Studio Technologies 5132 2012 - Manual (Page 14)

Issue 4, September 2012 Model 5132 User Guide
Page 14 Studio Technologies, Inc.
Model 5132
Party-Line Interface Module
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 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 milliamperes of DC current. By de-
sign, the internal power supply circuit is
protected so that an overload condition, or
even a complete short circuit, should not
cause damage. Exceeding 180 milliam-
peres for more than one second will cause
the auto shut-down mode to become ac-
tive. A continuous overload condition will
cause the internal power supply 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 internal power supply output to again
operate normally. In extreme cases, such
as where 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 operation will again take place.
Please don’t test the Model 5132’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 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 lights steadily when the internal
power supply’s DC output voltage is within
its normal range. During normal operation
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 milliamperes.
There’s really only one piece of advice
when it comes to understanding how to
use the pin 2 power status LED when the
internal power supply is enabled: if it flash-
es there’s a problem that must be correct-
ed! 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.
Observe the pin 2 status LED and see if
the problem has gone away. If not, review