Model 3580A
ADJUSTMENT
PROCEDURES
Section V
NOTE
Always select a
range
on the multimeter
so
that
a
range
change
is
not necessary for reading
2915 volts. For instance, when using the
-hp-
34740A/34702A Multimeter and 11045A
probe,
put
the 34
702A
on the 10 volt
range,
not
the 1 volt
range.
b. Turn the 3580A
POWER
switch to OFF and remove
the gray metal shield on the rear panel
of
the 3580A.
Remove the plastic shield on the CRT connector to expose
the wiring terminals. Turn the 3580A POWER switch to
ON
(AC). HIGH VOLTAGE LEADS ARE
NOW
EX-
POSED.
c. With the high voltage probe and digital multimeter,
measure the de voltage present at pin 2 (yellow lead)
of
the
CRT connector. Adjust A8Rl (HV ADJ.) for a voltage
reading
of
- 2915 volts ± 3 volts.
If
you calibrated your
own probe
as
described in Step a, adjust the voltage
to
the
appropriate value, ± 1
%.
NOTE
This adjustment affects the Sweep Alignment
and Dial Calibration
(Paragraph
5-63),
as
well
as
the Amplitude Calibration
(Paragraph
5-
74
).
Repeat the Frequency Tests
(Paragraph
5-9)
and Amplitude Tests
(Paragraph
5-18)
of
the
Performance Tests to determine
if
these
addi-
tional adjustments need to
be
made.
d. Turn the 3580APOWER switch
to
OFF and replace
the two CRT shields removed in Step b). Turn the 3580A
POWER
switch back
to
ON
(AC).
5-58.
Display
Adjustments.
5-59. These adjustments set the proper intensity limits,
astigmatism, and trace alignment on the CRT. In many
cases, these display parameters
will
require no adjustments.
5-60. Intensity Limit Adjustment.
a.
Turn the 3580A power switch to OFF. Unplug the
Al3J3
connector. Remove the nylon access screw from the
top
of
the high voltage power supply box. Turn the front
panel INTENSITY control to the
"9
o'clock" position.
Turn the 3580A
POWER
switch back
to
ON
(ac).
WARNING
I
The voltages present inside the high voltage
power supply box
can
cause serious injury.
Never place
an
uninsulated conductive tool or
object inside this box while the instrument
is
turned on.
b. Using
an
insulated non-metalic tuning wand, such
as
-hp- Part No. 8710-0033, adjust Al
lRl
(INTENSITY
UMIT, inside high voltage power supply box)
so
that the
dot on the CRT just disappears.
c. Replace the nylon screw in the high voltage power
supply box.
5-61. Astigmatism Adjustment.
a.
Adjust the front panel focus fully
CCW.
Turn the
front panel INTENSITY adjust
to
about
10
or
11
o'clock
so
that the dot on the CRT
is
bright enough to see, but
does not form a "halo".
b. Adjust A8R2 (ASTIG. ADJ.) for the largest circular
dot.
c. Turn the 3580A
POWER
switch to OFF. Reconnect
the connector to
Al3J3.
Turn the 3580A POWER switch
back to
ON
(ac).
5-62.,
Trace
Alignment Adjustment.
a.
Position the 3580A front panel controls
as
follows:
ADAPTIVE
SWEEP
...........•..
Centered
DISPLAY . . . • . . . .
All
pushbuttons released
AMPLITUDE
MODE
.......
LOG 10 dB/DIV
AMPLITUDE REF LEVEL
.......
NORMAL
dBv/LIN -dBm 600 n
............
dBv/LIN
INPUT SENSITIVITY . . . . . . . . . . . . -30
dB
VERNIER (Amplitude)
............
CAL
(Fully
CW)
FREQUENCY
.................
00.0
Hz
START-CTR
...................
START
RESOLUTION
BANDWIDTH
. . . . . . 300
Hz
DISPLAY SMOOTHING
.............
MIN
FREQ. SPAN/DIV
..............
0.2
KHz
SWEEP
TIME/DIV . . . . . . . . . . . . . 0.1
SEC
SWEEP
MODE
.....................
REP
Option 002: Set dBm 900 Q/LIN -
dBm
600 Q
switch
to
dBm
900 Q; set INPUT
MODE
switch
to
UNBAL.
b. Adjust the front panel ADAPTIVE
SWEEP
for a line
in the middle
of
the display. Adjust the front panel FOCUS
control for the narrowest and sharpest line.
c. Adjust A13R5 (TRACE ALIGN) for a level trace.
If
unable
to
achieve this, switch
Al3Sl
and readjust
Al3R5.
5-63.
Sweep
Alignment
and
Dial
Calibration.
5-64. These adjustments calibrate the front panel FRE-
QUENCY dial plus align the frequency sweep limits. They
should
be
done
if
the Frequency Tests (Paragraph 5-9) or
Sweep Tests (Paragraph 5-13)
of
the Performance Tests
cannot be passed by the instrument. In addition, the
adjustment should be made
if
the high voltage supply
was
previously adjusted.
5-17
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