3006-dva.ib.doc
Page 5 of 8
26.02.2003
Technical Description
The input circuit of the DVA-3006 consists of an adaptive cable equaliser IC, which automatically adapts to
equalise any cable length from zero metres to lengths that attenuate the signal by 40 dB at 200 MHz. This
corresponds to 300 metres of Belden 8281 cable. When link LK2 is closed equalisation is reduced to 200 metres for
use in noisy environments or when a short input cable is used. A carrier detect and output mute circuit is used to
mute the output when no signal is present. The DVA-3006 is insensitive to the pathological patterns that can be
present in the serial digital video signal.
The DVA-3006 also features an OUTPUT MONITOR point on the front panel. The output monitor is a isolated
copy of the signal present at the rear panel outputs.
The output of the input stage is coupled to cable driver circuits to provide the eight isolated in phase outputs from
the DVA-3006.
The input cable equaliser circuit U1 incorporates a carrier detection circuit to mute the output when no signal is
applied to the unit. The carrier detect signal energises a relay, RL1 via a transistor, Q1, when carrier is present.
The relay contacts are connected to SK10 on the rear panel to give a failure alarm in the form of a make (or break)
to ground on failure as set by a link LK1, on the circuit board.
The dual AC inputs are rectified and then regulated by a switch mode regulator circuit to provide the +5V
operating voltage for the unit.
+5Vdc is fed to pin 32a of the rear Euro-connector via a polyfuse, JP2. The +5V is to provide power for a signal
bypass relay on the optional ZVA-3006RL bypass rear assembly, should one be used. The polyfuse protects the
+5V power rail by going high impedance should pin 32a be shorted to ground. This protects against the accidental
insertion of the DVA-3006 in anything other than its standard rear assembly or the optional ZVA-3006RL rear
assembly.
Installation
Handling:
The DVA-3006 contains static sensitive devices and proper static free handling precautions should be observed.
When individual modules are stored, they should be placed in antistatic bags and proper antistatic procedures
should be followed when inserting and removing cards from these bags.
Power:
Ensure that the voltage selection of the IRT mounting frame used to house the DVA-3006 and the local AC mains
supply voltage match and that the correct rating fuse is installed in the mounting frame power supply.
Earthing:
Chassis earth connection of the equipment mounting frame is via the earth connection on the three pin (IEC) AC
mains supply inlet. This is a safety earth and must be connected.
Installation in frame or chassis:
See details in separate manual for selected frame type.
LK1 is factory set for a contact make to ground on signal failure at SK10 pin 2 on the rear panel, move LK1 from
the normally closed (N/C) to the normally open (N/O) position for a break to ground on signal or power loss.
Link LK2 closed reduces the input equalisation to 200m for use in noisy environments or when short input cable is
used.
The presence of signal is indicated by the ‘SIGNAL PRESENT’ front panel LED (green).
The presence of the in5 Vdc supply is indicated by the front panel LED (green).
It is recommended that unused outputs on the rear panel be terminated with 75 ohm termination plugs.
IRT
Communications
www.irtcommunications.com
