Tektronix SC 502, Instruction Manual

Page: 22 / 127

®
®
@
out, the sweep
o pera t e
s in
the s i
n
g l
e
sweep
mode. After the sweep runs once, further
sweeps c
a
n
n o
t be displayed u
n
t i l
the RESET
button
is
pushed.
The
triggering
LEVEL
con­
trol
adjustment
for
s i
n
g
l
e
sweep
operation
must be
m
a d e with the A U
T
O pushbutton in
the out posi
t
i
o
n
.
COUPling Push
buttons.
D
et e
r
m
i n
e
the coupling
of
the
trigger
s
i
g
n
a
l to
the trigger
generator
circuit.
AC Pushbutton In. S
i
g n
a
l
s
are capacitively
coupled
to
the
input of the trigger
generator
circuit.
DC is rejected
and s
i
g n
al
s
below about
50 kHz are
attenuated.
AC
P us h butt
o
n
Out . (DC)
All components
of
a
trigger s i g n
a
l
are coupled
to
the
Input
of the
t
r
i gg e r generator circuit.
LF REJ Pushbutton In. Signals are capacitively
coupled to the
input
ofthetrigger
circuit.
DC
is
reje�ed
and Signals
below
about
5 kHz
are
attenuated.
SOURCE PuSh buttons. Determine the s our
c
e
of
the Signal co u p
l
ed to the input of the trigger
circuit.
CH
1 P
us
h
b utt o
n
In.
A
sample
ofthe
C ha n n
e l 1
signal is coupled
to the
t
r
i
ggering circuit.
CH
2 Pushbutton In. A sample
oft
he Channel 2
s igna l is coupled to the triggering circuit.
LINE.
(Both CH
1
and
CH
2 push b utton s
depressed.)
A sample of
t h
e power
line si g n
a
l
is
coupled to
the triggering circuit.
EXT Pushbutton I n
.
Signals connected
to
the
EXT TRIG connector are coupled to the
triggering circuit.
SLOPE Switch. Selects the rising or falling slope
of the t r i gg
e
r s i gn a l to trigger the sweep.
LEVEL
Control. Selects t h e amplitude point on
the trigger signal at which the sweep is triggered.
GENERAL OPERATING INFORMATION
Gratlcule
The g ra t i cu
l
e of the SC
502 is
internally marked on the
faceplate of the crt to p rov
i
d e accurate, parallax-free
@
MAY 1980
Operating In"ructlons-SC 502
measurements.
The g r a
ti
cu l e
is
marked
with
e
i
g
h
t
vertical
and
ten
horizontal divisions. Each division is 0.25 inch by
0.25 inch.
In a dd i
t
i o
n,
each m
a
j o
r
division is
divided into
five minor divisions. The vertical gain and horizontal
timing are calibrated so that accurate measurements can
be
ma d e from the gratlcule.
Intensity Control
The Intensity of the display on the crt is controlled by
the
INTENSITY control. This control is n o rma ll y
adj
usted
so
the
display is easiiy visible but not overly
bright.
It will
probably require readjustment for different displays or
sweep r
a t
es
.
Be
careful
w
h e
n
only
a spot
is displayed .
A
high-intensity
spot
m
a y
burn
the
crt phosphor
and
cause
p e
r
m
a
n
e
nt damage
to the crt if allowed
to r
e
m
ai
n
too
long.
Display Focus
If a well-defined display cannot be
obtained with
the
FOCUS
con t r o
l
,
even
at
low intenSity
settings,
adjustment
of
the internal astigmatism c o n t r
o
l may be required. This
sh
o
ul d only be done by qualified personnel.
To
check for proper
s
e tt
in
g of the Astig control, slowly
turn the
FOCUS control
through
the optimum
setting
with
a s i g n a l d i spl a y ed on the crt screen. If t h e Astig
control
is
c or r e ct
l
y set, the vertical and
horizontal
portions o f .
the
t
r
a c e
will
come
into
sha
r
p e s
t
focus
at the
same position of
the FOCUS
control.
Trace
Alignment Adjustment
This is an internal adjustment and sh
o
u l d be done only
be
a
pe r s on qualified to do so.
IntenSity Modulation (Applies only if pin 24A of
Interface Connector has been
connected)
Intensity (Z-Axis) modulation can be used to relate a
t h i r d item of e
l
ectr ica l phenomena tothe vertical
(Y-Axis)
a n d the horizontal (X-Axis) coordinates without affecting
the
w
av
es
h ap
e
of t h e
displayed signal. The Z-Axis
modulating signal, applied to pin
24A ot the
rear interface
connector, c h
a
n g es the i n t
en
s it
y of the displayed
waveform
to pr
o v
id
e this
type
of
display.
The voltage
amplitude required for visible trace modulation depends
on the setting
01
the INTENSITY control. About +5 V will
turn on the d i sp l a y to a normal brightness level trom an off
level,
a nd about -5 V will turn the display off from a
normal brightness level. "Gray scale" intensity m
o
d ula
­
tion
can
b e obtained by
applying
s
i g
na
l
s
between
these
levels.
Maximum
safe i n p ut voltage is + or - 1 0 V. Usable
frequency range of
the Z-Axis
c
i
r
c
ui t is
dc to 2
MHz.
2·5