inches high
and is suitable for either rack or cabinet installation.
* Threshold is adjustable
PACKAGE CONTENTS
• Automatic Failure Detector & Substitutor unit
• Installation and Use Manual
TECHNICAL SPECIFICATIONS
Supervision Frequency:
40 kHz
Supervision Frequency Level:
5mV to 50mV into 47k ohms
Input Impedance:
1
0k ohms
Detector Input Signal:
2V @ 40 kHz
Detector Supervision Range:
2 dB (min.) to
1
2 db (max.)
Failure Indicators:
LEDs (visual) and tone module (aural)
Controls:
Screwdriver-adjustable controls for oscillator level and detector sensitivity
Remote Annunciation:
Status terminal provides
1
2V DC/500mA in the failure mode
Operating Temperatures:
1
4°F to
1
49°F (-
1
0°C to 65°C)
Power Consumption:
1
20V AC,
1
5W, or
1
2V DC @ 0.5A
Dimensions:
1
9" W x 3
1
/2" H x 7-
1
/2" D
Weight:
8 lb.
Accessories:
Two TL
1
00 transformers for 25V or 70V balanced systems;WMT
1
A Line-Matching Transformer to match
the input from a 600-ohm balanced line
EQUIPMENT CONNECTIONS
AC Power Connections:
The AC line cord has a three-prong plug which should be plugged into a three-wire
grounded
1
20V, 60 Hz outlet.This will automatically ground the chassis.
Auxiliary DC Power Connections:
The unit may be powered from the
1
2V DC supply. The positive lead must be con-
nected to the EXT PWR terminal on the chassis and the negative lead to the GND terminal.
Input Connections:
The input impedance of the AFDS2 is
1
0,000 ohms, accepting any unbalanced input capable of supply-
ing a signal at least
1
0% greater than that needed to drive the power amplifiers (which must have an input impedance of
1
0,000 ohms or greater). Provisions are incorporated for mounting an accessory Model WMT
1
A transformer to match the
input from a 600-ohm balanced line.
System Connections:
Single-conductor, low capacity shielded wire should be used for all input connections. These leads
should be as short as possible. The remaining connections can be made with either double-conductor shielded wire or
#20AWG hookup wire.
Note:
Input cables should be routed separately from output cables.
