Studio Technologies 74 - Manual (Page 13)

Issue 2, January 2006 Model 74/75 User Guide
Page 14 Studio Technologies, Inc.
for Surround
Pin Signal
1 Shield
2 Spare A (to Model 74)
3 Spare B (to Model 74)
5 Remote Mute All (to Model 75)
6 Remote Dim (to Model 75)
7 Remote Talkback (to Model 75)
8 Remote Input Select (to Model 75)
9 Remote Control Common (to Model 75)
Notes: 1) Connector type on Model 74 is 9-pin D-subminiature
female. Installer must provide plug (male). Connector
uses 4-40 threaded inserts for locking with mating plug.
Figure 10. Connector Pin Out for Remote
Control Inputs
for details. Balanced sources should be
wired so that signal high is connected to
+, signal low to –, and shield to the shield
connection. With an unbalanced source,
connect signal high to the + connection,
and shield to both the – and the shield
connections. If connecting to an unbal-
anced source in this manner results in
hum or noise, try connecting signal high to
+, and shield to –; leave the shield connec-
tion unterminated.
Remote Control Inputs
Support is provided for four hard-wired re-
mote control input functions: mute all, dim,
talkback, and remote input select. The in-
puts are “pulled up” to +5 volts DC by way
of resistors and are active when brought to
the logic low state. Inputs of this type are
commonly referred to as GPI inputs. While
the input circuitry is protected from over-
current and static (ESD) discharge, care
should be taken to prevent nasty signals
from reaching them. The inputs are active
only when held in the low state; they can’t
be confi gured to change state (“latch”) in
response to a logic pulse.
A female 9-pin D-subminiature connector,
labeled Remote Control Inputs, is located
on the back panel of the Model 74. It is
used to interface with the four remote
control inputs. Refer to Figure 10 for exact
connection details. Note that pin 1 (shield)
and pin 9 (remote control common) are
electrically identical. In addition to connect-
ing to system common, they connect to the
Model 74’s chassis and mains earth con-
nection. For convenience, the shield of the
interconnecting cable should be connected
to pin 1 (shield), while the return signals of
the remote control sources should connect
to pin 9 (remote control common).
Note that although the remote control
connections are physically made to the
D-sub on the Model 74’s back panel, the
remote control input circuitry is actually
located in the Model 75 Control Console.
Conductors in the cable linking the Model
74 to the Model 75 route the remote con-
trol signals to the actual input circuitry.
Connecting the Model 74 to
the Model 75
A cable with 9-pin D-sub plugs (males) on
each end is used to interconnect the Model
74 Central Controller with the Model 75
Control Console. A cable, approximately
20-feet (6.1-meters) long, is provided with
each system. The connector labeled To/
From Control Console on the back panel
of the Model 74 is used to connect to the
Model 75.
Should a cable of different length be re-
quired, it should be wired in a one-to-one
fashion for all nine pins. Pin 1 serves as
signal common and must be connected
at both ends. A shield connection for the