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Oscilloscope HM 303-4 GB

1. 0 05 4 6 0 23V pp Input voltage U DV set deflection coefficient D 1V div required display height H 5 1 5div Signal voltage U 230V 2 2 651V voltage gt 160V with probe 10 1 U 65 1 desired display height min 3 2div max 8div max deflection coefficient D 65 1 3 2 20 3V div min deflection coefficient D 65 1 8 8 1V div adjusted deflection coefficient D 10V div The input voltage must not exceed 400V indepen dent from the polarity an AC voltage which is superimposed on a DC voltage is applied the maximum peak value of both voltages must not exceed or 400V So for AC voltages with a mean value of zero volt the maximum peak to peak value is 800V If attenuator probes with higher limits are used the probes limits are valid only if the oscilloscope is set to DC input coupling If DC voltages are applied under AC input coupling conditions the oscilloscope maximum input voltage value remains 400V The attenuator consists of aresistorinthe probe and the 1M input resistor of the oscilloscope which are disabled by the AC input coupling capacity when AC coupling is selected This also applies to DC voltages with superimposed AC voltages It also must be noted that due to the capacitive resistance of the AC input coupling capacitor the attenuation ratio depends on the signal frequency For sinewave signals with frequencies higher than 40Hz this influence is neglig
2. able This is relatively easy on the HZ51 and HZ54 but slightly more difficult on the HZ52 The rising edge should be as steep as possible with a pulse top remaining as straight and horizontal as possible On the HZ52 each of the three trimmers has a clearly defined area of influence on the waveform shape see Fig offering the added advantage of being able to straighten out waveform abberations near the leading edge HZ51 HZ54 St Osc LF T CAL T T T 2016 Jj ns cm HF C T LF 252 alters the middle frequencies alters the leading edge alters the lower frequencies 13 Aftercompletionofthe HF adjustment thesignal amplitude displayed on the CRT screen should have the same value as during the 1kHz adjustment Adjustment 1MHz i ES Si Probes other than those mentioned above normally have a larger tip diameter and may not fit into the calibrator outputs Whilst it is not difficult for an experienced operator to build a suitable adapter it should be pointed out that most of these probes have aslowerrisetime withthe effectthatthe total bandwidth of scope together with probe may fall far below that of the HM 303 Furthermore the HF adjustment feature is nearly always missing so that waveform distortion can not be entirely excluded The adjustment sequence must be followed in the order described i e first at 1kHz then at 1M Hz The calibrat
3. selectable frequencies of approx 1kHz and 1M Hz from two output sockets below the CRT screen This signal should not be used for frequency cali bration Subject to change without notice One output providesO 2V 1 t 4ns for 10 1 probes and the other 2V 1 for 100 1 probes When the attenuator switches are settobmV div vertical deflection coefficient these calibration voltages correspond to a screen amplitude of 4diiv The output sockets have an internal diameter of 4 9mm to accommodate the intemationally accepted shielding tube diameter of modern M odular Probes and F series slimline probes Onlythis type of construction ensures the extremly short ground connections which are essential for an undistorted waveform reproduction of non sinusoidal high frequency signals Adjustment at 1kHz The C trimmer adjustment compensates the capacitive loading on the oscilloscope input approx 20 pF for the HM 303 By this adjustment the capacitive division assumes the same ratio as the ohmic voltage divider to ensurethe same division ratio forhigh and low frequencies as for DC For 1 1 probes or switchable probes set to 1 1 this adjustmentis neither required nor possible A baseline exactly parallel to the horizontal graticule lines is a major condition for accurate probe adjustments See also Trace rotation Connect the probes Types HZ51 52 53 54 or HZ36 to the input All pushbuttons should be releas
4. As previously written in the paragraph First Time Opera tion the AT NORM pushbutton should be switched in AT position as a baseline is then permanently displayed also without any input signal The trace disappears at times after applying an input signal The LED indication shows in which direction the trace has left the screen above or below the graticule Illumination of both LEDs at the same time after applying a signal means that the vertical deflection has overscanned the graticule edges in both vertical directions With DC input coupling and an applied signal with a relatively high DC offset smaller sizes also of displayed signals can overscan the raster edges because the DC voltage causes a vertical position shiftofthe display height which seemed correctly adjusted Inthis case asmaller display height must be accepted or AC input coupling has to be selected Component Tester General The HM 303 has a built in electronic Component Tester COMP TESTER which is used for instant display of a test pattern to indicate whether or not components are faulty The COMP TESTER can be used for quick checks of semiconductors e g diodes andtransistors resistors capacitors and inductors Certain tests can also be made to integrated circuits All these components can be tested in and out of circuit Thetest principle is fascinatingly simple A built in generator delivers a sine voltage which is applied across the component und
5. When using a 500 cable such as the 34 a50Q through termination type HZ22 is available from HAM EG When transmitting square signals with short rise times transient phenomena on the edges and top of the signal may become visible if the correct termination is not used A terminating resistance is sometimes recommended with sine signals as well Certain amplifiers generators or their attenuators maintain the nominal output voltage independent of frequency only if their connection cable is terminated with the prescribed resistance Here it must be noted that the terminating resistor HZ22 will only dissipate a maximum of 2 Watts This power is reached with 10 Vrms or at 28 3 V with sine signal If a x10 or x100 attenuator probe is used no termination is necessary Inthis case the connecting cable is matched directly to the high impedance input of the oscilloscope When using attenuators probes even high internal impedance sources are only slightly loaded approx 10 16 pF or 100 MQ II 9 pF with HZ 53 Therefore if the voltage loss dueto the attenuation of the probe can be compensated by a higher amplitude setting the probe should always be used The series impedance of the probe provides a certain amount of protection forthe input of the vertical amplifier Because of their separate manufacture all attenuator probes are only partially compensated therefore accurate compensation must be performed onthe oscilloscope see Pr
6. Both base lines are set onto the horizontal graticule center line with the Y POS knobs before the measurement With sinusoidal signals observe the zero crossover point transitions the sine peaks are less accurate If a sine signal is noticeably distorted by even harmonics or if a d c voltage is present AC coupling is recommended for both channels If it is a question of pulses of the same shape read off at steep edges 15 Phase difference measurement in DUAL mode t horizontal spacing of the zero transitions in div T horizontal spacing for one period in div Lo uem T In the example illustrated t 3div and T 10div The phase difference in degrees is calculated from 360 3 10 360 108 arcq i 2 2 1 885 rad Relatively small phase angles at not too high frequencies can be measured more accurately in the X Y mode with Lissajous figures Measurement of an amplitude modulation The momentary amplitude u at time t of a HF carrier voltage which is amplitude modulated without distortion by a sinusoidal AF voltage is in accordance with the equation u U sinQt 3 0 5m U cos Q o t 0 5m U cos Q 4o t unmodulated carrier amplitude Q 2 angular carrier frequency o 2rf modulation angular frequency m modulation factor i a lt 12 100 where The lowerside frequencyF fand the upper side freq
7. F between 0 5Hz and 30M Hz T between O 1us div and 0 2s div in 1 2 5 sequence with X MAG x10 in out position and T between 10ns div and 20ms div in 1 2 5 sequence with pushed X MAG x10 pushbutton Subject to change without notice mmmmmmm CO Examples Displayed wavelength L 7div set time coefficient T 0 1us div required period T 7 0 1 10 0 715 required rec freq 1 0 7 10 9 1 428MHz Signal period T 1s set time coefficient T 0 2s div required wavelength L 1 0 2 5div Displayed ripple wavelength L 1div set time coefficient 10ms div required ripple freq 1 1x10x10 100Hz TV line frequency 15625Hz set time coefficient T 10us div required wavelength L 1 15 625 105 6 4div Sine wavelength L min 4div max 10div Frequency 1kHz max time coefficient 1 4x10 0 25ms div min time coefficient T 1 10 10 0 1ms div set time coefficient T 0 2ms div required wavelength L 1 10 x0 2x10 5div Displayed wavelength L 0 8div set time coefficient T 0 5ys div pressed X MAG x10 button T 0 05us div required rec freq 1 0 8x0 05x10 25MHz required period T 1 25 105 40ns If the time is relatively short as compared with the complete signal period an expanded time scale should always be applied X MAG x10 button pressed In this case th
8. Hz Then alternately release and depress theCHOP pushbutton Checkfor negligible trace widening and periodic shadowing in the chopped mode It is important to note that in the I HI add mode only ADD depressed or the 1 difference mode INVERT CHII button depressed in addition the vertical position of the trace can be adjusted by using both the Channel and Channel 1 Y POS controls In X Y Operation XY pushbutton depressed the sensitivity in both deflection directions will be the same When the signal from the built in square wave generator is applied to the input of Channel II then as with Channel in the vertical direction there must be a horizontal deflection of 4div when the deflection coefficientis setto 50mV div position varia ble control set to its CAL position X MAG x10 button in out position The checkof the mono channel display withthe CHU llbutton is unnecessary itis contained indirectly in the tests above stated n Subject to change without notice Triggering Checks The intemal triggerthreshold is important as it determines the display height from which a signal will be stably displayed It should be approx 0 3 0 5div forthe HM 303 Anincreasedtriggersensitivity creates the riskof response to the noise level in the trigger circuit This can produce double triggering with two out of phase traces Alterationofthetriggerthresholdis only possible interna
9. Richtlinie 89 336 EWG erg nzt durch 91 263 EWG 92 EWG EMC Directive 89 336 amended by OU 263 EWG 92 31 Directive EMC 89 336 amend e par 91 263 EWG 92 31 Niederspannungsrichtlinie 73 23 EWG erg nzt durch 93 68 EWG Low Voltage Equipment Directive 73 23 amended by 93 68 Directive des equipements basse tension 73 23 CEE amend e par 93 68 CEE Angewendete harmonisierte Normen Harmonized standards applied Normes harmonis es utilis es Sicherheit Safety S curit EN 61010 1 1993 IEC CEI 1010 1 1990 A 1 1992 VDE 0411 1994 Uberspannungskategorie Overvoltage category Cat gorie de surtension Il Verschmutzungsgrad Degree of pollution Degr de pollution 2 Elektromagnetische Vertraglichkeit Electromagnetic compatibility Compatibilit lectromagn tique EN 50082 2 1995 VDE 0839 T82 2 ENV 50140 1993 IEC 1004 4 3 1995 0847 ENV 50141 1993 IEC 1000 4 6 VDE 0843 6 EN 61000 4 2 1995 IEC 1000 4 2 1995 0847 T4 2 Pr fsch rfe Level Niveau 2 EN 61000 4 4 1995 IEC CEI 1000 4 4 1995 VDE 0847 T4 4 Pr fscharfe Level Niveau 50081 1 1992 EN 55011 1991 CISPR11 1991 VDE0875 T11 1992 Gruppe group groupe 1 Klasse Class Classe B Datum Date Date Unterschrift Signature Signatur 14 12 1995 2 Dr J Herzog Technical Manager Directeur Tech
10. display heights Trouble Shooting the Instrument For this job at least an isolating variable mains line transformer protection class 11 a signal generator adequate precise multimeter and if possible an oscilloscope are needed This last item is required for complex faults which can be traced by the display of signal or ripple voltages As noted before the regulated high voltage and the supply voltages for the final stages are highly dangerous Therefore itis recommendedto use totally insulated extended probe tips when trouble shooting the instrument Accidental contact with dangerous voltage potentials is then unlikely Of course these instructions cannot thoroughly cover all kinds of faults Some common sense will certainly be required when a complex fault has to be investigated If trouble is suspected visually inspect the instrument thoroughly after removal of the case Look for loose or badly contacted or discolored components caused by overheating Checkto seethat all circuit board connections are making good contact and are not shorting to an adjacent circuit Especially inspect the connections betweenthe PCBs to front chassis parts to CRT PCB to trace rotation coil inside of CRTs shielding and to the control potentiometers and switches ontopof and beneath the PCBs This visual inspection can lead to success much more quickly than a systematic fault location using measuring instruments Prior to any extensi
11. e Connection of Test Signal Caution When connecting unknownsignals to the oscillo scope input always use automatic triggering and set the DC AC input coupling switchtoAC The attenuatorswitch should initially be set to 20V div Subject to change without notice Sometimes trace will disappear after input signal has been applied The attenuator switch must then be turned back to the left until the vertical signal height is only 3 8div With a signal amplitude greater than 160V an attenuator probe must be inserted before the vertical input If after applying the signal the trace is nearly blanked the period of the signal is probably substantially longer than the set value on the TIME DIV switch It should be turned to the left to an adequately larger time coefficient The signal to be displayed can be connected directly to the Y input of the oscilloscope with a shielded test cable such as HZ 32 or HZ 34 or reduced through a x10 or x100 attenuator probe The use of test cables with high impedance circuits is only recommended for relatively low frequencies up to approx 50 kHz For higher frequencies the signal source must be of low impedance i e matchedto the characteristic resistance of the cable as a rule 50 Ohm Especially when transmitting square and pulse signals a resistor equal to the characteristic impedance of the cable must also be connected across the cable directly at the Y input of the oscilloscope
12. horizontal PCBs They are highly dangerous and therefore precautions must be taken It should be noted furthermore that shorts occuring on different points of the CRT high voltage and unblanking circuitry will definitely damage some semiconductors and the opto coupler For the same reason it is very risky to connect capacitors to these points while the instrument is on Capacitors in the instrument may still be charged even when the instrument is disconnected from all voltage sources Normally the capacitors are discharged approx 6 seconds after switching off However witha defective instrument an interruption Subject to change without notice Service Instructions oftheload isnot impossible Therefore afterswitching off it is recommended to connect one by one all terminals of the check strips on the upper PCB across 1kQ to ground chassis for a period of 1 second Handling of the CRT needs utmost caution The glass bulb must not be allowed under any circumstances to come into contact with hardened tools nor should it undergo local superheating e g by soldering iron or local undercooling e g by cryogenic spray We recommend the wearing of safety goggles implosion danger The complete instrument with case closed and PO WER button depressed is after each intervention undergo a voltage test with 2200V DC between accessible parts to both mains line supply terminals This test is dangerous and requires an adequately
13. out of focus condition in the edge zone of the screen must be accepted It is limited by standards of the CRT manufacturer The same is valid fortolerances of the orthogonality the undeflected spot position the non linearity and the raster distortion in the marginal zone of Subject to change without notice Test Instructions the screen in accordance with international standards see CRT data book These limit values are strictly supervised by HAM EG The selection of a cathode ray tube without any tolerances is practically impossible Astigmatism Check Check whether the horizontal and vertical sharpness of the display are equal This is best seen by displaying a square wave signal with the repetition rate of approximately 1M Hz Focus the horizontal tops of the square wave signal at normal intensity then check the sharpness of the vertical edges If itis possible to improve this vertical sharpness by tuming the FOCUS control then an adjustment of the astigmatism control is necessary A potentiometer of 47kQ is provided inside the instrument for the correction of astigmatism see Service Instructions A certain loss of marginal sharpness of the CRT is unavoidable this is due to the manufacturing process of the CRT Symmetry and Drift of the Vertical Amplifier Both of these characteristics are substantially determined by the input stages of the amplifiers The symmetry of both channels and the vertical final amplifier can b
14. part of the square wave reduces to a needle pulse switching over to normal triggering and usingthe LEVEL control can be necessary With automatic triggering the trigger point lies approx inthe zero voltage crossing The time interval required for the time base start can be too short at a steep zero crossing of the needle pulse Then normal triggering should be used Automatic triggering is practicable not only with internal but also with external trigger voltage Normal Triggering With normal triggering AT NORM button depressed and LEVEL adjustment the sweep can be started by AC signals within the frequency range selected by the TRIG coupling switch In the absence of an adequate trigger signal or when the trigger controls particularly the LEVEL control are misadjusted no trace is visible i e the screen blanked completely When using the intemal normal triggering mode it is possible to trigger at any amplitude point of a signal edge even with very complex signal shapes by adjusting the LEVEL control Its adjusting range is directly dependent on the display height which should be at least O 5div If itis smallerthan 1div theLEVEL adjustment needs to be operated with a sensitive touch In the extemal normal Subject to change without notice triggering mode the same applies to approx 0 3V external trigger voltage amplitude Other measures fortriggering of very complex signals are the use of the time base variable
15. trained specialist Operating Voltages All operating voltages 6 3V 12V 12V 141V 185V 2025V are stabilized by the switch mode power supply The 12 supply is further stabilized and used as a reference voltage for 12V stabilisation These different operating voltages are fixed voltages except the 12V which can be adjusted The variation of the fixed voltages greater than 596 from the nominal value indicates a fault Measurements of the high voltage may only be accomplished by the use of a sufficient highly resistive voltmeter gt 10 You must make absolutely sure that the electric strength of the voltmeter is sufficiently high It is recommended to check the ripple and also the interaction from other possible sources Excessive values might be very often the reason for incomprehensible faults Maximum and Minimum Brightness Two variable resistors 220kQ and 470kQ located on the switch mode power supply PCB are used for these adjustment procedures see Adjusting Plan They may only be touched by a properly insulating screwdriver Caution High voltage The adjustments may possibly have to be repeated because the functions of both variable resistors are dependent on each other Correct adjustmentis achieved when the trace can be blanked while XY pushbutton is depressed and when the requirement described inthe Test Instructions are met Astigmatism control The ratio of vertical and horizonta
16. 0 probe is connected between the 2V output and Y input the same display height should result With highertolerances it should first be investigated whether the cause lies within the amplifier or in the amplitude of the square wave signal On occasions it is possible that the probe is faulty or incorrectly compensated If necessary the measuring amplifier can be calibrated with an accurately known DC voltage DC input coupling Thetrace position shouldthen vary in accordance with the deflection coefficient set With variable control atthe attenuator switch fully conter clockwise the input sensitivity is decreased at least by the factor 2 5 in each position In the 50mV div position the displayed calibrator signal height should vary from Adiv to at least 1 6div Transmission Performance of the Vertical Amplifier The transient response and the delay distortion correction can only be checked with the aid of a square wave generator with a fast risetime max 5ns The signal coaxial cable e g HZ34 must be terminated at the vertical input of the oscilloscope with a resistor equal to the characteristic impedance of the cable e g with HZ22 Checks should be made at 100Hz 1kHz 10kHz 100kHz and 1M Hz the deflection coefficient should be set atbmV div with DC input coupling Y variable control inCAL position Inso doing the square pulses must have a flat top without ramp off spikes and glitches no overshoot is permitted especia
17. 1096 Thus approximately 1196 should be added to the measured voltage at this frequency As the bandwidth of the amplifiers may differ slightly normally between 30 and 35M Hz the measured values in the upper frequency range cannot be defined exactly Additionally as already mentioned forfrequencies above 30M Hz the dynamic range of the display height steadily decreases The vertical amplifier is designed so that the transmission performance is not affected by its own overshoot Trace Rotation TR In spite of Mumetal shielding of the CRT effects of the earths magnetic field on the horizontal trace position cannot be completely avoided This is dependent upon the orientation of the oscilloscope on the place of work A centred trace may not align exactly with the horizontal center line ofthe graticule A few degrees of misalignment can be corrected by a potentiometer accessible through an opening on the front panel marked TR Probe compensation and use To display an undistorted waveform on an oscilloscope the probe must be matched to the individual input impedance of the vertical amplifier Forthis purpose a square wave signal with a very fast rise time and minimum overshoot should be used as the sinusoidal contents cover a wide frequency range The frequency accuracy and the pulse duty factor are not of such importance The built in calibration generator provides a square wave signal with a very fast risetime 4ns and switch
18. Comparingtwosignals of different frequency or bringing one frequency up to the frequency of the other signal This also applies forwhole number multiples orfractions of the one signal frequency Phase comparison between two signals of the same frequency Phase comparison with Lissajous figures The following diagrams show two sine signals of the samefrequency and amplitude with different phase angles d 35 90 180 Calculation of the phase angle or the phase shift between the X and Y input voltages after measuring the distances a and b on the screen is quite simple with the following formula and a pocket calculator with trigonometric functions Apart from the reading accuracy the signal height has no influence on the result sin 9 cos dr 1 b 9 arc sin Subject to change without notice The following must be noted here Because of the periodic nature of the trigonometric functions the calculation should be limited to angles lt 90 However here is the advantage of the method Do not use a too high test frequency The phase shift of the two oscilloscope amplifiers of the HM 303 in the X Y mode can exceed an angle of 3 above 120 kHz Itcannotbe seen as a matter of course fromthe screen display if the test voltage leads or lags the reference voltage A CR network before the test voltage input of the oscilloscope can help here The 1 MQ input resis tance can equally serve a
19. Ll 11 First Time Operation Before applying powerto the oscilloscope it is recom mended that the following simple procedures are performed Checkthat all pushbuttons are in the out position i e released Rotatethe variable controls with arrows i e TIME DIV variable control and CH II attenuator variable controls and HOLD OFF control to their calibrated detent Set all controls with marker lines to their midrange position marker lines pointing vertically TheTRIG selectorlever switch inthe X field should be Set to the position uppermost Both GD input coupling pushbutton switches for CH I andCH ll in the Y field should be settotheGD position Switch onthe oscilloscope by depressing the redPOWER pushbutton An LED will illuminate to indicate working order The trace displaying one baseline should be visible after a short warm up period of approx 10 seconds AdjustY POS l andX POS controls to centerthe baseline Adjust INTENS intensity and FOCUS controls for medium brightness and optimum sharpness of the trace The oscilloscope is now ready for use If only a spot appears CAUTION CRT phosphor can be damaged reduce the intensity immediately and check that the XY pushbutton is in the released out position If the trace is not visible check the correct positions of all knobs and switches particularlyAT NORM button in out position To obtain the maximum life from the cathode ray tube the
20. TR LED lights if sweep is triggered and triggering from channel II LED Trigger selection in DUAL mode ALT Triggering alternates between CHI and 29 Y MAG x5 When depressed increasing of pushbutton switch CHII in altemating DUAL Channel mode pushbutton switches Y sensitivity CH or CHII resp 5 fold only max 1mV div 41 SLOPE Selects the slope of the trigger signal DUAL Button released one channel only pushbutton switch edge pushbutton Button depressed channel I falling edge switch and channel II in alternating mode CHOP DUAL and ADD buttons depressed 42 TIME DIV Selects time coefficients speeds and CH II in chopped mode rotary switch of timebase from 0 2s div to 0 1ys div ADD ADD depressed only algebr addition pushbutton switch In combination with INVERT 43 Variable Variable adjustment of timebase difference timebase control Decreases X deflection speed center knob at least 2 5 fold 32 OVERSCAN Direction indicators Fortime measurements LED indicators Illuminated when trace passes turn to right hand stop vertical screen limits TRIG EXT Button released internal triggering 33 VAR GAIN Fine adjustment of Y amplitude CH II pushbutton switch Button depressed external triggering knob Increases attenuation factor trigger signal via TRIG INP 47 min by 2 5 left hand stop For amplitude measurement must be 45 AT NORM Button released autom t
21. Table of contents Oscilloscope datasheet Operating Instructions St 170698 h b goRR Subject to change without notice Su 6 General Information 6 Use of tilt 6 SLM 6 Operating 7 Warranty 7 a Maintenance 7 Osc 1 loscope Protective 7 Power supply 7 GB HM 303 4 Type of signal 8 Amplitude M easurement 8 Time Measurements 9 Connection of Test Signal 10 First Time Operation 12 Trace Rotation 12 Probe compensation and use 12 Operating Modes of the Y Amplifier 14 XY Operation iiiter teg nnno ste 15 Phase difference measurement In DUAL rriode 15 Measurement of an amplitude modulation 16 Triggering and Timebase 16 Automatic Triggering 17 Normal Triggering Slope 17 Trigger Coupling 17 Operating M odes CHI II TRIG I Il DUAL ADD Triggering of Video Signals 17 CHOP INV I Il and XY Operation 24 LINE TMOQGCHING EN 17 Trig
22. al pushbuttonswitches vertical amplifier adjustment with graticule line Compensates DC direct couplin screwdriver influence of earth s magnetic field coupling y Geh 4 FOCUS Focus control for m SE disconnected knob trace sharpness Y amplifier input grounded 5 X MAG x10 10 1 expansion in the X direction pushbutton switch Max resolution 10ns div INPUT CHI Channel signal input BNC connector Inputimpedance 1M QII20pF 6 X POS Controls horizontal knob position of trace 05 INVERT CHI Inversion of CH I display pushbutton switch In combination with ADD button 7 HOLDOFF Controls holdoff time difference CH II CH 1 knob betweensweeps Normal position full ccw VOLTS DIV Channel input attenuator 12 position Selects Y input sensitivity XY Selects X Y operation rotary switch in mV div or V div pushbutton switch stops sweep in 1 2 5 sequence X signal via CH Il Attention Phosphor burn in without X signal VAR GAIN Fine adjustment of Y amplitude CH I knob Increases attenuation factor 9 TRIG Trigger selector min by 2 5 left hand stop lever switch 10Hz 100M Hz For amplitude measurement must be AC DC LF TV DC 100 Hz in CAL position right hand stop LF DC 1 5kHz TV Triggering for frame and line CH I II TRIG 1 11 No button depressed CH only Internal line triggering pushbutton switch and triggering from channel When depressed channel II only
23. an only be measured with DC coupling Amplitude Measurements In general electrical engineering alternating voltage data normally refers to effective values rms root mean square value However forsignal magnitudes and voltage designations in oscilloscope measurements the peak to peak voltage V value is applied The latter corresponds to the real potential difference between the most positive and most negative points of a signal waveform If a sinusoidal waveform displayed on the oscilloscope screen is to be converted into an effective rms value the resulting peak to peak value must be divided by 2 2 2 83 Conversely it should be observed that sinusoidal voltages indicated in Vms Ver have 2 83 times the potential 8 difference Ma The relationship between the different voltage magnitudes can be seen from the following figure Voltage values of a sine curve Vms effective value V simple peak or crest value Vpp peak to peak value Vinom Momentary value The minimum signal voltage which must be applied to the Y input for a trace of 1div height is ImV when the Y MAG x5 pushbutton is depressed the VOLTS DIV switch is set to 5mV div and the vernier is set to CAL by tuming the fine adjustment knob of the VOLTS DIV switch fully clockwise However smaller signals than this may also be displayed The deflection coefficients on the input at
24. ated amplitude changes on a measuring signal AC voltage are displayable in Yt mode In this mode the signal voltage deflects the beam in vertical direction while the timebase generator moves the beam from the left to the right of the screen time deflection Normallythere are periodically repeating waveforms to be displayed Therefore the time base must repeat the time deflection periodically too To produce astationary display the time base must only be triggered if the signal height and slope condition coincide with the former time base start conditions A DC voltage signal can not be triggered as it is a constant signal with no slope Triggering can be performed bythe measuring signal itself internal triggering or by an external supplied but synchronous voltage external triggering The trigger voltage should have a certain minimum amplitude This value is called the trigger threshold It is measured with a sine signal When the trigger voltage is taken internally from the test signal the trigger threshold can be stated as vertical display height in div through which the time base generator starts the display is stable and the trigger LED lights 16 Subject to change without notice The internal trigger threshold of the HM 303 is given as lt 5div When the trigger voltage is externally supplied it canbe measured inV at the TRIG INP socket Normally the trig
25. be less than 3 meters long Signal lines must screened coaxial cable RG58 U A proper ground connection is required In combination with signal generators double screened cables RG223 U RG214 U must be used 3 Influence on measuring instruments Underthe presence of strong high frequency electric or magnetic fields even with careful setup of the measuring equipment an influence of such signals is unavoidable This will not cause damage or put the instrument out of operation Small deviations of the measuring value reading exceeding the instruments specifications may result from such conditions in individual cases December 1995 HAMEG GmbH KONFORMITATSERKLARUNG E DECLARATION OF CONFORMITY C FA r1 E E Instruments DECLARATION DE CONFORMITE Name und Adresse des Herstellers HAMEG GmbH Manufacturer s name and address Kelsterbacherstrafse 15 19 Nom et adresse du fabricant D 60528 Frankfurt HAMEG Sarl 5 av de la R publique F 94800 Villejuif Die HAMEG GmbH HAMEG Sarl bescheinigt die Konformit t f r das Produkt The HAMEG GmbH HAMEG Sarl herewith declares conformity of the product HAMEG GmbH HAMEG Sarl d clare la conformite du produit Bezeichnung Product name Designation Oszilloskop Oscilloscope Oscilloscope Typ Type Type HM303 4 mit with avec Optionen Options Options mit den folgenden Bestimmungen with applicable regulations avec les directives suivantes EMV
26. control and HOLDOFF time control hereinafter mentioned Slope The time base generator can be started by arising orfalling edge of the test signal This is valid with automatic and with normal triggering The selected slope is set with the SLOPE pushbutton The plus sign button released means an edge whichis coming from anegative potential and rising to a positive potential That has nothing to do with zero or ground potential and absolute voltage values The positive slope may also lie in a negative part of a signal A falling edge minus sign triggers when theSLOPE pushbutton is depressed However the trigger point may be varied within certain limits on the chosen edge using the LEVEL control The Slope directionis always related to the input signal andthe non inverted display Trigger coupling The coupling mode and accordingly the frequency range of the trigger signal can be changed using the TRIG selector switch AC Trigger range lt 20Hz to 100MHz This is the most frequently used trigger mode The trigger threshold is increasing below 20Hz and above 100M Hz Trigger range DC to 100MHz DC triggering is recommended if the signal is to be triggered with quiteslow processes orif pulse signals with constantly changing pulse duty factors have to be displayed With DC or LF trigger coupling always work with normal triggering and LEVEL adjustment LF Trigger range DC to 1 5kHz low pass filter The LF posi
27. d off control is in fully ccw position it triggers without line interlacing affects caused by the consecutive field M ore details in the video signal become visible if the X MAG x10 pushbutton is depressed in The X POS control allows to display any part of the expanded signal The influence of the integrating network which forms atrigger pulse from the vertical sync pulses may become visible under certain conditions Disconnecting the trigger circuit e g by rapidly pressing and releasing the EXT button can result in triggering the consecutive odd or even field On the 10us div setting line TV triggering is selected and approx 117 lines are visible Those lines originate randomly from the odd and even fields The sync separator circuit also operates with external triggering It is important that the voltage range 0 3 to for external triggering should be noted Again the correct slope setting is critical because the external trigger signal may not have the same polarity or pulse edge as the test signal This can be checked if the external trigger voltage itself is displayed first with internal triggering In most cases the composite video signal has a high DC content With constant video information e g test pattern or color bar generator the DC content can be suppressed easily byAC input coupling of the oscilloscope amplifier With achanging picture content e g normal program DC input coupling is recomm
28. e The bandwidth has been extended from 20 to 30MHz the sweep rate increased to 10ns div and improvements added to the already legendary auto triggering system The is the ideal instrument for waveform display in the DC to 70MHz frequency range A key feature of this oscilloscope is the vertical amplifier s pulse fidelity limiting overshoot to only 1 The HM303 offers a special fast rise time 1kHz 1MHz Calibratorpermitting high quality probe compensation across the entire frequency range to ensure probe tip thru to display integrity An Overscan Indicator assists in vertical display amplitude and position adjustment The is capable of triggering on input waveforms over 100MHz and on signal levels as small as 0 5 division Altemate triggering mode enables the display of two asynchronous signals simultaneously An active Video Sync Separator permits detailed examination of complex TV signal inputs A well proven built in component tester is now equipped with a stabilized measuring voltage The use of a switching type of power supply minimizes both weight and power consumption and universally accepts a wide range of input power line voltages without the requirement to change jumpers or switch positions The HM303 s CRT is fully mu metal shielded against outside magnetic fields is setting new price performance breakthroughs withthe introduction of this fine oscilloscope This performance packed scope wi
29. e ascertained time values have to be divided by 10 The time interval of interest can be shifted to the screen center using the X POS control When investigating pulse orsquare waveforms the critical feature is the risetime of the voltage step To ensure that transients ramp offs and bandwidth limits do not unduly influence the measuring accuracy the risetime is generally measured between 10 and 90 of the vertical pulse height For measurement adjust the Y attenuator switch with its variable control together with the Y POS control so that the pulse height is precisely aligned with the 0 and 100 lines of the internal graticule The 10 and 90 points of the signal will now coincide with the 10 and 90 graticule lines The risetime is given by the product of the horizontal distance in div between these two coincidence points and the time coefficient setting If X x10 magnification is used this product must be divided by 10 The fall time of a pulse can also be measured by using this method The following figure shows correct positioning of the oscilloscope trace for accurate risetime measurement 10 mE Si ttot r With a time coefficient of 0 2us div and pushed X M AG x10 button the example shown in the above figure results in a measured total risetime of 1 6div 0 2us div 10 32ns Whenveryfastrisetimes are being measured the risetimes of the oscilloscope amplifier and of the attenuator probe has to be deduc
30. e checked by inverting Channel 1 and Il depress the corresponding INVERT pushbutton The vertical position of the trace should not change by more thanO 5div However achange of 1div is just permissible Larger deviations indicate that changes have occurred in the amplifier A further check of the vertical amplifier symmetry is possible by checking the control range of the Y POS controls A sine wave signal of 10 100kHz is appliedto the amplifier input When the Y POS control is then tumed fully in both directions from stop to stop with a display height of approximately 8 amp div the upperand lower positions of the trace that are visible should be approximately of the same height Differences of up to 1div are permissible input coupling should be set to AC Checking the drift is relatively simple 20 minutes after switching on the instrument set the baseline exactly on the horizontal center line of the graticule The beam position must not change by more than O 5div during the following hour Calibration of the Vertical Amplifier Two square wave voltages of 0 2V and 2V 1 are present at the output sockets of the calibrator CAL If a direct connection is made between the0 2V output andthe 23 input of the vertical amplifier e g using a x1 probe the displayed signal in the 50mV div position variable control toCAL should be4div high DC input coupling Maximum deviations of 0 12div 396 are permissible If ax1
31. e negated by the use of an extension cord without a protective conductor The mains line plug should be inserted before connections are made to measuring circuits The grounded accessible metal parts case sockets jacks and the mains line supply contacts line live neu tral of the instrument have been tested against insulation breakdown with 2200V DC Under certain conditions 50Hz or 60Hz hum voltages can occur in the measuring circuit due to the inter connection with other mains line powered equipment orinstruments This can be avoided by using an isolation transformer Safety Class II between the mains line outlet and the power plug of the device being investigated Most cathode ray tubes develop X rays However the dose equivalent rate falls far below the maximum permissible value of 36pA kg 0 5mR h Whenever it is likely that protection has been impaired the instrument shall be made inoperative and be secured against any unintended operation The protection is likely to be impaired if for example the instrument shows visible damage fails to perform the intended measurements has been subjected to prolonged storage under unfavourable conditions e g in the open or in moist environments has been subjectto severe transport stress e g in poor packaging m X z Subject to change without notice Operating conditions The instrument has been de
32. e upper limit frequency of the vertical amplifier Displaying composite signals can be difficult especially if they contain no repetive higher amplitude content which can be usedfortriggering This is the case with bursts for instance To obtain a well triggered display in this case the assistance of the variable holdoff and or variable time control may be required Television video signals are relatively easy to trigger using the built in TV Sync Separator TV For optional operation as aDC orAC voltage amplifier the vertical amplifier input is provided with a DC AC switch The DC position should only be used with a series connected attenuator probe or at very low frequencies or if the measurement of the DC voltage content of the signal is absolutely necessary When displaying very low frequency pulses the flat tops may be sloping with AC coupling of the vertical amplifier AC limit frequency approx 1 6 Hz for 3dB In this case DC operation is preferred provided the signal voltage is not superimposed on a too high DC level Otherwise a capacitor of adequate capacitance must be connected to the input of the vertical amplifier with DC coupling This capacitor musthave asufficiently high breakdown voltage rating DC coupling is also recommended for the display of logic and pulse signals especially if the pulse duty factor changes constantly Otherwise the display will move upwards or downwards at each change Pure direct voltages c
33. ect comparison with a component of a known value Testing Capacitors and Inductors Capacitors and inductors cause a phase difference between current and voltage and therefore between the X and Y deflection giving an ellipse shaped display The position and opening width of the ellipse will vary according to the impedance value at 50Hz of the component under test A horizontal ellipse indicates a high impedance or a relatively small capacitance or a relatively high inductance A vertical ellipse indicates a small impedance or a relatively large capacitance or a relatively small inductance A sloping ellipse means that the component has a considerable ohmic resistance in addition to its reactance The values of capacitance of normal or electrolytic capacitors from O 1uF to 1000uF can be displayed and approximate values obtained M ore precise measurement can be obtained in a smaller range by comparing the capacitor under test with a capacitor of known value Inductive components coils transformers can also be tested The determination of the value of inductance needs some experience because inductors have usually ahigher ohmic series resistance However the impedance value at 50Hz of an inductor in the range from 200 to 4 7kQ can easily be obtained or compared Testing Semiconductors Most semiconductor devices such as diodes Z diodes transistors FETs can be tested The test pattern displays vary according to the comp
34. ed in the out position Set input coupling to DC the attenuator to 5 mV div and TIME DIV switch to 0 2 ms div and all variable controls to CAL position Plug the the probe tip into the appropriate calibrator output socket i e 10 1 probes into the 0 2V socket 100 1 probes into the 2V socket ATT ERT Mea 1 kHz I Yi incorrect correct incorrect Approximately 2 complete waveform periods are displayed onthe CRT screen Now the compensation trimmer has to be adjusted Normally this trimmer is located in the probe head Onthe 100 1 probe HZ53 however itis located inthe connecting box at the other end of the cable Adjust the trimmer with the insulating screw driver provided until the tops of the square wave signal are exactly parallel to the horizontal graticule lines see 1 kHz diagram The signal height should then be 4 div 0 12div 3 96 During this adjustment the signal edges will remain invisible Adjustment at 1MHz Probes HZ51 52 and 54 can also be HF compensated They incorporate resonance de emphasing networks R trimmer in conjunction with inductances and capacitors which permit probe compensation in the range of the upperfrequency limit of the vertical oscilloscope amplifier Subject to change without notice Only this compensative adjustment ensures optimum utilisation of the full bandwidth togeth
35. ended because the display varies its vertical position on screen with AC input coupling at each change of the picture content The DC content can be compensated using the Y POS control so that the signal display lies in the graticule area Then the composite video signal should not exceed a vertical height of Line triggering A voltage originating from mains line 50 to 60Hz is used for triggering purposes if the TRIG switch is set to This trigger mode is independent of amplitude and frequency of the Y signal and is recommended for all mains line synchronous signals This also applies within certain limits towhole number multiples orfractions of the line frequency Linetriggering canalso be usefulto display signals below the triggerthreshold less than 0 5div It is therefore particularly suitable for measuring small ripple voltages of mains line rectifiers or stray magnetic field in a circuit In this trigger mode theSLOPE pushbutton selects the positive or negati ve portion oftheline sinewave TheLEVEL control is usedfor trigger point adjustment in case of normal triggering AT NORM depressed Magnetic leakage e g from a power transformer can be investigated for direction and amplitude using a search or pick up coil The coil should be wound on a small former with a maximum of turns of a thin lacquered wire and connected to a BNC connector for scope input via a shielded cable Between cable and BNC center conduc
36. er test and a built in fixed resistor The sine voltage across the test object is used for the horizon tal deflection and the voltage drop across the resistor i e current through test object is used for vertical deflection of the oscilloscope The test pattern shows a current voltage characteristic of the test object Since this circuit operates with a frequency of 50Hz 10 and a voltage of 6V max open circuit the Subject to change withoutnotice Pn 19 indicating range of the component tester is limited The impedance of the component under test is limited to a range from 200 to 4 7kQ Below and above these values the test pattern shows only short circuit or open circuit Forthe interpretation of the displayed test pattem these limits should always be borne in mind However most electronic components can normally be tested without any restriction Using the Component Tester The component tester is switched on by depressing the COMP TESTER pushbutton on beneath the screen This makes the vertical preamplifier and the timebase generator inoperative A shortened horizontal trace will be observed It is not necessary to disconnect scope input cables unless in circuit measurements are to be carried out IntheCOMP TESTER mode the only controls which can be operated are INTENS FOCUS and X POS other controls and settings have no influence on the test operation For the component connection two simple test leads w
37. er with constant group delay at the high frequency end thereby reducing characteristic transient distortion near the leading edge e g overshoot rounding ringing holes or bumps to an absolute minimum Using the probes HZ51 52 and 54 the full bandwidth of the HM 303 can be utilized without risk of unwanted waveform distortion Prerequisite for this HF compensation is a square wave generator with fast risetime typically 4 ns and low output impedance approx 502 providing 0 2V and 2V at afrequency of approx 1M Hz The calibrator output of the 303 meets these requirements when the CAL pushbutton is depressed Connect the probe to input Depress CAL pushbutton for 1M Hz All other pushbuttons should be released out position Set the input coupling to DC attenuator switch to 5mV div and TIME DIV switch to 0 215 div Set all variable controls to CAL position Insert the probe tip into the output socket marked 0 2V A waveform will be displayed on the CRT screen with leading and trailing edges clearly visible For the HF adjustment now to be performed it will be necessary to observe the rising edge as well as the upper left corner of the pulse top The connecting boxes of the HZ51 and HZ54 contain one R trimmer screw each while that of the HZ52 provides three These R trimmers have to beadjusted such that the beginning of the pulse is as straight as possible Overshoot or excessive rounding are unaccept
38. g CHOP ADD button in out position Signals lt 1kHz or time coefficient 21ms div DUAL and CHOP buttons depressed Channel 1 1 or I II sum depress only ADD button Channel I HI or difference depress ADD and the corresponding INVERT button Triggering mode Select trigger mode with AT NORM button AT Automatic Triggering lt 20Hz to 80M Hz out position NORM Normal Triggering depressed Trigger edge direction select slope with SLOPE button Intemal triggering select channel with TRIG 1 11 CH I II button Alternating triggering internal ALT pushbutton depressed CHOP button in the out position External triggering TRIG EXT button depressed sync signal 0 3V to 3V to TRIG INP socket Line triggering TRIG selector switch to Select trigger coupling with TRIG selector switch Trigger frequency ranges AC lt 20Hz to 100MHz DC DC to 100MHz LF DC to 1 5kHz TV Composite video signal with line or horizontal frequency TIME DIV 0 2s div 0 2ms div field frequency TIME DIV 0 1ms div O 1ps div line frequency Select edge direction with SLOPE button sync pulse above below Pay attention to trigger indicator TR LED above the TRIG selector switch Measurements Apply test signal to the vertical input connectors of CH I and or CH Il Before use calibrate attenuator probe with built in square wave generator CAL Switch input coupling to AC or DC Adjust signal t
39. ger threshold may be exceeded up to amaximum factor of 20 The HM 303 has twotriggermodes whichare characterized in the following Automatic Triggering If the AT NORM pushbutton in the X field is in the out position AT the sweep generator is running without test signal or external trigger voltage A base line is always displayed even without a signal applied This trigger mode is therefore called Automatic Triggering Operation of the scope needs having a constantly visible trace only a correct amplitude and time base setting LEVEL adjustment is neither necessary nor possible with auto matic triggering This simple AT mode is recommended forall uncomplicated measuring tasks such as DC voltage measuring However automatic triggering is also the appropriate operation mode for the entry into difficult measuring problems e g whenthetestsignalis unknown relating to amplitude frequency or shape Presetting of all parameters is now possible with automatic triggering the change to normal triggering can follow thereafter The automatic triggering works above 20Hz The change over to the break down of the automatic triggering at frequencies below 20Hz is abrupt However it can not be recognized by the TRIG LED this is still blinking Break down of triggering is best recognizable at the left screen edge the start of the trace in differing display height If the pulse duty factor of a square wave signal changes 50 much that one
40. gering Checks isisisi iinis 25 Alternate 17 Timebase 25 External TriQQering 17 Component Tester 26 Trigger Indicator 17 Trace Alignment 26 Function of variable HOLD OFF control 17 Y Overscanning Operation 18 Service Instructions Component Tester 18 27 Test a En 22 Instrument Case 27 Operating 27 Test Instructions Maximum and Minimum Brightness 27 General 23 Astigmatism control 27 Cathode Ray Tube Brightness Focus Trigger Threshold 28 Linearity Raster Distortions 23 Trouble Shooting the Instrument 28 Astigmatism Check 23 Replacement of Components and Parts 28 Symmetry and Drift of the Vertical Amplifier 23 Adjustments 28 Calibration of the Vertical Amplifier 23 Transmission Performance Short Instruction ssssesessss 29 of the Vertical Amplifier 24 Front Panel Elements Front View 30 General information regarding the CE marking HAMEG instruments fulfill the regulati
41. gering is simultaneously switched over to Channel 11 with this button If the DUAL button is depressed both channels are working Two signals can be displayed together in this button position altemate mode if the time base setting and the repetition frequency of the signal are suited This mode is not suitable for displaying very slow running processes The display then flickers too much orit appears to jump If the ADD button is depressed in addition to DUAL both channels are switched over constantly at a high frequency within a sweep period CHOP mode Low frequency signals below 1kHz or with periods longer than Ims are then also displayed without flicker CHOP mode is notrecommendedforsignals with higherrepetition frequencies If only the ADD button is depressed the signals of both channels are algebraically added CO 1 Whether the resulting display shows thesumordifferenceis dependent onthe phase relationship orthe polarity of the signals and on the positions of the INVERT buttons In phase input voltages Both INVERT and INVERT buttons released or depressed sum Only one INVERT button depressed difference Antiphase input voltages Both INVERT buttons released or depressed difference INVERT CH IoANVERT button depressed sum IntheADD mode the vertical display positionis dependent upon the Y POS setting of both channels The same attenuator switch position is normally used for both channels
42. ggering AT NORM button depressed and LEVEL control adjustment is recommended Thefollow ing table shows which frequencies are required for the particular ranges 0 2 s div 5 Hz 0 1 ms div 10kHz 0 1 s div 10 Hz 50 us div 20kHz 50 ms div 20 Hz 20 us div 50kHz 20 ms div 50 Hz 10 us div 100kHz 10 ms div 100 Hz 5 ys div 200kHz 5 ms div 200 Hz 2 yus div 500kHz 2 ms div 500 Hz 1 ps div MH 1 ms div 1 kHz 0 5 us div 2MHz 0 5 ms div 2 kHz 0 2 us div 5MHz 0 2 ms div 5 kHz 0 1 us div 10MHz WhentheX MAG x10 button is depressed a marker or cycle peak will be displayed every 10div 5 with variable control in CAL position measurement in the 55 div range The tolerance is better measurable in the 50ps div range one cycle every 1div Holdoff time The variation of the holdoff time during turning the HOLD OFF knob can not be tested without opening the instrument However a visual check can be made Without input signal set TIME DIV and time variable control cw use automatic triggering Atthe left hand stop of the HOLDOFF knob the trace should be bright It should darken remarkably at the right hand stop of the HOLDOFF knob Component Tester After pressing the COMP TESTER button a horizontal straight line has to appear immediately when the COMP TESTER socket is open The length ofthis trace should be approx amp div With connection of the COMP TESTER Socke
43. ghtness may be the result of wrong setting or reduced high voltage The latter is easily recognized by the greatly increased sensitivity of the vertical amplifier Right setting means that the HOLD OFF control should be turned to the left stop theX MAG x10 button should be released amediumtime coefficient should be selected line triggering position should be used only with a suitable TIME DIV switch setting e g 2ms div The control range for maximum and minimum brightness intensity must be such that the beam just disappears before reaching the left hand stop of the INTENS control particularly when the XY button is depressed while with the control at the right hand stop the focus and the line width are just acceptable With maximum intensity the timebase fly back must on no account be visible Visible trace fault without input signal bright dot on the left side or decreasing brightness from left to right or shortening of the baseline Cause Incorrect Unblanking Pulse It should be noted that with wide variations in brightness refocusing is always necessary Moreover with maximum brightness no pumping of the display must occur If pumping does occur itis normally due to a fault in the regulation circuitry for the high voltage supply The presetting pots for the high voltage circuit minimum and maximum intensity are only accessible inside the instrument see Adjusting Plan and Service Instructions A certain
44. ible In the GD ground coupling setting the signal path is interrupted directly beyond the input This causes the attenuator to be disabled again but now for both DC and AC voltages Withthe above listed exceptions HAM EG 10 1 probes can be used for DC measurements up to 600V or AC voltages with a mean value of zero volt of 1200V The 100 1 probe HZ53 allows for 1200V DC or 2400V for AC It should be noted that its value is derated at higher frequencies If anormal x10 probe is usedto measure high voltages there is the risk that the compensation trimmer bridging the attenuator series resistor will break down causing damage to the input of the oscilloscope However if for example only the residual ripple of a high voltage is to be displayed on the oscilloscope anormal x10 probe is sufficient Inthis case anappropriate high voltage capacitor approx 22 68nF must be connected in series with the input tip of the probe Voltage DC AC peak 400V rax Total value of input voltage The dotted line shows a voltage alternating at zero volt level If super imposed on a DC voltage the addition of the positive peak and the DC voltage results the max voltage With Y POS control input coupling to GD it is possible to use a horizontal graticule line as reference line for ground potential before the measurement It can lie below or above the horizontal central line according to whether posit
45. ich are contained in push pull circuits If a selected semiconductor is defective both push pull transistors of a stage should be replaced by selected components because otherwise there are possibly deviations of the specified data or functions The Service Department can give you advice for troubleshooting and replaceable parts Replacement parts can be ordered by letter or telephone from the nearest HAM EG Service Office Please supply the following information Instru menttype and serial number description of the part type and part number on the circuit drawing 28 m X 9 Subjectto change without notice Short Instruction for Switching on and initial setting Connect instrument to power outlet depress red POWER button LED indicates operating condition Case chassis and all measuring terminals are connected to the safety earth conductor Safety Class I Do not depress any further button TRIG selector switch to AC AT NORM button released input coupling switch to GD set TIME DIV switch to 50us div Adjust INTENS control for average brightness Center trace on screen using X POS and controls Then focus trace using FOCUS control Vertical amplifier mode Channel I All buttons in the Y section in out position Channel II button depressed Channel and II DUAL button depressed Alternate channel switchin
46. information call or write to HAMEG Addresses are provided at the back of the manual It is recommended to use only the original packing material should the instrument be shipped to for service or repair see also Warranty page M 2 Instrument Case Removal The rearcover can be taken off after unplugging the power cords triple contact connectorand aftertwo cross recessed pan head screws M4x30mm with two washers on it have been removed While the instrument case is firmly held the entire chassis with its front panel can withdrawn forward When the chassis is inserted into the case later on it should be noticed that the case has to fit under the flange of the front panel The same applies for the rear of the case on which the rear cover is put Caution During opening or closing of the case the instrument must be disconnected from all power sources for maintenance work or a change of parts or components If a measurement trouble shooting or an adjustment is unavoidable this work must be done by a specialist who is familiar with the risk involved When the instrument is set into operation after the case has been removed attention must be paid to the acceleration voltage for the CRT 2025V and to the operating voltages for both final amplifier stages 185V and 141V Potentials of these voltages are on the PS Board the CRT PCB on the upper and lower PCBs Suchpotentials are moreoveron the checkpoint strips on the upper and lower
47. ith 4mm banana plugs and with test prod alligator clip orsprung hook are required Thetestleads are connected to the insulated socket and the adjacent ground socket beneath the screen The component can be connected to the test leads either way round After use to retum the oscilloscope to normal operation release the COMP TESTER pushbutton off Test Procedure Caution Do not test any component in live circuitry remove all grounds power and signals connected to the component under test Set up Component Tester as stated above Connect test leads across componentto betested Observeoscilloscopedisplay Only discharged capacitors should be tested Test Pattem Displays Page M 17 shows typical test patterns displayed by the various components under test Open circuit is indicated by a straight horizontal line Short circuit is shown by a straight vertical line Testing Resistors Ifthetestobject has alinearohmic resistance both deflecting voltages are in the same phase The test pattern expected from aresistoris therefore a sloping straight line The angle of Slope is determined by the resistance of the resistor under test With high values of resistance the slope will tend towards the horizontal axis and with low values the slope will move towards the vertical axis Values of resistance from 20 0 to 4 7kQ can be approxi mately evaluated The determination of actual values will come with experience or by dir
48. ive and or negative deviations from the ground potential are to be measured Time Measurements As rule most signals to be displayed are periodically repeating processes also called periods The number of periods persecondis the repetition frequency Depending on the time base setting of the TIME DIV switch one several signal periods or only a part of a period can be displayed The time coefficients are stated in s div ms div and ps div on the TIME DIV switch The scale is accordingly divided into three fields The duration of a signal period or a part of it is determined by multiplying the relevant time hori zontal distance in div by the time coefficient set on the TIME DIV switch The variable time control identified with an arrow knob cap must be in its calibrated position CAL arrow pointing horizontally to the right With the designations L displayed wave length in div of one period T time in seconds for one period recurrence frequency in Hz of the signal T time coefficient in s div on timebase switch and the relationF 1 the following equations can be stated L 26 T L T L T L 2 1 zc ow 1 F TT L ET T L F With depressed X MAG x10 pushbutton the value must be divided by 10 However these four values are not freely selectable They have to be within the following limits L between 0 2 and 10div if possible 4 to 10div T between 0 0145 and 25
49. ject to change without notice HZ20 Adaptor BNC to 4mm binding posts HZ39 Spare Cable for HZ36 HZ22 500 BNCFeed through termination 1GHz 1W HZ57 Spare Cable for HZ51 HZ54 HZ23 Attenuator 2 1 male to female for oscilloscope service only Spare parts for modular probes only HZ24 Set of 4BNC 500 attenuators 3 6 10 20dB 1GHz DN incl 1x HZ22 Spare part Kit HZ40 Test Cables HZ32 cable BNC to single stacking banana plugs 40 inch HZ39 HZ33 Coaxialcable BNC BNC 500 20 inch 240 257 HZ33S Coaxial cable BNC BNC 500 20 inch insulated HZ33W Coaxial cable BNC BNC 500 20 inch elbow HZ34 Coaxial cable BNC BNC 500 40 inch HZ34S Coaxial cable BNC BNC 500 40 inch insulated 2725 IEEE 488 Bus Cable 40 inch double shielded HZ72L IEEE 488 Bus Cable 60 inch double shielded i t HZ84 2 Spare Printer Cable for HD148 CE and 305 1007 HZ84 3 Spare Printer Cable for combination of 25pole D SUB 26pole plastic male HZ96 Carrying Case for oscilloscopes HM203 205 208 408 604 1005 and 1007 Attenuation ER HZ97 Carrying Case for HM303 Type Ratio Bandwidth Risetime Input Impedance Input Voltage 305 003 1004 and HM5005 Aged HZ36 11 1031 10 100MHz 35 3 5ns 1 10M 91157 12pF 10 1 600V The carying case provides protection HZ51 10 1 150 2 lt 2 4 5 10M Oll 12pF 600V DC peak AC during transpor Hz52 10 1 250M Hz l
50. justment If it is found that a trigger point cannot be located on extremely complex signals even after repeated and careful adjustment of the LEVEL control a stable display may be obtained using the HOLD OFF control in the X field This facility varies the holdofftime betweentwo sw eep periods approx up to the ratio 10 1 Pulses or other signal wave forms appearing during this off period cannot trigger the timebase Particularly with burst signals or aperiodic pulse trains of the same amplitude the start of the sweep can be delayed until the optimum or required moment Avery noisy signal ora signal with a higherinterfering frequency is at times displayed double It is possible that LEVEL adjustment only controls the mutual phase shift but not the double display The stable single display of the signal required for evaluation is easily obtainable by expanding the hold off time To this end the HOLD OFF knob is slowly tumed to the right until one signal is displayed A double display is possible with certain pulse signals where the pulses alternately show a small difference of the peak amplitudes Only a very exactLEVEL adjustment makes asingle display possible The use of theHOLD OFF knob simplifies the right adjustment After specific use the HOLD OFF control should be reset into its calibration detent fully ccw otherwise the brightness ofthe display is reduced drastically The function is shown in the following figures Func
51. l sharpness can be adjusted by the variable resistor of 47kQ located on the lower PCB see Adjusting Plan As a precaution however the voltage for the vertical deflecting plates approx 27 85V should firstly be checked because this voltage will affectthe astigmastism correction While the adjustment is being carried out with medium brightness and a 1M Hz square wave signal the upper horizontal square wave tops are firstly focussed with the FOCUS control Then the sharpness of the vertical lines are corrected with the 47kQ Astigm pot The correction should be repeated several times inthis sequence The adjustmentis finished when the FOCUS knob exclusively brings no improve ment of the sharpness in both directions Trigger Threshold The internal trigger threshold should be in the range 0 3 to O 5div display height It is strongly dependent on the comparator IC If there are compelling reasons to replace this comparator it may be that triggering becomes too sensitive ortoo insensitive caused by gain tolerances See Test Instructions Triggering Checks page T3 In extreme cases the 3 32kQ hysteresis resistor of the comparator should be changed Generally max halving or doubling of this resistance value should be sufficient A too small trigger threshold cause double triggering or premature trigger action due to interference pulses or random noise A too high trigger threshold prevents the display of very small
52. le Components Single Transistors Short circuit Resistor 5100 J unction B C J unction B E Mains transformer prim Capacitor33pF J unction E C FET Single Diodes In circuit Semiconductors m Z diode below 7V Z diode beyond 7V Diode paralleled by 6800 2 Diodes antiparallel Silicon diode Germanium diode Diode in series with 510 B E paralleled by 6800 Rectifier Thyristor G A together B E with 1pF 6800 Si Diode with 101 22 muu X Subject to change without notice General These Test Instructions are intended as an the most important characteristics of the HM 303 at regular intervals without the need for expensive test equipment Resulting corrections and readjustments inside the instrument indicated by the following tests are described in the Service Instructions or on the Adjusting Plan They should only be undertaken by qualified personnel As withthe First Time Operation instructions care should be taken that all knobs with arrows are set to their calibrated positions None of the pushbuttons should be depressed TRIG selectorswitchtoAC It is recommended to switch on the instrument for about 20 minutes prior to the commencement of any check Cathode Ray Tube Brightness and Focus Linearity Raster Distortions Normally the CRT ofthe HM 303 has very good brightness Any reduction of this brightness can only be judged visually However decreased bri
53. lifier via Channel II sensitivity see Channel II specification X Y phase shift 3 below 220kHz Component Tester Test voltage approx 6Vms open circuit Test current approx 5MA mn Shorted Test frequency approx 50Hz Test connection 2 banana jacks 4mm One test lead is grounded Safety Earth General Information D14 364GY 123 or ER151 GH 6 rectangular screen 8x10cm intemal graticule Acceleration voltage approx 2000V Trace rotation adjustable on front panel Calibrator square wave generator t lt 4ns 1kHz 1MHz Output 0 2V 1 and 2V Line voltage 100 240V AC 10 50 60Hz Power consumption approx 36 Watt at 50Hz Min Max ambient temperature 10 C 40 C Protective system Safety class IEC 1010 1 Weight approx 5 6kg color techno brown Cabinet W 285 H 125 D 380 mm Lockable tilt handle Subject to change without notice 3 95 OSCILLOSCOPES QU reos xr CN a n sos HAMEG 30 MHz OSCILLOSCOPE 4 VOLTS 9 ma fa 30MHz Standard Oscilloscope 303 Dual Channel DC to 30MHz 1mV div Overscan Indicator Time 0 55 to 10ns div Variable Holdoff Altemate Triggering Triggering DC 100MHz Auto Peak to Peak Active TV Sync Separator Additional Features Component Tester 1kHz 1MHz Calibrator The new HAMEG oscilloscope succeeds the HM 203 over 170 000 sold worldwid
54. ll tempt all users to run it through its paces Screen photo of 50 and 100M Hz sine wave with alternate triggering Screen photo of 1 M Hz square wave signal Accessories supplied Line cord Operators Manual 2 Probes 1 1 10 1 OSCILLOSCOPES HZ 56 AC DC Current Probe Utilising Hall Effect technology to provide a broad frequency response the probe will accurately measure AC DC and complex waveforms The compact clip on design conforms to the IEC1010 safety standard and allows non intrusive measurement of current from 5mA to 30A peak to an accuracy of 1 The probe gives a voltage output directly proportional to the measured current which is compatible with a wide range of measuring instruments 2 4 2 Specifications Re Si Current range 20A 30A ac Frequency range DC 100kHz Tm Accuracy 190 2mA Resolution 1 Dielectric strength 3 7kV 50Hz 1min Loadimpedance gt 100kQ Output sensitivity 100mV A Divers BNC cable 2m HZ 72 S L Accessories n supplied T d e 1 488 GPIB 238 i P 4 lt 4 Wide Band Probes with RF alignment HZ47 Viewing Hood for Oscilloscopes HM 205 408 604 1 2 1005 and 1007 HZ48 Viewing Hood for Oscilloscopes 303 304 305 604 3 and 1004 Sub
55. lly Checks can be made with anysine wave voltagebetw een 50Hz and 1M Hz The AT NORM button should be in out position Automatic Triggering Following this it should be ascertained whetherthe same trigger sensitivity is also present with Normal Triggering AT NORM button depressed In this trigger mode a LEVEL adjustment is necessary The checks should show the same trigger threshold with the same frequency On depressing the SLOPE button the start of the sweep changes from the positive going to the negative going edge of the trigger signal As described in the Operating Instructions the trigger frequency range is dependent on the trigger coupling selected Forlower frequencies theLF coupling mode can be selected In this mode triggering up to at least 1 5kHz sine wave is possible Internally the HM303 should trigger perfectly at a display height of approx O 5div when the appropriate trigger coupling mode is set For external triggering TRIG EXT button depressed the EXT TRIG input connector requires a signal voltage of at least 0 3V which is in synchronism with the Y input signal The voltage value is dependent on the frequency and the trigger coupling mode AC DC LF Checking of the TV triggering is possible with a video signal of any given polarity Use the TV position of the TRIG switch for video sync pulse separation In TV triggering mode the TIME DIV switch setting selects between ine horizontal pulse se
56. lly at 1M Hz and a display height of4 5div At the sametime the leading top corner of the pulse must not be rounded In general no great changes occur after the instrument has left the factory and it is left to the operators discretion whether this test is undertaken or not A suited generator for this test is HZ60 from HAM EG Of course the quality of the transmission performance is not only dependent on the vertical amplifier The input attenuators located in the front of the amplifier are frequency compensated in each position Even small capacitive changes can reduce the transmission performance Faults of this kind are as a rule most easily detected with a square wave signal with a low repetition rate e g 1kHz If a suitable generator with max output of 40V is available it is advisable to check at regular intervals the deflection coefficients on all positions of the input attenuators and readjust them as necessary A compensated 2 1 series attenuator e g HZ23 is also necessary and this must be matched to the input impedance of the oscilloscope This attenuator can be T2 made up locally It is important that this attenuator is shielded For local manufacture the electrical compo nents required are a 1M 1 resistor and in parallel with it a trimmer 3 15pF in parallel with approx 12pF One side of this parallel circuit is connected directly to the input connector of or and the other side is connected t
57. mains line or battery and no signal inputs are permitted Remove all ground connections including Safety Earth pull out power plug from outlet Remove all measuring cables including probes between oscilloscope and circuit under test Otherwise both COMP TESTER eads are not isolated against the circuit under test In circuit tests are possible in many cases However they are not well defined This is caused by a shunt connection of real or complex impedances especially if they are of relatively low impedance at 50Hz to the component under test often results differ greatly when compared withsingle components In case of doubt one component terminal may be unsoldered This terminal should then be connected to the insulated COMP TESTER socket avoiding hum distortion of the test pattern Another way is a test pattern comparison to an identical circuit which is known to be operational likewise without power and any external connections Using the test prods identical test points in each circuit can be checked andadefectcanbe determined quickly and easily Possibly the device itself under test contains a reference circuit e g a second stereo channel push pull amplifier symmetrical bridge circuit which is not defective The test patterns on page 22 show some typical displays for in circuit tests Subject to change without notice mmmmm EMm u XX X 21 Test pattems Sing
58. minimum intensity setting necessary forthe measurement in hand and the ambient light conditions should be used Particular care is required when a single spot is displayed as a very high intensity setting may cause damage to the fluorescent screen of the CRT Switching the oscilloscope off and on at short intervals stresses the cathode of the CRT and should therefore be avoided The instrumentis so designedthat even incorrect operation will not cause serious damage The pushbuttons control only minor functions and it is recommended that before commencement of operation all pushbuttons are in the out position Afterthis the pushbuttons can be operated depending upon the mode of operation required The HM 303 accepts all signals from DC direct voltage up to a frequency of at least 30M Hz For sinewave voltages the upper frequency limit will be 50M Hz 12 However in this higher frequency range the vertical display height on the screen is limited to approx 4 5div The time resolution poses no problem For example with 50M Hz and the fastest adjustable sweep rate 1Ons div one cycle will be displayed every 2div The tolerance on indicated values amounts to 3 in both deflection directions All values to be measured can therefore be determined relatively accurately However from approximately 10MHz upwards the measuring error will increase as a result of loss of gain At 18M Hz this reduction is about
59. nals Cathode Anode Cathode Anode Cathode Anode Connections CT GD CT GD CT GD The polarity of an unknown diode can be identified by comparison with a known diode Testing Transistors Three different tests can be made to transistors base emitter base collectorand emitter collector The resulting test pattems are shown below The basic equivalent circuit of a transistor is a Z diode between base and emitter and a normal diode with reverse polarity between base and collector in series connection There are three different test patterns Foratransistorthe figures b e and b c are important The figure e c can vary but a vertcal line only shows short circuit condition Transistor Ld D Terminals b e b c ec Connections CT GD P N P Transistor 1 Terminals Connections These transistor test patterns are valid in most cases but there are exceptions to the rule e g Darlington FETs With the COMP TESTER the distinction between a P N P to an N P N transistor is discenible In case of doubt comparison with a known type is helpful It should be noted that the same socket connection COMP TESTER or ground for the same terminal is then absolutely necessary A connection inversion effects a rotation of the test pattem by 180 degrees round about the center point of the scope graticule In Circuit Tests Caution During in circuit tests make sure the circuit is dead No power from
60. nique Specifications Vertical Deflection Operating modes Channel or Il separate both Channels alternated or chopped Chopperfrequency approx 0 5M Hz Sum or difference with Ch and Ch II both channels invertable XY Mode via channel and channel II Frequency range 2xDC to 30M Hz 3dB Risetime lt 12ns Overshoot lt 1 Deflection coefficients 12 calibrated steps from 5mV div to 20V div 1 2 5 sequence with variable 2 5 1 up to 50V div Accuracy in calibrated position 3 Y expansion x5 calibrated to 1mV div 5 in the frequency range from DC 10M Hz Input impedance 1M 20pF Input coupling DC AC GD ground Input voltage max 400V DC peak AC Triggering Automatic peak to peak lt 20HZ 1LOOMHz lt 0 5div Normal with level control DC 100MHz lt 0 5div ALT Triggering LED indicator for trigger action Slope positive or negative Sources Channel or Il CH I alternating CH II line external Coupling AC 10Hz to 100M Hz DC 0 to 100M HZ LF 0 to 1 5kHz Active TV Sync Separator pos and neg Extemal 20 3V from 30Hz to 30M Hz Horizontal Deflection Time coefficients 20 calibrated steps from 0 2s div 0 1ys div in 1 2 5 sequence Accuracy in calibrated position 3 396 Min speed incl variable 2 5 1 0 5s div with X M ag x10 3 596 10ns div 8 Holdoff time variable to approx 10 1 Bandwidth X amplifier 0 3M Hz Input X Amp
61. o ahorizontal surface the handleshould betumedtothe upperside of the oscilloscope C Forthe D position 10 inclination the handle should be tumedtothe opposite direction ofthe carrying position until itlocks in place automaticallyundemeaththe instrument For the E position 20 inclination the handle should be pulled to release it from the D position and swing backwards until it locks once more The handle may also be set to a position for horizontal carrying by turning it to the upper side to lock in the B position Atthe same time the instrument must be lifted because otherwise the handle will jump back Ek Safety This instrument has been designed and tested in accor dance with IEC Publication 348 Safety Requirements for Electronic Measuring Apparatus The CENELEC HD401 regulations correspond to this standard It has left the factory in a safe condition This instruction manual contains important information and warnings which have to be followed by the userto ensure safe operation and to retain the oscilloscope in a safe condition The case chassis and all measuring terminals are connected to the protective earth contact of the appliance inlet The instrument operates according to Safety Class I three conductor power cord with protective earthing conductor and aplug with earthing contact The mains line plug shall onlybeinsertedin asocket outlet provided with a protective earth contact The protective action must not b
62. o desired display height with attenuator switch Select time coefficient on the TIME DIV switch Set trigger point with LEVEL knob for normal triggering Trigger complex or aperiodic signals with longer HOLD OFF time Amplitude measurement with Y fine control at right stop CAL Time measurement with time fine control at right stop CAL Horizontal expansion 10 fold with X MAG x10 button depressed External horizontal deflection X Y mode with XY button depressed X input CH Il Component Tester Press COMP TESTER button on Connect both component terminals to COMP TESTER jacks In circuit test Circuit under test must be disconnected from battery or power pull out power plug signals and ground earth Remove all signal connections to HM 303 cable probe then start testing Subject to change without notice 29 Front Panel Elements HM 303 Brief Description Front View Element Function Element Function POWER Tums scope on and off 01 COMP TESTER Switch to convert oscilloscope pushbutton LED LED indicates operating condition pushbutton switch to component tester mode 2 INTENS Intensity control 2 Y POS I Controls vertical position knob fortrace brightness knob of channel I display TR Trace rotation 03 GD AC DC Selects input coupling of CH potentiometer To align trace with horizont
63. o the generator if possible via a low capacitance coaxial cable The series attenuator must be matched to the input impedance of the oscilloscope in the 5mV div position variable control to CAL DC input coupling square tops exactly horizontal no ramp off is permitted This is achieved by adjusting the trimmer located in the 2 1 attenuator The shape of the square wave should then be the same in each input attenuator position Operating Modes CH I Il DUAL ADD CHOP INVERT and X Y Operation On depressing the DUAL pushbutton two traces must appear immediately On actuation of theY POS controls the trace positions should have no effect on each other Nevertheless this cannot be entirely avoided even in fully serviceable instruments When one trace is shifted vertically across the entire screen the position of the other trace must not vary by more than 0 5mm A criterion in chopped operation is trace widening and shadowing around and within the two traces in the upper or lower region of the screen Set TIME DIV switch to Ausl div depress the DUAL and CHOP pushbutton set input coupling of both channels to GD and advance the INTENS control fully clockwise Adjust FOCUS for a sharp display With the Y POS controls shift one of the traces to a 2div the other to a 2div vertical position from the horizontal center line of the graticule Do not try to synchronize with the time variable control the chop frequency 0 5M
64. obe compensation page M 7 Standard attenuator probes on the oscilloscope normally reduce its bandwidth and increase the rise time In all cases where the oscilloscope bandwidth must be fully utilized e g for pulses with steep edges we strongly advise using the modular probes HZ 51 x10 HZ 52 x10 HF and HZ 54 x1 and x10 This can save the purchase of an oscilloscope with larger bandwidth and has the advantage that defective components can be ordered from HAMEG and replaced by oneself The probes mentioned have a HF calibration in addition to low frequency calibration adjustment Thus a group delay correctionto the upper limit frequency of the oscilloscope is possible with the aid of an 1M Hz calibrator e g HZ60 In factthe bandwidth and rise time of the oscilloscope are not noticably changed with these probe types and the waveform reproduction fidelity can even be improved because the probe can be matched to the oscilloscopes individual pulse response If a x10 or x100 attenuator probe is used DC input coupling must always be used at voltages above 400V With AC coupling of low frequency signals the attenuation is no longer independent of frequency pulses can show pulse tilts Direct voltages are suppressed but load the oscilloscope input coupling capacitor concerned Its voltage rating is max 400 V DC peak AC DC input coupling is therefore of quite special importance with a x100 attenuation probe which usually has a vol
65. onent type as shown in the figures below The main characteristic displayed during semiconductor testing is the voltage dependent knee caused by the junction changing from the conducting state to the non conducting state It should be noted that both the forw ard andthe reverse characteristic are displayedsimultaneously This is atwo terminal test therefore testing of transistor amplification is not possible buttesting of asingle junction is easily and quickly possible Since the test voltage applied is only very low all sections of most semi conductors can be tested without damage However checking the breakdown orreverse voltage of high voltage semiconductors is not possible M ore importantis testing components for open or short circuit which from 20 m Subjectto change without notice experience is most frequently needed Testing Diodes Diodes normally show at least their knee in the forward characteristic This is not valid forsome high voltage diode types becausethey contain aseries connection of several diodes Possibly only a small portion of the knee is visible Z diodes always show their forward knee and up to approx 7V their Z breakdown forms a second knee inthe opposite direction A Z breakdown voltage of more than 6 8V can not be displayed I NormalDiode High VoltageDiode ZDiode6 8V Termi
66. ons of the EMC directive The conformity test made by HAMEG is based on the actual generic and product standards In cases where different limit values are applicable HAM EG applies the severer standard For emission the limits for residential commercial and light industry are applied Regarding the immunity susceptibility the limits for industrial environment have been used The measuring and data lines of the instrument have much influence on emmission and immunity and therefore on meeting the acceptance limits For different applications the lines and or cables used may be different For measurement operation the following hints and conditions regarding emission and immunity should be observed 1 Data cables For the connection between instruments resp their interfaces and external devices computer printer etc sufficiently screened cables must be used Without a special instruction in the manual for a reduced cable length the maximum cable length of a dataline must be less than 3 meters long If an interface has several connectors only one connector must have a connection to a cable Basically interconnections must have a double screening For IEEE bus purposes the double screened cables HZ72S and HZ72L from HAM EG are suitable 2 Signal cables Basically test leads for signal interconnection between test point and instrument should be as short as possible Without instruction in the manual for a shorter length signal lines must
67. or frequencies should not be used for timebase calibration The pulse duty cycle deviates from 1 1 ratio Prerequisites for precise and easy probe adjustments as well as checks of deflection coefficients are straight horizontal pulse tops calibrated pulse amplitude and zero potential atthe pulse base Frequency and duty cycle are relatively uncritical For interpretation of transient response fast pulse risetimes and low impedance generator outputs are of particular importance Providing these essential features as well as switch selectable output frequencies the calibratorof the HM 303 can under certain conditions replace expensive squarewave generators when testing or compensating wideband attenuators or amplifiers In such a case the input of an appropriate circuit will be connected to one of the CAL outputs via a suitable probe The voltage provided at a high impedance input 1M 115 50pF will correspond to the division ratio of the probe used 10 1 20mV 100 1 also 20mV from 2V output Suitable probes are HZ51 52 53 and 54 14 Operating modes of the vertical amplifiers The vertical amplifier is setto the desired operating mode by using the pushbuttons CH DUAL and ADD inthe Y field of the front panel For Mono mode all 3 buttons must be intheir released positions only channel canthen be operated The button CH I II TRIG I II must be depressed in mono mode for Channel The internal trig
68. paration TIME DIV switch from 1ms div to 1ys div and frame vertical pulse separation TIME DIV switch from 2s div to 2ms div With the SLOPE button the correct slope of the sync pulse front edge must be selected This slope is then valid for both sync frequencies Perfect TV triggering is achieved when in both display modes the amplitude of the complete TV signal from white level to the top of the line sync pulse is limited between 0 8 and Thedisplay should notshift horizontally during a change of the trigger coupling from AC to DC with a sine wave signal without DC offset Subject to change without notice If both vertical inputs are AC coupled to the same signal and both traces are brought to coincide exactly on the screen when working in the alternate dual channel mode then no change in display should be noticeable when the CH UH TRIG UH button is depressed or released or when the TRIG selector switch is changed from AC to DC position Checking of the line mains frequency triggering 50 60Hz is possible when the input signal is time related multiple orsubmultiple tothe powerline frequency TRIG selector switch to There is no trigger threshold visible in this trigger mode Even very small input signals are triggered stably e g ripple voltage For this check use an input of approx 1V The displayed signal height can then be varied by turning the respective input attenuator switch and it
69. riggering in CAL position right hand stop pushbutton switch trace visible without input signal Button depressed normal triggering VOLTS DIV Channel II input attenuator with LEVEL adjustment 6 12 position Selects Y input sensitivity rotary switch in mV div or V div 10 Adjustment of trigger level in 1 2 5 sequence ol 65 INVERT CHII Inversion of CH II display 17 TRIG INP Input for external trigger signal pushbuttonswitch combination with ADD button BNC connector Pushbutton TRIG 44 depressed difference CH CH CAL 1kHz 1MHz Selects calibrator frequency 36 AC DC GD Selects input coupling of the CH II pushbutton switch Button released approx 1 pushbutton switches vertical amplifier Specs see Button depressed approx 1M Hz 87 INPUT CH II CH II signal input and input for 49 0 2V 2V Calibrator square wave output BNC connector horizontal deflection in X Y mode test sockets DAN or 2V e G8 Y POS II Controls vertical position 20 COMP TESTER Connectors for test leads knob of channel II display 4mm jacks of the Component tester Inoperative in X Y mode 9 SDD G9 Gollo G9 Q3 26 82 G2 Ge
70. rkmaship for a period of 2 years This warranty shall not apply to any defect failure or damage caused by improper use orinadequate maintenance and care HAM EG shall not obliged to provide service under this warranty to repair damage resulting from attempts by personnel other than HAMEG represantatives to install repair service or modify these products In orderto obtain service under this warranty Customers must contact and notify the distributor who has sold the product Each instrument is subjected to a quality test with 10 hour burn in before leaving the production Practically all early failures are detected by this method In the case of shipments by post rail or carrier it is recommended that the original packing is carefully preserved Transport damages and damage due to gross negligence are not covered by the guarantee In the case of acomplaint alabel should be attached to the housing of the instrument which describes briefly the faults observed If at the same time the name and telephone number dialing code and telephone or direct number or department designation is stated for possible queries this helps towards speeding up the processing of guarantee claims Maintenance Various important properties of the oscilloscope should be carefully checked at certain intervals Only in this way is it largely certain that all signals are displayed with the accuracy on which the technical data are based The test methods described in the
71. s variable control Timebase Before checking the timebase it should be ascertained that the trace length is approx 10div in all time ranges If not it can be corrected with the potentiometer X 1 see Adjusting Plan This adjustment should be made with the TIME DIV switch in a mid position i e 20 5 div Prior to the commencement of any check set the time variable control to CAL The X MAG x10 button should be in out position This condition should be maintained until the variation ranges of these controls are checked Check that the sweep runs from the left to the right side of the screen TIME DIV switch to O 1s div X POS control in mid range This check is only necessary after changing the cathode ray tube If a precise marker signal is not available for checking the Timebase time coefficients then an accurate sine wave generator may be used Its frequency tolerance should not be greater than 1 The timebase accuracy of the HM 30315 given as 3 butitis considerably better than this For the simultaneous checking of timebase linearity and accuracy at least 10 oscillations i e 1 cycle every div should always be displayed For precise determination set the peak of the first marker or cycle peak exactly behind the first vertical graticule line using the X POS control Deviation tendencies can be noted after some of the marker or cycle peaks If a precise Time Mark Generator is used for checking Normal Tri
72. s R here so that only a suitable capacitor C needs to be connected in series If the aperture width of the ellipse is increased compared with C short circuited then the test voltage leads the reference voltage and vice versa This applies only in the region up to 90 phase shift Therefore C should be sufficiently large and produce only arelatively small just observable phase shift Should both input voltages be missing or fail in the X Y mode a very bright light dot is displayed on the screen This dot can burn into the phosphor at a too high brightness setting INTENS knob which causes either a lasting loss of brightness or in the extreme case complete destruction of the phosphor at this point Phase difference measurement in DUAL mode A larger phase difference between two input signals of the same frequency and shape can be measured very simply on the screen in Dual mode DUAL button depressed The time base should be triggered by the reference signal phase position 0 The other signal can then have a leading or lagging phase angle Altemate mode should be selected for frequencies gt 1 kHz the Chop mode is more suitable for frequencies lt 1 kHz less flickering For greatest accuracy adjust not much more than one period and approximately the same height of both signals on the screen The variable controls for amplitude and time base and the LEVEL knob can also be used for this adjustment without influence on the result
73. signed for indoor use The permissible ambient temperature range during operation is 10 50 F 40 104 F It may occasionally be subjected to temperatures between 10 50 F and 10 C 14 F without degrading its safety The permissible ambient temperature range for storage or transportation is 40 C 40 F 70 158 F The maximum operating altitude is up to 2200m non operating 15000m The maximum relative humidity is up to 80 If condensed water exists in the instrument it should be acclimatized before switching on In some cases e g extremely cold oscilloscope two hours should be allowed before the instrumentis putinto operation The instrument should be kept in a clean and dry room and must not be operated in explosive corrosive dusty or moist environments The oscilloscope can be operated in any position but the convection cooling must not be impaired The ventilation holes may not be covered For continuous operation the instrument should be used in the horizontal position preferably tilted upwards resting on the tilt handle The specifications stating tolerances are only valid if the instrument has warmed up for 30 minutes at an ambient temperature between 15 C 59 F and 30 C 86 F Values without tolerances are typical for an average instrument Warranty HAMEG warrants to its Customers that the products it manufactures and sells will be free from defects in materials and wo
74. t circuit is 100V DC peak It must be noted that a different phase angle between the measuring and the triggering signal may cause a display not coinciding with the SLOPE pushbutton setting Thetrigger coupling selection can also be used in external triggering mode Unlike internal triggering the lowest frequency for extemal triggering is 20Hz in all trigger coupling conditions Trigger indicator An LED on condition above the TRIG switch indicates that the trigger signal has a sufficient amplitude and the LEVEL control setting is correct This is valid with automatic and with normal triggering The indication of trigger action facilitates a sensitive LEVEL adjustment particularly at very low signal frequencies The indication pulses are of only 100ms duration 18 SUD ECE to change without notice Thusforfastsignals the LED appears to glow continuously for low repetition rate signals the LED flashes at the repetition rate or at a display of several signal periods not only at the start of the sweep atthe left screen edge but also at each signal period In automatic triggering mode the sweep generator starts repeatedly without test signal or external trigger voltage If the trigger signal frequency is lt 20Hz the sweep generator starts without awaiting the trigger pulse This causes an untriggered display and a flashing trigger LED TR Holdoff time ad
75. t 1 4 5 10M QII1OpF 600V DC peak AC BN tation of an oscil HZ53 100 1 100M Hz lt 3 5ns 100M 14 5 1200V DC peak AC loscope Itis made 254 1 1 10 1 10 150M Hz lt 35 2 4ns 1 10M 57 12 10 1 600V AC of a durable vinyl coated material Special Probes thatis designedto HZ38 DemodulatorProbe 0 1 500MHz max 200V DC withstand the HZ58 High Voltage Probe 1000 1 Ri approx 500M Q DC 1M Hz max 15kV DC peak AC stress and wear and tear of field use 05 96 Operating Instructions Symbols N See user s manual N Danger high voltage gt Earth General Information This oscilloscope is easy to operate The logical arrangement of the controls allows anyone to quickly become familiar with the operation of the instrument however experienced users are also advised to read through these instructions so that all functions are understood Immediately after unpacking the instrument should be checked for mechanical damage and loose parts in the interior If there is transport damage the supplier must be informed immediately The instrument must then not be put into operation Use of tilt handle To view the screen from the best angle there are three different positions C D E for setting up the instrument If the instrument is set down on the floor after being carried the handle automatically remains in the upright carrying position A Inorderto placethe instrument ont
76. t to the ground jack in the Y Section a vertical straight line with approx 6div height should be displayed The above stated measurements have some tolerances Trace Alignment The CRT has an admissible angular deviation 5 between the X deflection plane D1 D2 and the horizontal center line of the internal graticule This deviation due to tube production tolerances and only important after changing the CRT and also the influence of the earths magnetic field which is dependent on the instruments North orientation are corrected by means of the TR potentiometer In general the trace rotation range is asymmetric It should be checked whether the baseline can be adjusted somewhat sloping to both sides round about the horizontal center line of the graticule With the 303 in its closed case an angle of rotation 0 57 0 1div difference in elevation per 10div graticule length is sufficient for the compensation of the earths magnetic field 26 XX Subjectto change without notice General The following instructions are intended as an aid for the electronic technician who is carrying out readjustments on the HM 303 if the nominal values do not meet the specifications These instructions primarily referto those faults which were found after using the Test Instructions However this work should only be carried out by properly qualified personnel For any further technical
77. tage rating of max 1200 V DC peak AC A capacitor of corresponding capacitance and voltage rating may be connected in series with the attenuator probe input for blocking DC voltage e g for hum voltage measurement With all attenuator probes themaximumAC input voltage must be derated with frequency usually above 20kHz Therefore the derating curve of the attenuator probe type concemed must be taken into account The selection of the ground point on the test object is important when displaying small signal voltages It should always be as close as possible to the measuring point If this is not done serious signal distortion may result from Spurious currents through the ground leads or chassis parts The ground leads on attenuator probes are also particularly critical They should be as short and thick as possible When the attenuator probe is connected to a BNC socket a BNC adapter which is often supplied as probe accessory should be used In this way ground and matching problems are eliminated Hum or interference appearing in the measuring circuit especially when a small deflection coefficient is used is possibly caused by multiple grounding because equalizing currents can flow in the shielding of the test cables voltage drop between the protective conductor connections caused by external equipment connected to the mains line e g signal generators with interference protection capacitors Subject to change without notice
78. ted from the measured time value The risetime of the signal can be calculated usingthe following formula t te 7 t Inthis tis the total measured risetime t s is the risetime of the oscilloscope amplifier approx 12ns and tp the risetime of the probe e g Anel If t is greater than 100ns then t can be taken as the risetime of the pulse and calculation is unnecessary Calculation of the example in the figure above results in a signal risetime t 32 12 2 29 6ns The measurement of the rise or fall time is not limited to the trace dimensions shown in the above diagram It is only particularly simple in this way In principle it is possible to measure in any display position and at any signal amplitude It is only important that the full height of the signal edge of interest is visible in its full length at not too great steepness and that the horizontal distance at 1096 and 90 of the amplitude is measured If the edge shows rounding or overshooting the 10096 should not be related to the peak values but to the mean pulse heights Breaks or peaks glitches next to the edge are also not taken into account With very severe transient distortions the rise andfall time measurement has little meaning For amplifiers with approximately constant group delay therefore good pulse transmission performance the following numerical relationship between rise time tr in ns and bandwidth B in MHz applies 350 t
79. tenuators are indicated in mV div or V div peak to peak value The magnitude of the applied voltage is ascertained by multiplying the selected deflection coefficient by the vertical display height in div If an attenuator probe x10 is used a further multiplication by afactorof 10 is required to ascertain the correct voltage value Forexactamplitude measurements the variable control on the attenuator switch must be set to its calibrated detent CAL When turning the variable control ccw the sensitivity will be reduced by a factor of 2 5 Therefore every intermediate value is possible within the 1 2 5 sequence With direct connection to the vertical input signals up to 400V may be displayed attenuator set to 20V div variable control to left stop With the designations display height in div signal voltage V at the vertical input D deflection coefficientin V div at attenuatorswitch the required value can be calculated from the two given quantities U D H U p D H However these three values are not freely selectable Theyhaveto be withinthefollowing limits triggerthreshold accuracy of reading Subject to change without notice H between 0 5 and 8div if possible 3 2 to 8div U between 1mV and 160 D between 1mV div and 20V div in 1 2 5 sequence Examples Set deflection coefficient D 50mV div 2 0 05V div observed display height 4 6div required voltage U
80. test plan of this manual can be Subject to change without notice performed without great expenditure on measuring instruments However purchase of the new HAMEG scope tester HZ 60 which despite its low price is highly suitable fortasks of this type is very much recommended The exterior of the oscilloscope should be cleaned regularly with a dusting brush Dirt which is difficult to remove on the casing and handle the plastic and aluminium parts can be removed with a moistened cloth 99 water 1 mild detergent Spirit or was hing benzine petroleum ether can be used to remove greasy dirt The screen may be cleaned with water or washing benzine but not with spirit alcohol orsolvents it must then be wiped with a dry clean lint free cloth Under no circumstances may the cleaning fluid get into the instrument The use of other cleaning agents can attack the plastic and paint surfaces Protective Switch Off This instrument is equipped with a switch mode power supply It has both overvoltage and overload protection which will cause the switch mode supply to limit power consumption to a minimum In this case a ticking noise may be heard Power supply The oscilloscope operates on mains line voltages between 100V4c and 240V4c No means of switching to different input voltages has therefore been provided The power input fuses are externally accessible The fuseholder is located above the 3 pole power connector The power inputf
81. tion is often more suited for low frequency signals than the DC position because the white noise inthe trigger voltage is strongly suppressed So jitter or double triggering of complex signals is avoidable or at least reduced in particular with very low input voltages The trigger threshold increases above 1 5kHz The built in active TV Sync Separator enables the separation of sync pulses from the video signal Even distorted video signals are triggered and displayed in a stable manner Video signals are triggered in the automatic mode The internal triggering is virtually independent of the display height but the sync pulse must exceed 0 5div height For TV sync pulse separation the TRIG switch must be set to TV The TIME DIV switch selects between field 2s div 2ms div and line 1ms div 1ps div 17 The slope of the leading edge of the synchronization pulse is critical fortheSLOPE pushbutton setting If the displayed sync pulses are above the picture field contents then the SLOPE pushbutton must be in position out In the case of sync pulses below the field line the leading edgeis negative andthe SLOPE pushbutton musttherefore be depressed to Since the INVERT function may cause a misleading display it must not be activated until after correct triggering is achieved On the 2ms div setting field TV triggering is selected and 1 field is visible if a 50 fields s signal is applied If the hol
82. tion of var HOLD OFF control heavy parts are displayed period signal S Fig 1 Juuiu OUL U L Ml adjusting HOLDOFF time Fig 2 Fig lshows acase where theHOLD OFF knobis inthe minimum position and various different waveforms are overlapped on the screen making the signal observation unsuccessful Fig 2shows a case where only the desired parts of the signal are stably displayed Y Overscanning Indication This indicator shows any vertical overscan of the usable 10 8 screen area if any part of the signal or baseline are outside the graticule The indication is achieved by 2 light emitting diodes marked OVERSCAN which are located between the attenuators Should one LED illuminate without an input signal this means that the respective vertical positioning control has been improperly adjusted Because each LED correlates with one of both possible directions it can be seen in which direction the trace has leftthe screen With dual channel operation misadjustment of both Y POS controls can occur If both traces lie in the same direction one LED illuminates likewise If one trace is positioned above andthe otherbelow the graticule both LEDs are illuminated The indication of the Y position after crossing the graticule area occurs each operating mode also when due to missing time deflection no baseline is displayed or when the oscilloscope is in the X Y mode
83. tor aresistor of at least 1000 should be series connected RF decoupling Often it is advisable to shield statically the surface of the coil However no shorted turns are permissible Maximum minimum and direction to the magnetic source are detectable at the measuring point by turning and shifting the coil Alternate triggering With altemate triggering ALT button depressed it is possible totriggertwo signals which are differentin frequency asynchronous Inthis casethe oscilloscope must be operated altemate DUAL mode with signals of sufficient height at each input To avoid trigger problems due to different DC voltage components AC input coupling for both channels is recommended The internal trigger source is switched in the same way as the channel switching after each time base sweep Phase difference measurement is not possible in this trigger mode External triggering The internal triggering is disconnected by depressing the TRIG EXT button The timebase can be triggered externally via the TRIG INP socket using 0 to voltage which is in syncronism with the test signal This trigger voltage may have completely different form from the test signal voltage Triggering is even possible in certain limits with whole number multiples or fractions of the test frequency but only with synchronous signals The input impedance of the TRIG INP socket is approx 100kQ II 10pF The maximum input voltage of the inpu
84. uency F4f arise because of the modulation apart from the carrier frequency F Ur 0 5m A Figure 1 F f Amplitude and frequency spectrum for AM display m 5096 The display of the amplitude modulated HF oscillation can be evaluated with the oscilloscope provided the frequency spectrum is inside the oscilloscope bandwidth The time base is set so that several wave of the modulation frequency are visible Strictly speaking triggering should be extemal with modulation frequency from the AF generator or a demodulator However internal triggering is frequently possible with normal triggering AT NORM button depressed using a suitable LEVEL setting and possibly also using the time variable adjustment Oscilloscope setting for a signal according to figure 2 Depress no buttons Y CH 1 20mV div TIME DIV 0 2ms div Triggering NORMAL with LEVEL setting internal or external triggering eo i DEES Figure 2 Amplitude modulated oscillation F 1 MHz f 1 kHz 50 Ur 28 3 mV If the two values a and bare read from the screen the modulation factor is calculated from _a b _a b 85 or 100 where 1 b U 1 m The variable controls for amplitude and time be set arbitrarily in the modulation factor measurement Their position does not influence the result Triggering and time base Time rel
85. uses are externally accessible if the rubberconector is removed The fuseholder can be released by pressing its plastic retainers with the aid of asmall screwdriver The retainers are located onthe right and left side of the holder and must be pressed towards the center The fuse s can thenbe replaced and pressed inuntil locked on both sides Use of patched fuses or short circuiting of the fuseholder is not permissible HAM EG assumes no liability whatsoever for any damage caused as aresult and all warranty claims become null and void C Fuse type Size 5x20mm 0 8A 250V AC fuse must meet IEC specification 127 Sheet or DIN 41 662 or DIN 41 571 sheet 3 Time characteristic time lag Attention There is a fuse located inside the instrument within the switch mode power supply Size 5x20mmy 0 5A 250V AC fuse must meet IEC specification 127 Sheet or DIN 41 662 or DIN 41 571 sheet 3 Time characteristic fast F This fuse must not be replaced by the operator Type of signal voltage With the HM 303 most repetitive signals in the frequency range up to at least 30MHz 3dB can be examined Sinewave signals of 50M Hz are displayed with a height of approx 5096 6dB However when examining square or pulse type waveforms attention must be paid to the harmonic content of such signals The repetition frequency fundamental frequency of the signal must therefore be significantly smaller than th
86. ve trouble shooting also check the extemal power source If the instrument fails completely the first and important step after checking the power fuses will be to measure the deflecting plate voltages of the CRT In almost any case the faulty section can be located The sections represent 2 Horizontal deflection 4 Power supply 1 Vertical deflection 3 CRT circuit Whilethe measurementtakes place the position controls of both deflection devices must be in mid position When the deflection devices are operating properly the separate voltages of each plate pair are almost equal then Y approx 80V and X approx 71V Ifthe separate voltages of a plate pair are very different the associated circuit must be faulty An absent trace in spite of correct plate voltages means a fault in the CRT circuit Missing deflection plate voltages is probably caused by a defect in the power supply Replacement of Components and Parts For the replacement of parts and components use only parts ofthe same orequivalenttype Resistors unspecified in the diagrams have a power dissipation of 1 5 Watt or 1 8 Watt Chip respectively and a tolerance of 196 Resistors in the high voltage circuit must have sufficient electric strength Capacitors without a voltage value must be rated for an operating voltage of 63V The capacitance tolerance should not exceed 2090 Many semiconductors are selected especially all amplifier transistors wh
87. with algebraic addition Please note that the Y POS settings are added too but are not affected by the INVERT pushbuttons Differential measurement techniques allow direct measurement of the voltage drop across floating components both ends above ground Two identical probes should be used for both vertical inputs In order to avoid ground loops use aseparate ground connection and do not use the probe ground leads or cable shields Subject to change without notice X Y Operation For X Y operation the pushbutton in the X field marked XY must be depressed The X signal is then derived from the INPUT CH II X The calibration of the X signal during X Y operation is determined by the setting of the Channel Il input attenuator and variable control This means that the sensitivity ranges and input impedances are identical for both the X and Y axes However the Y POS II control is disconnected in this mode Its function is taken over by the X POS control It is important to note that the X MAG x10 facility normally used for expanding the sweep should not be operated in the X Y mode It should also be noted that the bandwidth of the X amplifieris gt 3M Hz and therefore an increase in phase difference between both axes is noticeable from 50kHz upwards The inversion of the X input signal using theINVERT CH II button is not possible Lissajous figures can be displayed in the X Y mode for certain measuring tasks

Oscilloscope HM 303-4 GB

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