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7
Voltage Selector
A mains voltage selector switch is located beneath the top cover of the
unit, adjacent to the AC mains connector on the circuit board.
With
primary AC power disconnected,
slide the red actuator with a small
screwdriver so that the proper mains voltage (115 or 230) is visible.
You must always install an appropriate fuse, and should mark the rear-
panel voltage/fuse designation. It is factory practice to cross-out the
inappropriate
marking with an indelible black marking pen. You can
remove this strikethrough with solvent to redesignate.
BE SURE
that the mains voltage selector setting and pri-
mary fuse value are appropriate for the mains supply before
plugging the
DAVID-II
into the wall outlet.
Power Cord
The detachable power cord supplied with the
DAVID-II
is fitted with a
North-American-standard male plug. The individual cord conductors
are
supposed
to be color-coded in accordance with CEE standards:
BROWN = AC “HOT” BLUE = AC NEUTRAL GRN/YEL = GROUND
If this turns out
not
to be the case, we offer our apologies (cord vendors
vary) and advise that U.S. color coding applies:
BLACK = AC “HOT” WHITE = AC NEUTRAL GREEN = GROUND
RADIO FREQUENCY INTERFERENCE ( R F I )
Location
Although we have anticipated that the
DAVID-II
may be operated
adjacent to high-power transmitters, you should exercise care in
locating the unit away from
abnormally
high RF fields.
Ground Loops
In some installations a mains frequency or RF ground loop may be
formed between the input or output cable shield grounds and the AC
power cord ground. Use of a “ground-lifting” AC adapter should
remedy the situation, though the chassis ultimately must be returned
to earth ground for safety. Generally, being screwed-down in the
equipment rack will satisfy this requirement.
LINE INPUT AND INPUT RANGE SELECTION
Input
Connections
The
DAVID-II
has electronically-balanced (transformerless) left and
right channel
PROGRAM LINE INPUTS.
These are brought out to a
screw-terminal barrier strip on the rear panel and include chassis
ground connections for cable shields.
Please note that the screw-
terminal barrier block can be unplugged from the chassis!
This makes
connection a bit easier and permits quicker removal of the
DAVID-II
from the rack should maintenance ever be required.
Balanced Inputs
A balanced program audio feed to the
DAVID-II
will use both the
+
and the
–
terminals, plus the associated
G
, for each of the two stereo
channels. Since these are “bridging” (high impedance) inputs, they
