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3. Preliminary Display Adjustments (SN 3001A and Below)
28. Set the oscilloscope controls as follows:
Press
@iK]:
Channel 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . on
amplitude scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.6.25 V/div
Press
@iZZQ.
29. Adjust AlA4R7 X POS and AlA5R7 Y POS to either extreme to
position the CRT beam off-screen (to prevent possible damage to
the CRT phosphor). If it is not sealed, adjust
AlA2R5 INT GAIN
fully clockwise.
30. Adjust the spectrum analyzer’s front-panel INTENSITY control for
50V
peak-to-peak (8 divisions) as indicated on the oscilloscope.
See Figure 3-22.
1
8.00
V/div
offset:
45.00 v
10.00 : I dc
125.000
ns
375.000
ns
50.0
ns/dlv
1
f
50.00 v
Figure 3-22. 5OV,, Signal
31. Adjust AlA2R22 HF GAIN and
AIABCIO
for minimum overshoot
on rise and minimum rise and fall times of the pulse waveform.
32. Use the oscilloscope
[ml
markers to measure the risetime,
falltime, and percent overshoot of the pulse waveform. Rise
and falltimes should be less than 50 ns and 90 ns respectively.
Overshoot on
the rise should be less than 5% (approximately 0.4
divisions).
33. Set
the spectrum analyzer’s LINE switch to STANDBY, and center
potentiometers
AlA4R7 X POSN and AlA5R7 Y POSN.
34. Disconnect the oscilloscope channel 1 probe from the spectrum
analyzer. Remove
the Display Adjustment PC board from the
A3A2
slot, and reinstall the
A3A2
Intensity Control Assembly.
Replace the
A3
Section cover and cables.
35. Perform Adjustment Procedure 4, Final Display Adjustment (SN
3001A
and Below).
Adjustments 3-51