CVA-3120
VA-700
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Page 20 of 23
Revision 10
INSTALLATION
VA-700:
The following links should be in place:
LK 2 - LK 3,
LK 4 - LK 5
and the following link should be removed:
LK 6 - LK 7.
CVA-3120:
If a second equaliser sub-module is fitted to the VA-700 as is the case with the VA-700T this may first be unplugged
from its socket taking note of the correct alignment so as to facilitate replacement after the CVA-3120 is fitted. This
step is not essential, but will make insertion of the CVA-3120 easier.
Carefully position the sub board over the VA-700. Ensure that all pins of PL 2 & PL 3 of the VA-700 slide neatly into
the corresponding socket positions of SK 2 & SK 3 of the CVA-3120.
Press down firmly and evenly on the CVA-3120 sub board ensuring that the cut-out in the top left hand corner just
clears the gain potentiometer on the VA-700 as the board slides into place.
If second equaliser sub-board was removed from VA-700, re-insert it carefully ensuring that all pins are correctly
aligned with the socket.
Connect remote wiring to remote connection on rear assembly using the three pin IDC socket provided.
The remote gain control potentiometer should be wired as follows:
Gain adjustment:
Under normal circumstances no adjustments need to be made to the VDA in order to fit the CVA-3120.
Under normal operating conditions using a 1 k
Ω
potentiometer as the control device the normal operating
position for the potentiometer should be at approximately half setting. If it is desired to calibrate this position then
the central position should be set and marked and the front panel gain of the VA-700 adjusted until a 1:1 gain is
achieved through the VDA.
The remote gain control may now be varied and the resultant gain settings marked against the potentiometer
position.
If the CVA-3120 is fitted to the VDA and no external connection is made to the remote gain input control then this
control will default to the minimum attenuation setting and so the output of the VDA will be increased by
approximately 3 dB.
If the CVA-3120 is required to function only as an attenuator then the VDA gain should be adjusted for a 1:1 gain
when the CVA-3120 control input is at 0 Vdc. The CVA-3120 will now give 0 to 6 dB of attenuation from the 1:1
setting.
2
+12 Vdc
3
Control output
1
Gnd
Maximum attenuation
Maximum gain