lecroy AP034-OM-E-07 电路图.pdf

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1、AP034-OM-E Rev DISSUED: January 2000? ? ? INTRODUCTION You can use this procedure to adjust the AP034 Active Differential Probe to meet the warranted specifications. This procedure should only be performed if the instrument fails the Performance Verification tests. If the probe cannot be adjusted to

2、 meet the Performance Verification limits, repair may be necessary. To ensure instrument accuracy, check the calibration of the AP034 Active Differential Probe every year. Before calibration, thoroughly clean and inspect this unit as discussed in the “Cleaning” section. Completion of each step in th

3、e Adjustment Procedure ensures that the differential probe meets specifications. Some of the adjustments interact with other parts of the circuitry. Therefore, it is necessary that all adjustments be performed in the order listed. For best overall instrument performance, make each adjustment to the

4、exact setting, even when adjustment is within the limits stated in the procedure. Adequate guard bands were designed into the AP034 Active Differential Probe to ensure that it will meet or exceed published specifications over the entire operating temperature range. To continue to meet the environmen

5、tal specifications, all adjustments must be performed in a controlled environment with an ambient temperature of 25 5 ? ? ? ? Differential Probe must also be at stable operating temperature before performing adjustments. Caution The adjustment procedure will require removal of the probe covers. Thes

6、e covers are part of the ESD protection system of the AP034 Active Differential Probe. To protect the probe, you should perform the entire procedure on a static dissipating work surface. Wear an antistatic RadioFans.CN 收音机爱 好者资料库 ?ISSUED: January 2000AP034-OM-E Rev D ? grounding wrist strap and foll

7、ow standard static control procedures. The probe tip housing provides physical rigidity to the input pins of the probe. When the covers are removed, observe extra caution to avoid breaking the probe tip receptacles when mating the probe to the calibration fixture. TEST EQUIPMENT REQUIRED The table o

8、n the next page lists the test equipment and accessories, or their equivalents, that are required for complete calibration. Specifications given for the test equipment are the minimum necessary for accurate calibration. All test equipment is assumed to be correctly calibrated and operating within th

9、e specifications listed. Detailed operating instructions for the test equipment are not given in this procedure. Refer to the test equipment manual if more information is needed. If alternate test equipment is substituted, control settings or calibration equipment setups may need to be altered. Alte

10、rnate models of test equipment may have different connector styles requiring adapters not included in the equipment list. RadioFans.CN 收音机爱 好者资料库 AP034-OM-E Rev DISSUED: January 2000? ? TABLE 4. Test Equipment and Accessories DescriptionMinimum SpecificationsTest Equipment Examples Wide Band Oscillo

11、scope * 500 MHz bandwidth 2 mV to 200 mV vertical scale factors ProBus interface equipped* 2% vertical accuracy LeCroy LT342 LeCroy LC344A Digital Multimeter0.1% DC volts accuracy at 0.4 V 0.2% AC volts accuracy at 2 V and 1 kHz 5 digit resolution 0.01 mV AC volts resolution Agilent Technologies 344

12、01A Fluke 8842A-09 Keithley 2001 with test leads Function GeneratorSine and square wave output 20 Vp-p? 50 Hz to 1 MHz frequency range Sync. or Freq. Reference output Agilent Technologies 33120A Stanford Research Model DS340 Leader LAG-120B Fast Rise Pulse Generator Risetime 2 ns ? Over/Undershoot 6

13、% Calibrator signal from LeCroy oscilloscope Tegam / Tektronix PG506 with power unit Sine Wave GeneratorOutput 250 MHz at 1 V rmsAgilent Technologies 8648C, with male N to female BNC adapter for the output connector Tegam SG504 with TM series mainframe. DC Voltage Source0 to 2 VDC regulated output,

14、settable to 1 mV resolution HP 6633A Termination, precision? ?LeCroy TERM-CF01 Termination, BNC? ? ?!?#$?Pomona 4119-50 Calibration FixtureProBus Extension CableLeCroy PROBUS-CF01 Calibration FixtureAP033/AP034 Calibration Fixture LeCroy AP03X-CF01 RadioFans.CN 收音机爱 好者资料库 ?ISSUED: January 2000AP034-

15、OM-E Rev D ? TABLE 4. Test Equipment and Accessories DescriptionMinimum SpecificationsTest Equipment Examples BNC coaxial cable (2 required) male-male BNC, approx. 1 mPomona 5697-36 BNC Tee Adapterfemale-male-femalePomona 3285 Banana Plug Adapter (2 required) BNC female-to-dual male banana plug Pomo

16、na 1269 Shorting PlugTwo 0.025 in. square pins on 0.100 in. centers Supplied with AP03X-CF01 Adjustment Tool0.025 in. square tipJohanson 4192 Low Capacitance Screwdriver * Notes If a LeCroy ProBus equipped oscilloscope is not available, you may perform the adjustment procedure with an alternate osci

17、lloscope that meets the other Minimum Specifications, and the ?%?&?(?)?$?(?(?(?*?(?!? offset or position must remain at center screen, and the high-frequency adjustments must be performed with the ADPPS connected directly to the input of the oscilloscope. PRELIMINARY PROCEDURE 1. Using pliers, caref

18、ully remove each of the push buttons from the ProBus interface housing by gently pulling them away from the housing. 2. Remove the two screws that secure the plastic cover on the cable end of the ProBus interface housing. Gently pull on the probe cable to slide the circuit board assembly from the me

19、tal housing. 3. Remove the 5/64 in. (2 mm) Allen head cap screw from the small cover on the back of the probe tip. Remove the cover along with the small cover on the opposite side of the probe. Hold the shielded portion of the probe head in one hand and AP034-OM-E Rev DISSUED: January 2000? ? gently

20、 slide the larger cover off by pulling it away from the probe tip end. 4. Connect the AP034 Active Differential Probe output to the female end of the ProBus Extension Cable. Be careful to align the ProBus pins with the corresponding connector correctly. Connect the male end of the ProBus Extension C

21、able to Channel 1 of the oscilloscope. Note The Logic board is connected to the Amplifier board by four small 8-pin connectors. There are no additional mechanical fasteners holding the two boards together. A small foam pad mounted on the circuit board ensures that the connectors remain engaged while

22、 the assembly is mounted within the ProBus interface housing. Be sure that the connectors between the boards are firmly engaged before applying power to the probe. Operating the probe without the logic board will not damage it. However, to ensure reliable operation, the logic board should only be ma

23、ted with the Amplifier board with the power removed, and the ProBus connector disengaged. 5. Apply power to the oscilloscope and to the other test instrumentation. Allow at least 30 minutes warm-up time for the AP034 Active Differential Probe and test equipment before continuing the calibration proc

24、edure. Note The probe tip cover also serves to thermally stabilize the input circuitry. The differential input stage of the probe utilizes discrete transistors that need to maintain an approximate match of junction temperatures for correct DC balance. With the covers removed, this circuitry is susce

25、ptible to drift caused by air currents flowing over the ?ISSUED: January 2000AP034-OM-E Rev D ? components. Remove or redirect any fans that may be blowing air currents over the probe tip during adjustment. Note Correct operation of the AP034 Active Differential Probe controls requires software vers

26、ion 8.1.0 or higher. You can find out the software version loaded on your LeCroy scope by pressing SHOW STATUS, then selecting the System menu option. In version 8.1.0 and higher, the OFFSET controls on the front panel of the probe are disabled. Offset is controlled by the OFFSET knob in the oscillo

27、scope CHANNEL section. AP034-OM-E Rev DISSUED: January 2000? ? PROCEDURE A. Adjust Coarse DC Balance (R226) 1. If necessary, set the probe offset to 0.000 V by rotating the OFFSET knob in the CHANNEL section of the oscilloscope. 2. Insert the two-pin shorting plug into the socket on the Logic Board.

28、 Use the two holes closest to the probe cable (Figure 9). Figure 9. 3. To enter the Cal Mode, push either of the two offset buttons that protrude through holes in the Logic Board. 4. Plug the precision 50 +?%?&? the DMM to measure DC volts. 5. Using a low capacitance screwdriver, adjust Coarse DC Ba

29、l (R226) on the Amplifier Board for an output voltage of 0 mV 10 mV (Figure 10). AP033 Logic Board Installation Location for Shorting Strap ?ISSUED: January 2000AP034-OM-E Rev D ? Figure 10. Amplifier Board Adjustment Locations B. Adjust Fine DC Balance (R304) 1. Remove the shorting plug from the Lo

30、gic Board. 2. Reinsert the shorting plug into the two holes near the end of the Logic Board. (Figure 9.) 3. Reenter Cal Mode by pushing either of the two buttons that protrude through holes in the Logic Board. 4. ,?-.?*?$?(? connected to the DMM. 5. Short the output BNC connector by reconnecting the

31、 cable to the SHORT connector on the AP033/AP034 Calibration Fixture. The SHORT connector is the only BNC connector on the AP033/AP034 Calibration Fixture that does not have corresponding input pins for the probe tip. It is located on the end of the board beyond the Common Mode Terminated connector.

32、 6. In Cal Mode, the EFFECTIVE GAIN indicators serve as an adjustment indicator. The EFFECTIVE GAIN indicators are located on the Logic Board (Figure 11). It may be necessary to hold the boards in your hands to see the indicators while making the adjustment. R322C Gain R226 Coarse DC Bal R330 Offset

33、 R304 Fine DC Bal AP034-OM-E Rev DISSUED: January 2000? ? 7. Using a low capacitance screwdriver, adjust Fine DC Balance (R304) until the 10 EFFECTIVE GAIN indicator lights (Figure 11). Figure 11. 11 Effective Gain Indicator 8. Disconnect the BNC cable from the short connector. Remove the shorting p

34、lug from the logic board. C. Adjust Low Frequency CMRR (R7) 1. Leave the BNC cable connected to the probe end of the ProBus extension cable. Connect a 50 +? -.? ? ? Terminator on the other end of the BNC cable. Connect the male end of the 50 +?(? The scope end of the ProBus extension cable should re

35、main connected to channel 1 of the scope, although there is no signal cable connected. 2. Connect a BNC cable from the output of the Function Generator to the Channel 2 input of the oscilloscope. 3. Connect a second BNC cable from the Function Generator SYNC OUT to the external trigger input of the

36、oscilloscope. 4. Set the Function Generator waveform to Sine and the frequency to 70 Hz. AP033 Logic Board 10 Indicator: Adjustment correct Effective Gain Indicators Adjustment too far counter-clockwise Adjustment too far clockwise ?ISSUED: January 2000AP034-OM-E Rev D ? 5. Set the oscilloscope as f

37、ollows: Display:Channel 2 Channel 1 VOLTS/DIV:2 mV/div Channel 2 VOLTS/DIV:5 V/div Channel 2 Coupling:%? Channel 3 VOLTS/DIV:2 mV/div Channel 3 Coupling:AC 1M+ Trigger on:EXT10 cplg EXT10:DC TIME/DIV:10 ms/div Acquisition Mode:NORMAL 6. Adjust the trigger level for a stable display. 7. Set the Funct

38、ion Generator output voltage to 20 Vp-p as displayed on the oscilloscope. 8. Disconnect the output cable of the function generator from the channel 2 input of the oscilloscope and reconnect it to the Common Mode Drive No Termination connector of the AP033/AP034 Calibration Fixture. 9. Carefully alig

39、n the four pins that correspond to the Common Mode Drive No Termination portion of the AP033/AP034 Calibration Fixture with the input receptacles in the AP034 probe head. Press the probe into the fixture to fully engage the pins. 10. Set the oscilloscope to display channel 3. The waveform is the com

40、mon mode signal. Turn the offset as necessary to keep the trace on screen. Turn on Math Channel A. Press MATH SETUP, then REDEFINE A. Set the A Math type to Average, Avg Type to Continuous, with 1:15 weighting, of channel 3. Turn off the trace 3 display. Use the Math Zoom and Position controls as ne

41、cessary to view the waveform. 11. Adjust LF CMRR (R7) for minimum amplitude. (See Figure 12 for location.) AP034-OM-E Rev DISSUED: January 2000? ? Figure 12. Probe Tip Adjustment Locations 12. Remove the BNC cable from the output of the Function Generator and the calibration fixture. Leave the BNC c

42、able from the SYNC output to the oscilloscope external trigger input in place. D. Adjust OFFSET (R330) 1. Reconnect the BNC cable to both ends of the ProBus extension cable. The oscilloscope end of the extension cable should still be connected to channel 1. 2. Set the oscilloscope channel 1 scale fa

43、ctor to 10 mV/div, and the acquisition mode to Auto. Set the BWL to 20 or 25 MHz. Adjust the OFFSET to 0.0 mV 3. Carefully move the AP034 probe tip from the Common Mode Drive No Termination position of the AP033/AP034 Calibration Fixture to the Differential Drive No Termination position. Press the p

44、robe into the fixture to fully engage the pins. 4. Connect female BNC-to-dual male banana plug adapters to each end of the BNC cable. Plug one end into the output of the DC voltage source, making sure the plug corresponding to the BNC shield (marked “Ground”) is connected to the voltage source Outpu

45、t (or common for dual supplies) connector, and the other pin on the +Output connector. C17A Attenuator Comp C18A Attenuator CMRR R7 LF CMRR ?ISSUED: January 2000AP034-OM-E Rev D ? 5. Connect the other end of the cable to the DMM input, making sure that the plug corresponding to the BNC shield (marke

46、d “Ground”) is connected to the LO or COM input. 6. Set the DC Voltage Source to read as close as possible to +1.600 V on the DMM. 7. Autobalance the AP034 by pressing the AUTOBALANCE menu button located in the “COUPLING” menu twice, or by pressing and holding both probe offset buttons for at least

47、two seconds. 8. Disconnect the BNC cable from the female BNC-to-dual male banana plug adapter on the DMM. 9. Reconnect the BNC cable from the DC Voltage Source to the Differential Drive No Termination connector on the AP033/AP034 Calibration Fixture. 10. Set the probe offset to 1.600 V by rotating t

48、he OFFSET knob in the channel section of the oscilloscope. 11. Allow 10 seconds for the AP034 to stabilize. 12. Using a low capacitance screwdriver, adjust Offset (R330) to bring the trace back to exactly center screen. (See Figure 10 for adjustment location.) 13. Remove the dual banana plug adapter from the output of the DC voltage source and reconnect it, with the pins re