Lecroy AP034-OM-E-05 User Manual
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CLEANING
!
The exterior of the probe and cable should be cleaned only using
a soft cloth moistened with water or isopropyl alcohol. Abrasive
agents, strong detergents, or other solvents may damage the
probe. Always ensure that the input receptacles are free of debris
before connecting accessories.
CALIBRATION INTERVAL
To guarantee accurate performanc e, you should have the probe
calibrated every 12 months. Avoid exposing the probe to extreme
mechanical shock and excessive bending of the cable because
these may alter the calibration.
SERVICE STRATEGY
The AP034 circuits utilize fine pitch surface m ount devices; it is,
therefore, impractical to attempt repair in the field. Defective
probes must be returned to a LeCr oy service f a cility for diagnos is
and exchange. A defective probe under warranty will be replaced
with a factory refurbished probe. A probe that is not under
warranty can be exchanged for a factory refurbished probe. A
modest fee is charged for this s ervice. The defec tive probe mus t
be returned in order to receive credit for the probe core.
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TROUBLESHOOTING
If the probe is not operating properly, the problem may be the
way in which it is used. Before assuming the probe is defective,
perform the following troubleshooting procedures.
A. Trace Off Scale
This is typically caused by improper offset setting, or by an input
signal that exceeds the probe differential or common mode
range. Perform the following:
1. Remove the input signal from the pr obe, retur n the of f s et to
zero, and Autobalance the probe. Does the trace return to
approximately the center of the graticule? If not, proceed to
step 7.
AP034-OM-E Rev D ISSUED: January 2000 ²
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2. Set the oscilloscope calibrator to output a 100-m V, 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 c alibrator
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 sc ale, the input signal is probably
exceeding the common m ode range. Repeat with the other
input signal.
7. Is a ProBus Power Supply Overload error message
displayed? If so, remove all other ProBus ac cessories fr om
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 m ay be either
the probe or the oscilloscope. Repeat the test with a
different ProBus acces sory. If the mess age does not return
with a different accessory, the AP034 m ay be def ective and
should be returned for service.
B. Incorrect Frequency Response
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.
² ISSUED: January 2000 AP034-OM-E Rev D
C. DC Errors
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2. Connect the probe to another oscilloscope. If the probe
now measures properly, the problem may be in the
oscilloscope.
3. If the probe behaves as if it is ac-coupled at high frequency,
check for an open input connection.
4. Poor frequency or transient response and AC gain errors
may result when one of the two input connections is open.
5. Excessive “ring” and other transient problems can result
from exces sive lead length. To test this, shorten the input
leads to less than 1 cm. If the transient response changes
significantly, the lead parasitics are the cause.
Incorrect DC gain requires recalibration or factory repair. This
can be determined by completing the gain checks in the
Performance Verification Procedure.
1. Extremely high source resistance will result in DC gain
errors. Check the probe accuracy with the oscilloscope
calibrator signal.
2. Verify that the probe is not being overdriven into clipping for
its current gain setting.
3. Exces sive offset can result from large changes in ambient
temperature. Remove the input s ignal from the probe and
repeat the Autobalance cycle. With the Of fset set to zero,
did the trace return to the center of the graticule?
D. Poor Common Mode Rejection
Use the 1-kHz calibrator signal from the oscilloscope to check
common mode rejection. With both the + input and – input
connected to the calibrator signal, a f lat line at zero volts should
be seen on the graticule.
1. Check the probe with the plug-on attenuator installed and
removed. If excessive com mon mode signal appears only
when the attenuator is present, the attenuator m ay need to
be rematched to the probe. Use the proc edure listed in this
section to match the attenuator.
2. If the common mode signal appears when the probe is
connected to the test circuit, but not when it is attached to
AP034-OM-E Rev D ISSUED: January 2000 ²
RETURNING A DEFECTIVE PROBE
The procedure for returning a defec tive probe to be exchanged,
is as follows:
Contact your local LeCroy sales representative to find out where
to return the product. All returned products should be identified
by model and serial number. You should describe the defect or
failure, and provide your name and contact num ber. In the case
of products returned to the factory, a Return Authorization
Number (RAN) should be used. T he RAN can be es tablished by
contacting your nearest LeCroy office, or the New York Customer
Care Center.
Return shipments should be made prepaid. LeCroy cannot
accept COD or Collect Return shipments. We recommend airfreighting. It is important that the RAN be clearly shown on the
outside of the shipping package for prompt redirection to the
appropriate LeCroy department.
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the calibrator, the problem may be caused by large
mismatches in the source impedance. T ry connecting both
inputs to one of the input signals in the test circuit, then the
other. If the comm on mode signal disappears, try probing
lower impedance points within the circuit.
1. Contact your local LeCroy sales or service representative to
obtain a Return Authorization Number.
2. Remove all accessories, including all removable cables,
from the probe.
3. Pack the probe in its case, surrounded by the original
packing material (or equivalent) and box.
4. Label the case with a tag containing:
• The RAN
• Name and address of owner
• Instrument model and serial number
• Description of the failure mode
5. Package the pr obe case in a cardboard shipping box with
adequate padding to avoid damage in transit.
² ISSUED: January 2000 AP034-OM-E Rev D
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