OPERATION
Introduction
The
operating inStructions
are
broken into three sections: the
CRT display, the
AUIl>Trac:king'DI
digital functions. and the
Delta measurements. Operation of the CRT display is identical
to
that
of
a
standard
analog oscilloscope. The \"ertical and hori·
zontal controls
are
calibrated to allow analog measurements of
signals
when desired.
Most
measurements.
ho
.....
ever.
are
made
with the digital readout. These
special digital functions give
results that
are
faster, more accurate. and subject to less
operator error than conventional analog oscilloscope measure-
ments.
AC
Power
Connection
r-----
WARNING
The
SC61
must be used with a property
grounded
)..
....
ire
AC system for safe
operation
and
minimum
pickup
of external
interference.
AI\\'ays use an
Isolation transformer
on
any pie<e of equipment
(such as a
TV
receiver
or
radio)
that
is
AC
operated
and does not have an internal isolation transformer.
All
warranties
are
voided
if
the
3rd wire
ground
is
bypassed,
or
if
damage
occurs from making a
connection
to
an
unisolated hot-ground system.
The
SC61
is
~ired
for use
on
a
105-130
VAC,
50
or
60
Hz
AC
line
when shipped from the factory. The
SC6l
may
be convened for
21/).25(1
rAC operation by changing the
"iring
of
the primary
(If
the
pov
..
er
supply transformer. Details
on
converting the (lperat-
ing voltage
are
found
in
the
~laintenance
section
(If
this manual.
II
is important that the
SC61
be connected
to
a properly grounded
AC
outlel. The ground connection insures safe operation
in
the
event of a circuit failure inside the san. or
if
the ground
of
the
SC6l is connected to a lest point that hasa potentially dangerous
voltage.
In
either case. the ground connection insures that the
metal
parts
of
the
SCGI
do
not
become a sourceofa shock hazard.
Extra
care
must be taken when working
on
a device. such as a
TV
receiver or radio. that does not ha\'e an internal isolation
transformer. Such
de\'iCi:$
must
be
connected to
an
isolation
transformer. such
as
the Sencore
PRS7
AC
POW"ERITE' . The
isolation transformer must
be
conn!'<:ted
to the de\'ice bt'ing
tested. not the SOil. The isolation transformer breaks the
circuit path fonned. by the
3-"ire
ground system to allow the
"hot chassis" to float
in
reference to earth ground_
The
ground connection
on
the
SOH
also provides a return path
for
interference when the
unit
is
used
in
electrically noisy
en\'ironments. This is especially important when the
SC61
is
usedclose
to
a high power RF transmitler.
Setting
up
the
waveform,
a
simplified
approach
The fastest way to learn the
SC61
is
to
use the
same
procedure to
set up every wavefonn. The front panel has all controls grouped
by function to allow
you
to move clockwise around the panel
as
you apply the signals. adjust the trigger circuits. and then
adjust
the horizontal sweep circuits. Always
stan
from the
10
same
point when you applya new signal or experience difficulty
in locking thewaveform.
Use
the follo
....
ing
procedures
as
a "checklist"
to
follov.·
as
you
learn to use the
SC61.
Each of these simplified procedures
is
co\'ered
in
detail
in
other sections
of
this manual.
Be
sure to
read all the follo
....
ing
sections to
fuJly
understand the effects
each control has
on
the waveform. Then. use these simplified
instructions (or the ones in the Simplified
SC61
Operating
Instructions located in the pocket
on
the bottom of the
SC611
as
a
reminder
of
the steps needed toobtain a trace.
To
set up any
.....
aveform:
1. Pull I:o..JEXSITY control outward
to
apply po
.....
er
to
the
50;1.
2.
Press
the desired CRT display button to produce a single-
trace. dual·trace.
or
vectordisplay.
3.
Apply thesignaHs) to the vertical inpuUs).
a.
Make
sure
the
I1\"'PliT
COUPLI!'\G
s";tch
is not set to the
"ground" position.
It
should be
in
the "AC" position
for
most
measurements.
b.
set
the VOLTS/DIVISION switch
to
a position that
is
one-
half to one-eighth the amplitude
of
the input signal. NOTE:
Remember
the
VOLTS/DIVISION
switehesare
colibrated to
read
directly
l4'hen
using
the
supplied
1014'
capacil)'
probt's:
il
is
no!
necenar;r
to
muftipl)' times
fen.
.;,.
Adjust
the
four TRIGGER controls to lock thesignal:
a. Set the TRIGGER SOURCE s
....
;tch
to the signal you
.....
ant
to use as your reference: "CH
A"
.....
ill
trigger
on
a sample of
the signal applied to the Channel A input, "CH B"
....
;11
trigger
on a sampleof theChannel Binput
AC
L1:\"E"
will trigger on
a sample
of
the
AC
Line. "EXT" ill trigger
on
the signal
applied to the EXT TRIG
INPUT jack.
b.
Set the TRIGGER MODE switch to the desired posit:on;
"Auto" will be used for most signals. "TV"
is
used for com-
posite \'ideo signals. or
"Norm"
is
used for special triggering
conditions.
c. Set the TRIGGER
POLo\RITY
s";tch
for the desired start-
ing point. The
polarity
is
often unimportant.
When
using the
"TV"
position
of
the TRIGGER
MODE
s,,;!ch.
ho
.....
ever. the
TRIGGER
POLo\RITI' s
.....
itch must be set to the polarity
of
the
s~-nc:
pulses.
d_
Adjust the TRIGGER LEVEL control until the trace
is
properly locked
on
theCRT.
5.
Adjust the TIMEBASE·FREQ
s~'itch
for
the desired
number
of
waveforms across the CRT. Remember to use the
frequency markings
on
the outside ring
as
a guide when the
frequency
of
thesignal is known. Use the position
wit~
a
~arked
frequency that is
lo
.....
er
than the frequency
of
theapphed SIgnal.
6.
Adjust the VERTICAL POSITtoX.
HORIZ
POSITIOX.
FOCUS. and IXTEXSITY controls
as
desired
for
the best wave-
form.
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