Studio Technologies 76D V.2.02 - Manual (Page 38)

Issue 2, June 2009 Model 76D/77 User Guide
Page 38 Studio Technologies, Inc.
for Surround
In most cases the sync signal will be con-
nected to the sync input BNC connector
located on the Model 76D’s back panel. A
configuration setting also allows the signal
connected to the L/R input of surround input
A to serve as an AES3id timing reference.
Whenever a valid sync signal has been
connected to the Model 76D the sync status
LED, located on the unit’s front panel, will
light. The sample rate of the monitor output
channels will reflect the rate of the sync
input and, if a video sync source is utilized,
the configured rate.
If a valid sync signal is not present several
visual indications are provided. On the Mod-
el 76D the sync status LED will flash. On all
connected Model 77 Control Consoles the
4-digit LED display will cease normal opera-
tion, instead alternating between the words
no and sync. When a valid sync signal
is again connected the Model 76D’s sync
status LED will light steadily. On the Model
77 units the word sync will momentarily be
displayed followed by a brief display of the
monitor output sample rate. The sample
rate will display as 32.0, 44.1, 48.0, 88.2,
96.0, 176.4, or 192.0, reflecting the impact
of the sync source rate and the Model 76D’s
configuration.
If during normal operation the sync source
changes from one valid rate to another a
visual indication is provided. On the Model
77 units the new sample rate—
32.0, 44.1,
48.0, 88.2, 96.0, 176.4, or 192.0—will
momentarily be displayed.
Any time a valid sync signal is not connect-
ed to the Model 76D the monitor outputs will
automatically revert to an internally gener-
ated sample rate of 48 kHz with no digital
audio content present. This audio “black”
signal will allow most connected equipment
to continue to function correctly, of course
with no meaningful audio signal present. As
soon as a valid sync signal is again connect-
ed to the Model 76D the monitor outputs will
automatically switch to their correct sample
rate and audio signals will again be present.
Power Down
Great care was taken in the Model 76D’s
design to minimize the chance that clicks,
pops, or other objectionable audio signals
will be present on the monitor outputs. A
power-down circuit supplies the main micro-
controller integrated circuit with an indication
that a power loss is imminent. When this con-
dition is detected the monitor outputs auto-
matically switch to silent audio (audio “black”)
in preparation of a complete loss of signal.
Power-Up Messages and Error
Codes
Upon mains power being applied to the
Model 76D all connected Model 77 units
will go through a power-up sequence. The
sequence starts by each of the individual
LEDs lighting in a “walk-through” sequence.
Then the 4-digit display tests all its LED
segments. Finally, a set of messages provide
details on the specific Model 77 and connect-
ed Model 76D software versions:
1. Displays 77
2. Displays Model 77 software version
3. Displays Model 77 unit address
(A1, A2, A3, or A4)
4. Displays 76d
5. Displays Model 76D main software
version
6. Displays FPGA
7. Displays 76D’s logic device software
version