Tektronix SC 502, Instruction Manual

Page: 55 / 127

Calibration
Procedure-SC 502
Adju.tment
Procedure
7.
Adjust
Channel 1 " 2
Preamplifier
AHenuator
Balance R 1 35
and R235
(Main
Circuit
Board)
Set
the CH
1 AC-GND-DC switch to GND a
nd the
VO L TSlOIV
s w
itc
h to
0.2.
Position the crt
trace
to the
center
horizontal
gratlcule line u
s
i n
g the CH 1
vertical
POSITION control.
Rotate
the CH
1
VO
L
T5/DI
V
switch to
1 m.
Adjust CH 1
Step
Bal
R1 35 (CH
2
Step
Bal R23S) to bri ng
the crt trace
back to the
c
e
n
t e r horizontal graticule li ne.
Return
the
CH
1
VO L
TS/DIV
switch
to
0.2
and return the crt trace to
the
center horizontal graticule
line
u s i
n
g the vertical
position control, then repeat this step unt i l all i nteraction
is removed.
Change the SC S02 MODE switch to CH 2 and
repeat
the above
step for
channel 2.
8.
Adjust
Channel 1 " 2
Preamplifier Input
Capacitance
C1 05, C1 15, C1 1 9, C205, C215
and
C219
(Mai n
Circuit Board)
Set the CH
2 AG-GN D-DC
switch to
DC, the
VOL TSI
DIV
switch to 10 m and the triggering
SOURCE to
CH
2.
Connect
a
47
pF Input
normalizer to the CH 2 i nput
connector.
Connect a properly terminated
high amplitude
signal from
the pulse
generator through a l OX
attenautor
to the CH 2
i
n
p
u
t
connect,or
via
the 47
pF
input nor­
malizer.
Ad
j
ust the pulse generator tor
a
1 ms
peri od
and
an output
amplitude
of approximately SO
mV
( 1 0
mV X
S
div). Adj ust
the
triggering
LEVEL
control for
a
stable
display.
Adjust
C205 (C105) for
a
flat top.
Remove the
1 0X
attenuator
from the cable. Change the VOL TSIDIV switch
to
.S
and i ncrease the output amplit ude
of the
pulse
generator
to obtai n
agai n a
S major division Signa l .
Adjust
C21 S
(C1 1 S) for a f
l
a t
top
and
C21 9. (C1 1 9)
for a square
front
c o rner
having
2%
peak or
3% peak-to-peak
or
less
of
aberrations on
the
displayed waveform. (C333 is
selected
to
balance
Channel 1 aberrati ons with
Channel 2.)
Change
the
SC
S02
MODE
switch to
CH 1,
along
with
the
applicable CH 1 control s, and repeat the
above
step
for Channel 1 . Disconnect
the pulse
generator
and the
47 pF normalizer.
9.
Adjust
Channel 1 " 2 Preamplifier Gain R180 and
R280
(Main
Circuit
Board)
Set
the CH 1 VOL TSlOIV
switch
to
1 0 m and rotate
the
triggeri ng
LEVEL fully clockwise. Connect
a
SO
mV stan­
dardized amplitude s
i
g n a
l
from the
pulse
generator to the
4- 1 2
CH
1
i nput
connector.
Adj ust CH
1 (CH 2 ) PO SI TI ON
control to
c
e
n
te r
display.
Adjust CH
1
Gai n R1S0
(CH
2 Gain R2S0)
for a
waveform
ampl itude
ot
exactl y S major grati cul e
divisi ons.
Check
that
the remaining
VOL
TS/DIV switch positi ons are
withi n
the tolerance listed in
Table
4-4.
VOLTs/DIV ATTENUATOR CHECK
DI.pI.y
Amplitude Amplitude
VOLTS/DIV Applied
10 In
M.jor
Setting Input
DIvisions
ToI .... nee
1 m V
S mV S S%
2 mV 1 0 mV
S S%
S m V
20 mV
1 0
m
V
SO mV
S
20 mV
. 1
mV
SO mV .2 V
. 1 V
.S V
.2 V
1 V
5
.5 V
2 V
1 V
5V
2 V
1 0
V
S V
20 V
4
1 0 V
SO V
20
V
1 00
V
Change the SC S02 MOD E switch
to
CH
2.
along
with
the a p p l i ca b l e
CH
2 controls. and repeat
the above
step
for channel 2. Disconnect the pulse
generator.
10.
Adjust
Channel 1 " 2
Preamplifier Position
Centering R335 and R394 (F
" I
Circuit Board)
Set
the CH 2 AC-G NO-DC
to AC, the VOL TS/DIV
switch
to 10 m
and the triggeri ng SOURCE to
CH 2.
Connect a 200 m V pulse
with
a 1 ms period from the pulse
generator to the
CH
2
input
connector. Adjust
the trigger­
ing LEVEL
control
for a stable
display.
Rotate the
CH 2
vertical POSITI ON
c
o
n
tr o l
to
each
of its
extremes
and
check that the bottom of the
pulse
display can
be
positioned at least one
major
division above
(when
positioni ng
upward) .
and
that
the top
of the
pulse
can be
positioned at
least one
major diviSion
below.
(when
positioni ng
downward) the graticule horizontal
center
li ne.
Adj ust Vert Pos CH
2 R394 (CH 1
R335) so that the top
and bottom of the
pulse waveform
are
brought
wit hi n an
equal
distance of
the graticule
center
Ii ne at the two
extremes of
the
vertical
POSITION
control.
REV 0 APR 1 980