Incorrect Frequency Response - LeCroy AP034 Instruction Manual

B. Incorrect Frequency Response
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2. Set the oscilloscope calibrator to output a 100-mV, 1-kHz
square wave. Using the flex lead set, connect the probe +
input to the calibrator output signal, leave the – input open.
Set the oscilloscope to 50 mV/div and 500 µs/div. Is the
displayed waveform a 100-mV, 1-kHz square wave with the
correct polarity?
3. Repeat step 2 with the – input connected to the calibrator
and the + input left open. In this case, the displayed
waveform should be inverted.
4. Connect both the + input and – input to the calibrator
output. Is the trace approximately a flat line near zero volts?
5. If steps 1 to 4 give the correct results, the problem is likely
a result of the input signal exceeding the differential or
common mode range.
6. Connect both the + input and – input to one of the two input
signals. If the trace is off scale, the input signal is probably
exceeding the common mode range. Repeat with the other
input signal.
7. Is a ProBus Power Supply Overload error message
displayed? If so, remove all other ProBus accessories from
the oscilloscope. Is the message still displayed? If so,
remove the AP034. Is the message still displayed? If so,
the oscilloscope should be returned for service.
8. If, after removing the AP034, the Power Supply Overload
error message is not displayed, the problem may be either
the probe or the oscilloscope. Repeat the test with a
different ProBus accessory. If the message does not return
with a different accessory, the AP034 may be defective and
should be returned for service.
Possible causes are a defective probe or oscilloscope, poor
connections, or poor grounding. Try the following:
1. Verify that the BW limiting of the oscilloscope is off.
ISSUED: January 2000
$3 $FWLYH 3UREH
AP034-OM-E Rev D