Adjustment - HP 182C Operating And Service Manual

Model
182C Operation
SECTION
III
OPERATION
3-1.
INTRODUCTION.
3-2.
This section of the
manual
presents
information
on
Che
operation, function and
capabilities
of
(he
instru-
ment
controls.
Information regarding control turn-on
procedures and
front panel
adjustments
is
explained to
assist
the operator
in
properly setting
up and
using the
Model 182C.
3-3.
GENERAL.
3-4.
The Model
182C
is
designed to operate with
plug-in
time
bases,
and
vertical
amplifiers or sampling and time
domain
reflectometers.
These
plug-ins are
accommodated
in
the
lower portion of the instrument.
The
required oper-
ating
power
is
obtained
from
the oscilloscope
mainframe
Time
base
and
vertical amplifier units
must
be locked
together
before being
installed
in
the mainframe.
3-5.
The
vertical
amplifier
is
always
installed in
the
left-
hand
side
and
the time base
on
the right-hand
side
of the
mainframe compartment.
Refer
to
the
plug-in
operating
and service
manuals
for
mating and
installation instruc-
tions.
3-6.
PUSHBUTTON
SWITCHES.
3
7.
Three switches
are
of the two
position
push-push
type.
These
are;
MAGNIFIER. DISPLAY
and
EXT
COUPLING.
The
pushbuttons
for these functions are color
coded
to indicate the function selected.
When
the released
position
is
selected,
the
white
skirt
of the pushbutton
is
exposed. This
corresponds
to the control function
on
the
panel outlined
in
while. For example:
if
MAGNIFIER
is
depressed,
only the
black portion of the
pushbutton
is
visible.
Magnification
is
therefore
XI
0.
When
MAGNI
FIER
is
released,
the white
skirt
of the
pushbutton can be
seen
and magnification
is
XI.
3-8.
FRONT PANEL CONTROLS
AND
CON-
NECTORS.
3-9.
All
operating controls and
front panel adjustments
are identified
and described
in
Figure 3-1
The
information
presented
gives
the operator
a
quick
reference regarding
the operating function of each. Additional information
regarding
some
of these
is
explained
below
in
greater
detail.
3-10.
CALIBRATOR.
3-11.
The
calibrator
has
two
outputs.
10V
and 250
mV
peak-to-peak. negative-going
from
ground, with an am-
plitude
accuracy
of
The
output
is
a
square
wave
at
a
frequency
of
approximately
1
kHz. Risetime
of the
signal
is
less
than
3
microseconds. These outputs
are
useful for checking
vertical
and
horizontal
sensitivity
calibration,
and
divider
probe
calibration.
A
3-way
bind-
ing
post provides
a
convenient ground connection point
and
may
be used with banana
plug,
wire
or spade
lug
connection.
3-12.
SCALE.
3-13. This control
adjusts
the
overall
brightness of the
CRT
graticule.
It
should be adjusted for
good
contrast
between
the
background and
the
graticule.
The
SCALE
control
is
useful
when
using a
hood
to
view
the display
or
when
photographing waveforms. Rotate
the
SCALE
control counterclockwise to
OFF
when
graticule
illumir>-
atlon
is
not
needed.
3-14.
TRACE
ALIGN.
3-15.
This
screwdriver adjustment
is
used to
compensate
for external
magnetic
fields
that
may
affect
alignment
of
the horizontal trace
with
the
graticule
Use
it
to position
the
trace parallel
to the
graticule horizontal
lines.
The
alignment should be
checked when
the instrument
is
moved
to
a
new
location
and adjustment
made
whenever
necessary.
3-16.
FOCUS
AND
ASTIGMATISM.
3-17. These
controls are used to obtain
a display of
uniform
focus. Adjust both
controls
for
the sharpest
display
possible.
3-18.
FIND BEAM.
3-19. Occasionally the
CRT
beam
may
be
driven
off-
screen
by
large
dc
input
levels
or improper
control
settings.
Pressing the
pushbutton
increases intensity
and
reduces
horizontal
and
vertical
amplifier gains
enough
to
always
return a displaced
beam
to
the viewing
area.
This enables
the operator to determine
the action necessary to center
the display.
All
operating controls function while the
FIND
BEAM
control
is
depressed. Obtaining
a
centered
display
may
require adjustment of the deflection
factor,
horizontal
and
vertical position, coupling, trigger
level
or intensity for
example.
If
the controls are properly
set,
the display
will
remain
visible
when FIND
BEAM
is
released.
3-1