HM400 - Uncategorized HAMEG - Free user manual and instructions

USER MANUAL HM400 HAMEG

Unterschrift / Signature / Signatur Holger Asmussen Manager Hersteller HAMEG Instruments GmbH KONFORMITÄTSERKLÄRUNG Manufacturer Industriestraße 6 DECLARATION OF CONFORMITY Fabricant D-63533 Mainhausen DECLARATION DE CONFORMITE General information regarding the CE marking HAMEG instruments fulfi ll the regulations 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, HAMEG 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 infl uence on emission 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:

For the connection between instrument interfaces and external devices, (computer, printer etc.) suffi ciently 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 and not be used outside buildings. 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 cable HZ72 from HAMEG is suitable.

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 be less than 3 meters and not be used outside buildings. 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. Infl uence on measuring instruments

Under the presence of strong high frequency electric or magnetic fi elds, even with careful setup of the measuring equipment, infl uence 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 specifi cations may result from such conditions in individual cases.

4. RF immunity of oscilloscopes.

4.1 Electromagnetic RF fi eld

The infl uence of electric and magnetic RF fi elds may become visible (e.g. RF superimposed), if the fi eld intensity is high. In most cases the coupling into the oscilloscope takes place via the device under test, mains/line supply, test leads, control cables and/or radiation. The device under test as well as the oscilloscope may be effected by such fi elds. Although the interior of the oscilloscope is screened by the cabinet, direct radiation can occur via the CRT gap. As the bandwidth of each amplifi er stage is higher than the total –3dB bandwidth of the oscilloscope, the infl uence of RF fi elds of even higher frequencies may be noticeable.

4.2 Electrical fast transients / electrostatic discharge

Electrical fast transient signals (burst) may be coupled into the oscilloscope directly via the mains/line supply, or indirectly via test leads and/or control cables. Due to the high trigger and input sensitivity of the oscilloscopes, such normally high signals may effect the trigger unit and/or may become visible on the CRT, which is unavoidable. These effects can also be caused by direct or indirect electrostatic discharge. HAMEG Instruments GmbH25 Subject to change without notice Content Deutsch 3 Español 42 Français 64 English Declaration of Conformity 24 General information regarding the CE marking 24 HM400 Analog Oscilloscope 40 MHz 26 Specifi cations 27 Important hints 28 Placement of the instrument 28 Removing/mounting the handle 28 Safety 28 Proper operation 28 CAT I 28 Areas of use of the instrument 29 Environmental conditions. 29 Maintenance 29 Warranty and repair 29 Line voltage 29 Overview of the controls 30 Basic signal measurement 31 Nature of the signal voltages 31 Amplitude of signals. 32 Time measurements 32 Applying the signal voltages 32 First time operation and initial settings 33 Trace rotation 33 Probe adjustment and use of probes 33 1 kHz adjustment 33 1 MHz adjustment 33 Operating modes of the vertical amplifi er 34 XY mode 34 Measurement of phase differences in dual channel operation 34 Triggering and time base 34 Automatic peak-to-peak triggering 34 Normal trigger 35 SLOPE selection 35 Trigger coupling 35 TV (video signal) triggering (PAL) 35 Frame pulse triggering 35 Line sync triggering 35 LINE triggering 36 External triggering 36 Triggered state indicator LED TRIG’d 36 Hold-off time adjustment 36 AUTOSET 37 Component test 37 In-circuit tests 38 Function of the controls 38

DC/AC – LED buttons (CH 1 / CH 2) 40

INV – LED button for CH 2 40

Mode buttons with LED 41

COMPONENT TESTER – 4126 Subject to change without notice Reference-Class in sensitivity and input voltage range 2 Channels with deflection coefficients 1 mV/div.…20 V/div., variable up to 50 V/div. Time Base 100 ns/div.…0.2 s/div., with X magnification to 10 ns/div. Low noise measuring amplifiers with high pulse fidelity and minimum overshoot Peak to peak trigger for stable triggering 0…50 MHz at 0.5 div. signal level (up to 80 MHz at 1 div.) Autoset, Save/Recall Memories for 6 instrument settings Yt- and XY-Mode with Z-Input for intensity modulation Component characterisation with component tester (two terminal network measurement) for use within service etc. Low power consumption, no fan 40MHz Analog Oscilloscope HM400 HM400 Caracteristic of a Z-Diodewith component test modeLine triggered compositevideo signal No signal distortionresulting from overshoot HM40027 Subject to change without notice Specifications 40MHz Analog Oscilloscope HM400 All data valid at 23 °C after 30 minute warm-up Vertical Deflection Operating Modes: Channel 1 or 2 only Channels 1 and 2 (alternate or chopped) Sum or Difference of CH 1 and CH 2 Invert: CH 2 XY Mode: CH 1 (X) and CH 2 (Y) Bandwidth (-3 dB): DC, 5mV/div.…20V/div.: 0…40MHz AC, 5mV/div.…20V/div.: 2Hz…40MHz DC, 1…2mV/div.: 0…10MHz AC, 1…2mV/div.: 2Hz…10MHz Rise Time (calculated): ‹ 35 ns (1 mV/div.…2 mV/div.) ‹ 8,75 ns (5 mV/div.…20 V/div.) Deflection Coefficient: 1-2-5 Sequence ± 5% (1mV/div.…2mV/div.) ± 3% (5mV/div.…20V/div.) Variable (uncalibrated): › 2.5:1 to › 50 V/div. Input Impedance: 1 MΩ II 15 pF Input Coupling: DC, AC, GND (ground) Max. Input Voltage: 400 V (DC + peak AC) Triggering Automatic: Linking of peakdetection and triggerlevel Min. signal height 0.5div Frequency range 5Hz…50MHz Level control range From peak- to peak+ Normal (without peak): Min. signal height 0.5div Frequency range 0…50MHz Level control range –10….+10div. Slope: Rising or falling Sources: Channel 1 or 2, Line and External Coupling: AC (5 Hz…80 MHz), DC (0…80 MHz), LF (0…1.5 kHz) Trigger Indicator: LED External Trigger: Input Impedance: 1MΩ II 15pF External Trigger Signal: 0,3 V

Important hints Immediately after unpacking check the instrument for any mechanical damage and loose parts inside. In case of transport damage inform the supplier. Do not operate the instrument. Symbols Consult the manual High voltage Please observe this note Ground, earth Placement of the instrument The pictures show how to move the handle into various positions. A: Carrying position B: Position for horizontal carrying resp. for removing the handle C: Horizontal operating position D and E: Operating positions with different angles F: Position for removing the handle T: Position for transport in its shipping carton, the handle will not lock in this position STOP In order to change the position of the handle, the scope must fi rst be fi rmly positioned e.g. on a table so that it cannot drop. Pull both knobs of the handle and move it to the desired position. If the knobs are released while moving, the handle will automatically lock in the next possible position. Removing/mounting the handle Removing is possible in positions B and F by pulling it out farther, mounting by doing the reverse. Safety This instrument was manufactured and tested according to VDE 0411,

part 1, safety norms for electrical measuring, control and laboratory

instruments. The instrument left the factory in perfectly safe condi- tion. It fulfi lls hence also the European norm EN 61010-1 resp. the international norm IEC 1010-1. The user is requested to observe all safety notes in this manual in order to preserve this safe condition and guarantee safe operation. Housing, chassis and measuring signal inputs are connected to the mains safety earth conductor. The instrument fulfi lls the requirements of safety class I. All metal parts which can be touched were tested with 2200 V

against the mains conductors. For safety reasons the oscilloscope may only be connected to outlets with safety earth conductor. The mains plug must be inserted fi rst before any signals are connected to the instrument. It is prohibited to disconnect the safety earth. Most electron tubes generate gamma rays. With this instrument the dose remains far below the limit of 36 pA/kg, set by the applicable laws. Whenever it must be assumed that safe operation is endangered, the instrument must be disconnected and stored in a safe place where inadvertent use is precluded. This assumption is always valid – if the instrument shows signs of damage – if the instrument contains loose parts – if the instrument does not function any more – if the instrument was stored for an extended period of time under unfavourable ambient conditions (e.g. in the open or in rooms at high humidity) STOP This instrument is solely destined for use by personnel well familiar with the dangers of electrical measurements! Proper operation Please note: This instrument is only destined for use by personnel well instructed and familiar with the dangers of electrical measurements. For safety reasons the oscilloscope may only be operated from mains outlets with safety ground connector. It is prohibited to separate the safety ground connection. The plug must be inser ted prior to connecting any signals. CAT I This oscilloscope is destined for measurements in circuits which are not or not directly connected to the mains. Direct measurements (without galvanic isolation) in circuits of the categories II, II or IV are prohibited! The circuits of a measuring object are not directly connected to the29 Subject to change without notice Important hints mains if the measuring object is operated via an isolation transformer of safety class II. Indirect measurements on the mains are also possible with special probes, e.g. current probes, which fulfi ll the requirements of the safety class II. With such measurements the measurement cate- gory specifi ed by the manufacturer for the probe has to be observed. Measurement categories The measurement categories relate to transients on the mains. Such transients are short but very fast (short rise time) voltage or current excursions which may be periodic or not. The amplitude of possible transients increases the shorter the distance to the source of the mains installation is. Measurement category IV: Measurements directly at the source of the mains installation, e.g. at the electricity meters. Measurement category III: Measurements within the mains installa- tions, e.g. at distribution points, power switches, wall outlets, perma- nently mounted motors etc. Measurement category II: Measurements at circuits which are directly connected to the mains, e.g. household appliances, portable tools etc. Measurement category I: Electronic apparatus and fused circuits within such apparatus. Areas of use of the instrument The oscilloscope is destined for use in the following areas: industrial, housing, business, workshops. Environmental conditions. The permissible operating temperature range is +5 to +40 °C. During storage or transport the temperature range is –20 to +70 °C. Conden- sation of water during transport or storage requires a 2 hour drying period before operation. The oscilloscope is destined for use in dry, clean rooms. It must not be operated if there is severe dust or if the humidity is excessive nor if there is danger of explosion or aggressive chemical reaction. The orientation during operation may be any. Suffi cient air circulation has to be provided, however. Continuous operation requires a horizontal or tilted (handle) position. STOP Do not cover the ventilation holes! All nominal specifi cations and tolerances are valid after a warm-up time of at least 30 min. and at an ambient temperature of + 23 degr. C. Speci- fi cations without a tolerance given are those of a typical instrument. Maintenance Clean the outside of the housing regularly with a brush. Dirt on the housing, the handle, plastic, and aluminum parts may be removed with a cloth and a mild detergent (1 %). Dirt containing fat may be removed with alcohol or petrol ether. The screen may be only cleaned with water or benzine, but not with alcohol or solvents, after cleaning it should be wiped with a dry clean cloth. After cleaning it should be treated with a customary antistatic solution for plastics. Under no circumstances any cleaning fl uid should enter the instrument. Use of any other cleaning agent may damage the plastic and lacquered surfaces. Warranty and repair HAMEG instruments are subjected to a strict quality control. Prior to leaving the factory, each instrument is burnt-in for 10 hours. By inter- mittent operation during this period almost all defects are detected. Following the burn-in, each instrument is tested for function and quality, the specifi cations are checked in all operating modes; the test gear is calibrated to national standards. The warranty standards applicable are those of the country in which the instrument was sold. Reclamations should be directed to the dealer. Only valid in EU countries In order to speed reclamations customers in EU countries may also contact HAMEG directly. Also, after the warranty expired, the HAMEG service will be at your disposal for any repairs. Return material authorization (RMA): Prior to returning an instrument to HAMEG ask for a RMA number either by internet (http://www.hameg.com) or fax. If you do not have an original shipping carton, you may obtain one by calling the HAMEG service dept (phone: [phone], fax: [phone]) or by sending an e-mail to [e-mail]. Line voltage The instrument may be operated with any voltage between 105 V to 253 V, 50/60 Hz, hence there is no line voltage selector. The line fuses is accessible from the outside. The mains connector and the fuse holder are one unit. The fuses can only be exchanged (if the fuse holder was not damaged) after the mains cable has been detached. In order to remove the fuses, use a small screw driver (appr. 2 mm) and push it into the two slanted slots at both sides of the fuse holder, this will release it, it will pop out by spring force. The fuses may then be exchanged. Please take care not to bend the contact springs. Inserting the fuse holder requires that the protruding notch points to the mains connector. The fuse holder has to be pushed in against the spring force until both latches catch it. It is prohibited to use „repaired“ fuses or to short -circuit the fuse. Any damages incurred by such manipulations will void the warranty. Type of fuse Size 5 x 20 mm 250 V AC, C IEC 127, p. III, DIN 41 662 (also DIN 41 571, p. 3) Slow blow T 0.8 A.30 Subject to change without notice Overview of the controls Overview of the controls

ADJUST – / + (buttons) 36 Allows to change diverse settings depending on the selection with the button SELECT

Indicator LEDs 36 INTENS: The LED will light up if intensity adjustment was selected with the button SELECT

FOCUS: The LED will light up if focus adjustment was selected with the button SELECT

TRACE: The LED will light up if trace rotation adjustment was selected with the button SELECT

SELECT (button) 37 Allows to change some settings relating to the crt like intensity, focus, trace rotation by pressing the buttons ADJUST

when the respective LED lights up.

SAVE / RECALL (LED button) 37 In conjunction with any of the mode buttons

this button allows to address the settings memories

AUTOSET (button) 37 Automatically selects a reasonable instrumentsetting for most signals

AUTO / NORM (LED button) 37 Selects either automatic (AUTO) or normal (NORM) triggering. The LED will light up if normal triggering was selected, other- wise automatic triggering is enabled.

SLOPE (LED button) 37 Selects either the positive or the negative signal slope. The LED will light up if the negative slope was selected.

TRIG’d (LED) 37 The LED will light up if the instrument receives a valid trigger signal and operates in triggered mode

X-MAG/x 10 (LED button) 37 If the x 10 magnifi er is enabled, the display will be expanded in X direction around the screen center ten times with a cor- responding change of the time base speed. The LED will light up if the magnifi er is active.

VOLTS/DIV; CH1 + CH2 (knobs) 37 Channel 1 or channel 2 sensitivity selection. By pressing the corresponding knob, the variable will be activated, and, as long as it is activated, the display of the sensitivity will blink, because the sensitivity is uncalibrated.

TIME/DIV (knob) 37 Selects the time base speed. By pressing the knob, the variable will be activated, and, as long as it is activated, the display of the time base speed will blink, because the time base speed is uncalibrated.This knob also has a third function: hold-off time adjustment, see

CH 1 (LED button) 38 Selects channel 1 as the trigger source as indicated by the LED.

CH 2 (LED button) 38 Selects channel 2 as the trigger source as indicated by the LED.

Subject to change without notice Basic signal measurement

LINE (LED button) 38 Selects the mains as the trigger source as indicated by the LED.

EXT (LED button) 38 Selects the external input as the trigger source as indicated by the LED.

AC (LED button) 38 Selects AC coupling for the trigger source as indicated by the LED.

DC (LED button) 38 Selects DC coupling for the trigger source as indicated by the LED.

LF (LED button) 38 Switches a low pass fi lter into the trigger channel as indicated by the LED

TV (LED button) 38 Selects TV signal triggering as indicated by the LED.

DC/AC; CH1 + CH2 (LED buttons) 38 Selects DC or AC coupling for channel 1 or channel 2 resp.. If AC is selected, the LED will light up.

GND; CH1 + CH2 (LED buttons) 38 Disconnects the input of channel 1 or channel 2 resp. and connects it to ground internally as indicated by the LED.

INV (LED button) 38 Inverts the signal of channel 2 (CH 2) as indicated by the LED. (Inversion of channel 1 is not available.)

HOLD OFF / ON (LED button) 38 By pressing this button a hold-off time can be selected, the amount of hold-off can be adjusted with the knob TIME/DIV.

for intensity modulation as indicated by the LED.

INPUT CH 1 + CH 2 (BNC connectors) 38 Signal input for channel 1 or channel 2 resp.. In XY mode the CH1 input will control the horizontal movement (X) of the trace.

PROBE ADJUST (contact) 39 1 KHz/1 MHz square wave output for the adjustment of probes other than 1:1. PROBE ADJUST (contact) 39 Ground connection for the probe adjustment.

EXT. TRIG/Z-INP (BNC connector) 39 Input for external trigger or intensity modulation signals.

Mode select buttons with LED: 39 CH 1: Activates the channel 1 (CH 1) input or selects access to the settings memory 1 as indicated by the LED. CH 2: Activates the channel 2 (CH 2) input or selects access to the settings memory 2 as indicated by the LED. DUAL:Selects dual channel operation or access to the settings memory 3 as indicated by the LED. ADD:Selects the add mode of the vertical amplifi er or access to the settings memory 4 as indicated by the LED. XY: Selects the X Y mode or access to the settings memory 5 as indicated by the LED. COMP: Activates the COMPONENT tester or selects access to the settings memory 6 as indicated by the LED.

COMPONENT TESTER (two 4 mm test jacks) 39 Terminals of the component tester, the left one is connected to the chassis and thus to the safety earth connector of the mains cable. Basic signal measurement Nature of the signal voltages The oscilloscope HM400 displays in real time most repetitive signals containing frequencies from DC to beyond 40 MHz (- 3 dB). The vertical amplifi er is designed for minimum overshoot. The display of simple electrical waveforms like LF or HF sine waves or mains frequency ripple is no problem. When measuring the amplitude of sine waves, the frequency response of the oscilloscope has to be taken into account which begins to fall off at fairly low frequencies. At 25 MHz the amplitude error will amount to appr. –10 %. Due to the tolerance of the –3 dB frequency the exact amount of the amplitude error may vary. Square wave or pulse signals, in general all nonsinusoidal signals, contain frequencies well above their repetition frequency, depending on their shape and rise resp. fall times. This oscilloscope has a rise time of 8.5 ns and will reproduce signals fairly well if their rise times remain 3 to 5 times slower. It follows that the repetition rate of such nonsinusoidal signals must remain considerably lower than the –3 dB frequency of 40 MHz, otherwise their harmonics will be attenuated too much, i.e. the edges will be rounded. It is more diffi cult to display socalled mixed signals unless there is a repetition frequency with outstanding amplitudes, so the scope can trigger on them. This may be the case with burst signals. In order to obtain a stable display, it may be necessary to vary the hold-off time. The active TV sync separator will allow stable triggering on video signals. The fastest time base speed using the magnifi er is 10 ns/div which allows to spread a period of 40 MHz over 2.5 divisions, consequently, time resolution is no problem. The vertical amplifi er is DC coupled, when AC coupling is selected, a capacitor is switched in series with the signal input. The normal coupling mode is DC; if the DC content of the input signal is too high, AC coupling will be required. In this case, however, two effects need to be considered. Signals with a very low frequency content may be distorted, e.g. low frequency square waves will show tilt (appr. 1.6 Hz – 3 dB) . Signals with varying duty cycle will be displayed with a vertical shift depending on the duty cycle corresponding to their DC content. The low frequency limit could be reduced by selecting DC coupling and connecting an external larger capacitor of suffi cient voltage rating, but use of this method is discouraged, a 10:1 probe will reduce the low frequency –3 dB point to 0.16 Hz. Due to their internal circuit, 100:1 and 1000:1 probes do not reduce the lower frequency –3 dB frequency. As outlined in more detail later, oscilloscopes are rarely used without probes.32 Subject to change without notice Basic signal measurement Amplitude of signals. In electrical engineering, ac voltages are given in rms units. Oscilloscopes show the actual peak-to-peak voltages, hence they are calibrated in V

In order to arrive at the RMS value of a sine wave, its pp – value must be divided by 2.83. RMS voltages will be displayed larger by that factor. The highest sensitivity of this scope is 1 mV/DIV, a signal of 1 division will amount to 1 mV

±5 % unless the variable is activated. Calibrated measurements require that the „variable“ is off. The variable allows to decrease the sensitivity by a factor of appr. 2.5 to a lowest of appr. 50 V/DIV. The variable also allows to bridge the 1 – 2 – 5 steps of the input attenuators. Without a probe signals of up to 400 V

may be displayed (50 V/DIV x 8 divisions). In order to measure the amplitude of a signal, it is only necessary to read the height of the display and multiply it by the sensitivity selected in V/DIV. STOP Without a probe the maximum input voltage at both inputs is + or – 400 Vp. In case the signal consists of DC and AC, the DC plus peak AC must not exceed + or – 400 V

(of which only 400 Vpp can be displayed on the screen.) STOP If 10:1 probes are used, their possibly higher maximum voltages may only be made use of if the scope input is switched to DC coupling. This does not apply to 100:1 or 1000:1 probes. Considering the foregoing, HAMEG HZ154 10:1 probes allow to measure DC up to 400 V and pure ac voltages up to 800 V

, and HAMEG HZ53 100:1 probes dc voltages up to 1200 V and pure ac voltages up to 2400

. Please observe the decrease of the permissible input voltage with increasing frequency for each probe type, see the respective probe ma- nuals. Risking the measurement of excessive voltages with a standard 10:1 probe may cause a short of the probe’s input capacitor which could destroy the scope input circuitry! It is possible to measure the ripple on a high voltage by inserting a high voltage capacitor in series with a 10:1 probe, but it is mandator y to switch the input to DC; in order to avoid excessive transients, the input must fi rst be switched to ground, then the high voltage applied, then the input switched to DC. The high voltage capacitor has to be discharged with proper care using a resistor of suffi cient voltage rating! The GND position of the input coupling selector is used to set the base line using the POSITION control as desired before switching to DC. Time measurements As a rule, scopes are used to display repetitive signals, the designation period is used here for simplicity. The repetition frequency is equal to the number of periods per second. Depending on the setting of the TIME/DIV switch one or more periods may be displayed or just portions of one period. The time base speeds are indicated by the LEDs around the circumference of the TIME/DIV knob in us/DIV, ms/DIV, s/DIV. In order to measure the period or portions of a signal, read the number of divisions and multiply this by the time base speed selected. The HORIZONTAL position knob allows to shift the horizontal position of the trace. Rise and fall times are defi ned between 10 and 90 % of the full amplitude. Applying the signal voltages Use AUTOSET for a quick automatic selection of suitable display parameters (see AUTOSET). The following paragraph applies to ma- nual operation. The function of the controls is detailled in the chapter „Controls“. STOP Be careful when applying unknown signals to the vertical amplifi er. Without a probe set the VOLTS/DIV switch to 20 V/DIV and use AC coup- ling. If the trace disappears after application of the signal, it is possible that the signal amplitude is much too large and overdrives the vertical amplifi er. Decrease the sensitivity (increase the VOLTS/DIV setting) until the signal remains fully within the screen area. If portions of the signal fall outside this area, they may still overdrive the amplifi er which can cause distortions! With calibrated 20 V/DIV a probe will be required if the signal exceeds 160 V

, if the variable is activated up to 400 V

may be displayed without a probe. The probe used must be specifi ed for the maximum voltage applied. Please note that the display of signals with a low repetition rate at high sweep speeds will cause the trace to dim, the intensity may be increased until the trace starts to blur. In such case the time base speed must be decreased so far that the trace remains visible. The signals may be connected to the scope either through shielded cables or by using probes. The use of cables is restricted to low frequencies and low impedance signal sources because they add typically 100 pF/m load capacitance. At higher frequencies cables with standard characteristic impedances like 50 Ω can be used if they are correctly terminated at both ends. HAMEG HZ22 feedthrough terminations at the scope can be used together with HAMEG 50 Ω cables such as HZ34. Incorrect or missing terminations will cause massive pulse distortions. Generators, ampli- fi ers etc. will only perform to specifi cations if they are feeding properly terminated cables. The HZ22 is specifi ed for a maximum of 2 W which is reached if the signal increases to 10 V rms or 28.3 V

With probes no terminations are needed nor allowed, the probes are directly connected to the scope’s BNC connectors. Probes load high impedance sources only moderately (10:1 probes with 10 MΩ II 12 pF, 100:1 with 10 MΩ//5 pF), but this applies only up to appr. 100 KHz, above the loading increases with increasing frequency, see the probe manuals for details, also for the necessary derating. Passive probes are unsuited for measurements on high Q HF circuits! As mentioned, in most applications probes are used, at least as long as the loss in sensitivity can be compensated by increasing the scope’s sensitivity. Also, a probe offers protection for the scope’s input circuit. Because probes are manufactured separated from the scopes, they are only coarsely preadjusted, it is absolutely necessary to adjust each probe to the input it is used on (see Probe Adjustment). Probes may decrease the bandwidth of a scope considerably if they are the wrong type! We recommend to use the HAMEG HZ51 (10:1), HZ52 (10:1 HF), HZ154 (1:1 and 10:1) probes. Replacement parts may be ordered from HAMEG and may be exchanged by the user. The probes mentioned have a HF adjustment in addition to the basic 1 KHz adjustment. By using the 1 MHz probe adjust signal, the HF adjustment corrects for group delay aberrations near the –3 dB frequency. With these probes the HM400 rise time/bandwidth remain nearly constant. The probe HF adjustment also allows for an optimum pulse response of the combination probe and scope. STOP With a 10:1 or 100:1 probe DC coupling has to be used if the signal voltage exceeds 400 Vp. As mentioned if AC coupling is used, the 1.6 Hz –3 dB frequency comes into play which causes distortions with low frequency signals, e.g. square waves are displayed with tilt. With a 10:1 probe the low frequency response is improved by a factor of ten (0.16 Hz). If the sensitivity with this probe is insuffi cient, DC coupling and an external capacitor can be used e.g. for ripple superimposed on a high dc potential. First the input must be switched to GND, then the voltage applied, then the input switched to DC. The measurement of small voltages requires proper ground connec- tions as close to the measuring point as possible. Use short ground cables.33 Subject to change without notice First time operation and initial settings STOP If a probe is to be used to contact a BNC connecto, a probe to BNC adapter should be used in order to prevent groun- ding problems. If ripple or noise appears on small signals at high sensitivity settings, multiple grounds resp. ground loops may cause the problem. The mains safety earth is quite often the cause, because other test equipment will also be connected to the same safety earth, this can generate currents through the shields of cables etc. Most instruments have socalled Y capacitors connected from the mains to safety earth. First time operation and initial settings Prior to any use of the instrument make sure the power plug is inserted before any other contacts are established. Turn the instrument on by pressing the red button POWER, several indicators will light up, the oscilloscope will perform a self-test. If any errors are detected, there will be 5 acoustic signals; it is recommended to submit the instrument to a service station. After a successful self-test the instrument will be ready to operate, it will use the settings stored from its last use. If there is no trace after a 20 s wait, press the AUTOSET button. If the trace is now visible, use the SELECT button, the ADJUST + / – buttons to set the desired intensity and optimum focus. For best focus adjustment it is recommended to display a full screen sine wave. If no input signal is connected, switch the input to GND in order to prevent any noise from disturbing the focus adjustment. In order to extend the life of the crt, set the intensity no higher than needed for the specifi c measurement under the given ambient light conditions. Take care not to leave a bright spot as this could burn the crt phosphor. Do not turn the instrument on and off in short intervals. It is recommended to always use fi rst the button AUTOSET and select the buttons AC and CH 1 in the TRIGGER select area. Trace rotation In spite of the mumetal crt shield the earth’s magnetic fi eld still has some infl uence on the crt beam. Depending on the orientation of the ins- trument the trace may not always remain parallel to the graticule lines. See the chapter Controls for the adjustment of the trace rotation. Probe adjustment and use of probes. Probes have to be adjusted to the input they are connected to; this adjustment has to be performed each time a probe is moved to another input. A generator in the HM400 delivers a fast rise time ( < 5 ns) square wave signal of appr.

0.2 Vpp the frequency of which can be selected by using the knob TIME/

DIV (see the chapter Controls). The square wave signal is accessible at the two contacts below the controls. The 0.2 V

are destined for 10:1 probes, suffi cient for 4 divisons at 5 mV/DIV. 1 kHz adjustment This basic adjustment compensates for the input impedance of the scope, the probe’s capacitor is adjusted so that the capacitive division equals the resistive division, the division will thus be identical from DC to high frequencies. With 1 : 1 probes or probes which can be switched to 1 : 1, an adjustment is neither necessary nor possible. Before this adjustment make sure the trace rotation adjustment was performed (see TRACE rotation). Connect the 10:1 probe to the input, e.g. CH 1, do not press any button, set the coupling to DC, the sensitivity with VOLTS/DIV to 5 mV/DIV, the TIME/DIV switch to 0.2 ms/DIV; make shure that both are calibrated, i.e. the variables disabled. Connect the probe tip (and ground cable) to the contact(s) „PROBE ADJUST“ (see the photo); a 4 DIV display of two signal periods should appear. Now adjust the probe capacitor (see the probe manual for its location) until the square wave is perfectly fl at, i.e there are neither under- nor overshoots. The transitions are invisible at this sweep speed (see the pictures). The amplitude of the square wave should be within 4 ±0.12 DIV. undershoot correct overshoot 1 MHz adjustment The probes supplied with the scope have additional adjustment ele- ments which allow to correct for aberrations at high frequencies. After this adjustment maximum bandwidth and best pulse response of the combination scope and probe are obtained by achieving maximally fl at group delay; overshoots, undershoots, ripple are minimized. This adjustment requires a fast square wave generator ( < 5 ns) and low output impedance (50 ohms) which delivers 0.2 Vpp at 1 MHz; the PROBE ADJUST output of the scope fulfi lls these requirements. Connect the 10:1 probe to the input to be used. Select PROBE ADJUST signal 1 MHz with the knob „TIME/DIV (see the chapter Controls) switch the coupling to DC, the VOLTS/DIV selector to 5 mV/DIV and the TIME/DIV selector to 100 ns/DIV. Connect the probe tip and ground to the two PROBE ADJUST contacts. The square wave will now be visible and also its rising and falling slopes. See the probe manual for the location of the adjustment elements. Adjustment criteria: Only the rising slope and the top of the square wave are of concern, disregard the other portions of the signal. – Short rise time – Clean transition from the rising slope to the top of the square wave with no over- or undershoot, fl at top. undershoot correct overshoot The amplitude of the square wave should be identical to that with the 1 kHz signal. It is important to always fi rst perform the 1 kHz adjustment, in general a readjustment of the 1 kHz will not be necessary. Please note that the probe adjust frequencies are not precise and hence must not be used for any checks of the accuracy of the time base, also their duty cycle is not controlled. The probe adjust signal must conform to the requirements of zero potential at the bottom of the square wave, precise amplitude and fl at tops; its frequencies and duty cycles need not be precise. INV

POWER34 Subject to change without notice Operating modes of the vertical amplifi er The most important controls determining the operating modes of the vertical amplifer are the mode buttons CH 1, CH 2, DUAL, ADD and

Changing the modes is described in the chapter Controls. Yt is by far the mode most used: the input signal defl ects the trace vertically while a time base moves the trace from left to right. The Y amplifi er offers these modes:1. Single channel operation of CH 1.2. Single channel operation of CH 2.3. DUAL trace two channel operation.4. Algebraic addition of CH 1 + CH 2 and subtraction of CH 1 – CH 2.In DUAL trace mode both channels are operating, the time base de-termines the exact mode of representation, see the chapter Controls. Switching of the channels may either happen alternately after the com-pletion of each time base cycle, or the switching occurs at a high rate during the course of a time base cycle (chopped). The alternating mode is unsuited at slow time bases because the alternation becomes visible with disturbing fl icker, here, the chopped mode will yield a fl icker-free display. At high sweep speeds the chopped mode is unsuited because the switching transients are disturbing. In the ADD mode the signals of both channels are algebraically added (CH 1 + CH 2) or subtracted (CH 1 – CH 2) if CH 2 is inverted. If the si-gnals of CH 1 and CH 2 happen to be of opposite phase they may fully or partly cancel, of course. It is important to bear in mind that the two inputs of the scope are not to be mistaken as the inputs of a true difference amplifi er! When using this feature to measure the difference signal between two measuring points, restrictions must be observed: both input attenuators must be switched to the same setting, the common mode rejection is very mo-derate, and the common mode range is limited to the normal operating range of the input amplifi ers. This means in practice that, before the ADD mode is entered, it has to be checked whether each input signal can be displayed, i.e. that is in within the normal operating range; if that is the case for both signals, switch to ADD. Please note further that both POSITION controls affect the vertical position of the added signals. If probes are used, their tolerances will also diminish the common mode rejection; this can be checked by connecting both probes to the same measuring signal, the resulting display should be zero. It is preferable to use the probe adjust or a pulse generator for this test. XY mode For this mode use the button XY as described in the chapter Controls under

In this mode the time base is disabled. The CH1 input signal will defl ect the trace horizontally, the CH 2 input signal vertically. The horizontal position is controlled as usual with the X-POSITION control , the CH 1 position control is disabled. The magnifi er is also disabled. When using this mode, the low bandwidth of the X amplifi er (see the specifi cations) has to be observed, the phase difference between the wide band vertical amplifi er and the X amplifi er increases with frequency. STOP The Y signal may be inverted by pressing the button INV CH 2.Using Lissajous patterns it is possible– to compare two signals of different frequency and to adjust one to the frequency of the other until both are synchronized. This applies also to multiples or fractions of one of the frequencies– to measure the phase difference between two signals of the same frequency. Measurement of phase differences in dual channel operation A much more precise and convenient method of measuring phase differences which is also applicable up to high frequencies is the measurement of the time difference in dual channel operation. Please note: It is mandatory that the trigger signal is taken from only one signal.The phase difference can be easily calculated as the frequency is known. Another advantage of this me-thod is the fact that the time difference is still measurable even if the signals are corrupted by hum, ripple or noise. Also, there are no ambiguities. Alterna-tively Lissajous patterns can be used for measurement of phase differences. Triggering and time base The pertinent controls are located to the right of the VOLTS/DIV knobs, see the chapter Controls. In Yt operation the signal defl ects the trace vertically while it is defl ected horizontally with constant selectable velocity from left to right. The time base is started by a socalled trigger signal which is derived from any of the available sources. The time base performs one cycle and rests waiting for the next trigger. It is hence immaterial when the next signal arrives, the signal needs only to be repetitive, it need not be periodic! The time between triggers may be any, at low repetition frequencies the display becomes darker, at very low ones the trace will not be visible any more. In order to achieve a stable display, the trigger must always be derived from the very same portion of the signal. The slope and the level of the triggering signal can be chosen. Note: Various trigger sources are available: the two input channels, an external input, a signal taken from the mains, a TV trigger. Of course, the triggering signal must be synchronous to the signal to be displayed. The minimum amplitude for stable triggering is called the trigger threshold. With internal triggering the trigger signal is taken off in the two input amplifi ers, the minimum amplitude here is given in mm vertical defl ec- tion, independent of the positions of the VOLTS/DIV switches. With external triggering the minimum amplitude is given in Vpp at the external trigger input connector. The trigger amplitude may be much larger than the threshold, but it is advisable not to exceed 20 times the threshold.The oscilloscope features two trigger operation modes to be descri- bed. Automatic peak-to-peak triggering Please refer to the chapter Controls for specifi c information about the controls SLOPE , TRIGGER-LEVEL , and TRIGGER

When using AUTOSET, this trigger mode will be automatically selected. If DC coupling is selected, the peak-to-peak detection will be disabled, while the function of the auto trigger will remain active. With auto trigger selected, there will be always a trace visible, because the time base will restart periodically if no trigger signal is present or if only a DC voltage is applied. The auto trigger function implies that the user is only required to operate the VOLTS/DIV and TIME/DIV controls.The TRIGGER-LEVEL knob is active with auto peak-to-peak triggering, its range is automatically adjusted to the peak-to-peak level measured, Operating modes of the vertical amplifier

b35 Subject to change without notice it becomes hence independent of the amplitude and the shape of the signal. The duty cycle may e.g. vary from 1 : 1 to 1 : 100 without loss of the trigger. It may, however, be sometimes necessary to set the TRIGGER- LEVEL control close to one of its extremes. The next measurement may require another setting. The simplicity of operation recommends the auto peak-to-peak triggering for most uncomplicated measurements. It is also a good start with diffi cult problems, especially, if the properties of a signal like amplitude, frequency and shape are unknown. The auto peak-to-peak trigger mode is independent of the trigger source and operates above 5 Hz, i.e., if the repetition frequency of the triggering signal is lower, the time base will freerun. Normal trigger In this mode all settings are up to the user, and there is no visible trace if there is no suffi cient trigger signal. See the chapter Controls for specifi c information about the functions of the controls SLOPE

. Complex signals may require the additional use of the functions Time Base Variable (VAR) and HOLD-OFF time adjustment. STOP In the normal trigger mode the trigger signal can be derived from any portion of the rising or falling slopes of the signal by proper setting of the TRIGGER-LEVEL knob. The available trigger range depends on the amplitude of the signal. If the signal amplitude on the screen is < 1 DIV with internal triggering, the adjustment may become critical due to the small range available and require some care. As mentioned there will be no visible trace if the TRIGGER-LEVEL setting is false or if the trigger signal is missing or insuffi cient. The normal trigger mode allows to also trigger on complicated signals. With mixed signals it is, however, necessary that repetitive signal peaks are present which can be caught by careful operation of the TRIGGER-LEVEL control. SLOPE selection With the SLOPE

button the signal slope is selected, see the chapter Controls. This selection is always valid, also in AUTOSET mode. A rising slope is defi ned as a portion of a signal which rises from a given potential to a more positive one, a falling slope correspondingly is defi ned as a down slope from a given potential to a more negative one. Trigger coupling See the chapter Controls for specifi c information about the controls SLOPE

. The selection of trigger coupling AC or DC remains unaffected by AUTOSET. See the specifi cations for the passbands of the various modes of trigger coupling. With DC or LF coupling use the normal trigger mode and the TRIGGER-LEVEL knob. These modes are available: AC: This is the standard coupling mode. It has a low and a high frequency limit, below resp. above these limits the trigger threshold rises. DC: DC coupling is effective from DC to the upper frequency limit. This mode is recommended for slowly varying signals when triggering on a defi nite portion is desired or when the duty cycle of signals varies. LF: When LF is selected, a low pass fi lter is inserted in the trigger path. In combination with the normal trigger mode there is no lower frequency limit, the same as with DC coupling (galvanic coupling). In auto (peak-to-peak) trigger mode AC coupling will be automati- cally used, this will cause a lower frequency limit which, however, is below the functional limit of the auto trigger. For low frequency signals LF coupling is often the preferred mode, because high frequency noise is reduced. This eliminates or diminishes trigger jitter resp, multiple displays, especially with small input voltages. Above the bandwidth of the low pass fi lter the trigger threshold rises sharply. LINE: See separate description TV: See below. TV (video signal) triggering (PAL) When T V triggering is selected, the T V sync separator will be activated, it separates the sync pulses from the video content and thus allows a stable display independent of the video content. Depending on the point of measurement, video signals (Complete composite video signals) are either positive or negative. It is necessary to select the correct SLOPE (13) in order to effectively separate the sync pulses. The direction of the fi rst slope of the snyc pulses is important, the signal display must not be inverted. If the sync pulses are above the video, negative slope is to be selected. If the sync pulses are below the video, their fi rst slopes are negative, hence positive SLOPE must be selected. If the slope selection was wrong, the display will be unstable resp. will not be triggered, because it will be the video which generates the trigger. TV triggering should use the auto trigger function. If internal triggering is selected, the height of the display must be > 5 mm. The sync signals consist of frame and line pulses which differ in their duration. In the PAL standard, the line sync pulses are 5 μs of 64 μs for a full line. The frame pulses consist of several pulses of 28 μs each with a repetition period of 20 ms for each half frame. Both sync pulses differ hence in their duration and their rep rate. Triggering is available from both line and frame pulses. Frame pulse triggering For frame synchronization a TIME/DIV setting of 0.2 s/DIV to 1 ms/DIV is appropriate, at 2 ms/DIV a full half frame will be shown. STOP Triggering on the frame pulses with chopped dual trace operation is discouraged because this will cause visible interference. This is why in TV trigger mode automatically the alternating dual trace mode will be set. If desired, pressing the DUAL

mode button for some time will manually change between alternate and chopped modes; As soon as the TIME/DIV selector is operated, the alter- nate DUAL mode will be automatically selected. At the left side of the screen a portion of the triggering frame pulses will be visible, at the right hand side of the screen the frame pulse for the next half frame is visible, consisting of several pulses. The next half frame will thus not be displayed under these circumstances. The frame pulse following that half frame will trigger again a display. With the shortest available hold-off time selected each 2nd half frame will be displayed. Which half frame will be displayed is up to chance. A short disruption of the trigger may cause triggering on the other half frame. The X magnifi er X-MAG/x 10 can be used to expand the display in order to see individual lines. Starting from the frame pulse also the TIME/DIV knob can be used for expansion, however, this will cause an apparently untriggered display as each half frame will trigger a display; the reason is the ½ line displacement between the half farmes. Line sync triggering Each sync pulse can trigger a line display; the TIME/DIV

knob should be set between 0.5 ms/DIV to 0.1 μs/DIV. In order to display single lines a setting of 10 μs/DIV is recommended, appr. 1 1/2 lines will be visible. In general, the complete composite video signal has a sizeable dc content. If the video content is constant (as is the case with test patterns), the dc can be removed by selecting AC trigger coupling. If the video con- tent changes as is normal with any program, DC coupling is required, Triggering and time base36 Subject to change without notice otherwise the display will shift vertically depending on the video content. Use the POSITION control to keep the display within the screen area. The sync separator circuit is also effective with external triggering. Of course, the specifi ed voltage range (see the specifi cations) must be observed. Note that the polarity of external sync signals can be any, i.e. it can differ from that of the composite signal at the vertical input, hence the SLOPE must be selected accordingly. In order to check the external trigger signal, display it by applying it to a vertical input with internal triggering. LINE triggering In the LINE trigger mode a signal from the mains power supply is taken (50/60 Hz). This mode is recommended for all signals of mains frequency or synchronous with it. Within limits this also applies for multiples or submultiples of the mains frequency. LINE triggering will also yield stable displays if the input signal is very small, i.e. below the trigger threshold. It is hence especially handy for all kinds of mains frequency ripple or interference measurements. With LINE triggering the SLOPE selection will select the positive or negative half wave and not the slope, hence it may be necessary to pull the mains plug and insert it upside down if that is possible (not in all countries). In the auto trigger mode the TRIGGER-LEVEL

will allow to move the trigger point within the half wave selected. In the normal trigger mode the trigger point can also be moved outside the selected half wave. Magnetic interference from the mains can be detected by using a pick- up coil which allows to determine the direction and the amplitude. The coil should preferably sport a high number of turns of thin enamel wire on a small coil former, a shielded cable with a BNC connector should be used for the connection to the scope. A 100 Ω resistor should be inserted between the cable and the BNC in order to reduce HF inter- ference, a ceramic capacitor to ground may be additionally required. Also, the coil should have a static shield (no short circuit winding). By turning the coil the minima and maxima of the magnetic interference are detectable. External triggering External triggering is selected by pressing the button EXT

, this will disconnect the internal triggering. The external signal is to be connected to the EXT.TRIG/Z-INP

BNC connector, see the specifi cations for the required signal levels. The external trigger signal must be synchronous to the measuring signal at the Y input(s), but its shape may be entirely different. Within limits triggering is even possible from multiples or submultiples of the measuring frequency. A stable phase relationship is, however, necessary. There may be a phase difference between the measuring and triggering signals; if the phase difference happens to be 180 degrees, the other slope has to be selected, else the signal will be displayed with a starting negative slope although the positive slope was selected. STOP The maximum input voltage at the EXT.TRIG./Z-INP

BNC connector is 100 V (DC plus peak AC). The input impe- dance is 1 MΩ//15 pF. The trigger coupling modes are also effective with external triggering. The only difference to internal triggering is a capacitor in the signal path (except with DC coupling), the lower bandwidth limit is 20 Hz. Triggered state indicator LED TRIG’d The following explanations refer to the TRIG’d – LED – indicator which is listed under

in the chapter Controls. It will light up if

1. an internal or external trigger signal of suffi cient amplitude is

available at the trigger comparator.

2. and if the reference voltage at the trigger comparator is set to a

level such that the signal slopes will cross this level. If these conditions are fulfi lled, the trigger comparator will deliver pulses for starting the time base, and a stable display will result. This indicator is handy for adjusting and controlling the trigger con- ditions, especially in case of very low frequency signals or very short pulses. With signals with extremely slow rep rates the LED will light up pulsed. The indicator will also blink not only when the time base is started at the left hand side of the screen, but with dual trace operation with every start of a trace. Hold-off time adjustment Further information is available in the chapter Controls under HOLD- OFF/ON

If no stable display can be obtained even with very careful adjustment of the TRIGGER-LEVEL

control in normal trigger mode, an adjustment of the hold-off time may help. The hold-off time is required in each analog scope in order to allow suffi cient time for the retrace of the beam from the right hand to the left hand side of the screen. During this time trigger pulses from the trigger comparator are ignored. The HM400 allows for an adjustment (increase) of 10:1 of the hold-off time. With complex signals, burst signals or non-periodic signals the time when the time base will accept the next trigger pulse can then be changed such that a stable display is achieved. Sometimes a noisy signal or one which is corrupted by HF will cause multiple displays. Mostly, the TRIGGER-LEVEL control can only affect the apparent time difference between the displays. By increasing the hold-off time a stable display is almost always possible. The following pictures demonstrate the function of the hold-off. Fig. 1 shows the screen display with minimum hold-off time (basic setting). A double display is shown because different portions of the signal are displayed. Fig. 2: Here, the hold-off time was adjusted such that always the same signal portions are displayed, a stable display is obtained. In order to change the hold-off time, press the HOLD-OFF/ON button and turn the TIME/DIV

knob slowly CW until a stable display is found. Double displays are also possible with pulse trains when the amplitudes alternately differ by a small amount. Careful setting of the trigger level and of the hold-off time may be required for correct displays. Any time the hold-off time was changed from its basic minimum setting it should be reset because too long a hold-off time will cause the time base rep rate to decrease which can dim the display. Triggering and time base periodheavy parts are displayedsignaladjustingHOLD OFF timesweepFig. 1Fig. 237 Subject to change without notice AUTOSET See also the information given under AUTOSET

in the chapter Controls As mentioned in the chapter Controls all front panel controls are electronically read out, hence the instrument can also be completely electronically controlled. This allows for a fully automatic signal-derived setting of all controls in the Yt mode. In most cases manual settings will be superfl uous. When AUTOSET is activated, the instrument will enter the Yt mode if XY was selected; if it was already in Yt mode, the settings will remain unaffected unless ADD was selected which will be set to DUAL. In one-channel mode the sensitivity is automatically chosen so that the signal will be displayed with appr. 6 divisions; in DUAL channel mode each channel display will be appr. 4 divisions. The foregoing and the description of the time base setting apply to signals which do not differ too much from a duty cycle of 1:1. The auto- matic selection of a suitable time base speed will show appr. 2 signal periods. With signals which contain several frequencies the settings obtained are governed by chance. Pressing the AUTOSET button will have these results: – The input coupling (AC, DC) remains unchanged resp. the last setting before switching to GND is resumed. – Internal triggering. – Automatic triggering. – Automatic selection of the trigger source – The trigger level will be set to the center of its range. – VOLTS/DIV set to calibrated (variables off) – TIME/DIV set to calibrated (variable off) – AC or DC trigger coupling unchanged – Magnifi er off – X and Y positions automatic – Trigger slope selection unchanged – Visible trace Selecting AUTOSET will leave the selected AC or DC input coupling unchanged. In case DC trigger coupling was selected, this will not be changed to AC. The automatic triggering functions without peak-to-peak detection. The AUTOSET settings will override any former settings. In case variables were activated, they will be disabled, such that all settings will be calibrated. After AUTOSET was activated, manual control can be executed. Due to the reduced bandwidth in 1 and 2 mV/DIV these ranges will not be used in AUTOSET. STOP If a pulse signal is applied the duty cycle of which reaches or exceeds 1:400, an automatic display will in most cases become impossible. In such cases only the freerunning trace will be visible. It is recommended to switch to normal trigger mode and to set the trigger point about 5 mm above or below the screen center. If the TRIG’d LED lights up, the signal was recognized. In order to render it visible, the time base speed and the sensitivity must be increased, however, the trace may dim so much that the pulse may remain invisible. Component test The oscilloscope HM400 has a built-in component tester which is activated by pressing the mode button COMP . The unit under test is connected to the two contacts right and left below the screen. After pressing the COMP button, the Y preamplifi ers and the time base will be disconnected. While using the component tester, signals may be present at the inputs as long as the unit under test is not connected to any other circuit. It is possible to test components remaining in their circuits, but in such cases all signals must be disconnected from the three front panel BNC connectors! (See the following paragraph: „Test in circuits“). With the exception of the SELECT button

knob, and the X-MAG/x 10

button all other controls will be disabled. Two cables with 4 mm plugs are necessary to connect the unit under test to the component tester. After completion of the component test pressing the COMP button again is all that is needed to resume normal scope operation. STOP As outlined in the chapter Safety, all measurement con- nectors are connected to the mains safety earth (in proper operation). This implies also the COMP.TESTER contacts. As long as individual components are tested, this is of no consequence because these components are not con- nected to the mains safety earth. STOP If components are to be tested which are located in circuits or instruments, these circuits resp. instruments must be disconnected fi rst under all circumstances! If they are operated from the mains, the mains plug of the test object has to be pulled out. This ensures that there will be no loops between the scope and the test object via the safety earth which might cause false results. Only discharged capacitors may be tested! The test principle is quite simple. A generator within the HM400 ge- nerates a 50 Hz ±10 % sine wave which feeds the series connection of the test object and a sense resistor. The sine wave voltage is used for the X defl ection and the voltage drop across the resistor for the Y defl ection. If the test object has only a real part such as a resistor, both defl ection voltages will be in phase; the display will be a straight line, more or less slanted. Is the test object short-circuited, the line will be vertical (no vol- tage, current maximum). If the test object is open-circuited or missing a horizontal line will appear (voltage, but no current). The angle of the line with the horizontal is a measure of the resistance value, allowing for measurements of resistors between 20 Ω and 4.7 K. Capacitors and inductors cause phase shift between voltage and current and hence between the defl ection voltages. This will cause displays of ellipses. The location and the form factor of the ellipse are determined by the apparent impedance at 50 Hz. Capacitors can be measured between 0.1 and 1000 μF. – An ellipse with its longer axis horizontal indicates a high impedance (small capacitance or large inductance) – An ellipse with its longer axis vertical indicates a low impedance (large capacitance or small inductance) – An ellipse with its longer axis slanted indicates a relatively large resistive loss in series with the impedance of the capacitor or inductor. With semiconductors the transition from the non-conducting to the conducting state will be indicated in their characteristic. As far as is pos- sible with the available voltages and currents the forward and backward characteristics are displayed (e.g. with zener diodes up to 9 V). Because this is a two-pole measurement, the gain of a transistor can not be de- termined, however, the B-C, B-E, C-E diodes can be measured. Please Component test38 Subject to change without notice Function of the controls

POWER Pushbutton switch with indications of off (0) and on (I) positions. After turn-on all LEDs will light up, the instrument performs a self-test. As soon as this has been successfully completed, the oscilloscope will switch to normal operation, all settings which were valid before switching off will be resumed.

ADJUST – / + Allows to change the value of diverse settings selected by SELECT

Indication LEDs INTENS The LED will light if the function intensity adjustment was selected by SELECT

the intensity may be Function of the controls note that most bipolar transistors can only take an E-B voltage of appr. 5 V and may be damaged if this is exceeded, sensitive HF transistors take even much less! With this exception the diodes can be measured without fear of destruction as the maximum voltage is limited to 9 V and the current to a few mA. This implies, however, that a measurement of breakdown voltages > 9 V is not possible. In general this is no dis- advantage because, if there is a defect in a circuit, gross deviations are to be expected which will point to the defective component. Rather exact results may be achieved if the measurements are com- pared to those of intact components. This is especially true for semi- conductors. The polarity of diodes or transistors can thus be identifi ed if the lettering or marking is missing. Please note that with semiconductors changing the polarity (e.g. by exchanging the COMP.TESTER and ground terminals) will cause the display to rotate 180 degrees around the screen center. More important in practice is the quick determination of plain shorts and opens which are the most common causes of requiring service. STOP It is highly recommended to observe the necessary pre- cautions when handling MOS components which can be destroyed by static charges and even tribo electricity. The display may show hum if the base or gate connection of a transistor is open, i.e. it is not being tested. This can be verifi ed by moving a hand closeby. In-circuit tests They are possible in many cases but deliver rarely clear results. By par- alleling of real or complex impedances – especially if those are fairly low impedance at 50 Hz – there will be mostly great differences compared to individual components. If circuits of the same type have to be tested often (service), comparisons with intact circuits may help again. This is also quickly done because the intact circuit has not to be functional, also it should not be energized. Just probe the various test points with the cables of the component tester of the unit under test and the intact unit and compare the screen displays. Sometimes the unit under test may already contain an intact portion of the same type, this ist e.g. the case with stereo circuits, push-pull circuits or symmetrical bridge circuits. In cases of doubt one side of the dubious component can be unsoldered, and this free contact should then be connected to the COMP.TESTER contact which is not identifi ed as the ground contact. This will reduce hum pick-up. The contact with the ground symbol is connected to the scope chassis and is thus not susceptible to hum pick-up.

decreased resp. increased. It is recommended to set the intensity no higher than needed for easy viewing, this depends on signal parameters, oscilloscope settings and the ambient light conditions. FOCUS The LED will light up if the function focus adjustment was selected by SELECT

the focus can be changed. The focus adjustment depends on the intensity, the lower the intensity, the better the focus. Also, the focus depends on the location of the trace on the screen, the best focus is always in the center and it decreases towards the edges. A reasonable focus setting is hardly possible with only the trace on screen. Due to the interaction between intensity and focus, the best procedure is this:

1. Apply a sine wave signal which covers the whole screen.

2. Set the intensity.

3. Adjust the focus for a uniform well focussed display over most of

the screen area. Please note that the display of signals with a low rep rate at high sweep speeds will ask for a higher intensity setting, this will entail a readjustment of the focus. TRACE The LED will light up if the function trace rotation was selected by SE- LECT

the trace rotation can be adjusted. Due to the earth’s magnetic fi eld the trace may not be parallel to the graticule lines, adjust for exact parallelism. See also under „Trace Rotation“ in the chapter „First time operation“.

SELECT This button allows to select and change the settings related to the trace in conjunction with the buttons ADJUST – / +

. By pressing one of this buttons shortly the functions intensity, focus and trace rotation will be enabled in turn as indicated by the associated LEDs.

These knobs control the trace position of channel 1 respectively cannel

2. In ADD mode both position controls will be effective. In XY mode the

Y position control is disabled; the X position is always controlled by the knob HORIZONTAL position

Measurement of DC voltages If there are no voltages present at the Y amplifi er inputs

CH1 resp. CH2, or if GND was selected, the trace positions correspond to zero volts, however, they are also influenced by the position controls! (The trace will be visible only if automatic triggering AUTO

was selected.) In order to measure a DC voltage, fi rst the input must be disconnected or switched to GND. Then it is up to the user to choose a reference trace position with the respective position control, i.e.

for channel 1. Then the DC voltage can be connected resp. the input switched from GND to DC; the trace will move by an amount depending on the polarity and value of the dc voltage and the sensitivity (and probe) selected. The same is true for measuring the dc content of any signal. In regular operation, the position controls will mostly be set to the screen center representing zero. It should be kept in mind, that it can not be just assumed that a trace position at the screen center corresponds to zero volts, this has to be checked by switching to GND.39 Subject to change without notice Function of the controls

SAVE / RECALL This button allows access to the settings memories in conjunction with the MODE buttons

. The oscilloscope has 6 settings memories, settings can be stored or recalled. SAVE: In order to store a setting, fi rst press the SAVE/RECALL button for some time, until the MODE buttons

start blinking. By pressing the respective mode button, the associated memory will be called and the present setting will be stored, the mode button LEDs will then extinguish. If the SAVE/RECALL button was pressed inadvertently, this can be repaired by pressing it again or any other button except the mode buttons. RECAL: For recalling press the SAVE/RECALL button just shortly, the mode buttons

will light up. By pressing the desired mode button, the settings stored in that memory will be taken over by the oscil- loscope. The mode buttons will then extinguish. If the SAVE/RECALL button was pressed inadvertently, this can be repaired by pressing it again or any other button except the mode buttons. STOP Please note that the signal presently displayed should be similar to that which was present at the time the setting was stored! If any other signal (frequency, amplitude) is being displayed when recalling, seemingly „false“ displays may result as the recalled settings may not be appropriate for the other signal.

AUTOSET See also the chapter AUTOSET. Pressing this button will cause the instrument to automatically choose a setting which generates a meaningful display. If the modes XY or Component Tester were active before pressing this button, AUTOSET will switch to the Yt mode last used (CH 1, CH 2, DUAL).

AUTO / NORM –LED button By pressing this button shortly the trigger mode will be alternated between AUTO and NORMAL triggering. The LED will light up when NORMAL triggering is selected. AUTO: Automatic triggering is available with or without peak-to-peak measurement. The TRIGGER LEVEL

knob is active in both cases. The automatic triggering circuit will also provide a bright baseline if there is no signal or an insuffi cient one for triggering. See the specifi cations for the lower frequency limit below which automatic triggering does not function, i.e. the display will not be triggered. With peak-to-peak triggering the range of the TRIGGER LEVEL

con- trol will be automatically adjusted to the present peak-to-peak signal level. Without this function there is no relationship between the signal amplitude and the range of the trigger level control, hence the trigger level may then be set too high or too low. The automatic triggering circuit will display the signal, but it will not be triggered. Whether peak-to-peak triggering is active or not depends on the ope- rating mode and the trigger coupling selected. By turning the TRIGGER LEVEL knob and looking for the start of the display, it will be obvious whether it is active or not. NORM: This is called the normal mode because it is the only one which allows triggering of complex waveforms and of very low frequency signals; in this mode the automatic and the peak-to-peak functions are disabled. A disadvantage of this mode is the fact that there will no trace visible if there is no signal, if the signal is insuffi cient for triggering or if the TRIGGER LEVEL

control is set inappropriately for the signal applied. The best procedure is to use auto peak-to-peak triggering as the standard and use NORM only if necessary.

SLOPE – LED button This button selects either the plus ( ) or the minus ( ) slope of the trig- gering signal. The LED will light up if the negative slope is selected.

TRIGGER LEVEL – Knob With this control the level of the triggering signal is determined at which the trigger comparator will respond and generate a signal to start the time base. The slope is selected with the above slope button. The trig- ger point is the point on the signal at which the display starts, it can be moved along the signal with the TRIGGER LEVEL control. See also the explanations in the foregoing paragraphs about automatic, peak-to- peak and normal triggering. In some combinations it is possible to loose triggering if the trigger level control is not set appropriately. Pressing AUTOSET

will restore a triggered display in most cases.

TRIG’d – LED This LED will light if up the time base receives start pulses from the trigger comparator. Depending on the frequency of the pulses the LED will blink or appear to light steadily.

control. The magnifi cation expands the display around the screen center, hence the normal procedure is to move the portion to be magnifi ed to the center with the X-POSITION control and then to activate the magnifi er. In XY mode the magnifi er is disabled.

X-POSITION With this knob the display can be moved in X direction (horizontally). See the paragraph above for its use together with the magnifi er.

VOLTS/DIV, CH1 + CH2 – knobs These are dual function knobs: it is used to select the appropriate sensitiviy for the signal of each channel’s input, by pressing it shortly it will assume the „Variable“ (VAR) function (see below), while this is active, the sensitivity indicators (ring of LEDs around the knob) will blink as a warning that the sensitivity is now uncalibrated. The knob is only enabled if CH1 or CH2 was activated or selected as the trigger source (CH1 or CH2 only, dual trace, ADD, XY). Sensitivity selection (Input attenuator) If the sensitivity indicator LED does not blink, the sensitivity selected will be calibrated. The sensitivity can be decreased CCW to 20 V/DV and increased CW to 1 mV/DIV in 1 – 2 – 5 steps. VAR (CH1 + CH2) By pressing the VOLTS/DIV

knobs shortly, its function will be changed to „Variable“ which will be indicated by blinking of the sensitivity indicator LEDs around the knob. Pressing it again will restore the calibrated sensitivity, the blinking will stop. As long as the variable function is enabled, the display will be uncalibrated! CCW rotation will decrease the sensitivity, CW rotation will increase it. The variable allows hence to bridge the 1 – 2 – 5 steps of the sensitivity switch. If any of the two limits of the variable range is reached, an acoustic signal will indicate this. This function is frequently used e.g. for measuring rise times: be- cause the rise time is defi ned from 10 to 90 % of the full amplitude, the variable comes in handy to set the (uncalibrated) signal amplitude e.g. precisely to 6 divisions peak-to-peak; by shifting the display horizontally with the X position control, the rise time can be read from 6 mm from the bottom to 6 mm below the top of the waveform.

TIME/DIV – knob This knob has a triple function:

1. It selects the time base speed.

2. By pressing it shortly, it will assume the „Variable“ VAR function,

this will be indicated by blinking of the LEDs around the knob.

3. After pressing the HOLD-OFF/ON

button, it will assume the function of hold-off time adjustment, this will be indicated by the button

lighting up, refer to

The time base speed is selectable in 1 – 2 – 5 steps, turning the knob CCW, it can be decreased to 0.2 s/DIV, turning it CW, it can be increased to 100 ns/DIV, the speed will be indicated by the LEDs around the knob,40 Subject to change without notice e.g. 10 μs (/DIV). By activating the X-MAG / x10

, the speed can be further increased by a factor of 10 up to the maximum of 10 ns/DIV. VAR: If the variable function was selected by pressing the knob shortly, the time base speed can be reduced by turning it CCW and increased by turning it CW, uncalibrated. Whenever the limits are reached, an acoustic signal will be heard. By pressing the knob again, the function variable can be left any time and calibrated operation resumed. Hold-off time adjustment: Please rever to item

CH 1 – LED button This button selects CH 1 as the trigger source. In all operating modes of the vertical amplifi er except XY, CH 1 can be selected as the active internal trigger source by pressing this button which will be indicated by the LED lighting up. STOP INTERNAL TRIGGERING: The trigger signal is taken off internally.

CH 2 – LED button This button selects CH 2 as the trigger source. In all operating modes of the vertical amplifi er except XY, CH 2 can be selected as the active internal trigger source by pressing this button which will be indicated by the LED lighting up.

LINE – LED button This button selects the line (mains) as the trigger source. In all ope- rating modes of the vertical amplifi er except XY the line (mains) can be selected as the active trigger source which will be indicated by the LED lighting up. STOP LINE TRIGGERING: The trigger signal is not derived from an input signal but from the mains and taken from the power supply.

EXT – LED button This button selects the external input as the trigger source. In all ope- rating modes of the vertical amplifi er except XY pressing this button will select the external BNC input EXT.TRIG/Z-INP

as the trigger source which will be indicated by the LED lighting up. The external Z-INP for intensity modulation will be disabled. STOP EXTERNAL TRIGGER SOURCE: The trigger signal is not taken from the measuring signals but from an external source.

AC – LED button In all operating modes of the vertical amplifi er except XY pressing this button shortly will select AC trigger coupling which will be indicated by the LED lighting up.

DC – LED button In all operating modes of the vertical amplifi er except XY pressing this button shortly will select DC trigger coupling which will be indicated by the LED lighting up. The peak-to-peak detection will be disabled.

LF – LED button In all operating modes of the vertical amplifi er except XY pressing this button will insert a low pass fi lter (see the specifi cations) into the trigger path which will be indicated by the LED lighting up. The low pass will suppress high frequency interference which could disturb triggering.

TV – LED button In all operating modes of the vertical amplifi er except XY pressing this button shortly will activate the TV trigger separator which will be indicated by the LED lighting up. The following remarks apply to the PAL TV standard. For frame synchronization the TIME/DIV

knob should be set between

0.2 s/DIV and 1 ms/DIV, at 2 ms/DIV a full frame will be displayed.

knob should be set between

0.5 ms/DIV and 0,1 μs/DIV. At 10 μs/DIV single lines can be displayed,

about 1 ½ lines will be visible.

DC/AC – LED buttons for CH 1 + CH2 By pressing these buttons shortly, the coupling of channel 1 or 2 resp. can be alternated between DC and AC, the LED will light up if AC is selected.

GND – LED buttons for CH 1 + CH2 By pressing these buttons shortly, the input of the channel 1 or 2 preamplifi er will be connected to ground resp., which will be indicated by the LED lighting up. The signal present at the input BNC connector can not infl uence the trace. In Yt-mode with auto trigger an undefl ected trace will be visible (zero-volts trace position) .In XY-mode there will be no defl ection in X and Y directions respectively.

INV – LED button for CH 2 By pressing this button shortly, the display of the channel 2 signal can be alternated between normal and inverted. The LED will light up if inversion is selected.

HOLD-OFF/ON – LED button By shortly pressing this button, adjustment of the hold-off time by turning the knob /TIME/DIV

will be activated which will be indicated by the LED lighting up. Refer to item

for information about the triple function of this knob. The knob allows an increase of the hold-off time from its minimum value by turning it CW, if the end of the range is reached, an acoustic signal will be heard. Also, when the knob is turned CCW, the acoustic signal will sound when the minimum value is reached. As soon as the hold-off time adjustment is disabled by again pressing

, the hold-toff ime will be automatically reset to its minimum value. By shortly pressing the TIME/DIV knob while

is activated, it is possible to alternate between setting the time/div. and hold-off time adjustment. See also under „Hold-off time adjustment“.

Z-INP – LED button By shortly pressing this button, the function of the input EXT.TRIG / Z-INP

is changed from external trigger input to external intensity modulation input which will be indicated by the LED lighting up. If ex- ternal triggering or the COMPONENT TESTER are selected, no intensity modulation will be possible resp. it will be disabled. 0 V at the input will not change the trace intensity, with 5 V TTL level the trace will be fully suppressed, higher voltages are not allowed.

INPUT CH1 + CH2 – BNC connectors These are the CH1 and CH2 inputs in Yt-mode and the X input in XY mode. The ground of this connector is connected to the chassis and thus to the mains safety earth. The buttons DC/AC

(CH2 only) corresponf to this input. Function of the controls

Subject to change without notice

PROBE ADJUST – Contact At this contact a square wave signal of 1 kHz or 1 MHz with a rise time

<5 ns and an output impedance of 50 Ω is available for the adjust- ment of probes other than 1:1, the amplitude is appr. 0.2 V

. For probe adjustment purposes neither the frequency, nor the duty cycle nor the exact amplitude are of concern. The frequency of the square wave depends on the setting of the TIME/ DIV

selector: between 0.2 s/DIV and 100 μs/DIV the frequency will be 1 kHz and between 50 μs/DIV to 100 ns/DIV it will be 1 MHz. See the chapter „First time operation and initial settings and „Probe adjustment and application.“ PROBE ADJUST : This contact is the ground connection for the probe.

EXT.TRIG/Z-INP – BNC connector This is either the external trigger or the external intensity modulation input . The input impedance is 1 MΩ II 15 pF. The ground of this con- nector is connected to the chassis and thus to the mains safety earth. By shortly pressing the Z-INP

button the function of the input can be changed. EXT.TRIG: This BNC connector is the external trigger input if the Z-INP LED is extinguished. The trigger source is selected with the buttons

; if external triggering is selected, the Z input will be automatically disabled. Z-INP: Z modulation is only possible if the Z-INP

button is illuminated. It is not possible to combine Z modulation with either external triggering or with the „Component Tester“ function, selecting one of these will disable the Z modulation. With 0 V at this input the trace intensity will not be infl uenced, with 5 V TTL level the trace will be fully suppressed; do not apply higher voltages.

MODE select buttons with LED Selection of CH1, CH 2, DUAL, ADD, XY and Component Tester modes, the active mode is indicated by the respective LED lighting up. Change of modes just requires shortly pressing the button of the desired function. The modes do not affect the trigger control status. CH 1: This button has a dual function: it either selects single channel 1 operation or allows access to the settings memory 1. Single channel CH 1 operation will automatically also select CH 1 as the trigger source unless external or line triggering were selected, this will be indicated by the trigger source button

lighting up. The last function of the VOLTS/DIV

knob will be preserved. All control elements belonging to this channel will be activated. CH 2: This button has a dual function: it either selects single channel 2 operation or allows access to the settings memory 2. Single channel CH2 operation will automatically also select CH2 as the trigger source unless external or line triggering were selected, this will be indicated by the trigger source button

lighting up. The last function of the VOLTS/DIV

knob will be preserved. All control elements belonging to this channel will be activated. DUAL: This button has a dual function: it either selects the dual channel mode or allows access to the settings memory 3. The trigger settings existing before selecting DUAL mode remain valid unless they are now changed intentionally. In DUAL mode the LED will light up. In dual channel mode the channel switching may be alternated or chopped. ADD: This button has a dual function: it either selects the ADD mode or allows access to the settings memory 4. The trigger settings existing before switching to ADD remain valid unless they are now changed in- tentionally. The active ADD mode is indicated by the LED lighting up. Addition of CH 1 and CH 2 mode: In this mode the signals of channels 1 and 2 are algebraically added, if CH 2 is inverted CH1 – CH 2 will be displayed. CH 2 – CH 1 is not available. For a correct result the settings of the two VOLTS/DIV selectors must be identical. The vertical position is now infl uenced by both Y position controls. See the respective paragraph in the introductory part of this manual for further information, because the use of this mode requires much care in order to avoid false measurements! XY: This button has a dual function: it either selects the X Y mode or it al- lows access to the settings memor y 5. If X Y is active, the LED will light up. XY operation: In XY mode the following displays/indicators will be turned off:

1. The time base speed display.

2. The displays/indicators of trigger source, slope, coupling, hold-

off time. The existing trigger control settings before switching to XY are pre- served, however. Also all controls belonging to these displays/indicators will be disabled. The POSITION 1

and the TRIGGER LEVEL

knobs are disabled, too. The X position will remain to be controlled by the X-POSITION

knob. COMP: This button has a dual function: it either selects the COMPO- NENT TESTER function or it allows access to the settings memory 6. If COMPONENT TESTER mode is selected, the LED will light up. By pressing any other button the COMPONENT TESTER will be disabled. Operation of the COMPONENT TESTER The button COMP alternates between scope and Component TESTER operation; when returning to scope operation, the last settings will be resumed. See also the chapter „Component Tester“. In this mode the following controls and LED indicators are important: – ADJUST – / + buttons

, with their LEDs: INTENS, FOCUS, and TRACE

The test of electronic components is a two-pole measurement. The unit to be tested is connected to the two contacts below the screen by using 4 mm plugs

COMPONENT TESTER – 2 contacts for 4 mm plugs The test leads from the unit under test are plugged in here, the left contact is connected to the chassis und thus to the mains safety earth. For DC or low frequency measurements it may be used as a ground terminal. Function of the controls CH1CH2DUALADDXYCOMPCH I: 500 mVPOWER POWER CH1 CH2 DUAL ADD

DECLARATION OF CONFORMITY