Studio Technologies 76D V.2.02 - Manual (Page 12)

Issue 2, June 2009 Model 76D/77 User Guide
Page 12 Studio Technologies, Inc.
for Surround
audio sources. DARS (digital audio refer-
ence source) is a timing signal compliant
with the AES11 standard. It’s sometimes
referred to as “AES3-black.” Technically it
is similar to an AES3 or AES3id signal but
is generated specifically as a timing refer-
ence signal. Bi-level video sync signals are
typically provided to support NTSC or PAL
broadcast applications, although they’re
also used by some later-generation equip-
ment. Tri-level sync signals are primarily
associated with facilities that support high-
definition (HD) video equipment. These
tri-level signals can be found at numerous
rate combinations, configured to allow for
compatibility with the various video for-
mats. With the wide range of allowable
sync sources proper Model 76D operation
should be easy to obtain. Extensive testing
has been done using many different sync
source types and rates. Interested users
can refer to Appendix B of this user guide
for details.
The external sync reference source should
be connected to the sync input BNC con-
nector located on the Model 76D’s back
panel. For flexibility the input can be con-
figured to be high-impedance (“floating”) or
terminated with an impedance of 75 ohms.
A sync source that is dedicated for use by
the Model 76D’s sync input will typically
have input termination enabled. If the sync
signal connected to the Model 76D is be-
ing connected (“multed”) to other inputs it
may be desirable for the termination to be
disabled. A general “rule of thumb” is that
termination should be applied only at the
location of the last physical device using
a sync signal. Refer to the Configuration
section of this guide for details on how to
select the desired termination settings.
Remote Control Inputs
Support is provided for two remote con-
trol input functions: remote mute all and
remote dim. The inputs use logic gates,
“pulled up” to +5 volts DC by way of resis-
tors, which are active whenever they are
brought to their 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) dis-
charge, 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 configured to change
state (“latch”) in response to a logic pulse.
A 9-pin D-subminiature connector is used
for the remote control inputs. Refer to
Figure 5 or Appendix A for the exact con-
nection details. Note that pin 4 (remote
common) connects to the Model 76D’s
internal circuit common connection as
well as the Model 76D’s chassis and
mains earth connections. Figure 5 also
shows two spare remote control inputs
(pins 8 and 9). These are provided for
future applications and should remain
unconnected. This connector also allows
Signal Pin Direction
Data + (RS-485/RS-422) 7 Not used
Data – (RS-485/RS-422) 2 Not used
Data Shield 1 Shield
Remote Mute All 5 Input
Remote Dim 6 Input
Remote Spare 1 8 Input
Remote Spare 2 9 Input
Remote Input Common 4 Common
Note: Connector type on Model 76D is 9-pin D-subminiature
female. Connector uses 4-40 threaded inserts for
locking with mating plug.
Figure 5. Connector Pin Out for Remote Control
Inputs