Astigmatism Adjustment; Auto Dc Balance Routine - Tektronix 2467 Manual

Checks and Adjustments
Astigmatism Adjustment
1. Obtain a display as described in "Initial Setup."
2. Set 20 MHz BW LIMIT on and adjust the CH 1 POSITION control to center
the display on the screen.
3. Select
~
V and position the cursors near the top and bottom of the screen.
4. Set SEC/DIV to 1
µS.
5. Slowly adjust the FOCUS control to its optimum setting (best defined
display of cursor dots).
6. Use a small-bladed screwdriver to adjust the ASTIG control for best defined
display of cursor dots. The waveform and the entire readout should be well
defined.
7. Since the ASTIG and FOCUS adjustments interact, repeat steps 5 and 6
until the best-defined display over the entire graticule area is obtained.
NOTE
Once set, the ASTIG adjustment should be correct for any display. How-
ever, it may be necessary to reset the FOCUS control slightly when the
INTENSITY control setting is changed.
Auto DC Balance Routine
4-2
The oscilloscope can automatically de-balance Channel 1 and Channel 2. This
routine minimizes trace shifts when adjusting the VOL TS/DIV and VOL TS/DIV VAR
controls, and when switching Channel 2 between noninverted and inverted. This de
balance remains valid as long as the instrument is operating within 5°C of the
ambient temperature at which the routine was performed, provided the instrument
had had a 20-minute warm-up period.
To initiate the adjustment, press the upper, input-coupling buttons for both
Channel 1 and Channel 2 at the same time. When the Auto DC Balance cycle is
complete, the instrument will return to normal operation.
2467 Operators