5080A
Service Manual
68
How to Adjust the Aberrations for the Edge Function
You must adjust the edge aberrations after you repair the edge function.
1. Set the Product into edge mode.
2. Set the Product output to 1 V p-p at 1 MHz.
3. Push .
4. Connect the Product to the oscilloscope.
5. Set the oscilloscope to 1 mV/div vertical scale and 1 ns/div horizontal scale.
6. Set the oscilloscope to show the 90 % point of the edge signal. See
Figure 20. Record this voltage (or set to the center of the display) as it will be
used as a reference for future adjustments.
7. Set the oscilloscope to show the first 10 ns of the edge signal with the rising
edge at the left edge of the oscilloscope display.
R36
R12
R13
R35
T
1st Aberration
2nd Aberration
3rd Aberration
om050f.eps
Figure 20. Edge Aberrations Adjustment
8. Adjust R13 to set the edge signal at the 10 ns point to the reference level.
9. Adjust R12 for a flat edge signal. If necessary, adjust R13 again to keep the
edge signal at the reference level.
10. Adjust R35 so the first overshoot is the same amplitude as the second
aberration.
11. Adjust R36 to center the first two aberrations about the reference level.
12. If necessary, adjust R13 again to keep the edge signal at 10 ns to be at the
reference level.
13. Adjust R36, R35, or R12 again to set the same amplitude of the aberrations
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