Studio Technologies 5132 2014 - Manual (Page 15)

Model 5132 User Guide Issue 5, October 2014
Studio Technologies, Inc. Page 15
Model 5132
Party-Line Interface Module
For the Model 5132S the nominal line-level
input and output signal levels are +4 dBu.
For the Model 5132E 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.
To confirm correct party-line intercom
operation at locations away from where the
Model 5132 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 func-
tions. Two 5-segment LED meters display
the audio levels present on pins 2 and 3.
Two “dry” line-level audio outputs are also
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 5132’s internal party-line power
supply circuit is designed to provide up
to 180 mA of DC current. By design, the
internal power supply circuit is protected
so that an overload condition, or even a
complete short circuit, should not cause
damage. Exceeding 180 mA for more than
one second will cause the auto shut-down
mode to become active. A continuous
overload condition will cause the internal
power supply to cycle through a 4-sec-
onds-on, 5-seconds-off sequence. Restor-
ing the output load to be within the rated
180 mA will allow the internal power sup-
ply output to again operate normally. In
extreme cases, such as when the Model
5132 is located in an environment with
elevated temperatures, a few minutes
may be required from the time an overload
condition is removed to when normal op-
eration will again take place. Please don’t
test the Model 5132’s ability to sustain fre-
quent 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 Status LED makes it easy to
know if an excessive load, or a short cir-
cuit, is being placed on the internal power
supply output. Technically the LED, under
software control, provides a direct indica-
tion of the party-line’s DC voltage. And,
when the internal party-line power supply
is active, the output voltage is directly relat-
ed to the amount of current being drawn.
The LED will light steadily when the inter-
nal power supply’s DC output voltage is
within its normal range. During normal op-
eration the DC level on pin 2 of the party-
line XLR connector will be approximately
28 volts. The LED will begin to flash on and
off if the level falls below approximately
24 volts for at least one second. This will
typically occur because the current draw is
greater than nominally 180 mA.
There’s really only one piece of advice
when it comes to understanding how to
use the Pin 2 Status LED when the inter-
nal power supply is enabled: 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
pin 1 (common) and pin 2 (power with
channel one audio) pins. Troubleshoot-
ing should prove quick and easy. Begin by
disconnecting the party-line user devices
while leaving the cabling connected. Ob-
serve the Pin 2 Status LED and see if the