Display Adjustments; Sweep Alignment And Dial Calibration - HP 3580A Operating And Service Manual

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