Functional
Section 4
Jaguar Audio
page 4.5
3/98
P/N 81905903730
F UNCTIONAL
4
DESCRIPTI ON
Input
The input circuits on the 64X32 Audio Matrix Card provide the initial condi-
tioning and termination of the audio input signals. The input circuits are
comprised of an operational amplifier and its associated components.
Common mode rejection ratio adjustments in each input circuit provide the
means to eliminate unwanted common mode hum and noise on the input
audio signals. The input circuits also provide the connection of the audio
input signals to the 64X1 crosspoint switch circuits.
Output
The output circuits on the 64X32 Audio Matrix Card are responsible for
providing an electronically balanced output and driving the output lines.
The output circuits are comprised of two dual staged operational amplifi-
ers and their associated components. The first stage of primary opera-
tional amplifier is responsible for conditioning the audio output signal and
the second stage of the primary operational amplifier is responsible for in-
verting the audio output to provide an electronically balanced output. The
secondary operational amplifier is responsible for driving the audio output
lines. The audio output lines are driven through precision 33.2 ohm resis-
tors. An adjustment is provided in each output circuit to adjust the output
for unity gain for either high impedance termination or 600 ohm termina-
tion.
Power
The power regulator circuits on the 32X32 Audio Matrix Card are respon-
sible for producing all of the regulated operational voltages required by the
matrix card's electronic circuits. The heart of the power supply circuit on
the audio matrix card is a switching regulator (U300) which produces the
+20V DC and -20V DC. Adjustment of the output of the switching regula-
tor is provided by R492, a variable resistor. Regulation of the +5V DC sup-
ply is provided by U281. CR2 provides a visual indication that power is
being applied to the input of the regulator circuits. Fuses F1 and F2 pro-
tect the power regulator circuits from overload conditions and protect the
audio matrix card from overload damage. The power circuits also contain
a fan speed regulator circuit which controls the speed of the associated
chassis fans. As the temperature of the hottest matrix card's circuits in-
crease the fan speed will increase. Inversely as the hottest matrix card's
circuits decrease in temperature the fan speed will slow down.
4.5 64X32 Analog Audio Matrix Card Continued: