Service manual
IMl035
A
connection
to
system
ground must
be
made
at
both
JlOl-l
and
JlOl-lO.
When
the
frame
is
an
integral
part
of
system
ground,
one
of
three
possible
ground
config-
urations
can
be
used.
1.
When
a good
electrical
ground
connection
cannot
be
made
between
the
monitor
frame and
system
ground,
then
JlOl-l
and
JlOl-lO
is
wired
separately
to
the
system
ground.
2.
When
a good ground
connection
can
be
made
between
the
monitor
frame and
system
ground,
then
JlOl-lO
is
wired
to
the
system
ground and
JlOl-l
is
left
open.
3.
When
the
ground
connection
between
the
monitor
frame and
the
system
ground
is
acceptable
and
it
is
desired
to
omit
the
wire
from
JlOl-lO,
then
add a jumper
wire
to
the
board
to
connect
JlOl-5
and
JlOl-lO
to-
gether.
JlOl-5
is
then
wired
to
the
system
ground.
The
monitor
is
normally
supplied
without
the
jumper
wire
from
JlOl-5
to
JIOl-lO
to
prevent
horizontal
circuit
ground
currents
from
flowing
in
the
video
ground
circuit.
In
cases
of
severe
arc
related
problems,
the
jumper between
JlOI-1
and
JlOl-5
can
be removed and
JlOI-5
or
EllO
can
be
connected
separately
to
the
frame
or
CRT
aquadag
ground.
JIOl-l
or
El02 must
then
be
connected
either
to
the
frame
or
system
ground.
To
isolate
the
frame from
system
ground,
JlOI-1
and
JlOI-IO
should
be
wired
separately
to
system
ground.
Add
another
wire
to
JlOI-l
and
connect
it
and
JlOl-5
to
the
frame (aquadag ground)
through
a
capacitor.
The frame
cannot
be
completely
isolated,
since
an
AC
connection
between
the
signal
ground and frame must
be
maintained
to
assume a
complete
circuit
for
the
CRT
aquadag
capacity.
When
the
video
is
routed
in
by a
long
cabling,
shielded
cable
should
be
used.
To
avoid
a ground
loop,
only
one end
of
the
shield
should
be
grounded.
2.5
INPUT SIGNAL
LEAD
ROUTING
The
input
signal
leads
probably
will
carry
high
frequency
signals
and
should
be
given
the
following
considerations:
A.
To
minimize
distributed
capacity
and
capacitive
pickup
of
nearby
radiated
fields,
route
the
video
leads
separately
and away from
all
other
wiring.
B.
Make
the
lead
length
as
short
as
possible,
consistent
with
the
packaging
requirements.
C.
Ideally,
the
video
line
should
meet
the
requirements
of
a
terminated
coaxial
system;
i.e.,
the
video
line
should
exhibit
a
constant
impedance
from
source
load.
2-3