INPUT MODULE
7
cable clamp and the terminals such that there is no
tension in the cables. Tighten the cable clamp to
provide strain relief.
The 9VDC power cable must be inserted into V+
and V-, however there is more than one way to
install the audio cables.
For balanced audio, there are four wires: two for
the left channel and two for the right channel.
Insert each channel’s pair into the appropriate
terminals: R+ and R- for the right channel and L+
and L- for the left channel. The center connection
of the terminal block is not required. As a
reminder, note that for this configuration there is a
gain of two applied to the audio signal.
Figure 4: Unbalanced audio cable installation is
shown on the left.
For unbalanced audio, where there are wires for
left audio, right audio, and a signal return, place the
right and left audio into R+ and L+ respectively,
and attach the signal return to the center terminal
of the audio terminal block.
Note that it is also possible to install the four wire
configuration as unbalanced audio: install R+ and
L+ the same way as for balanced audio, but insert
the remaining two wires into the center terminal
instead of R- and L-.
Remember to install the metal cable shield using
two screws on the ISV3000 to protect the cables
coming out of the back.
Step 5. Installation Test
To perform this test, a 9VDC 500mA power supply
is needed, as well as a video and audio source
such as a computer with a sound card. For video
and audio output, a monitor and audio amplifier
(with speakers) is sufficient. Note that the
ISV3000 is designed with compensation for 75 to
100 feet of cable attenuation, so the best image will
be seen with an appropriate amount of cable.
There are a few common items to check before
testing:a) Make sure that the monitor and sound
system works with the source computer
first, before the test of the ISV3000.
b) Make sure that source computer
screen-savers do not shut down the
video source before you are ready to
test the system.
c) Make sure that all connections are good
and the LED on the ISV3000 is lit before
proceeding. The LED should be green
when a valid video signal is present.
d) The very best image quality is observed
when the output of the ISV3000 is run
through 100 feet of cable.
e) Make sure that the source level audio
signal is in a reasonable range, not too
low or too high. For very small audio
output signals, the audio amplifier for
the speakers must necessarily amplify
both the signal and any noise in the
system. For very large audio output
signals, distortion and clipping may
occur. Both the source and the audio
amplifier function best when the audio
levels are set to reasonable midrange
values. This is normal for an audio
system regardless of whether an
ISV3000 is used.
f) If unwanted noise is heard on the audio
circuit, consider some of the alternate
ways of wiring the audio output. Also
examine the system for possible
sources of noise and route the audio
signals as far as possible from the noise
sources.
