Balanced System Applications:
In a balanced 25V or 70V constant voltage system, two accessory input isolation trans-
formers (Model TL
1
00) are required. To install the transformers, remove the cover, plug the transformers into the nine-pin
sockets T
1
and T2 on the PC board and cut the jumpers between terminals 9 and
1
0 and between terminals 22 and 23.
Status Terminal Connection:
Remote identification of failure of the main amplifier and/or standby amplifier can be
obtained by connecting a pair of wires and an annunciator to the Status Terminal.
1
2V DC @ 500mA (maximum) are provid-
ed in the failure mode.
SETUP PROCEDURES
MAIN AMPLIFIER
1
. Connect an AC DVM across the output terminals of the main amplifier on the constant voltage setting being used (25V or 70V).
Note:
Make certain that the AFDS2 is installed with all speaker loads by connecting the amplifier rated load across the Speaker Line
(Hi and Lo) terminals.Turn the Main Amp Detector Sensitivity control, R33, and the Standby Amp Detector Sensitivity control, R2, fully
clockwise. If the DVM reads zero, rotate the 40 kHz Oscillator Level control, R2
1
, clockwise until the Speaker Line switches to the
main power amplifier.
2. Set the audio source and main amplifier volume controls to their normal settings for maximum level of required program
material. Record the settings. Use a tone generator, tuner, tape or phono input as the program input source.
3. Disconnect the audio source input to the AFDS2 and set the Oscillator Level control, R2
1
, so that the DVM reads approx-
imately 2 volts.This control requires no further adjustments.
4. Main Amplifier Detector Sensitivity Adjustment
a.The AFDS2 will annunciate failure and switch in the standby power amplifier for any gain change in the main power ampli-
fier from 2 dB to total failure.To determine this switchover point, observe the DVM reading.The following table shows
this relationship between the DVM reading and this gain change for the switchover.
DVM READING
SUPERVISION GAIN
CHANGE
1
.60V
-2 dB
1
.42V
-3 dB
1
.26V
-4 dB
1
.
1
2V
-5 dB
1
.00V
-6 dB
0.80V
-8 dB
0.62V
-
1
0 dB
