Studio Technologies 5130 2013 - Manual (Page 13)

Model 5130 User Guide Issue 5, July 2013
Studio Technologies, Inc. Page 13
Model 5130
Party-Line Interface Module
reaching audio “clipping.” Obviously, these
cautions are not unique to the Model 5130,
but apply to most audio equipment. The
front-panel level meters provide an easy
means of confirming that a Model 5130
is being presented with the correct audio
levels.
For the Model 5130S the nominal 4-wire
input and output signal levels are +4 dBu.
For the Model 5130E the nominal levels are
0 dBu. For both versions the nominal output
level to the two channels associated with the
party-line interface is –10 dBu. (Of course
pin 2 on the party-line interface connector
has both DC and audio present on it.)
To confirm correct party-line intercom
operation at locations away from where the
Model 5130 is installed, it’s possible to use
the Model 72 Level Meter/Interface, also
available from Studio Technologies. The
Model 72 is a compact, portable device that
plugs directly into a party-line intercom or
IFB circuit and provides two useful functions.
Two 5-segment LED meters display the au-
dio levels present on pins 2 and 3. And two
“dry” line-level audio outputs are provided,
one for each channel. Complete information
on the Model 72 is available on the Studio
Technologies website.
Party-Line Interface Current
Draw
The Model 5130’s party-line output is de-
signed to provide up to 180 milliamperes
of DC current. By design, the power sup-
ply circuit is protected so that an overload
condition, or even a complete short circuit,
should not cause damage. Exceeding 180
milliamperes for more than one second will
cause the auto shut-down mode to become
active. A continuous overload condition will
cause the output voltage to cycle through a
4-seconds-on, 5-seconds-off sequence.
Restoring the output load to be within the
rated 180 milliamperes will allow the party-
line output to again operate normally. In
extreme cases, such as where the Model
5130 is located in an environment with
elevated temperatures, a few minutes may
be required from the time an overload con-
dition is removed to when normal opera-
tion will again take place. Please don’t test
the Model 5130’s ability to sustain frequent
overload or short-circuit conditions! The
long-term reliability of the unit can be
impacted by the stresses caused by these
fault conditions.
The pin 2 power LED makes it simple
to know if an excessive load, or a short
circuit, is being placed on the party-line
output. Technically the LED, under soft-
ware control, provides a direct indication
of the party-line’s DC output voltage. And
the output voltage is directly related to the
amount of current being drawn.
The LED lights steadily when the party-
line DC output voltage is within its normal
range. During normal operation the DC
level on pin 2 of the party-line XLR output
connector will be approximately 28 volts.
The LED will begin to flash on and off if the
level falls below approximately 24 volts DC
for at least one second. This will typically
occur because the current draw is greater
than nominally 180 milliamperes.
There’s really only one piece of advice
when it comes to understanding how
to use the pin 2 power LED: if it flashes
there’s a problem that must be corrected!
The most likely cause will be too many
user devices being connected to the party-
line output connector. It’s also possible that
a wiring problem could cause a partial or
full short circuit between the output XLR’s