Studio Technologies 5132 2014 - Manual (Page 18)

Issue 5, October 2014 Model 5132 User Guide
Page 18 Studio Technologies, Inc.
Model 5132
Party-Line Interface Module
Operating Modes
The Model 5132 allows its overall operat-
ing mode to be configured. This topic was
discussed in the Operation section of this
guide but additional information is provided
in the following paragraphs.
To allow optimal performance in a vari-
ety of applications the Model 5132 can
function in either of two operating modes.
The difference between the two modes is
somewhat subtle, mainly relating to how
the line-level audio output muting function
responds to the party-line interface’s DC
output current/DC voltage detection func-
tion. It also impacts operation of the auto
null function and the Pin 2 Status LED.
When the Model 5132 has been config-
ured for operating mode 1 the two line-lev-
el audio outputs will remain muted unless
a DC current of 5 mA or greater is actively
being supplied by the party-line interface
(if the module is set to provide party-line
power). Requiring that a party-line device
be connected (as evidenced by DC current
being drawn) will minimize the chance that
undesirable audio signals will be sent to
the connected line-level audio equipment.
These undesirable signals would typi-
cally consist of a portion of the audio input
being “bounced” back through the Model
5132’s unterminated 2-wire-to-4-wire
hybrid circuit. This condition is especially
undesirable for optimal audio performance
with 4-wire matrix intercom systems.
A similar scenario will take place for oper-
ating mode 1 if the Model 5132 has be set
to not supply party-line power. If 18 volts
DC or greater is not present on pin 2 of the
party-line interface the line-level audio out-
puts will remain muted. And in both cases
if the line-level audio outputs are muted the
auto null function can’t be enabled and the
Pin 2 Status LED will not light.
When the Model 5132 has been selected
for operating mode 2 the two line-level au-
dio outputs are always active and the auto
null function can always be enabled. In
operating mode 2 there is no requirement
that a minimum amount of DC current be
drawn from the party-line interface or that
a DC voltage be present on pin 2 of the
party-line interface connector. This mode
is provided for atypical, but legitimate, ap-
plications where devices connected to the
Model 5132’s party-line interface do not
draw DC current or supply DC voltage.
Viewing and Changing the Operating
Mode
A Model 5132’s operating mode can be
viewed and, if desired, changed by way of
a power-up/button-press sequence. With
the Model 5132 in the un-powered state
(no source of 12 volt DC applied), press
and hold the Auto Null pushbutton. Then
apply power while continuing to press
the Auto Null button. The module will go
through its normal power-up sequence and
upon completion light one of two meter
LEDs. If the Model 5132 is configured for
operating mode 1 the CH1 to –18 LED will
light. If the module is configured for operat-
ing mode 2 the CH1 to –12 LED will light.
Refer to Figure 7 for details. From the fac-
tory the Model 5132 is typically configured
for operating mode 1.
If the Auto Null button is released within
a few seconds of the meter LED display-
ing the operating mode no change will be
made and the Model 5132 will begin nor-
mal operation. However, if after the operat-
ing mode is displayed, the Auto Null button
remains pressed for approximately five