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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.
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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.
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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.
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REPLACEMENT PARTS
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6. Mark the outside of the box with the shipping address given
to you by the LeCroy representative; be sure to add the
following:
• ATTN: <RAN assigned by the LeCroy
representative>
• FRAGILE
7. Insure the item for the replacement cost of the probe.
8. Ship the package to the appropriate address.
The probe connection access ories, and other com mon parts c an
be ordered through the regional customer care centers. Ref er to
Figure 7 for LeCroy Part numbers. Defective probes can be
replaced on an exchange basis. The replacement exchange
probe will have been factory repaired, inspected and calibrated to
the same standards as a new product. In order to obtain an
exchange probe, you must return the defective probe. The
returned probe should be sent back to the regional customer
care center without any accessories, manual, or case.
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10
3
2
1
4
5
7
6
9
8
11
12
13
14
Figure 7. Replceable Parts
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Reference LeCroy Part Number Description Rev Qty.
1 529-304-001 Plastic probe tip housing Top A 1
2 377-000-007 LeCroy AP034 Probe Tip Label A 1
3 529-304-003 Plastic probe tip housing End A 1
4 529-304-002 Plastic probe tip housing Bottom A 1
5 555-001-000 #2 Allen Screw, Black A 1
6 554-425-003 Screw, M 2.5x6, self tapping A 4
7 709-3XX-P53 ProBus End Cap A 1
8 70A-P03-303 Termination Box A 1
9 337-000-018 LeCroy Termination Box Label with
cutouts
10 416-090-004 Grey Switch Cap A 4
11 377-000-008 LeCroy Termination Box Rear
Label
12 PK033 Accessory Kit, AP033/34 without
AC Coupler and Attenuator
13 AP03X-FLEX-LEAD Flex Lead B 1
14 AP03X-OFFSET-PIN Offset Pin, package of 10 B --
A1
A1
A1
-- AP034-PROBE-FRU AP034 Probe only Exchange A --
-- AP034-DA10 Plug-On Attenuator, ÷10, AP034 A 1
-- AP034-DA20 Plug-On Attenuator, ÷20, AP034 A 1
-- AP03X-AC-COUPLER Plug-On AC Coupler,
AP033/AP034
-- AP034-OM-E Instruction Manual, AP034, English D 1
AP034-OM-E Rev D ISSUED: January 2000 ²
B1
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MATCHING PROCEDURE FOR ÷10 PLUG-ON EXTERNAL ATTENUATOR
The ÷10 and ÷20 Plug-on attenuators provided as standard
accessories with the AP034 are calibrated to match the specific
probe they are shipped with. Individual probes will have small
variations in parasitic capacitance within the input circuits. To
obtain maximum common mode rejection performance, the
attenuators are calibrated to match a specific probe during the
manufacturing process. In order to preserve the maximum
Common Mode Rejection, do not interchange external
attenuators between probes.
The Plug-on AC coupling adapter is not matched to a specific
probe and, therefore, does not need to be matched when
interchanged.
If the ÷10 or ÷20 Plug-on attenuators becom e accidentally mixed
between probes, you can use the procedure listed below to
restore the compensation m atc h. T his adj ustment does not affect
any of the parameters in the warranted specific ations. Ther efore,
the required test equipment does not need to be calibrated.
Note
The AP033 and AP034 Active Differential Probes have
÷
different input capacitance. The
supplied with model AP033 cannot be properly adjusted
for use with model AP034. Make sure that the attenuator
is marked “AP034” before attempting this procedure.
EQUIPMENT REQUIRED
Test Oscilloscope
The oscilloscope must support ProBus. Otherwise use a nonProBus oscilloscope and ADPPS power supply.
Signal Source
Low frequency square wave: frequency from 50 Hz to 5 kHz,
amplitude from 1 V to 10 V. The output waveform m ust have a
square corner and flat top with minimum overshoot suitable for
adjusting compensation. The generator should have trigger
output, or use a BNC Tee connector and separate BNC cable
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10 Plug-on attenuator
Interconnect Cable
Tools
PROCEDURE
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from the output to provide the trigger signal for the test
oscilloscope.
This is for connecting the output of the signal source to the
probe. A BNC cable and a pair of small alligator clips or “lead
grabber” adapter (Pomona #3788) may be used.
0.025 in. (0.635 mm) Squar e Pins ( 3 r equired) . T he pins f r om the
header supplied in the probe accessory kit are suitable.
Flat bladed screwdriver, 0.040 in. (1 mm) wide
Adjustment Tool: 0.025 in. (0.635 mm) square head
Note
You can fabricate the Adjustment Tool by flattening the
end of a 0.025 in. (0.635 mm) square pin with a file.
Then, using heat from a soldering iron, insert the pin into
a short length of rigid plastic tubing to serve as a handle.
1. Attach the AP034 to the test oscilloscope. If the test
oscilloscope is not equipped with ProBus, use the ADPPS to
provide power for the AP034.
2. Attach the ÷10 or ÷20 Attenuator Adapter to the AP034 probe
tip.
3. Insert 0.025 in. (0.635 mm) square pins into the +, –, and
input connectors of the Plug-on Attenuator.
4. Attach the interconnect cable to the output of the signal
source.
5. Attach the Trigger Out signal from the signal source to the
External Trigger Input of the test oscilloscope. If the signal
source does not have a separate Trigger Out signal, use a
BNC Tee connector in the output. Run one cable to the
External Trigger Input of the test oscilloscope. Connect the
other to the probe inputs.
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6. Using the alligator clips on the end of the interconnect cable,
connect the signal source ground to the square pin on the
Attenuator Adapter’s “–“ input. Attach the signal output to the
square pin on the Attenuator Adapter’s “+” input.
7. Turn on the test oscilloscope. The EFFECTIVE GAIN
indicator for ÷10 or ÷20 should be lit. (NOTE: If the X1
EFFECTIVE GAIN indicator is lit instead of the ÷10 or ÷20
indicator, make sure that the plug-on adapter installed on the
probe tip is the Attenuator, and not the AC Coupler.)
8. Set the test oscilloscope 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;
5 µs/Div; AUTO trigger mode; Trigger source: External. Set
the Bandwidth Limiting to 20–30 MHz and Average the
waveform 1:31 to reduce noise.
9. Turn on the signal source. Set the output frequency to
approximately 5 kHz. Set the output amplitude to
approximately 1 V for matching the ÷10 Attenuator Adapter,
or 2 V for matching the ÷20 Attenuator Adapter.
10. Adjust the test oscilloscope trigger level for a stable trace. If
necessary, use the probe offset to position the waveform to
show the square corner of the test signal. NOTE: Do not use
the oscilloscope offset or position controls to reposition the
trace. Many of the signal generators used for compensation
calibration only have square corners on one of the two edges
of the output waveform. (Rising or falling edge, but not both.)
Be sure to display the correct edge for this step.
11. Using the square adjustment tool, adjust the +LF Comp (See
Figure 8) 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.
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+LF Comp.
Adjust
–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
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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. The correct adjustment is achieved when
the overshoot is minimized with the adjustment tool removed.
# # #
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