control buttons are provided on the front panel of the unit for confidence monitoring of the
incoming feed. XLR balanced outputs conform to + 4 dBm output referenced to – 20 dBFS digital
output.
III.
Features and Operation
The AES-402 Digital Audio System is designed to select one of two AES3 compatible feeds and
route it to up to four balanced digital outputs. It also contains a high quality digital to analog
converter providing a balanced left and right output. The unit features a front panel headphone
output and volume control for easy confidence monitoring. The AES-402 can be used as a totally
automatic switcher sensing loss of clock or any error displayed on the front panel to command the
switcher to select the alternate feed. In addition to digital error switching, the unit features a
silence sense circuit for switching upon audio failure conditions. All automatic switching functions
are user defined and can be initialized with a simple DIP switch setting upon installation of the
unit. Command of the switcher can also be performed manually at the front panel or remotely.
Remote control of the unit is accessed through the rear panel 9 pin D connector for simple
momentary closure or through the RS232/485 serial interfaces on the rear panel of the unit. For
simple momentary ground closure to the appropriate pin selects channels and error reset. Status
of channel selected and error flag is also available at this connector. Refer to the connection table
3 for connection information. The interface is compatible with open collector command. The AES-
402 su5 V.D.C. for powering open collector actuators. The AES-402 unit includes power
fail feed through of the selected input to AES output #4. With no power connected to the unit, the
AES-402 will pass the A input signal to the #4 AES output through dry relay contacts. Upon
power application the relays energize and AES #4 output receives its signal from the last selected
input before power was removed. An optional delay is provided to prevent the unit from switching
on momentary interruptions that can occur in external equipment. Through application of a DIP
switch the unit can either switch immediately upon detection of digital errors or wait 5 seconds
and then switch. This delay prevents the unit from switching under transient conditions.
IV.
Initial Operating Set up
Attach input and output connections to the unit using the appropriate connector. Plug the remote
control plug in and tighten the connector screws in place. You may select any or all of the error
flag and/or silence sense switching which will command the switcher to switch to the alternate
path. Refer to
AES-402 DIP Switch Programming Guide of Operation
on page 5 for switch
options. Refer to the factory default section of the table for supplied switch conditions. If the
default conditions are satisfactory for your intended use no further changes need to be made. In
order to change the DIP SW 1, 2 settings remove the front panel by removing 1 - #4-40 Phillips
head screw in of the top cover located in the front center of the cover and 4 - #6-32 front panel
screws. The front panel can now be removed and the DIP switches located which are on the front
panel PC board. Other error flags and the silence sense error are selected by placing the
designated DIP switches to the on position. Once DIP switch positions are selected the unit is
ready to be powered up for operation. When the silence sense error is selected for switching,
there are several configurations possible. It is possible to monitor both left and right channels and
switch upon complete audio loss or to have the silence sensor switch upon loss of left or right
channel individually. This feature was added so that non correlated audio feeds can cause the
silence sensor to switch where one feed may take precedence over another. Selection of L+R,
Left, or Right only audio is done by DIP SW S1 selection.
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