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KENWOOD 20MHz C O M P A C T O S C I L L O S C O P E CS-3025 INSTRUCTION MANUAL KENWOOD CORPORATION ©PRINTED IN JAPAN B50-7683-00(T) 90/12 1110 9 8 7 6 5 4 3 2 1 89/12 11 10 9 8 7 6 5 4 3 2 SAFETY Symbol in T h i s Manual This symbol indicates where applicable cautionary or other imformation is to be found. Power Source T h i s equipment operates from a power source that does not apply more than 2 5 0 V rms between the supply conductors or between either supply conductor and ground. A protective ground connection by w a y of the grounding conductor in the power cord is essential for safe operation. Grounding the Product This equipment is grounded through the grounding conductor of the power cord. T o avoid electrical shock, plug the power cord into a properly wired receptacle before connecting to the equipment input or output terminals. Use the Proper Power Cord Use only the power cord and connector specified for your product. Use the Proper Fuse T o avoid fire hazard, use a fuse of the correct type. Do not Operate in Explosive Atmospheres T o avoid explosion, do not operate this product in an explosive atmosphere. Do not Remove Cover or Pane! T o avoid personal injury, do not remove the cover or panel. Refer servicing to qualified personnel. Voltage Conversion If the power source is not applied to your product, contact your dealer. T o avoid electrical shock, do not perform the voltage conversion. 2 CONTENTS SAFETY OVERVIEW AND CONFIGURATION SPECIFICATIONS PREPARATION FOR USE CONTROLS AND INDICATORS FRONT PANEL REAR PANEL BOTTOM PANEL 2 4 5 7 9 9 14 15 OPERATION • INSTAL STARTING PROCEDURE [1] NORMAL S W E E P DISPLAY OPERATION [2] MAGNIFIED S W E E P OPERATION [3] X - Y OPERATION [4] VIDEO SIGNAL OBSERVATION APPLICATION PROBE COMPENSATION T R A C E ROTATION COMPENSATION DC VOLTAGE MEASUREMENTS MEASUREMENT OF THE VOLTAGE B E T W E E N TWO POINTS ON A WAVEFORM ELIMINATION OF UNDESIRED SIGNAL COMPONENTS 16 16 16 19 19 19 20 20 20 20 22 23 TIME MEASUREMENTS FREQUENCY MEASUREMENTS APPLICATION OF X - Y OPERATION MAINTENANCE AND A D J U S T M E N T MAINTENANCE ADJUSTMENT 24 24 26 27 27 28 3 OVERVIEW AND CONFIGURATION OVERVIEW This unit is a compact, light-weight, high performance portable oscilloscope equipped with rectangular C R T w i t h internal graticule. T h e frequency bandwidth of 2 0 MHz and selectable s w e e p time of 0 . 2 jis/div to 1 s/div for the vertical axis allows use for a wide range of applications. It is also equipped with such features as magnification functions for the vertical and horizontal a x e s , single s w e e p function, and T V sync function. These features make it the ideal oscilloscope for the service bench and various types of maintenance. CONFIGURATION T h e following items are contained in the packing c a s e . W h e n unpacking, make sure that all items have been included. Oscilloscope 1 pc. Probe (PC-30) 2 pes. Panel cover 1 pc. Instruction manual 1 pc. In addition, the following are also available a s optional accessories (sold separately). Carrying c a s e (soft) MC-81 Carrying case (hard) MC-82 4 SPECIFICATIONS CRT Type Acceleration Voltage Display Area Rectangular high luminance C R T (with internal graticule) Approx. 1.8 k V 8 x 10 div flat-face (1 div = 6 . 3 5 mm) VERTICAL A X I S Operating Modes C H 1 , C H 2 , A L T , CHOP, ADD Sensitivity 5 mV/div to 5 V/div, + / - 3 % Sensitivity Magnification . . . 5 times +1-5% ( x 5 M A G used) Attenuator 1-2-5 step sequence, 10 ranges, adjustable between ranges Frequency Response 5 mV/div to 5 V/div D C : D C to 2 0 MHz, - 3 dB A C : 5 Hz to 2 0 MHz, - 3 dB x 5 M A G used D C : D C to 4 MHz, - 3 dB A C : 5 Hz to 4 MHz, - 3 dB Input Impedance 1 Mohm, approx. 4 0 pF Rise Time 1 7 . 5 ns or less ( 2 0 MHz) Crosstalk - 4 0 dB minimum Polarity Inversion C H 2 only Chop Frequency Approx. 5 0 kHz / \ Maximum Input Voltage 8 0 0 Vp-p or 4 0 0 V (DC + A C peak) HORIZONTAL A X I S Operating Modes Sensitivity Input Impedance Frequency Response X - Y Phase Difference /f\ Maximum Input Voltage X - Y operation selectable with s w e e p knob X axis selectable w i t h T R I G or X Y axis selectable with V or Y MODE S a m e a s vertical axis Same a s vertical axis D C : DC to 2 0 0 kHz, - 3 dB A C : 5 Hz to 2 0 0 kHz, - 3 dB 3 ° or less at 10 kHz S a m e as vertical axis 5 SWEEP Sweep Type Sweep Time S w e e p Magnification TRIGGERING Internal S y n c External S y n c External S y n c Input Impedance A Maximum External Trigger Voltage S y n c Coupling Polarity Trigger Sensitivity N O R M : Triggering s w e e p A U T O : S w e e p free runs in absence of trigger 0 . 2 ^s/div to 1 s/div + / - 3 % in 21 ranges, 1-2-5 s e quence, adjustable between ranges 5 times + / - 5 % INT, LINE EXT 1 Mohm, Approx. 9 0 pF 5 0 V (DC + ACpeak) A C , DC, TV-V, TV-H + /Coupling Frequency INT EXT DC D C ~ 2 MHz - 2 0 MHz 0.5 div 1 div 0.1 Vp-p 0.2 Vp-p AC 10 H z ~ 2 MHz - 2 0 MHz 0.5 div 1 div 0.1 Vp-p 0.2 Vp-p 2 div 0.4 Vp-p TV-H, V CALIBRATION V O L T A G E Amplitude (Voltage) Square w a v e (positive polarity) 1 Vp-p ± 3 % , 1 kHz ± 3 % POWER REQUIREMENTS Power Supply Voltage Power Consumption A C 1 0 0 / 1 2 0 / 2 2 0 / 2 4 0 V ± 1 0 % 5 0 / 6 0 Hz Approx. 2 2 W (at 1 0 0 V A C ) DIMENSIONS AND WEIGHT Dimensions. Weight 2 1 6 (width) x 8 9 (height) x 2 9 8 (depth) mm Approx. 4 kg OPERATING TEMPERATURE AND HUMIDITY FOR GUARANTEED SPECIFICATIONS 5 to 3 5 ° C , 8 5 % maximum RH ACCESSORIES 6 Probe (PC-30) Instruction Manual Panel Cover 2 pes. 1 pc. 1 pc. PREPARATION FOR U S E SAFETY Before connecting the instrument to a power source, carefully read the following information, then verify that the proper power cord is used and the proper line fuse is installed for power source. T h e specified voltage is s h o w n at the left side of the power cord on the rear panel. If the power cord is not applied for specified voltage, there is a l w a y s a certain amount of danger from electric shock. Line voltage This instrument operates using A C - p o w e r input voltages that 1 0 0 / 1 2 0 / 2 2 0 / 2 4 0 V at frequencies from 5 0 Hz to 6 0 Hz. Power cord The ground wire of the 3-wire A C power plug places the chassis and housing of the oscilloscope at earth ground. Do not attempt to defeat the ground wire connection or float the oscilloscope; to do so may pose a great safety hazard. The appropriate power cord is supplied by an option that is specified w h e n the instrument is ordered. The optional power cords are s h o w n as follows in Fig. 1 . Line fuse The fuse holder is located on the rear panel and contains the line fuse. Verify that the proper fuse is installed by replacing the line fuse. EQUIPMENT PROTECTION 1. Never allow a small spot of high brilliance to remain stationary on the screen for more than a f e w seconds. T h e screen may become permanently burned. A spot will occur only w h e n the scope is set up for X - Y operation and no signal is applied. Either reduce the intensity so the spot is barely visible, s w i t c h back to normal s w e e p operation w h e n no signal is applied, or set up the scope for spot blanking. 2. Never cover the ventilating holes on the top of the oscilloscope, a s this will increase the operating temperature inside the c a s e . 3 . Never apply more than the maximum rating to the oscilloscope inputs. ^ C H 1 , C H 2 INPUT j a c k s : 8 0 0 Vp-p or 4 0 0 V ( D C + A C peak) E X T T R I G INPUT jack: 5 0 V (DC + A C peak) Never apply external voltage to the oscilloscope output terminals. 4 . A l w a y s connect a cable from the earth ground (GND) terminal of the oscilloscope to the chassis of the equipment under test. Without this caution, the entire current for the equipment under test may be d r a w n through the probe clip leads under certain circ u m s t a n c e s . S u c h conditions could also pose a safety hazard, w h i c h the ground cable will prevent. 5. A l w a y s use the probe ground clips for best results. Do not use an external ground wire in lieu of the probe ground clips, as undesired signals may be introduced. 7 6. Operation adjacent to equipment w h i c h produces strong A C magnetic fields should be avoided where possible. This includes such devices as large power supplies, transformers, electric motors, etc., that are often found in an industrial environment. Strong magnetic shields can exceed the practical C R T magnetic shielding limits and result interference and distortion. 7. Probe compensation adjustment matches the probe to the input of the scope. For best results, compensation of probe should be adjusted initially, then the same probe alw a y s used with the input of scope. Probe compensation should be readjusted whenever a probe from a different scope is used. (See page 2 0 ) 8. In X - Y operation, do not pull out the P U L L x 5 M A G s w i t c h . If pulled out it, noise may appeare on the w a v e f o r m . Plug configuration Power cord and plug type Line cord plug fuse North American 120 volt/60 Hz Rated 15 amp (12 amp max; NEC) 0.5 A, 250 V Fast blow AGC/3AG None Universal Europe 2 2 0 volt/50 Hz Rated 16 amp 0.3 A, 250 V Fast blow 5 x 2 0 mm None U.K. 2 4 0 volt/50 Hz Rated 13 amp 0.3 A, 250 V Fast blow 5 x 3 0 mm 0.3 A Type C Australian 2 4 0 volt/50 Hz Rated 10 amp 0.3 A, 250 V Fast blow 5 x 3 0 mm None North American 2 4 0 volt/60 Hz Rated 15 amp (12 amp max; NEC) 0.3 A, 250 V Fast blow AGC/3AG None Switzerland 2 4 0 volt/50 Hz Rated 10 amp 0.3 A, 250 V Fast blow AGC/3AG 5 x 30 mm None Fig. 1 8 Factory installed instrument fuse Power input Voltage Configuration CONTROLS AND INDICATORS FRONT PANEL Fig. 2-1 © POWER Power s w i t c h for the oscilloscope. Pressing this control once turns the power on and pressing it again turns the power off. ® Pilot Lamp Lamp lights w h e n the oscilloscope is on. (3) C A L Terminal Voltage terminal for calibration of probes. Provides an approximately 1 kHz square w a v e at 1 V with positive polarity. 0 $ POSITION/PULL x 5 MAG Rotation adjusts the vertical position of channel 1 trace on the display. Pulling this knob increases the vertical axis sensitivity 5 times. ® VOLTS/DIV S e t s the vertical axis sensitivity using the vertical attenuator for channel 1 . T h i s knob can be switched in a 1-2-5 sequence. Setting the V A R I A B L E knob (6) to the C A L position provides calibrated vertical axis sensitivity. During X - Y operation, this control serves as the attenuator for the X axis or Y axis. 9 Fig. 2-2 © VARI ( A B L E ) Rotation provides fine control of channel 1 vertical attenuation. A l l o w s continuous adjustment between V O L T S / D I V ranges. In the fully c l o c k w i s e ( C A L ) position, the vertical attenuator is calibrated. During X - Y operation, this control serves as the X axis or Y axis attenuator fine adjustment. © AC-GND-DC This lever selects the coupling method used for the C H 1 vertical axis input signal. AC: Input signal is A C coupled, and D C component is blocked. GND: Input signal and vertical amplifier are separated and input to vertical amplifier is grounded. T h i s allows for confirmation of the ground potential. DC: Input signal is D C coupled allowing for measurement including D C component. T h i s lever servers as the X axis or Y axis input selector during X - Y operation. ® C H 1 INPUT Vertical axis input jack for channel 1 . Serves as the X axis or Y axis input j a c k during X - Y operation. (D $ POSITION/PULL x 5 MAG Performs the same function for channel 2 as the channel 1 * POSITION control. Serves as the Y position adjustment control during X - Y operation. 10 © VOLTS/DIV Vertical axis attenuator for channel 2. Performs the same function for channel 2 a s the channel 1 V O L T S / D I V control. S e r v e s as the X axis or Y axis attenuation adjustment control during X - Y operation. © V A R I (ABLE) Rotation provides fine control of channel 2 attenuation. Performs the same function for channel 2 as the channel 1 V A R I A B L E control. S e r v e s a s the X axis or Y axis attenuation fine adjustment control during X - Y operation. © AC-GND-DC This lever selects the coupling method used for the channel 2 vertical axis input signal. Performs the same function as the channel 1 A C - G N D - D C control. Serves as the Y axis or Y axis input selector during X - Y operation. © C H 2 INPUT Vertical axis input jack for channel 2 . S e r v e s as the X axis or Y axis input jack during X - Y operation. @ V o r Y MODE T h i s s w i t c h selects the vertical axis operation mode and serves as the Y axis selection s w i t c h during X - Y operation. CH1: Channel 1 input signal is displayed on the C R T . Channel 1 is the Y axis if this mode is selected during X - Y operation. CH2: Channel 2 input signal is displayed on the C R T . Channel 2 is the Y axis if this mode is selected during X - Y operation. ALT: Channel 1 and channel 2 signals are displayed alternately on the C R T w i t h each s w e e p . CHOP: Channel 1 and 2 signals are displayed alternately on the C R T at a repetition rate of 5 0 kHz or more. ADD: The algebraic sum of the channel 1 and 2 signal is displayed on the C R T . If C H 2 INV © is engaged, the difference is displayed on the C R T . Note: The A L T , CHOP, and ADD modes cannot be used during X - Y operation. © C H 2 INV Inverts the polarity of the channel 2 signal. © TRIG o r X 1 C H I / _m. C H 2 T h i s button selects the trigger source w h e n an internal trigger (INT) is selected. S e r v e s as the X axis selection s w i t c h during X - Y operation. CH1: Channel 1 input signal serves as the trigger source. Channel 1 becomes the X axis if this button is pressed during X - Y operation. CH2: Channel 2 input signal serves as the trigger source. Channel 2 becomes the X axis if this button is pressed during X - Y operation. 11 Fig. 2-3 © INTENSITY Adjusts the brightness of the trace. @ LEVEL/PULL SLOPE ( - ) LEVEL: Trigger level adjustment control. Determines point on trigger signal w a v e form where s w e e p starts. SLOPE: Trigger polarity selector. Pulling the knob triggers the s w e e p at the falling slope of the input w a v e f o r m . <§) AUTO/NORM (TRIG MODE) Knob for selecting the triggering mode. AUTO: Triggered s w e e p operation w h e n trigger signal is present, automatically generates s w e e p (free run) in absence of trigger signal. NORM: Normal triggered s w e e p operation. Unlike A U T O , no s w e e p appears w h e n the proper trigger signal is not applied. © © NORM/LINE (TRIG SOURCE) Select the trigger source (sync signal source). T h e following trigger sources can be selected. When NORM is selected with the s w i t c h @>, s w i t c h @ selects either internal triggering ( _•_ INT) or external triggering ( E X T ) . INT: Internal triggering is selected and the s w e e p is triggered by the signal input for the vertical a x i s . Either the channel 1 or channel 2 signal can be selected as the trigger source using T R I G or X © . EXT: T h e trigger source is the signal applied to the E X T . T R I G jack @ . W h e n LINE is selected w i t h s w i t c h (§): LINE: T h e s w e e p is triggered by the line power frequency. 12 ® (23) TRIG COUPLING Select the coupling method used for the trigger signal. W h e n NORM is selected w i t h s w i t c h @ , either A C coupling ( J I _ A C ) or DC coupling ( _M_ DC) can be selected with s w i t c h (§). AC: Trigger signal is A C coupled to the s y n c circuit. Blocks D C component of input signal. Most commonly used position for w a v e f o r m observation. DC: Trigger signal is DC coupled to the s y n c circuit. S w e e p is trigger by signal including D C component. W h e n T V ( J L ) is selected with s w i t c h (22), vertical s y n c (_•_) or horizontal s y n c ( J * . ) is selected by s w i t c h (23). V: S w e e p is triggered by vertical s y n c pulses of video signal. H: S w e e p is triggered by horizontal s y n c pulses of video signal. ® S W E E P VARIABLE Provides fine adjustment of s w e e p time; continuous adjustment is possible between steps selected by S W E E P TIME/DIV © . S w e e p time is calibrated by in the extreme clockw i s e ( C A L ) position. (25) S W E E P TIME/DIV S w e e p time coarse selector. Selects s w e e p times between 0 . 2 /ts/div and 1 s/div in 21 steps. Indicated values are calibrated w h e n S W E E P V A R I A B L E ® control is set to C A L position (fully c l o c k w i s e ) . Oscilloscope is set to X - Y operating mode w h e n this knob is rotated to fully counterclockwise ( X - Y ) position. In X - Y operation, sweeping stops and the source selected by T R I G or X © becomes the X axis amplifier and the source selected by V or Y MODE ® becomes the Y axis amplifier. © % POSITION/PULL x 5 MAG Rotation adjusts the horizontal position of the trace on the display. Pulling this knob increases the s w e e p time five times. T h e S W E E P T I M E / D I V value is 1 / 5 of the indicated value at this time. 13 Rear Panel Fig. 3 @ GND Terminal C h a s s i s ground terminal used for establishing a common ground with other equipment. <§) E X T . TRIG Jack Input terminal for external trigger signal. W h e n the T R I G S O U R C E @> control is set to NORM and © is set to E X T , the signal input to this terminal becomes the trigger signal. (§) Fuse Holder Contains the line fuse. Verify that the proper fuse is installed when replacing the line fuse. 1 0 0 V to 1 2 0 V 0.5A 2 0 0 V to 2 4 0 V 0.3A 14 BOTTOM PANEL Fig. 4 (§) T R A C E R O T A T I O N Electrically rotates trace to horizontal position, Adjust w h e n strong magnetic fields cause the trace to be tilted. © FOCUS Adjusts the trace for optimum f o c u s . 15 OPERATION INITIAL STARTING PROCEDURE Until you familiarize yourself with the use of all controls, the following procedure may be used to standarize the initial setting of controls as a reference point and to obtain trace on the C R T in preparation for waveform observation. W h e n using the probe(s), refer to probe's instructions and " P R O B E C O M P E N S A T I O N " listed in A P P L I C A T I O N of this manual. Fig. 5 [1] NORMAL SWEEP DISPLAY OPERATION 1 . Push the P O W E R s w i t c h © — the power supply will be turned on and the pilot lamp will light. Set these modes a s follows; V or Y M O D E @ : CH1 TRIG MODE ® : AUTO 2. T h e trace will appear in the center of the C R T display and can be adjusted by the C H 1 ^ POSITION © and ^ • P O S I T I O N © controls. Next, adjust the I N T E N S I T Y @ and, if necessary, the F O C U S (fj) for ease of observation. 3 . Vertical Modes Apply an input signal to the C H 1 INPUT ® jack and adjust the V O L T S / D I V © control for a suitable size display of the w a v e f o r m . If the waveform does not appear in the display, adjust the V O L T S / D I V and y POSITION controls to bring the waveform into the center portion of the C R T display. Operation with a signal applied to the C H 2 INP U T (J3) jack and the V or Y MODE set to C H 2 is similar to the above procedure. In the A D D mode, the algebraic sum of CH1 + C H 2 is displayed. If the C H 2 INV © switch has been engaged, the algebraic difference of the t w o w a v e f o r m s , C H 1 — C H 2 is displayed. If both channels are set to the same V O L T S / D I V , the sum or difference can be read directly in V O L T S / D I V from the C R T . In the A L T mode, one s w e e p displayes the channel 1 signal and the next s w e e p displays the channel 2 signal in an alternating sequence. 16 In the C H O P mode, the s w e e p is chopped at an approximate 5 0 kHz rate and s w i t c h e d between C H 1 and C H 2 . Note that in the C H O P mode of operation, the trigger source becomes the chopping signal itself, making waveform observation impossible. Use A L T mode instead in s u c h c a s e s , or select a trigger S O U R C E of C H 1 or C H 2 . If no trace is obtainable, refer to the following T R I G G E R I N G procedures. 4 . After setting the S O U R C E s w i t c h , adjust the S L O P E control. The display on the screen will probably be unsynchronized. Refer to T R I G G E R I N G procedure below for adjusting synchronization and s w e e p speed to obtain a stable display showing the desired number of w a v e f o r m . TRIGGERING T h e input signal must be properly triggered for stable w a v e f o r m observation. T R I G G E R ING is possible the input signal INTernally to create a trigger or with an EXTernally provided signal of timing relationship to the observed signal, appliying s u c h a signal to the E X T T R I G INPUT jack. T h e S O U R C E s w i t c h selects the input signal that is to be used to trigger the s w e e p , w i t h INT s y n c possibilities ( C H 1 , C H 2 , LINE) and E X T s y n c possibility. * Internal S y n c W h e n the S O U R C E selection is in NORM and INT ( C H 1 or C H 2 ) , the input signal is connected to the internal trigger circuit. In this position, a part of the input signal fed to the INPUT ® or © jack is applied from the vertical amplifier to the trigger circuit to cause the trigger signal triggered with the input signal to drive the s w e e p . W h e n the V or Y MODE selection is in A L T , the A L T position is very convenient for m e a s uring the time duration of the w a v e f o r m . However, for phase or timing comparisons between the channel 1 and channel 2 w a v e f o r m s , both traces must be triggered by the same s y n c signal. W h e n the S O U R C E selection is in NORM and INT ( C H 1 ) , the input signal at the channel 1 INPUT (8) jack becomes trigger regardless of the position of V or Y M O D E . W h e n the S O U R C E selection is in NORM and INT ( C H 2 ) , the input signal at the channel 2 INPUT © jack becomes trigger regardless of the position of V or Y M O D E . W h e n the S O U R C E selection in LINE, the A C line voltage powering the oscilloscope is used as s y n c triggering. * External Sync W h e n the S O U R C E selection is in NORM and E X T , the input signal at the E X T T R I G INPUT © jack becomes the trigger. T h i s signal must have a time or frequency relationship to the signal being observed to synchronize the display. External s y n c is prefered for w a v e form observation in many applications. For example, Fig. 6 s h o w s that the s w e e p circuit is driven by the gate signal w h e n the gate signal in the burst signal is applied to the E X T T R I G INPUT jack. Fig. 6 also s h o w s the input/output signals, where the burst signal generated from the signal is applied to the instrument under test. T h u s , accurate triggering can be achieved without regard to the input signal fed to the INPUT (8) or @ jack so that no further triggering is required even w h e n the input signal is varied. 17 Trigger signal (Gate signal) • CH1 (Input signal to amplifier, etc.) C H 2 (Output signal from amplifier, etc.) Fig. 6 * Triggering Level Trigger point on waveform is adjusted by the L E V E L / P U L L S L O P E ® control. Fig. 7 s h o w s the relationship between the S L O P E and L E V E L of the trigger point. Triggering level can be adjusted as necessary. SLOPE " - " RANCE S L O P E " + " RANGE LEVEL Fig. 7 * Auto Trigger W h e n the T R I G MODE (jj) selection is in A U T O , the s w e e p circuit becomes free-running as long a s there is no trigger signal, permitting a check of GND level. W h e n a trigger signal is present, the trigger point can be determined by the L E V E L control for observation as in the normal trigger signal. When the trigger level exceeds the limit, the trigger circuit also becomes free-running where the w a v e f o r m starts running. When the L E V E L control is pushed in and/or, w h e n the trigger signal is absent or the triggering level exceeds the limit, there is no s w e e p . 18 [2] MAGNIFIED SWEEP OPERATION Sfnce merely shortening the s w e e p time to magnify a portion of an observed w a v e f o r m can result in the desired portion disappearing off the screen, such magnified display should be performed using the MAGNIFIED S W E E P . Using the POSITION control, adjust the desired portion of w a v e f o r m to the C R T . Pull out the PULL x 5 M A G control to magnify the display 5 times. For this type of display the s w e e p time is the S W E E P T I M E / D I V setting divided by 5 . [3] X - Y OPERATION For some measurements, an external horizontal deflection signal is required. T h i s is also referred to a s an X - Y measurement, where the Y input provides vertical deflection and X input provides horizontal deflection. X - Y operation permits the oscilloscope to perform many types of measurements not possible with conventional s w e e p operation. T h e C R T display becomes an electronic graph of t w o instantaneous voltages. T h e display may be a direct camparison of t w o voltages s u c h a s during phase measurement, frequency measurement with Lissajous w a v e f o r m s . To use an external horizontal input, use the following procedure; 1. Set the S W E E P T I M E / D I V control to the X - Y position. 2. Use the channel 1 probe for the vertical input and the channel 2 probe for the horizontal input. 3 . Adjust the amount of horizontal deflection w i t h the C H 2 V O L T S / D I V and V A R I A B L E controls. 4 . T h e C H 2 (vertical) POSITION (§) control now serves as the horizontal position control, and the ^ POSITION control is disabled. 5 . All s y n c controls are disconnected and have no effect. [4] VIDEO SIGNAL OBSERVATION The T V - V / H s w i t c h permits selection of vertical or horizontal s y n c pulse for s w e e p triggering w h e n viewing composite video w a v e f o r m s . In the T V - H position, horizontal s y n c pulses are selected as triggers to permit viewing of horizontal line of video. T h i s is also the position used for viewing all non-video w a v e f o r m s . In the T V - V position, vertical s y n c pulses are selected as triggers to permit viewing of vertical fields and frames of video. W h e n observing the video w a v e f o r m s , stable display is obtained on the screen regardless the T R I G L E V E L @ control. A t most points of measurement, a composite video signal is of the polarity, that i s , the s y n c pulses are negative and the video is positive. In this c a s e , use " - " S L O P E . If the waveform is taken at a circuit point where the video w a v e f o r m is inverted, the s y n c pulses are positive and the video is negative. In this c a s e , use " + " S L O P E . 19 APPLICATION PROBE COMPENSATION T o obtain an accurate measurement result, the probe must be adjusted correctly before measurement. 1 . Connect the probe to the INPUT terminal and set the control for a normal s w e e p display. 2. Connect the probe to the C A L terminal on the front panel, and adjust the S W E E P T I M E / D I V control to display a f e w c y c l e s of the signal output from it. 3 . Adjust the trimmer on the probe to obtain the following correct compensation waveform. Correct compensation Over compensation Insufficient compensation Fig. 8 T R A C E ROTATION COMPENSATION Rotation from a horizontal trace position can be the cause of measurement errors. Adjust the controls for a single display. Set the AC-GND-DC switch to GND and T R I G MODE to A U T O . Adjust the y POSITION control s u c h that the trace is over the center horizontal graticule line. If the trace appears to be rotated from horizontal, align it with the center graticule line using the T R A C E R O T A T I O N control located on the front panel. DC V O L T A G E MEASUREMENTS T h i s procedure describes the measurement procedure for DC w a v e f o r m s . Procedure: 1 . Connect the signal to be measured to the INPUT jack.Set the V or Y MODE to the channel to be used. Set the V O L T S / D I V and S W E E P T I M E / D I V s w i t c h to obtain a normal display of the waveform to be measured. S e t the V A R I A B L E control to the C A L position. 20 2. Set the T R I G MODE to A U T O and A C - G N D - D C to the GND position, w h i c h established the zero volt reference. Using the f POSITION control, adjust the trace position to the desired reference level position, making sure not to disturb this setting once made. 3 . Set the A C - G N D - D C s w i t c h to the D C position to observe the input w a v e f o r m , including its DC component. If an appropriate reference level or V O L T S / D I V setting w a s not made, the waveform may not be visible on the C R T screen at this point. If s o , reset V O L T S / D I V and/or the $ POSITION control. 4 . Use the -< • POSITION control to bring the portion of the waveform to be measured to the center vertical graduation line of the C R T screen. 5. Measure the vertical distance from the reference level to the point to be measured, (the reference level can be rechecked by setting the A C - G N D - D C s w i t c h again to GND). Multiply the distance measured above by the V O L T S / D I V setting and the probe attenuation ratio as well. Voltages above and below the reference level are positive and negative values respectively. Using the formula: DC level = Vertical distance in d i v i s i o n s x ( V O L T S / D I V setting) x (probe attenuation ratio). Vertical distance Measuring point adjusted to the center vertical scale by M • POSITION Ground potential adjusted by £ POSITION (reference line) Fig. 9 [EXAMPLE] For the example, the point being measured is 3.8 divisions from the reference level (ground potential). If the V O L T S / D I V w a s set to 0 . 2 V/div and a 10:1 probe w a s used. (See Fig. 9) Substituting the given values: DC level = 3.8 (div) x 0 . 2 ( V / d i v ) x 10 = 7.6 V 21 M E A S U R E M E N T OF T H E V O L T A G E B E T W E E N T W O POINTS ON A WAVEFORM T h i s technique can be used to measure peak-to-peak voltages. Procedure: 1. Apply the signal to be measured to the INPUT jack. S e t the V or Y MODE to the channel to be used. Set the A C - G N D - D C to A C , adjusting V O L T S / D I V and S W E E P T I M E / D I V for a normal display. S e t the V A R I A B L E to C A L . 2. Using the * POSITION control, adjust the waveform position such that one of the t w o points falls on a C R T graduation line and that the other is visible on the display screen. 3 . Using the •< • POSITION control, adjust the second point to coincide with the center vertical graduation line. 4 . Measure the vertical distance between the t w o points and multiply this by the setting of the V O L T S / D I V control. If a probe is used, further multiply this by the attenuation ratio. Using the formula: Volts Peak-to-Peak = Vertical distance (div) x ( V O L T S / D I V setting) x (probe attenuation ratio) Adjust to the center vertical scale with •+ POSITION Vertical distance between two points Points to be measured Adjust to the horizontal scale with ± POSITION Fig. 10 [EXAMPLE] For the example, the t w o points are separated by 4 . 4 divisions vertically. S e t the V O L T S / D I V setting be 0 . 2 V/div and the probe attenuation be 1 0 : 1 . (See Fig. 10) Substituting the given value: Voltage between t w o points = 4 . 4 ( d i v ) x 0 . 2 ( V / d i v ) x 10 = 8 . 8 V 22 ELIMINATION OF UNDESIRED SIGNAL COMPONENTS The A D D feature can be conveniently used to cancel out the effect of an undesired signal component which superimposed on the signal you w i s h to observe. Procedure: 1 . Apply the signal containing an undesired component to the C H 1 INPUT jack and the undesired signal itself alone to the C H 2 INPUT jack. 2. Set the V or Y MODE to C H O P and S O U R C E to C H 2 . Verify that C H 2 represents the unwanted signal in reverse polarity. If necessary reverse polarity by setting C H 2 to INV. 3 . Set the V or Y MODE to A D D and C H 2 V O L T S / D I V and V A R I A B L E so that the undesired signal component is cancelled a s much as possible. T h e remaining signal should be the signal y o u w i s h to observe alone and free of the unwanted signal. Signal containing undesired component (Broken lines undesired component envelope) Undesired component signal Fig. 1 1 Signal without undesired component 23 TIME MEASUREMENTS T h i s is the procedure for making time measurements between t w o points on a w a v e f o r m . The combination of the S W E E P T I M E / D I V and the horizontal distance in divisions between the t w o points is used in the calculation. Procedure: 1. Apply the signal to be measured to the INPUT jack. S e t the V or Y MODE to the channel to be used. Adjust the V O L T S / D I V and S W E E P T I M E / D I V for a normal display. Be sure that the V A R I A B L E control is set to C A L . 2. Using the f POSITION control, set one of the points to be used as a reference to coincide w i t h the horizontal centerline. Use the ^ • POSITION control to set this point at the intersection of any vertical graduation line. 3 . Measure the horizontal distance between the t w o points. Multiply this by the setting of the S W E E P T I M E / D I V control to obtain the time between the t w o points. If horizontal " x 5 M A G " is used, multiply this further by 1/5. Using the formula: Time = Horizontal distance (div) x ( S W E E P T I M E / D I V setting) x " x 5 M A G " value" (1/5) 1 Adjust to the vertical scale with •< POSITION Fig. 1 2 Adjust to horizontal center line with * POSITION Horizontal distance [EXAMPLE] For the example, the horizontal distance between the t w o points is 5.4 divisions. If the S W E E P T I M E / D I V is 0 . 2 ms/div w e calculate. (See Fig. 12) Substituting the given value: Time = 5.4 (div) x 0 . 2 (ms/div) = 1.08 ms FREQUENCY MEASUREMENTS Frequency measurements are made by measuring the period of one cycle of w a v e f o r m and taking the reciprocal of this time value a s the frequency. Procedure: 1. Set the oscilloscope up to display one cycle of w a v e f o r m (one period). 2. T h e frequency is the reciprocal of the period measured. Using the formula: 24 Freq = p e r 1 j j o c Fig. 13 1 cycle = 4 0 /*s (5 /ts/div. x 8 div.) [EXAMPLE] A period of 4 0 is observed and measured. (See Fig. 13) Substituting the given value: Freq = 1 / [ 4 0 x 1 0 " ] = 2 . 5 x 1 0 = 2 5 kHz 6 4 While the above method relies on the measurement directly of the period of one c y c l e , the frequency may also be measured by counting the number of c y c l e s present in a given time period. 1 . Apply the signal to the INPUT jack. Set the V or Y MODE to the channel to be used and adjusting the various controls for a normal display. Set the V A R I A B L E to C A L . 2. Count the number of cycles of waveform between a chosen set of vertical graduation lines. Using the horizontal distance between the vertical lines used above and the S W E E P T I M E / D I V , the time span may be calculated. Multiply the reciprocal of this value by the number of cycles present in the given time span. If " x 5 M A G " is used multiply this further by 5. Note that errors will occur for displays having only a f e w c y c l e s . Using the formula: # of cycles x " x 5 M A G " value Freq = Horizontal distance (div) x S W E E P T I M E / D I V setting [EXAMPLE] For the example, within 7 divisions there are 10 c y c l e s . The S W E E P T I M E / D I V is 5 jis/div. (See Fig. 14) Substituting the given value: Freq= 7 ( d i v ) x 10 5 („ /div) = 2 8 5 7 k H z s Fig. 1 4 Count cycles between this portion 25 APPLICATION. OF X-Y OPERATION * Phase Shift Measurement A method of phase measurement requires calculations based on the Lissajous patterns obtained using X - Y operations. Distortion due to non-linear amplification also can be displayed. A sine w a v e input is applied to the audio circuit being tested. T h e same sine w a v e input is applied to the vertical input of the oscilloscope, and the output of the tested circuit is applied to the horizontal input of the oscilloscope. T h e amount of phase difference bet w e e n the t w o signals can be calculated from the resulting w a v e f o r m . T o make phase measurements, use the following procedure. 1 . Using an audio signal generator with a pure sinusoidal signal, apply a sine w a v e test signal at the desired test frequency to the audio network being tested. 2. S e t the signal generator output for the normal operating level of the circuit being tested. If desired, the circuit's output may be observed on the oscilloscope. If the test circuit is overdriven, the sine w a v e display on the oscilloscope is clipped and the signal level must be reduced. 3 . Connect the channel 2 probe to the output of the test circuit. 4 . Select X - Y operation by rotating the S W E E P T I M E / D I V control clockwise to the X - Y position. 5 . Connect the channel 1 probe to the input of the test circuit. (The input and output test connections to the vertical and horizontal oscilloscope inputs may be reserved.) 6. Adjust the channel 1 and 2 gain controls for a suitable viewing size. 7. S o m e typical results are s h o w n in Fig. 1 6 . If the t w o signals are in phase, the oscilloscope trace is a straight diagonal line. If the vertical and horizontal gain are properly adjusted, this line is at a 4 5 ° angle. A 9 0 ° phase sift produces a circular oscilloscope pattern. Phase shift of less (or more) than 9 0 ° produces an elliptical oscilloscope pattern. T h e amount of phase shift can be calculated from the oscilloscope trace as shown in Fig. 1 5 . SINE 4>= — B No amplitude distortion, no out of phase No amplitude distortion, out of phase Amplitude distortion, no out of phase Amplitude distortion, out of phase 1 8 0 ° out of phase 9 0 ° out of phase Where 0 = phase angle Fig. 1 5 Phase shift calculation 28 Fig. 1 6 Typical phase measurement oscilloscope displays MAINTENANCE AND ADJUSTMENT A Caution : Read this page carefully to keep your safety. For Electric Shock Protection: Be sure to disconnect the power cable from the socket before conducting the following operation. MAINTENANCE There is high voltage used inside this unit. Never open the case. R E P L A C E M E N T OF FUSES This oscilloscope will not function if the fuse has blown. If the fuse blows, determine the c a u s e , and contact your dealer if the cause lies in this equipment. If the cause w a s external to this equipment, remove the cause, detach the fuse holder from the rear panel using a flatblade screwdriver, and insert a n e w f u s e . Rear Panel Flatblade Screwdriver Fig. 17 27 ADJUSTMENT This oscilloscope w a s already fully adjusted w h e n shipped from the factory. If adjustment becomes necessary, heed the following precautions. 1. S e t the power supply voltage to the proper level. 2 . Use only insulated adjustment screwdrivers for adjustment. 3 . Turn on the power and allow the unit to warmup sufficiently before adjustment. 4 . For any adjustment requiring measurement instruments, leave the unit in its current state and contact your dealer. OSCILLOSCOPE ADJUSTMENT This unit has a total of eight trimmers (see diagram below) which can be externally adjusted. If misadjustment occurs during u s e , adjust according to the procedures outlined below. Use plastic tipped screwdrivers for adjustment and use care to prevent shorting any of the circuits. Fig. 18 28 ADJUSTMENTS ® CH1 • ® CH2 S T E P BAL: Adjusts any vertical movement in the trace occurring w h e n the V O L T S / D I V knob is rotated. @) CH1 • © CH2 DC BAL: Adjusts any vertical movement in the trace occurring w h e n the V A R I A B L E knob is rotated. © C H 1 • © C H 2 GAIN: Adjusts the sensitivity of the vertical a x i s . © T R A C E ROTATION: Adjusts the trace w h e n it is tilted due to effects of a strong magnetic field. © FOCUS: Adjusts the focus. ADJUSTMENT PROCEDURES T R A C E ROTATION: Set the selector to the GND position, position the trace over the reference scale on the display, and adjust if tilted. FOCUS: Adjust the focus for optimum sharpness of the w a v e f o r m . The S T E P B A L and DC B A L adjustment begin w i t h S T E P B A L adjustment due to the circuit design. S T E P BAL: Set the selector to the GND position, and adjust for C H 1 and C H 2 so that the trace does not move w h e n the V O L T S / D I V knob is switched between the 1 , 2 , and 5 ranges. DC BAL: In the same manner as S E T B A L , adjust for C H 1 and C H 2 so that the trace does not move V A R I A B L E knob is rotated from the right to the left extreme. A highly accurate calibrator is needed for the GAIN adjustment. If s u c h an instrument is not available, contact your dealer. (These trimmer are for correcting any sensitivity shifts in C H 1 and C H 2 ) . GAIN: A c c u r a c y will be improved if a calibration signal with an amplitude of 4 or 5 divisions on the C R T is used. Contact your dealer if adjustment is not possible by the above procedures. 29 MEMO 30 MEMO 31 A product of KENWOOD CORPORATION 17-5, 2-chome, S h i b u y a , Shibuya-ku, Tokyo 150, J a p a n ">
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