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AdJustmant
Procedure
-
494A/4g4Ap
Service
Vot.
.l
Figure
5-3. Adiustment
and
test
point
locations
on Hlgh
Voltage
module.
(3)
Switch POWER
back on.
After
the
instrument
initializes,
activate
2
dB/Dtv
and
switch
Digital
Storage off.
(4)
Adjust
Intensity
Limit
R1027 (Figure
5-2) for a
voltage
reading
of 0.9
V at
Tp402B.
(5)
Switch POWER
off and
re-instail
the
jumper
P4036 on
the High Vottage
board.
Turn
pOWER
on
and
adjust
the
INTENSITy
for
normalviewing.
f. Apply
the
CAL OUT signat
to
the RF tNpUT
and
set
the
Spectrum
Analyzer
controls
as
follows:
FREQ
SPAN/D|V
10
MHz
FREQUENCY
100
MHz
AUTO
RESOLN
On
REF
LEVEL
_2OdBm
MIN
RF
ATTEN
O
dB
VERT|CAL
DTSPLAY
2
dBiDtv
NARROW
VTDEO
FTLTER
On
VIEW
A and
V|EW B
Off
TIME/DIV
AUTO
TRIGGERING
FREE
RUN
g.
Activate
zERo
spAN and
FINE.
s€t
th€
REFER_
ENCE LEVEL
such
that
the trace is
approximately
mid-
screen.
h. Adjust
the Trace Rotation
R1021 (Figure
S-2) so
the
trace is aligned
with
the
graticule
lines.
i.
Activate
VIEW
A
and
VIEW
B
then
us€ the
PEAK/AVERAGE
cursor,
positioned
at
the
top then
bot-
tom of
the
screen,
as a
reference
line
to adjust
Geometry
R1051
(Figure
S-2)
for
the straightest
trace
at
top and
bottom of
the screen.
j.
Change
the REF LEVEL to
position
the
trace
within
the
graticule
area
with
the
Vertical
Display
mode
of
2 dB/DlV. Adjust
INTENSITY
so the trace is
just
visi-
ble.
k. Adiust A
Intensity R1030
(Figure
5-2)
so
the
brightness of
the readout characters is
slightly
higher
than
the trace.
Readout
characters should
be
just
visi-
ble
after
the trace
has
disappeared.
This
ratio
provides
the best setting
for
photograph purposes.
Disconnect
CAL OUT
signal
from the
RF
INPUT.
3.
Adiust
Deflection
Amplifier Gain
and
Frequency
Response
(C4057,
C4061, C5021,
C5104,
R1055,
and
R1066
on
the
Deflection
Amplifiers
board)
O
o
O
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
,r:**
When adjusting
Option 42
instruments,
the
output of
th€ Function
Generator
must
be
connected
to the PEN LIFT connector at
the
rear
of
the
instrument,
rather
than
as
shown
in Figure
5-4. Be
sure
to
ground pin
1 of
the
ACCESSORIES
connector
when
using
the
PEN
LIFT connector in
this
manner.
a.
Connect the test equipment
as shown
in Figure
5-4.
Set the
TIME/DIV
to 1 ms.
b. set the
Function
generator
controls for a
500 Hz
sinewave signal,
with an amplitude of
0 to
+4 V,
as
viewed on
the test
oscilloscope.
Connect
a
jumper
between
pins
'l
and
5
(Ext
Video
Select
and
Ground
respectively) on
the AoCESSoRIES connector. Deac-
tivate
VIEW A and
VIEW B. and
set
TRIGGERING
to
INT.
c. Adiust Vert
Gain, R1066
(Figure
5-2) for a full
screen
display.
d.
Disconnect
the 500
Hz
signal
from
the
MARKERIVIDEO input. Remove
the
jumper
between
pins
1 and
5
of
the
ACCESSORIES
connector.
Reset
Triggerlng
to
FREE
RUN.
e.
Set TIME/OIV to MNL.
Monitor TP2 on
the
Sweep board
(Figure
5-2)
with
a
voltmeter
(Digital
Mul-
timeter). Set the
MANUAL
SCAN
controlfor 0.0 V read-
ing on
the
voltmeter
$P2).
Set the
horizontal POSI-
TION control
to
center
the
CRT
beam
(dot).
f.
Reset
the
MANUAL
SCAN
control for
a
reading
of
+5 V at
TP2.
g.
Adjust Horiz
Gain,
R1055
(Figure
5-2) to
position
the
crt
beam to
the right
graticule
edge
(10th
graticule
line).
h.
Reset the
MANUAL SCAN
control
such
that
crt
beam
(dot)
moves
to the
left edge of
the
graticule
and
check
that the
voltage atTP2 is
now
-5.0
V
*0.2
V.
5-6