Orban 8182A Operating Manual page 32

Without
applying
power
to
the
line
cord, turn the
power
switch
ON
and check the
position
of the
LINE
VOLTAGE SELECTOR
switch. All
units are shipped with
this
switch
in
the "115 Volt"
position. Adjust the selector switch so that the appropriate
voltage
is
indicated.
(If
OPTIMOD-TV
is
installed within a transmitter,
208/230V
may
be the
only
power
available.)
Check
the
fuse,
and
replace with the following
values
if
necessary:
110/115
VOLT:
1/2
amp SLO-BLO, 3AG-type
(as
supplied);
208/230
VOLT:
1/4
amp
SLO-BLO,
3AG-type.
AC
connection
to the chassis
is
made
through
an
RF
filter
with lEC-standard
mains
connector. This
filter
is
designed
to
meet
the standards
of all
international
electrical safety authorities, and
leaks less
than
0.5mA
to
the
chassis
when
operated from 230V
mains.
A
U.S.
A. -standard "U-ground"
power cord
is
supplied to
connect
to the
IEC
socket.
Users
in
other countries should be able to obtain
a
power
cord compatible with
their country's
standard.
If
you choose
to
cut the
"U-Ground"
plug
from
the cord
and
replace
it
with
a
plug appropriate
to
your standards, refer to Fig.
3-1 below.
Fig. 3-1:
POWER CORD
COMPATIBILITY
Initialization Options:
The
section describes
how
to
change
certain operating
characteristics
of
OPTIMOD-TV
to
suit
your needs.
If
your needs correspond
to
the
"factory-standard"
characteristics,
then no modifications need
to be
made, and you
may
skip to
Reassembly
below.
All modifications
are
made
on
the plug-in circuit cards.
If
the steps
above
regarding
physical inspection
have
been followed, the
cards are
now
readily
accessible.
1)
Output
Preemphasis:
OPTIMOD-TV
is
shipped to provide
a flat
output, requiring
use
of
the preemphasis network
built into
your
aural exciter.
As mentioned
in
Exciters
in
Part 2 (Applications), better
peak
control
is
obtained
if
the exciter's
input transformer,
preemphasis network, and any
filtering
are bypassed, since
OPTIMOD-TV
can
provide these
functions with greatly
improved
peak-control
accuracy.
Note
that
OPTIMOD-TV
is
shipped with
either
75us
or
50us
internal
preemphasis, depending on government requirements
in
the
Region
to
which
it is
shipped
unless ordered otherwise.
Even
if
you
are operating
"flat" at
the output,
the
HF
limiter
is still
operating on the
preemphasis
curve, and a
"flat"
output
is
obtained by
complementary deemphasis
after the processing.
Thus even with
"flat" operation,
this internal
preemphasis and deemphasis must complement
that
used
in
the aural exciter.
Changing
preemphasis
is
non-trivial,
and
requires
changing
the values
of a
substantial
number
of
components.
If
you wish
to
change
preemphasis, please
consult the
factory.
To
restrap
for
preemphasized
output,
move jumpers on Card
//7
according
to
Fig. 3-2.
Card #7
contains
two
active
balanced output
amplifiers
(for stereo);
thus,
two
jumpers must
be
moved.
3-2