Orban 674A - Rear Panel Connections; AC Power Setup

REAR
PANEL
DESCRIPTION
AC
POWER
The
HIGHPASS
FILTER
IN/OUT switch
defeats the highpass
filter action.
The
HIGHPASS
FILTER
TUNING
control adjusts
the corner
frequency of
the
highpass
filter
over two
ranges.
The
RANGE switch determines
whether
the range
is
20-200Hz
or
200-2000Hz.
The
LOWPASS
FILTER
IN/OUT switch
adjusts
the corner
frequency of
the lowpass
filter in
two ranges.
The
RANGE
switch
determines
whether
the range is
2-20kHz
or
200-2000Hz.
The
POWER switch
and green
LED
pilot
lamp
complete
the front
panel.
The
FUSE used
in
the
674A is a
3AG
slo-blo
type:
1/4
amp
for
1
15V
operation
and 1/8
amp
for
230V
operation.
Replace
with
the
same
type
only.
The
INPUT and
OUTPUT connectors
provided
allow
connection
via
barrier
strip
(#5
screw).
In
addition,
a
cover
plate
masks
holes
for
user-installed
XLR-type
connectors
and/or
1/4" phone
plugs.
The
BLOCK
DIAGRAM outlines
the
signal flow
through
the
various
sections
of
each channel
of
the
674A. It
is
reproduced
here:
Please refer to the
Electrical
Installation
section for connection instructions.
The
power
transformer
can be
strapped
for 1 15
volt
or
230
volt 50
or
60Hz
AC
operation.
If the unit
was ordered for
230 volts, a
tag on the power cord
warns of
the modification.
The two primary
windings of
the power
transformer
are connected in
parallel for
115 volt
operation,
and
in
series
for 230
volt operation.
(See the
Schematic
Diagram at
the back of
this manual.)
To strap
the power
transformer for a
different
voltage,
remove the
top cover of
the
674A. Strapping
instructions
are found on
the insulating
fishpaper
around the
power tranformer.
It
is
not necessary to
rearrange the
heavy
insulated wiring;
all
strapping can be
performed
with bare
jumper wire.
Take care
not to
burn the
insulation.
The
power
cord
is
terminated in
a
"U-Ground" plug
to
USA standards.
The green
(or
green/yellow)
wire (which
is connected
to the
long prong) is
connected
directly
to
the
674A
chassis.
If
it becomes
necessary
to lift this
ground
to suppress
ground
loops,
this should
be
done
with
a
three-prong
to two-prong
adapter
plug,
rather
than
by
damaging
the power plug.
It is not
recommended
that this
ground be
defeated
unless
absolutely
necessary
because
it eliminates
the
intrinsic safety
feature of
the
three-wire
system.
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