Studio Technologies 5132 2012 - Manual (Page 13)

Model 5132 User Guide Issue 4, September 2012
Studio Technologies, Inc. Page 13
Model 5132
Party-Line Interface Module
voltage present on pin 2 of the party-line
intercom interface is at an acceptable
level for the selected operating mode.
When the Model 5132’s internal party-line
power source is enabled the under-volt-
age threshold for pin 2 is 24 volts. This is
four volts less than the normal level of 28
volts DC. The LED will “flash” at a moder-
ate cadence if the voltage on the interface
falls below the acceptable 24 volt value.
This can be caused by a temporary over-
current or short-circuit condition, such as
when interconnecting user devices to the
party-line intercom interface using portable
cabling.
If the Model 5132’s operating mode is
selected for use with an external party-line
system the pin 2 status LED will function in
a slightly different way. It will light whenever
the voltage on pin 2 is greater than approx-
imately 12 volts DC. The LED will not light
if the voltage is less than 12 volts DC and
the 4-wire auto mute function will become
active. When the 4-wire auto mute function
is active both the 4-wire audio inputs and
outputs will mute. The status LED functions
will allow a user to quickly determine if an
active party-line circuit has been connect-
ed as well as maintaining audio integrity.
Fault Condition
If the Model 5132 is providing party-line
power in an under-voltage condition that’s
present for a continuous 1-second period
it will cause a fault condition to be recog-
nized. The pin 2 status LED will indicate
this condition by changing from being con-
tinuously lit to flashing. In addition, the out-
put voltage on the internal party-line power
supply circuit will automatically shut down
to an essentially off condition. A 5-second
“cool-down” period will then take place,
after which the output voltage will again
become active. As soon as the output is
enabled normal output voltage monitoring
will again take place. A continuous
short circuit presented to the party-
line intercom output will result in a
continuous 4-seconds-on, 5-seconds-
off error cycle. It’s important to note that
during the 5-second-off period no voltage
monitoring takes places. Removing the
fault condition will not result in the output
voltage immediately turning on again;
the 5-second shut-down period must first
elapse.
Technical Notes
Maintaining Correct Input
Signal Levels
The Model 5132’s 4-wire audio inputs and
outputs are designed for compatibility with
either SMPTE (5132S) or EBU (5132E)
audio level standards. Applying signals to
these audio inputs at a significantly lower
level than the intended nominal will re-
duce the signal-to-noise ratio (raising the
perceived noise floor) and can prevent the
connected user devices from operating op-
timally. Applying signal levels significantly
higher than nominal will reduce the head-
room and greatly increase the chance of
reaching audio “clipping.” Obviously, these
cautions are not unique to the Model 5132,
but apply to most audio equipment. The
front-panel level meters provide an easy
means of confirming that a Model 5132
is being presented with the correct audio
levels.
For the Model 5132S the nominal 4-wire
input and output signal levels are +4 dBu.
For the Model 5132E the nominal levels
are 0 dBu. For both versions the nominal