HP 8568B, Performance Tests And Adjustments Manual, Page: 148 / 313

2. High-Voltage Adjustment (SN and Below)
27. On
the
oscilloscope press
28. Connect the oscilloscope channel 1 probe to using a long
probe extension. See Figure 3-7 for the location of
29. Reconnect the ac line cords to each instrument section. Adjust
the front-panel INTENSITY control fully counter-clockwise, and
then set the LINE switch to ON (the INSTR CHECK I LED will
light.)
30. Wait approximately 30 seconds for the dc regulator circuits to
stabilize again.
31. With the front-panel INTENSITY control fully counter clockwise,
adjust INT LIMIT (clockwise) until a spot is just visible
in the lower left corner of the CRT. See Figure 3-8 for the location
of the adjustment.
Note
The INT LIMIT adjustment compensates for the variation
in beam cut-off voltage of different CRTs and indirectly sets the
maximum beam intensity.
INT LIMIT should have enough
range to turn the CRT spot on and off. If the spot is always on,
decrease the value of
If the spot is always off, increase
the value of Refer to Table 3-3 for the acceptable range of
values, and to Table 3-4 for HP part numbers. Refer to Figure 3-8 for
the location of
I N T N T
L I M I T G A I N
I
Figure 3-8. Location of Components
32. Using a non-metallic alignment tool, center the front panel FOCUS
control and adjust ASTIG and FOCUS LIMIT
for a sharp, focused dot on the CRT display.
33. Adjust INT LIMIT until the dot just disappears.
3-34 Adjustments