Teledyne LeCroy AP033 - Manual (Page 30)

AP033 Active Differential Probe
24 922260-00 Rev A
11. Using the square adjustment tool, adjust the +LF Comp (See Figure 6) to achieve the best square
corner and flat top of the displayed waveform. Note that the added capacitance of the
adjustment tool may change the compensation of the waveform when it is inserted. The correct
adjustment is achieved when the best corner is displayed with the adjustment tool removed
.
Figure 6, ÷10 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 Teledyne LeCroy oscilloscopes with ProBus) or
2 mV/Div when using the ADPPS with an oscilloscope without scale factor correction; 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 feedthrough. Using the adjustment screwdriver
with the flat blade, adjust the DC Atten. Balance (Figure 6) 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
Teledyne 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

s.
17. Return the signal source output frequency to approximately 5 kHz. Set the output amplitude to
approximately 1 Volt.
18. Using the 0.025 in. square adjustment tool, adjust the –LF Comp (Figure 6) to minimize the
amplitude of overshoot during the transition of the displayed waveform. It may not be
possible to completely eliminate the overshoot. As with the +LF Comp adjustment, the added
capacitance of the adjustment tool may change the amplitude of the waveform when it is
inserted into the adjustment. The correct adjustment is achieved when the overshoot is
minimized.