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1. 11 Operating Tips 2e RO ne ns aren ee os 12 Initial Starting Procedure 12 Single Trace Display 0000 12 Dual Trace Display 0 2 0 2 ee eee ee 12 WP RCMNG shu ide FS Geet oe ade ca eS 13 Magnified Sweep Operation 15 X Y Op ra oneee Ee EEA E cee ED ure 15 Video Signal Observation 15 Page OPERATING INSTRUCTIONS Continued Digital Storage Operation 15 Applications Guidebook 17 MAINTENANCE oso uuu a Sa hers eels 18 Fuse Replacement 00 000005 18 Line Voltage Selection 0000 18 Periodic Adjustments sast iiris esea genio 18 Calibration Check sss boe te eee 19 Instrument Repair Service 19 APPENDIX Ix nne rEg sera CES quee EET 20 Important Considerations for Rise Time and Fall Time Measurements sse suus 20 APPENDIX IL oet ayau pedit ubenUS Pen 21 Unique Characteristics of Digital Storage Oscilloscopes oe yupa baa a y ws US 21 Alasmpe vex Sewn eee ee des ed 21 Equivalent Time Sampling 21 Service Information u L yu y T tuw elles 22 Limited Warranty c socecceecre Re bene A 23 Guidebook To Oscilloscopes Availability 0000 inside back cover FEATURES LOW COST HIGH PERFORMANCE B K Precision s Model 2522B is one of the lowest cost digital storage oscilloscopes in the industry2. Use an insulated floor material or a large insulated floor mat to stand on and an insulated work surface on which to place equipment make certain such surfaces are not damp or wet Use the time proven one hand in the pocket technique while handling an instrument probe Be particularly careful to avoid contacting a nearby metal object that could provide a good ground return path When using a probe touch only the insulated portion Never touch the exposed tip portion When testing ac powered equipment remember that ac line voltage is usually present on some power input circuits such as the on off switch fuses power transformer etc any time the equipment is connected to an ac outlet even if the equipment is turned off Some equipment with a two wire ac power cord including some with polarized power plugs is the hot chassis type This includes most recent television receivers and audio equipment A plastic or wooden cabinet insulates the chassis to protect the customer When the cabinet is removed for servicing a serious shock hazard exists if the chassis is touched Not only does this present a dangerous shock hazard but damage to test instruments or the equipment under test may result from connecting the ground lead of most test instruments including this oscilloscope to a hot chassis To make measurements in hot chassis equipment always connect an isolation transformer between the ac outlet and the equipment under tes
3. position the vertical attenuator is calibrated Coun terclockwise rotation decreases gain sensitivity In X Y operation this control becomes the vernier X axis sensitivity control PULL X5 MAG When pulled out increases vertical sensitivity by a factor of five Effectively provides two extra sensi tivity settings 2 mV div and 1 mV div In X Y mode increases X sensitivity by a factor of five CH1 POSition PULL CHOP Control POSition Adjusts vertical position of channel trace 14 15 16 PULL CHOP When this switch is pulled out in the dual trace mode the channel 1 and channel 2 sweeps are chopped and displayed simultaneously normally used at slower sweep speeds When it is pushed in the two sweeps are alternately displayed one after the other normally used at higher sweep speeds CH2 POSition PULL INVert Control POSition Adjusts vertical position of channel 2 trace In X Y operation rotation adjusts vertical position of X Y display PULL INVert When pushed in the polarity of the channel 2 signal is normal When pulled out the polarity of the channel 2 signal is reversed thus inverting the waveform CH2 VOLTS DIV Control Vertical attenuator for channel 2 Provides step adjustment of vertical sensi tivity When channel 2 VARiable control is set to CAL vertical sensitivity is calibrated in 10 steps from 5 mV div to 5 V div in a 1 2 5 sequence When the X Y mode of operation is selected
4. to 50 C 10 80 relative humidity Storage 30 to 70 C 10 90 relative humidity ACCESSORIES SUPPLIED Two Switchable X1 X10 Probes Instruction Manual AC Line Cord CONTROLS AND INDICATORS BK MODEL 25228 Gr 4 F vA 39 VOLT DIV Fig 1 Model 2522B Controls and Indicators GENERAL FUNCTION CONTROLS 1 ON Indicator Lights when oscilloscope is on 2 POWER Pushbutton Turns oscilloscope on and off INTENSITY Control Adjusts brightness of trace TRACE ROTATION Control Adjusts to maintain trace at a horizontal position FOCUS Control Adjusts trace focus 6 GND Terminal Oscilloscope chassis ground jack and earth ground via three wire ac power cord 7 CAL Terminal Terminal provides 0 5 V p p 1 kHz nominal square wave signal This signal is useful for checking probe compensation adjustment as well as providing a rough check of vertical calibration VERTICAL CONTROLS 8 VERTical MODE Switch Selects vertical display mode Four position lever switch with the following positions CHI Displays the channel 1 signal by itself CH2 X Y CH2 displays the channel 2 signal by itself X Y used in conjunction with the X Y control and Trigger SOURCE switch to enable X Y display mode DUAL Displays the channel 1 and channel 2 signals simul taneously Dual trace mode may be either alternate or chopped sweep see the description under CHan nel 1 P
5. PULL X10 knob to magnify the display ten times For this type of display the sweep time is the Time Base TIME DIV control setting divided by 10 Rotation of the lt gt pOSition control can then be used to select the desired portion of the waveforms X Y OPERATION X Y operation permits the oscilloscope to perform many measurements not possible with conventional sweep opera tion The CRT display becomes an electronic graph of two instantaneous voltages The display may be a direct com parison of the two voltages such as stereoscope display of stereo signal outputs However the X Y mode can be used to graph almost any dynamic characteristic if a transducer is used to change the characteristic frequency temperature velocity etc into a voltage One common application is fre quency response measurements where the Y axis corresponds to signal amplitude and the X axis corresponds to frequency 1 Depress the X Y switch and set the Trigger Source and VERTical MODE switches to X Y 2 In this mode channel becomes the X axis input and channel 2 becomes the Y axis input The X and Y positions are now adjusted using the lt gt position and the channel 2 Y POSition controls respectively 3 Adjust the amount of vertical Y axis deflection with the CH 2 VOLTS DIV and VARIABLE controls 4 Adjust the amount of horizontal X axis deflection with the CH 1 VOLTS DIV and VARIABLE con trols VIDEO SIGNAL OBSERVATION Setting the C
6. Rotation of control is ver nier adjustment for sweep rate In fully clockwise CAL position sweep rate is calibrated 21 gt POSition PULL X10 MAG Control lt gt position Horizontal X position control PULL X10 MAG Selects ten times sweep magnification when pulled out normal when pushed in Increases maximum sweep rate to 10 nS div 22 X YSwitch Used with the VERTical MODE switch and Trigger SOURCE switch to select X Y operating mode The channel 1 input becomes the X axis and the channel 2 input becomes the Y axis Trigger source and coupling are disabled in this mode TRIGGERING CONTROLS 23 HOLDOFF PULL NORM TRIG Control HOLDOFF Rotation adjusts holdoff time trigger inhibit period beyond sweep duration When control is rotated fully counterclockwise the holdoff period is MIN inum normal The holdoff period increases pro gressively with clockwise rotation 24 25 26 CONTROLS AND INDICATORS PULL NORM TRIG When pushed in selects AUTOmatic triggering mode In this mode the oscilloscope generates sweep free runs in absence of an adequate trigger itautomatically reverts to triggered sweep operation when an adequate trigger signal is present On the Model 2522B automatic triggering is applicable to both the main sweep and delayed sweep When pulled out selects NORMal triggered sweep operation A sweep is generated only when an ade quate trigger signal is present Trigger SOURCE Sw
7. Selectable normal triggered or automatic sweep modes Triggered Sweep Sweep remains at rest unless adequate trigger signal is applied Fully adjustable trigger level and or slope AUTO Sweep Selectable AUTO sweep provides sweep without trig ger input automatically reverts to triggered sweep operation when adequate trigger is applied Five Trigger Sources Five trigger source selections including CH 1 CH 2 alternate EXT and LINE Video Sync Frame TV V or Line TV H triggering selectable for observing composite video waveforms TV H position can also be used as low frequency reject and TV V position can be used as high frequency reject Variable Holdoff Trigger inhibit period after end of sweep adjustable Permits stable observation of complex pulse trains OTHER FEATURES X Y Operation Channel 1 can be applied as horizontal deflection X axis while channel 2 provides vertical deflection Y axis Built in Probe Adjust Square Wave A 0 5 V p p 1 KHz square wave generator permits probe compensation adjustment Channel 2 Y Output A buffered 50Q output of the channel 2 signal is available at the rear panel for driving a frequency counter or other instruments The output is 50 mV div nominal into 509 Supplied With Two Probes SPECIFICATIONS CRT Type 6 inch rectangular with integral graticule P31 phosphor Display Area 8 x 10 div 1 div 1 cm Accelerating Voltage 2 kV Phospho
8. pre paid shipping The flat rate repair charge includes return shipping to locations in North America For overnight shipments and non North America shipping fees contact B K Precision Corp IMPORTANT Include with the instrument your complete return shipping address contact name phone number and description of problem Service Department B K Precision Corp 1031 Segovia Circle Placentia CA 92870 Phone 714 237 9220 Fax 714 237 9214 E mail service bkprecision com 22 LIMITED WARRANTY B K Precision Corp warrants to the original purchaser that its product and the component parts thereof will be free from defects in workmanship and materials for a period of three years from the date of purchase B K Precision Corp will without charge repair or replace at its option defective product or component parts upon delivery to an authorized B K Precision service contractor or the factory service department accompanied by proof of the purchase date in the form of a sales receipt To obtain warranty coverage in the U S A this product must be registered by completing and mailing the enclosed warranty registration card to B K Precision 1031 Segovia Circle Placentia CA 92870 within fifteen 15 days from the date of purchase Exclusions This warranty does not apply in the event of misuse or abuse of the product or as a result of unauthorized alterations or repairs It is void if the serial number is altered defaced or remove
9. produce even one division of vertical deflection are adequate for normal triggered sweep operation Trigger COUPLING Switch 1 The AC position is used for most waveforms except video The trigger signal is capacitively coupled Thus it blocks the dc component and references the average of the changing portion of the waveform The TV H and TV V positions are primarily for viewing composite video waveforms Horizontal sync pulses are selected as trigger when the trigger COU PLING switch is set to the TV H position and vertical sync pulses are selected as trigger when the trigger COUPLING switch is set to the TV V position The TV H and TV V positions may also be used as low frequency reject and high frequency reject coupling respectively Additional procedures for observing video waveforms are given later in this section of the manual Trigger SOURCE Switch The trigger SOURCE switch CH 1 CH 2 etc selects the signal to be used as the sync trigger 1 If the SOURCE switch is set to CH 1 or CH 2 the channel 1 or channel 2 signal becomes the trigger source regardless of the VERTICAL MODE selec tion CH 1 or CH 2 are often used as the trigger source for phase or timing comparison measurements By setting the SOURCE switch to ALT alternating triggering mode is activated In this mode the trigger source alternates between CH 1 and CH 2 with each sweep This is convenient for checking amplitudes waveshape or
10. signal to appear to be of a lower frequency than that of the input signal Unless you have an idea what the input signal is supposed to look like you will usually be unaware that Aliasing is occurring Aliasing Example To see what actually occurs when a Digital Storage Oscil loscope is Aliasing perform the following example 1 Apply a 10 kHz signal to the input jack and set the sweep TIME DIV control to 50 us div You should see about 5 cycles of the waveform on the display Since the DSO samples the input waveform 200 times per division each cycle is sampled 400 times 2 Nowchangethe sweep TIME DIV control to 2 ms div The display should look crowded Because the DSO takes 200 samples per division the sample points are 10 us apart Since the input signal is at a frequency of 10 kHz it is being sampled 10 times per cycle The resulting display is too crowded to be useful however it is not incorrect it is very similar to what you would see on a conventional analog oscilloscope 3 Change the setting of the sweep TIME DIV control to 20 ms div Vary the frequency a slight amount until the display is readable to obtain as few cycles as possible on the CRT If you were to calculate the frequency of the signal from the display you would come up with a much lower frequency than that of the actual frequency of the signal at the input jack As an example if three cycles are displayed the calculated frequency would be approximately
11. the CRT 3 Select digital storage operation by setting the ANA LOG STORAGE switch to STORAGE engaged When all digital storage control switches are released the refresh mode is selected The waveform should appear on the display relatively unchanged from the previously displayed analog version In the refresh mode the display is continually updated as long as a suitable trigger signal remains present OPERATING INSTRUCTIONS 4 Once a waveform is digitized it can be stored in long term memory by pressing the SAVE ALL or SAVE CH2 switches The SAVE CH2 switch imme diately stores the channel 2 waveform The SAVE ALL switch immediately freezes the display and stores both waveforms Once a waveform is stored by engaging either of these switches it will be stored until the switch is disengaged or the power is turned off NOTES Any of the operating modes previously dis cussed in analog operation e g DUAL ADD etc can be used in digital mode except for X Y operation Time base settings of 10 us div and faster result in a display that is acquired through equivalent time sampling This process develops the digitized image over many cycles of the repetitive signal therefore these higher sweep speeds cannot be used for capture of one time events Equivalent time sampling is discussed in detail in Ap pendix II Unique Characteristics of Digi tal Storage Oscilloscopes Digitizing One Time Events One of the most
12. the red POWER pushbutton 3 A trace should appear on the CRT Adjust the trace brightness with the INTENSITY control and the trace sharpness with the FOCUS control SINGLE TRACE DISPLAY Either channel or channel 2 may be used for single trace operation To observe a waveform on channel 1 1 Perform the steps of the Initial Starting Procedure 2 Connect the probe to the CH 1 X input jack 3 Connect the probe ground clip to the chassis or com mon of the equipment under test Connect the probe tip to the point of measurement 4 Move the CH1 AC GND DC switch out of the GND position to either DC or AC 5 If no waveforms appear increase the sensitivity by turning the CH 1 VOLTS DIV control clockwise to a position that gives 2 to 6 divisions vertical deflection 6 Position the waveform vertically as desired using the CH1 POSition control 7 The display on the CRT may be unsynchronized Refer to the Triggering paragraphs in this section for pro cedures on setting triggering and sweep time controls to obtain a stable display showing the desired number of waveforms DUAL TRACE DISPLAY In observing simultaneous waveforms on channel 1 and 2 the waveforms are usually related in frequency or one of the waveforms is synchronized to the other although the basic frequencies are different To observe two such related waveforms simultaneously perform the following 1 Connect probes to both the CH 1 X and CH
13. yet it includes all the basic features needed by most technicians and engi neers Unlike other digital oscilloscopes it has a full analog mode with infinite resolution Digital storage modes include refresh roll and single sweep Equivalent time storage techniques allow storage of repetitive waveforms up to 20 MHz This oscilloscope is built by and backed by B K Precision a company that has been selling reliable durable value priced test instruments for over 50 years DIGITAL STORAGE FEATURES High Resolution 2048 samples across the width of the screen 200 samples per division assures good resolution of stored waveforms 1024 samples taken at sweep rates of 10 us div to 0 1 us div High Sampling Rate Sampling Rate up to 10 Ms s Megasamples per sec ond for storing one time events down to 50 nS Slow Event Display X100 time base selections extend sweep time to 50 seconds division Excellent for displaying slow speed events Equivalent Time Sampling Allows repetitive waveforms up to 20 MHz to be stored Pretrigger Capture Permits viewing activity before the trigger occurs Selectable 096 2596 5096 or 7596 pre trigger view Plotter Output Analog output plus TTL Pen Down control for strip chart recorder or X Y plotter CRT FEATURES Rectangular CRT Rectangular CRT with large 8 x 10 centimeter viewing area Convenience Trace rotation electrically adjustable from front panel 0 10 90 and 100 markers for rise time
14. 1 100 rate expands time base from 1 sec div to 50 sec div in 1 2 5 sequence Equivglent Time Sampling Bandwidth 20 MHz for repetitive waveforms Dot Joining Linear interpolation between samples Digital Display Modes Roll Stored data and display updated continually Refresh Stored data and display updated by triggered sweep Hold Freezes channel 1 and channel 2 data immediately Save CH 2 Freezes channel 2 data immediately Pretrigger Storage Available in single sweep mode switchable to 0 25 50 or 75 PLOT OUTPUT Analog output of the stored display CH 1 and CH 2 Outputs Selected by PLOT switch Output via CHI OUTPUT and CH2 OUTPUT jacks on rear panel Amplitude 0 2 V div 2 V maximum Output Sweep Rate Output sweep rate is 1 10 of TIME DIV setting and 1 100 switch when applicable Pen Lift Output Available at PEN DOWN jack on rear panel TTL high pen up TTL low pen down OTHER SPECIFICATIONS Cal Probe Compensation Voltage 0 5 V p p 3 square wave kHz nominal CH 2 Y Output Output Voltage 50 mV div nominal into 50 ohm load Output Impedance Approximately 50 ohms Frequency Response 20 Hz to 20 MHz 3 dB Power Requirements 100 130 VAC or 200 260 VAC 50 60 Hz 55 watts Dimensions H x W X D 5 2 X 12 8 X 15 7 132 X 324 X 398 mm Weight 18 7 Ibs 8 5 kg Environment Within Specified Accuracy 10 to 4 35 C 10 80 relative humidity Full Operation 0
15. 15 Hz This is 21 obviously incorrect This occurs because the DSO is taking one sample every 0 1 ms and a 10 KHz signal has one cycle every 0 1 ms Whatis actually happening is that the frequency is off not perfectly 10 KHz by just enough to cause the DSO to take one sample at a slightly different place on each cycle of the waveform Avoiding Aliasing Aliasing is not limited to the above example This phe nomenon can occur anytime that at least two samples per cycle are not taken whenever the sweep TIME DIV setting is much too slow for the waveform being applied to the input Whenever the frequency of the signal is unknown always begin with the fastest real time sweep speed 20 us div or by viewing the waveform in the analog mode of operation first NOTE Viewing one time events or glitches is not possible when sweep TIME DIV settings higher than 20 us div are selected Viewing one time events poses no problem with Ali asing because Aliasing can occur only with repetitive waveforms EQUIVALENT TIME SAMPLING This oscilloscope uses a sampling method called Equiva lent Time Sampling when sweep speeds higher than 20 us div are selected This method permits viewing of repetitive waveforms to 20 MHz although the maximum digital sampling rate is 10 Msamples sec When the Equiva lent Time Sampling mode is activated one sample is taken during each cycle Of course if one sample is taken during each cycle at the trigger point th
16. 2 Y input jacks 2 Connect the ground clips of the probes to the chassis or common of the equipment under test Connect the tips of the probes to the two points in the circuit where waveforms are to be measured 3 To view both waveforms simultaneously set the VERTical MODE switch to DUAL and select either ALT alternate or CHOP with the PULL CHOP switch 4 In the ALT sweep mode PULL CHOP switch pushed in one sweep displays the channel 1 signal and the next sweep displays the channel 2 signal in an alternating sequence Alternate sweep is normally used for viewing high frequency or high speed wave forms at sweep times of 1 ms div and faster but may be selected at any sweep time 5 In the CHOP sweep mode PULL CHOP switch pulled out the sweep is chopped switched between channel 1 and channel 2 Using CHOP one channel does not have to wait for a complete swept display of the other channel Therefore portions of both chan nel s waveforms are displayed with the phase relation ship between the two waveforms unaltered Chop sweep is normally used for low frequency or low speed waveforms at sweep times of 1 ms div and slower or where the phase relationship between chan nel 1 and channel 2 requires measurement If chop sweep is used at sweep times of 0 2 ms div and faster the chop rate becomes a significant portion of the sweep and may become visible in the displayed waveform However you may select chop sweep
17. BK e 3 2 V Pike WiviVit INSTRUCTION MANUAL MODEL 2522B 20 MHz DIGITAL STORAGE ANALOG OSCILLOSCOPE BK PRECISION TEST INSTRUMENT SAFETY Normal use of test equipment exposes you to a certain amount of danger from electrical shock because testing must often be performed where exposed high voltage is present An electrical shock causing 10 milliamps of current to pass through the heart will stop most human heartbeats Voltage as low as 35 volts dc or ac rms should be considered dangerous and hazardous since it can produce a lethal current under certain conditions Higher voltage poses an even greater threat because such voltage can more easily produce a lethal current Your normal work habits should include all accepted practices that will prevent contact with exposed high voltage and that will steer current away from your heart in case of accidental contact with a high voltage You will significantly reduce the risk factor if you know and observe the following safety precautions Don t expose high voltage needlessly in the equipment under test Remove housings and covers only when necessary Turn off equipment while making test connections in high voltage circuits Discharge high voltage capacitors after removing power If possible familiarize yourself with the equipment being tested and the location of its high voltage points However remember that high voltage may appear at unexpected points in defective equipment
18. Holdoff Continuously adjustable for main time base from NORM to 5 times normal TRIGGERING Trigger Modes AUTO free run NORM TV V TV H Trigger Source CH 1 CH 2 Alternate EXT LINE Slope or Trigger Coupling AUTO Sweep free runs in absence of suitable trigger signal NORM Sweep triggered only by adequate trigger signal TV V Video vertical sync pulses are selected Also usable for high frequency reject TV H Video horizontal sync pulses are selected Also usable for low frequency reject SPECIFICATIONS Trigger Sensitivity AC 1 0 div internal 20 5 Vp p external 30 Hz 30 MHz TV V 1 0 div internal 20 5 Vp p external 20 Hz 30 kHz TV H 1 0 div internal 20 5 Vp p external 3 kHz 100 kHz Maximum External Trigger Voltage 300 V dc ac peak DIGITAL STORAGE FACILITIES Storage Word Size 2048 X 8 bits channel 2 k channel with direct sam pling 1 k channel with equivalent time sampling Vertical Resolution 8 bit 1 in 256 approximately 25 steps div Horizontal Resolution 1 in 2048 approximately 200 samples div Sampling Rate 10 M samples sec to 4 samples sec reduced in propor tion to time base Direct sampling at time base settings of 20 us div and slower equivalent time sampling at time base settings of 10 us div and faster Time Base Expander For storage of slow time events time base steps 10 ms div and slower have selectable 1 1 or 1 100 rate
19. IME AND FALL TIME MEASUREMENTS Error in Observed Measurement The observed rise time or fall time as seen on the CRT is actually the cascaded rise time of the pulse being meas ured and the oscilloscope s own risetime The two rise times are combined in square law addition as follows Tobserved Tue y T scope y The effect of the oscilloscope s rise time is almost negli gible when its rise time is at least 3 times as fast as that of the pulse being measured Thus slower rise times may be measured directly from the CRT However for faster rise time pulses an error is introduced that increases progres sively as the pulse rise time approaches that of the oscillo Scope Accurate measurements can still be obtained by calculation as described below Direct Measurements The Model 2522B has a rated rise time of 18 ns Thus pulse rise times of about 54 ns or greater can be measured directly Most fast rise times are measured at the fastest sweep speed and using X10 magnification This sweep rate is 10 ns div A rise time of less than about five divisions at this sweep speed should be calculated 20 Calculated Measurements For observed rise times of less than 54 ns the pulse rise time should be caluclated to eliminate the error introduced by the cascaded oscilloscope rise time Calculate pulse rise time as follows 2 2 Tpulse PLNS T cope Limits of Measurement Measurements of pulse rise times that are faster
20. ND INDICATORS 27 PULL SLOPE Two position push pull switch The in position selects a positive going slope and the out position selects a negative going slope as triggering point for main sweep EXTernal TRIGger Jack External trigger input for single and dual trace operation DIGITAL STORAGE CONTROLS 28 29 30 31 32 33 34 STORAGE ANALOG Pushbutton When released scope is in ANALOG mode When engaged scope is in digital STORAGE mode In ANALOG mode all digital mode controls 29 38 are disabled In STOR AGE mode all digital mode controls 29 38 are enabled In STORAGE mode with all digital mode controls 29 38 released scope is in REFRESH mode of storage in which it updates the stored waveform each time an adequate trigger signal is received if the previous update has been completed REFRESH mode is applicable at all TIME DIV settings SAVE CH2 Pushbutton Engaging this switch freezes and stores the channel 2 trace immediately The channel 2 display and memory cannot be updated until this switch is released SAVE ALL Pushbutton Engaging this switch freezes and stores the channel 1 and channel 2 traces immediately The display and memory cannot be up dated until this switch is released SLOW X100 Pushbutton Engaging this switch ex pands the time base settings of 10 ms div to 0 5 S div by a factor of 100 to become settings of 1 sec div to 50 sec div Time base settin
21. OSition PULL CHOP control ADD The inputs from channel and channel 2 are summed and displayed as a single signal If the Channel 2 POSition PULL INVert control is pulled out the input from channel 2 is subtracted from channel and the difference is displayed as a single signal CH1 AC GND DC Switch Three position lever switch with the following positions AC Channel input signal is capacitively coupled dc component is blocked GND Opens signal path and grounds input to vertical amplifier This provides a zero volt base line the position of which can be used as a reference when performing dc measurements CONTROLS AND INDICATORS 10 11 12 13 WARNING SERIALNO Fig 2 Rear Panel Controls and Indicators DC Direct coupling of channel 1 input signal both ac and dc components of signal produce vertical de flection CH1 X Input Jack Vertical input for channel 1 X axis input for X Y operation CHI X VOLTS DIV Control Vertical attenuator for channel 1 Provides step adjustment of vertical sensitivity When channel 1 VARiable control is set to CAL vertical sensitivity is calibrated in 10 steps from 5 mV div to 5 V div in a 1 2 5 sequence When the X Y mode of operation is selected this control provides step adjustment of X axis sensitivity CH1 VARiable PULL X5 MAG Control VARiable Rotation provides vernier adjustment of channel 1 vertical sensitivity In the fully clockwise CAL
22. OUPLING switch to the TV H or TV V position permits selection of horizontal or vertical sync pulses for sweep triggering when viewing composite video waveforms When the TV H mode is selected horizontal sync pulses are selected as triggers to permit viewing of horizontal lines of video A sweep time of about 10 us div is appropriate for displaying lines of video The VAR SWEEP control can be set to display the exact number of waveforms desired When the TV V mode is selected vertical sync pulses are selected as triggers to permit viewing of vertical fields and frames of video A sweep time of 2 ms div is appropriate for viewing fields of video and 5 ms div for complete frames two interlaced fields of video 15 OPERATING INSTRUCTIONS At most points of measurement a composite video signal is of the polarity that is the sync pulses are negative and the video is positive In this case use SLOPE If the waveform is taken at a circuit point where the video wave form is inverted the sync pulses are positive and the video is negative In this case use 4 SLOPE DIGITAL STORAGE OPERATION Digitizing Repetitive Waveforms While the most powerful feature of a digital storage oscilloscope DSO is its ability to capture one time events a DSO can also digitize conventional repetitive waveforms such as those observed on a standard analog scope An analog digital unit such as the Model 2522B allows the user to set up sensitivi
23. The maximum ratings of the inputs are as follows CH 1 and CH 2 400 V dc ac peak EXT TRIG 300 V dc ac peak Z AXIS INPUT 30 V dc and ac peak Always connect a cable from the ground terminal of the oscilloscope to the chassis of the equipment under test Without this precaution the entire current for the equipment under test may be drawn through the probe clip leads under certain circumstances Such condi tions could also pose a safety hazard which the ground cable will prevent The probe ground clips are at oscilloscope and earth ground and should be connected only to the earth ground or isolated common of the equipment under test To measure with respect to any point other than the common use CH 2 CH 1 subtract operation ADD mode and invert channel 2 with the channel 2 probe to the point of measurement and the channel 1 probe to the point of reference Use this method even if the reference point is a dc voltage with no signal OPERATING INSTRUCTIONS OPERATING TIPS The following recommendations will help obtain the best performance from the oscilloscope 1 Always use the probe ground clips for best results attached to a circuit ground point near the point of measurement Do not rely solely on an external ground wire in lieu of the probe ground clips as undesired signals may be introduced 2 Avoid the following operating conditions a Direct sunlight b High temperature and humidity c Mechanical
24. aper surface This will allow you to exercise initial trial and error sweeps without using up exces sive ink Consult the manual for the particular plotter for details 6 Engage the PLOT switch This will gate a TTL level square wave through to the PEN DOWN output jack The repetition rate of this square wave is controlled by the front panel TIME DIV control The relationship is as follows Each low or high portion of the square wave represents the output of one screen i e ten divisions of waveform 10 24 divisions to be more exact This output takes place at a rate that is 1 10th that of the TIME DIV setting For example if the TIME DIV setting is 10 ms div the plotter output sends out waveform information at a rate of 17 OPERATING INSTRUCTIONS 100 ms div For the full 10 24 divisions of screen this means a total interval of 1 024 seconds Thus the square wave has low and high portions that are each 1 024 seconds long The PEN DOWN indicator on the front panel of the oscilloscope lights during each low portion NOTE Though many plotters use a TTL low level as the pen down signal and technically only require plotting information during that low portion this oscilloscope outputs a full screen of data on both the low and high intervals of the square wave This discussion assumes a plotter using TTL low as the pen down command When the PLOT switch is released the PEN DOWN output is at a constant TTL high E
25. at any sweep time for special applications Adjust the channel 1 and 2 POSition controls to place the channel 1 trace above the channel 2 trace Set the CH 1 and CH 2 VOLTS DIV controls to a position that gives 2 to 3 divisions of vertical deflec tion for each trace If the display on the screen is unsynchronized refer to the Triggering paragraphs in this section of the manual for procedures for setting triggering and sweep time controls to obtain a stable display showing the desired number of waveforms When the VERTical MODE switch is set to ADD the algebraic sum of CH 1 CH 2 is displayed as a single trace When the PULL INV switch is pulled out the algebraic difference of CH 1 CH 2 is displayed If two waveforms have no phase or frequency relation ship there is seldom reason to observe both wave forms simultaneously However these oscilloscopes do permit the simultaneous viewing of two such unre lated waveforms using alternate triggering Refer to the paragraphs on Triggering Trigger SOURCE Switch for details on alternate triggering TRIGGERING The Model 2522B Oscilloscope provides versatility in sync triggering for ability to obtain a stable jitter free dis play in single trace or dual trace operation The proper settings depend upon the type of waveforms being observed and the type of measurement desired An explanation of the various controls which affect synchronization is given to help you sele
26. ct the proper setting over a wide range of conditions AUTO or NORM Triggering 1 In the AUTO mode PULL NORM TRIG pushed in automatic sweep operation is selected In automatic sweep operation the sweep generator free runs to generate a sweep without a trigger signal However it automatically switches to triggered sweep operation if an acceptable trigger source signal is present The AUTO mode is handy when first setting up the scope to observe a waveform it provides sweep for wave 13 OPERATING INSTRUCTIONS form observation until other controls can be properly set Once the controls are set operation is often switched back to the normal triggering mode since it is more sensitive Automatic sweep must be used for dc measurements and signals of such low amplitude that they will not trigger the sweep In the NORM mode PULL NORM TRIG pulled out normal triggered sweep operation is selected The sweep remains at rest until the selected trigger source signal crosses the threshold level set by the TRIG LEVEL control The trigger causes one sweep to be generated after which the sweep again remains at rest until triggered In the normal triggering mode there will be no trace unless an adequate trigger signal is present In the ALT VERTICAL MODE of dual trace operation with the SOURCE switch also set to ALT there will be no trace unless both channel and channel 2 signals are adequate for triggering Typi cally signals that
27. d B K Precision Corp shall not be liable for any consequential damages including without limitation damages resulting from loss of use Some states do not allow limitation of incidental or consequential damages so the above limitation or exclusion may not apply to you This warranty gives you specific rights and you may also have other rights which vary from state to state 23 OSCILLOSCOPE APPLICATIONS INFORMATION ga RECISIONS GUIDEBOOK TO sSCILLOSCOPES O One of the best tutorials on oscilloscopes in the industry Valuable to those with little knowledge of oscilloscopes as well as the experienced technician or engineer who wishes to refresh their memory or explore new uses for oscilloscopes CONTAINS e Numerous Application Examples Showing How To Gain The Most From Your Scope s Features And Capabilities e Proper Probe Selection And Use e Oscilloscope Terminology e Typical Scope Controls And Their Usage e Scope Theory Of Operation Download your FREE copy from our Web site www bkprecision com BK PRECISION 1031 Segovia Circle Placentia CA 92870 2000 B K Precision Corp 481 315 9 001 Printed in Taiwan
28. ded by a factor of 100 by depressing the SLOW X100 switch For example the 10 ms div setting becomes 1000 ms 1 sec div when this switch is engaged This time base expansion is extremely useful for observing very slow events With it the scope is capable of recording an event up to 500 seconds in duration 5 sec div x100 becomes 50 sec div Using Plotter Output The Model 2522B oscilloscope provides facilities for driving an analog plotter The following instructions explain how to output a waveform however since plotters vary greatly only general instructions have been given Consult the manual for the particular plotter for more specific in structions Also it is recommended that you read this entire procedure first because some steps may need to be per formed in a different sequence depending on the plotter 1 Initially se the PLOT switch to off released 2 Useany ofthe digital modes described above to obtain a digitized display to be plotted Once the desired display is obtained freeze it using the SAVE ALL switch 3 Connect the plotter s Y vertical input to either the CHI or CH2 OUTPUT jack on the rear panel of the oscilloscope depending on which channel display you wish to plot 4 Connectthe plotter s pen lift control input to the PEN DOWN output jack on the rear of the scope 5 Momentarily disable external up down control of the plotter pen that is set the pen to be permanently lifted from the p
29. e It may be downloaded free of charge from our Web site www bkprecision com MAINTENANCE The following instructions are for use by qualified service personnel only To avoid electrical shock do not perform any serv icing other than contained in the operat ing instructions unless you are qualified to do so High voltage up to 2000 V is present when covers are removed and the unit is oper ating Remember that high voltage may be retained indefinitely on high voltage capacitors Also remember that ac line voltage is present on line voltage input circuits any time the instrument is plugged into an ac outlet even if turned off Unplug the oscilloscope and dis charge high voltage capacitors before performing service procedures FUSE REPLACEMENT If the fuse blows the ON indicator will not light and the oscilloscope will not operate The fuse should not normally open unless a problem has developed in the unit Try to determine and correct the cause of the blown fuse then replace only with the correct value fuse For 110 125 V line voltage operation use an 800 mA 250 V fuse For 220 240 V line voltage operation use a 600 mA 250 V fuse The fuse is located on the rear panel adjacent to the power cord receptacle Remove the fuseholder assembly as follows 1 Unplug the power cord from rear of scope 2 Insert a small screwdriver in fuseholder slot located between fuseholder and receptacle Pry fuseholder away fr
30. e same point on each cycle only a flat trace would be produced Therefore it is neces sary to take each sample further in time from the trigger point than the last sample This incremental delay is deter mined by the sweep TIME DIV control setting Because 1024 1 k samples are needed to fill the display the oscil loscope must sample 1024 cycles of the waveform Therefore only repetitive waveforms should be observed in this mode Irregularities that are present on an otherwise repetitive waveform are not likely to show up when the Equivalent Time Samplling method is used With only one sample being taken during each cycle it is very likely that glitches and other irregularities will be skipped over SERVICE INFORMATION Warranty Service Please return the product in the original packaging with dated proof of purchase to the address below Clearly state in writing the performance problem and return any leads connectors and accessories that you are using with the device Non Warranty Service Return the product in the original packaging to the address below Clearly state in writing the performance problem and return any leads connectors and accessories that you are using with the device Customers not on open account must include payment in the form of a money order or credit card For the most current flat rate repair charges contact the factory before shipping the product Return all merchandise to B K Precision Corp with
31. es the display The TRIG LEVEL control adjusts the start of the sweep to almost any desired point on a waveform On sine wave signals the phase at which sweep begins is variable Note that if the TRIG LEVEL control is rotated toward its extreme or setting no sweep will be developed in the normal trigger mode because the triggering threshold ex ceeds the peak amplitude of the sync signal When the PULL SLOPE control is set to the in position the sweep is developed from the trigger source waveform as it crosses a threshold level in a positive going direction When the PULL SLOPE control is set to the out position a sweep trigger is developed from the trigger source waveform as it crosses the threshold level in a negative going direction Slope Range Slope Range Fig 3 Function of Slope and Level Controls 14 TIME BASE Control Set the Time Base TIME DIV control to display the desired number of cycles of the waveform If there are too many cycles displayed for good resolution switch to a faster sweep time If only a line is displayed try a slower sweep time When the sweep time is faster than the waveform being observed only part of it will be displayed which may appear as a straight line for a square wave or pulse waveform HOLDOFF Control Refer to Fig 4 A holdoff period occurs immediately after the comple tion of each sweep and is a period during which trigge
32. gs are normal when this switch is released ROLL Pushbutton Engaging this switch selects the ROLL mode of operation in which the trace moves across the CRT from right to left like a strip chart recorder opposite of conventional oscilloscope opera tion and the display is continuously updated This update takes place even in the absence of any trigger signal The rolling speed equals the TIME DIV set ting and SLOW X100 if engaged ROLL mode is applicable only at time base settings of 10 ms div to 0 5 S div SINGLE Pushbutton Engaging this switch enables the single sweep mode of digital storage operation in which the memory is filled in a single sweep and continuously displayed Single sweep mode is appli cable for all real time settings of the TIME DIV control that is 20 us div and slower RESET Pushbutton With the SINGLE switch en gaged this switch readies the scope for single sweep 10 operation A suitable trigger signal arriving after press ing the RESET switch initiates the single sweep 35 READY Indicator Lights when the RESET switch readies the scope for single sweep and goes out when trigger signal occurs 36 PRE TRIGGER Pushbuttons Selects post trigger or pre trigger storage conditions In post trigger con dition 096 pre trigger the entire stored waveform occurs after the trigger The trigger point is at the extreme left of the display as in a conventional analog oscilloscope display In pre t
33. itch Selects source of sweep trigger Four position lever switch with the following positions CH1 Causes the channel 1 input signal to become the sweep trigger regardless of the VERTical MODE switch setting CH2 The channel 2 signal becomes the sweep trigger regardless of the VERTical MODE switch setting ALTernate Selects alternate triggering used in dual trace mode permits each waveform viewed to become its own trigger source Must be used with alternate sweep cannot be used with chop sweep EXT Signal from EXTernal TRIGger jack becomes sweep trigger Trigger COUPLING Switch Selects trigger cou pling Four position lever switch with the following positions AC Trigger signal is capacitively coupled Used for most waveforms except video TV V Used for triggering from television vertical sync pulses Also serves as lo pass dc high frequency reject trigger coupling TV H Used for triggering from television horizontal sync pulses Also serves as hi pass low frequency reject trigger coupling LINE Signal derived from input line voltage 50 60 Hz becomes trigger TRIGger LEVEL PULL SLOPE Control TRIGger LEVEL Trigger level adjustment determines the point on the triggering waveform where the sweep is trig gered Rotation in the direction counterclock wise selects more negative triggering point rotation in the direction clockwise selects more positive triggering point CONTROLS A
34. meas urements DUAL TRACE FEATURES Dual Trace Model 2522B has two vertical input channels for dis playing two waveforms simultaneously Selectable single trace either CH 1 or CH 2 or dual trace Alternate or chop sweep selectable at all sweep rates Sum and Difference Capability Permits algebraic addition or subtraction of channel 1 and channel 2 waveforms displayed as a single trace Useful for differential voltage and distortion measure ments HIGH FREQUENCY FEATURES Wide Bandwidth Conservatively rated 3 dB bandwidth is dc to 20 MHz Fast Rise Time Rise time is less than 18 nS Fast Sweep Maximum sweep speed of 10 nS div with X10 MAG assures high frequencies and short duration pulses are displayed with high resolution VERTICAL FEATURES High Sensitivity 5 mV div sensitivity for full bandwidth High sen sitivity 1 mV div and 2 mV div using PULL X5 gain control Calibrated Voltage Measurements Accurate voltage measurements 3 on 10 cali brated ranges from 5 mV div to 5 V div Vertical gain fully adjustable between calibrated ranges SWEEP FEATURES Calibrated Time Measurements Accurate 3 time measurements The main sweep has 21 calibrated ranges from 0 5 s div to 0 1 uS div Sweep time is fully adjustable between calibrated ranges X10 Sweep Magnification Allows closer examination of waveforms increases maximum sweep rate to 10 nS div FEATURES TRIGGERING FEATURES Two Trigger Modes
35. ngaging the SLOW X100 switch slows the plot output by a factor of 100 on the 10 ms div to 0 5 S div TIME DIV ranges 7 With the plotter s pen control input still disabled observe the PEN DOWN indicator on the scope to determine the repetition rate of the square wave Ad just as desired using the TIME DIV control It will be necessary to use the plotter s own time base to move its pen in the horizontal X direction If possible set that movement to begin on the high to low transition of the PEN DOWN signal Through trial and error with the pen still up run the plotter horizontally to determine the speed that produces the desired plot width during the PEN DOWN interval as observed on the LED Also adjust the vertical deflection and offset for the desired height 8 Finally during the high portion of the square wave PEN DOWN indicator off re enable external pen control on the plotter At the next transition of PEN DOWN to low the plotter should produce the desired results NOTE If you are unable to trigger the horizontal plotter sweep from the PEN DOWN sig nal you may have to enable that sweep manually using the PEN DOWN indicator as a timing guide APPLICATIONS GUIDEBOOK B K Precision offers a Guidebook to Oscilloscopes which describes numerous applications for this instrument and important considerations about probes It includes a glossary of oscilloscope terminology and an understanding of how oscilloscopes operat
36. om receptacle 3 When reinstalling fuseholder be sure that the fuse is installed so that the correct line voltage is selected see LINE VOLTAGE SELECTION LINE VOLTAGE SELECTION To select the desired line voltage simply insert the fuse and fuse holder so that the appropriate voltage is pointed to by the arrow Be sure to use the proper value fuse see label on rear panel 18 PERIODIC ADJUSTMENTS Probe compensation and trace rotation adjustments should be checked periodically and adjusted if required These procedures are given below Probe Compensation 1 Connect probes to CH 1 and CH 2 input jacks Per form procedure for each probe one probe at a time 2 Setthe probe to X10 compensation adjustment is not possible in the X1 position Touch tip of probe to CAL terminal 4 Adjustoscilloscope controls to display 3 or 4 cycles of CAL square wave at 5 or 6 divisions amplitude 5 Adjust compensation trimmer on probe for optimum square wave minimum overshoot rounding off and tilt Refer to Fig 5 Correct Compensation Over Compensation Insufficient Compensation Fig 5 Probe Compensation Adjustment Trace Rotation Adjustment 1 Set oscilloscope controls for a single trace display in CH 1 mode and with the channel 1 AC GND DC switch set to GND 2 Use the channel 1 POSition control to position the trace over the center horizontal line on the graticule scale The t
37. positive and negative transition of PEN DOWN The TIME DIV switch sets the period of this output except plotting is at 10x the TIME DIV setting 44 Y OUTPUT Jack Output terminal where sample of channel 2 analog signal is available Amplitude of output is 50 millivolts per division of vertical deflec tion seen on CRT when terminated into 50 ohms Output impedance is 50 ohms OPERATING INSTRUCTIONS SAFETY PRECAUTIONS EQUIPMENT PROTECTION PRECAUTIONS The following precautions must be ob served to help prevent electric shock When the oscilloscope is used to make measurements in equipment that contains high voltage there is al ways a certain amount of danger from electrical shock The person using the oscilloscope in such conditions should be a qualified electronics technician or other wise trained and qualified to work in such circum stances Observe the TEST INSTRUMENT SAFETY recommendations listed on the inside front cover of this manual Do not operate this oscilloscope with the case removed unless you are a qualified service technician High voltage up to 2100 volts is present when the unit is operating with the case removed The ground wire of the 3 wire ac power plug places the chassis and housing of the oscilloscope at earth ground Use only a 3 wire outlet and do not attempt to defeat the ground wire connection or float the oscil loscope to do so may pose a great safety hazard Special precautions are req
38. powerful features of a digital storage oscilloscope DSO is its ability to capture one time events To capture one time events single sweep operation is em ployed This is done through the use of the SINGLE switch When pushed this switch releases the REFRESH or ROLL mode if previously engaged and readies the digital storage circuit to receive a trigger signal presumably the event to be captured or some other time related occurrence When the event arrives it is stored in the memory and displayed The procedure is as follows 1 Set the oscilloscope to run in analog mode ANA LOG DIGITAL switch to ANALOG Select NORM triggering and adjust the TRIG LEVEL control so that the unit triggers on the event to be captured 2 Set the oscilloscope to digital STORAGE mode by engaging the ANALOG STORAGE switch 3 Initially set the PRE TRIG switch to 50 A more detailed discussion of pre and post triggering is given later in this section of the manual 4 Press the RESET switch The READY indicator will momentarily light as the scope awaits the arrival of the trigger signal When that trigger occurs the READY indicator will go off and the event being monitored will roll to the center of the display and stop NOTES Depending on the sweep TIME DIV set ting the anticipated event may roll to the center of the screen very rapidly or very slowly after the READY indicator goes out 16 Single sweep mode can be used in the pre
39. r P31 Trace Rotation Electrical front panel adjustable VERTICAL AMPLIFIERS CH 1 and CH 2 Sensitivity 5 mV div to 5 V div 1 mv div to 1 V div at X5 MAG Attenuator 10 calibrated steps in 1 2 5 sequence Vernier control provides fully adjustable sensitivity between steps range 1 1 to at least 1 3 Accuracy 3 5 mV to 5 V div 596 at X5 MAG Input Resistance 1 MQ 2 Input Capacitance 25 pF 10 pF Frequency Response 5 mV div to 5 V div DC to 20 MHz 3 dB X5 MAG DC to 10 MHz 3 dB Rise Time 18 nS 35 nS at X5 MAG Overshoot Less than 5 Operating Modes CH 1 CH 1 single trace CH 2 CH 2 single trace DUAL CH 1 and CH 2 dual trace Alternate or Chop selectable at any sweep rate ADD Algebraic sum of CH 1 CH 2 Chop Frequency Approximately 500 kHz Polarity Reversal CH 2 invert Maximum Input Voltage 400 V dc ac peak HORIZONTAL AMPLIFIER Input through channel input X Y mode CH 1 X axis CH 2 Y axis Sensitivity Same as vertical channel 2 Input Impedance Same as vertical channel 2 Frequency Response DC to 1 MHz 3 dB X Y Phase Difference 3 or less at 50 KHz Maximum Input Voltage Same as vertical channel 1 SWEEP SYSTEM Time Base 0 1 uS div to 0 5 S div in 1 2 5 sequence 2 steps Vernier control provides fully adjustable sweep time between steps Accuracy 3 except 20 on 0 1 n S div Sweep Magnification X10 10
40. race should be exactly parallel with the horizontal line 3 Usethe TRACE ROTATION adjustment on the front panel to eliminate any trace tilt CALIBRATION CHECK A general check of calibration accuracy may be made by displaying the output of the CAL terminal on the screen This terminal provides a square wave of 0 5 V p p This signal should produce a displayed waveform amplitude of five divisions at 0 1 V div sensitivity for both channel 1 and 2 with probes set for direct With probes set for X10 there should be five divisions amplitude at 10 mV div sensitivity The VARIABLE controls must be set to CAL during this check NOTE The CAL signal should be used only as a general check of calibration accuracy not as a signal source for performing recali bration adjustments a voltage standard calibrated at several steps and of 0 3 or better accuracy is required for calibration adjustments The CAL signal should not be used as a time base standard 19 MAINTENANCE INSTRUMENT REPAIR SERVICE Because of the specialized skills and test equipment re quired for instrument repair and calibration many custom ers prefer to rely upon B K Precision for this service To use this service even if the oscilloscope is no longer under warranty follow the instructions given in the SERVICE INFORMATION portion of this manual There is a flat rate charge for instruments out of warranty APPENDIX I IMPORTANT CONSIDERATIONS FOR RISE T
41. rigger conditions a por tion of the waveform occurring before the trigger is displayed Pre trigger selections of 2596 5096 and 75 are selectable For 0 pre trigger release both PRE TRIGGER pushbuttons For 2596 pre trigger engage the left pushbutton For 50 pre trigger en gage the right pushbutton For 75 pre trigger engage both pushbuttons Pre trigger operation is applicable only to single sweep operation not to ROLL or REFRESH modes 37 PLOT Pushbutton When engaged this switch acti vates the PLOT mode Output is available at the CH1 OUTPUT CH2 OUTPUT and PEN DOWN jacks on the rear of the scope At the appropriate time the PEN DOWN output goes TTL low to permit plotting on an analog plotter or strip chart recorder The PLOT mode is applicable only when the SAVE ALL push button is engaged 38 PEN DOWN Indicator In the PLOT mode this indicator lights when the PEN DOWN output on the rear panel is TTL low REAR PANEL CONTROLS see Fig 2 39 Fuse Holder Line Voltage Selector Contains fuse and selects line voltage 40 Power Cord Receptacle 41 CHI OUTPUT Jack Supplies channel 1 digital stor age contents for use with an analog plotter 42 CH2 OUTPUT Jack Supplies channel 2 digital stor age contents for use with an analog plotter 43 PEN DOWN Output Jack TTL open collector out put to raise and lower plotter pen Plotter information is output at the CHI OUTPUT and CH2 OUTPUT jacks starting at each
42. ring of the next sweep is inhibited The normal holdoff period varies with sweep rate but is adequate to assure complete retrace and stabilization before the next sweep trigger is permitted The HOLDOFF control allows this period to be extended by a variable amount if desired This control is usually set to the MIN position fully counterclockwise because no additional holdoff period is necessary The HOLDOFF control is useful when a com plex series of pulses appear periodically such as in Fig 4B Improper sync may produce a double image as in Fig 4A Such a display could be synchronized with the VAR SWEEP control but this is impractical because time meas urements are then uncalibrated An alternate method of synchronizing the display is with the HOLDOFF control The sweep speed remains the same but the triggering of the next sweep is held off for the duration selected by the HOLDOFF control Turn the HOLDOFF control clock wise from the MIN position until the sweep starts at the same point of the waveform each time A Holdoff not used B Holdoff used Fig 4 Use of HOLDOFF Control MAGNIFIED SWEEP OPERATION Since merely shortening the sweep time to magnify a portion of an observed waveform can result in the desired portion disappearing off the screen magnified display should be performed using magnified sweep Using the lt P position control move the desired portion of waveform to the center of the CRT Pull out the
43. s ence of very rapidly occurring events even continuous waveforms if desired In that case the period between pushing the RE SET switch and the arrival of the trigger may be very short or almost instantaneous As a result the READY indicator may light for only a very short time perhaps not being visible at all Pushing the SINGLE switch automatically disengages both the REFresh and ROLL modes which are continuous modes 5 Once the waveform is captured it can be stored in long term memory through the use of the SAVE CH2 or SAVE ALL switches Pre and Post Trigger Capture Another powerful feature of a DSO is is ability to display pre trigger information that is events occurring before the arrival of a trigger event On the Model 2522B pre trig ger operation is available in single sweep mode by setting the PRE TRIG switches As shown in the above section on Digitizing One Time Events when 50 pre trigger op eration is selected the event to be captured is situated in the center of the memory roughly the center of the display after storage The waveform to the left of center represents activ ity which occurred before that trigger arrived Pre Trigger selection of 25 and 75 are also available If the PRE TRIG switches are released 0 pretrigger then no pre trigger information is stored and the trigger event rolls to the extreme left of the display In this case all the information displayed on the screen repre
44. sents activity after the trigger event You may wish to use post trigger operation first to observe where the trigger is occurring on the waveform of interest and then switch to pre trigger mode Roll Mode In this mode of operation the waveform rolls across the CRT from right to left as opposed to standard oscilloscopes which have the trace moving from left to right in the same manner as most strip chart recorders It is most commonly used for viewing very slow events 1 Setup the oscilloscope in analog mode so that the event to be observed is properly positioned on the display you may wish to use AUTO triggering so that the scope continues to draw a trace even if the event is especially slow 2 Switch to digital mode ANALOG STORAGE switch to STORAGE and depress the ROLL switch Select a TIME DIV setting that produces a roll at the desired speed As the sweep speed is decreased the waveform will move across the screen more slowly and the Roll feature will become more apparent It can also be slowed by a factor of 100 on some ranges see the discussion in the next section 3 The rolling display can be frozen at any time by pressing the SAVE CH2 or SAVE ALL switches as discussed in the section on Digitizing Repetitive Waveforms NOTE ROLL mode cannot be used on sweep speeds greater than 10 ms div Expanded Sweep Settings SLOW X100 Mode In digital mode the 10 ms div to 0 5 s div TIME DIV ranges can be expan
45. t The B K Precision Model TR 110 or 1604A Isolation Transformer or Model 1653A or 1655A AC Power Supply is suitable for most applications To be on the safe side treat all two wire ac powered equipment as hot chassis unless you are sure it has an isolated chassis or an earth ground chassis Never work alone Someone should be nearby to render aid if necessary Training in CPR cardio pulmonary resuscitation first aid is highly recommended Instruction Manual for BK PRECISION Model 2522B 20 MHz Digital Storage Analog Oscilloscope 2000 B K Precision Corp This symbol on oscilloscope means refer to instruction manual for further precautionary information This symbol appears in the manual where the corresponding information is given BK PRECISION 1031 Segovia Circle Placentia CA 92870 TABLE OF CONTENTS Page TEST INSTRUMENT SAFETY inside front cover FEATURES 5 eeiurRPPRPEPP ARES eenen ee 3 SPECIFICATIONS e eei so 3 ee eee bn esas 5 CONTROLS AND INDICATORS 7 General Function Controls 7 Vertical Controls uuu ss ee estan ver Re ee 7 Horizontal Controls s s scesu i aasawa s esee 9 Triggering Controls au gua pana as 9 Digital Storage Controls 10 Rear Panel Controls v ceriose r kd causa a wa 10 OPERATING INSTRUCTIONS 11 Safety Precautions llle eese 11 Equipment Protection Precautions
46. than the scope s rated rise time are not recommended because a very small reading error introduces significant error into the calculation This limit is reached when the observed rise time is about 1 3 times greater than the scope s rated rise time about 23 ns minimum for the Model 2522B Probe Considerations For fast rise time measurements which approach the limits of measurement direct connection via 50 Q coaxial cable and 50 Q termination is recommended where possible When a probe is used its rise time is also cascaded in square law addition Thus the probe rating should be considerably faster than the oscilloscope if it is to be disregarded in the measurement APPENDIXII UNIQUE CHARACTERISTICS OF DIGITAL STORAGE OSCILLSCOPES Digital Storage Oscilloscopes DSO s use a digital sam pling technique to convert analog input signals to a series of digital words that can be stored in memory Since digital sampling has disadvantages as well as advantages it is important to be aware of these unique characteristics of DSO s ALIASING This DSO uses Real Time Sampling when sweep TIME DIV settings of 50 sec div to 20 us div are selected Real Time Sampling simply means that samples of the input signals are taken at equal spaces e g every 0 25 ms when the 50 ms div range is selected With Real Time Sampling a phenomena called Aliasing can occur when the input signal is not sampled often enough This causes the digitized
47. this control pro vides step adjustment of Y axis sensitivity CH2 VARiable PULL X5 MAG Control VARiable Rotation provides vernier adjustment of channel 2 vertical sensitivity In the fully clockwise CAL position the vertical attenuator is calibrated Coun terclockwise rotation decreases gain sensitivity In X Y operation this control becomes the vernier Y axis sensitivity control PULL X5 MAG When pulled out increases vertical sensitivity by a factor of five Effectively provides two extra sensi tivity settings 2 mV div and 1 mV div In X Y mode increases Y sensitivity by a factor of five 17 CH2 Y Input Jack Vertical input for channel 2 Y axis input for X Y operation 18 CH2 AC GND DC Switch Three position lever switch with the following positions AC Channel 2 input signal is capacitively coupled dc component is blocked GND Opens signal path and grounds input to vertical amplifier This provides a zero volt base line the position of which can be used as a reference when performing dc measurements DC Direct coupling of channel 2 input signal both ac and dc components of signal produce vertical de flection HORIZONTAL CONTROLS 19 Time Base TIME DIV Control Provides step selec tion of sweep rate for the time base When the VARi able Sweep control is set to CAL sweep rate is calibrated This control has 21 steps from 0 1 uS div to 0 5 S div in a 1 2 5 sequence 20 VARiable Sweep Control
48. ty sweep and triggering in a familiar analog setting and then switch to the digital mode This is a good way to gain familiarity with the digital features of the instrument You may wish to pursue this method as described below in the Refresh Mode paragraph Also some repetitive signals can be viewed and measured much more effectively in the digital store mode than in the analog mode One example is slow signals below 60 Hz Signals that appear as a flickering waveform or just a moving dot on the screen in the analog mode are displayed as a bright non flickering easily viewed entire waveform in the digital store mode The digital store mode also improves viewing and meas urement of repetitive signals with low trigger repetition rates relative to the sweep rate In the analog mode such wave forms may be too faint for viewing In the digital store mode the display is equivalent to a CRT with infinite persistence The waveform can be easily viewed Refresh Mode In the refresh mode the waveform is digitized and dis played on the screen After the complete waveform is digit ized the next trigger causes the stored waveform to be replaced refreshed by a new waveform 1 Setup the oscilloscope to view a periodic waveform in the ANALOG mode Adjust the trigger VOLTS DIV sweep TIME DIV and vertical posi tion controls as desired 2 Initially disengage all of the digital storage control switches the group of switches beneath
49. uired to measure or observe line voltage waveforms with any oscilloscope Use the following procedure a Do not connect the ground clip of the probe to either side of the line The clip is already at earth ground and touching it to the hot side of the line may weld or disintegrate the probe tip and cause possible injury plus possible damage to the scope or probe b Insert the probe tip into one side of the line voltage receptacle then the other One side of the recepta cle should be hot and produce the waveform The other side of the receptacle is the ac return and no waveform should result 11 CAUTION The following precautions will help avoid damage to the oscilloscope Never allow a small spot of high brilliance to remain stationary on the screen for more than a few seconds The screen may become permanently burned A spot will occur when the scope is set up for X Y operation and no signal is applied Either reduce the intensity so the spot is barely visible apply signal or switch back to normal sweep operation It is also advisable to use low intensity with AUTO triggering and no signal applied for long periods A high intensity trace at the same position could cause a line to become perma nently burned onto the screen Do not obstruct the ventilating holes in the case as this will increase the scope s internal temperature Excessive voltage applied to the input jacks may dam age the oscilloscope
50. vibration d Electrical noise and strong magnetic fields such as near large motors power supplies transformers etc 3 Occasionally check trace rotation probe compensa tion and calibration accuracy of the oscilloscope using the procedures found in the MAINTENANCE section of this manual 4 Terminate the output of a signal generator into its characteristic impedance to minimize ringing espe cially if the signal has fast edges such as square waves or pulses For example the typical 50 output of a square wave generator should be terminated into an external 50 Q terminating load and connected to the oscilloscope with 50 coaxial cable 5 Probe compensation adjustment matches the probe to the input of the scope For best results compensation should be adjusted initially then the same probe al ways used with the same channel Probe compensation should be readjusted when a probe from a different oscilloscope is used INITIAL STARTING PROCEDURE Until you familiarize yourself with the use of all controls the settings given here can be used as a reference point to obtain a trace on the CRT in preparation for waveform observation 1 Set these controls as follows VERTical MODE to CHI CH1 AC GND DC to GND Select AUTO triggering HOLD OFF pushed in Trigger COUPLING to AC Trigger SOURCE to CH1 All POSition controls and INTENSITY control centered pointers facing up Time Base control to 1 mS div 2 Press
51. waveform period measurements and even permits simultaneous observation of two wave forms which are not related in frequency or period However this setting is not suitable for phase or timing comparison measurements For such measurements both traces must be triggered by the same sync signal Alternate triggering can only be used in dual trace OPERATING INSTRUCTIONS mode VERT MODE set to DUAL and with alter nate sweep only PULL CHOP not engaged 3 In the EXT position the signal applied to the EXT TRIG jack becomes the trigger source This signal must have a timing relationship to the displayed wave forms for a synchronized display 4 In the LINE position of the COUPLING switch triggering is derived from the input line voltage 50 60 Hz and the trigger SOURCE switch is disabled This is useful for measurements that are related to line frequency TRIG LEVEL PULL SLOPE Control Refer to Fig 3 A sweep trigger is developed when the trigger source signal crosses a preset threshold level Rotation of the TRIG LEVEL control varies the threshold level In the direction clockwise the triggering threshold shifts to a more posi tive value and in the direction counterclockwise the triggering threshold shifts to a more negative value When the control is centered the threshold level is set at the approximate average of the signal used as the triggering source Proper adjustment of this control usually synchro niz
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