2. High-Voltage Adjustment (SN 3001A and Below)
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.
The
INT LIMIT adjustment compensates for the variation
in beam cut-off voltage of different
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
off, increase
the value of
Refer to
3-3 for the acceptable range of
values, and to
3-4 for HP part numbers. Refer to Figure 3-8 for
the location of
R35 R5
I N T
I NT
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.
34. On the oscilloscope, adjust the channel 1 offset voltage as
necessary
to measure the peak-to-peak CRT cut-off voltage, V,,,
at
See Figure 3-9. This peak-to-peak voltage should be
between 45-75
Note this voltage for use in step 39.
V
3-36 Adjustments
