LeCroy AP034 Instruction Manual page 37

AP034-OM-E Rev D
+LF Comp.
Adjust
DC Atten.
Balance
Figure 8. Attenuator Adjustment Locations
12. Move the connections on the interconnect cable so the signal
generator ground is connected to the square pin inserted in
the ground connector of the Attenuator Adapter. Connect the
signal generator output to BOTH the + input and – input
square pins in the Attenuator Adapter.
13. Set the signal generator frequency to about 50 Hz, and the
output amplitude to about 10 V.
14. Set the test oscilloscope Volts/Div to 20 mV (for LeCroy
oscilloscopes with ProBus) or 2 mV/Div when using the
ADPPS with an oscilloscope without scale factor correction;
and set the time scale to 2 ms/Div. It may be necessary to
increase the averaging to 1:127 to remove noise.
15. The displayed waveform is the common mode response.
Using the adjustment screwdriver with the flat blade, adjust
the DC Atten. Balance (Figure 8) to minimize the amplitude
of the flat portions of the displayed waveform. This
adjustment only affects the flat portions of the square wave.
Do not be concerned with any overshoot at the transitions.
16. Reduce the Test Oscilloscope Averaging weighting to 1:31.
Return the Volts/Div to 200 mV (for LeCroy oscilloscopes
with ProBus) or 20 mV/Div when using the ADPPS with an
oscilloscope without scale factor correction, and the Time/Div
to 5 µs.
17. Return the signal source output frequency to approximately
5 kHz. Set the output amplitude to approximately 1 V for the
÷10 Attenuator Adapter, 2 V for the ÷20 Attenuator Adapter.
18. Using the 0.025 in. square adjustment tool, adjust the –LF
Comp (Figure 8) to minimize the amplitude of overshoot
ISSUED: January 2000
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–LF Comp.
Adjust
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