OSCILLOSCOPE



Fig: 1 Front Panel / Control Panel

1. 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.

2. ADJUST – / +

Allows changing the value of diverse settings selected by SELECT

3. Indication LEDs

INTENS: The LED will light if the function intensity adjustment was selected by SELECT 7 . With the buttons ADJUST – / + 2 the intensity may be 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 4 . With the buttons ADJUST – / + 2 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 focused 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 SELECT 4. With the buttons ADJUST – / + 2 the trace rotation can be adjusted. Due to the earth’s magnetic field 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”.

4. SELECT

This button allows to select and change the settings related to the trace in conjunction with the buttons ADJUST – / + 2 . 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.

5. POSITION 1 + POSITION 2, CH1 + CH2

These knobs control the trace position of channel 1 respectively channel 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 13. Measurement of dc voltages If there are no voltages present at the Y amplifier inputs 29 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 8 was selected.)

In order to measure a dc voltage, first 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. 5 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 cannot be just assumed that a trace position at the screen center corresponds to zero volts; this has to be checked by switching to GND.

6.  SAVE / RECALL

This button allows access to the settings memories in conjunction with the mode buttons 32. The oscilloscope has 6 settings memories, settings can be stored or recalled.

SAVE: In order to store a setting, first press the SAVE/RECALL button for some time, until the mode buttons 32 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 32 will light up. By pressing the desired mode button, the settings stored in that memory will be taken over by the oscilloscope. 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.

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.

7.  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).

8.  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 10 knob is active in both cases. The automatic triggering circuit will also provide a bright baseline if there is no signal or an insufficient one for triggering. See the specifications for the lower frequency limit below which automatic triggering do not function, i.e. the display will not be triggered.

With peak-to-peak triggering the range of the TRIGGER LEVEL 10 control 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 operating 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 traces visible if there is no signal, if the signal is insufficient for triggering or if the TRIGGER LEVEL 10 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.

9. SLOPE – LED button

This button selects either the plus ( ) or the minus ( ) slope of the triggering signal. The LED will light up if the negative slope is selected

10.  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 trigger 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 lose triggering if the trigger level control is not set appropriately. Pressing AUTOSET 7 will restore a triggered display in most cases.

11. 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.

12. X-MAG/ x10 – Button with “x 10” LED

This button switches the X magnifier on/off, the LED wil indicate if the magnifier is on. The magnified portion of the display can be shifted with the X-POSITION 13 control. The magnification expands the display around the screen center, hence the normal procedure is to move the portion to be magnified to the center with the X-POSITION control and then to activate the magnifier. In XY mode the magnifier is disabled.

13. X-POSITION

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

Fig: 2 Front Panel / Control Panel


14. VOLTS/DIV, CH1 + CH2 – knobs

These are dual function knobs: it is used to select the appropriate sensitivity 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 un calibrated. 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 14 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 un calibrated! CCW rotation will decrease the sensitivity, CW rotation will increase it. The variable allows hence bridging 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: because the rise time is defined from 10 to 90 % of the full amplitude, the variable comes in handy to set the (un calibrated) 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.

15. 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 27 button, it will assume the function of hold-off time adjustment, this will be indicated by the button 27 lighting up, refer to 27 .

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, e.g. 10 μs (/DIV). By activating the X-MAG / x10 12 , 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, un-calibrated. 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 refer to item 27 .

16. CH 1 – LED button

This button selects CH 1 as the trigger source. In all operating modes of the vertical amplifier 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.

Internal triggering: The trigger signal is taken off internally.

17. CH 2 – LED button

This button selects CH 2 as the trigger source. In all operating modes of the vertical amplifier 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.

18. LINE – LED button

This button selects the line (mains) as the trigger source. In all operating modes of the vertical amplifier except XY the line (mains) can be selected as the active trigger source which will be indicated by the LED lighting up.

Line triggering: The trigger signal is not derived from an input signal but from the mains and taken from the power supply.

19. EXT – LED button

This button selects the external input as the trigger source. In all operating modes of the vertical amplifier except XY pressing this button will select the external BNC input EXT.TRIG/Z-INP 31 as the trigger source which will be indicated by the LED lighting up. The external Z-INP for intensity modulation will be disabled.

External trigger source: The trigger signal is not taken from the measuring signals but from an external source.

20. AC – LED button

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

21. DC – LED button

In all operating modes of the vertical amplifier 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.

22.  LF – LED button

In all operating modes of the vertical amplifier except XY pressing this button will insert a low pass filter (see the specifications) 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.

23. TV – LED button

In all operating modes of the vertical amplifier 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 15 knob should be set between 0.2 s/DIV and 1 ms/DIV, at 2 ms/DIV a full frame will be displayed For line synchronization the TIME/DIV 15 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.

24. 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.

25. GND – LED buttons for CH 1 + CH2

By pressing these buttons shortly, the input of the channel 1 or 2 pre-amplifier will be connected to ground resp., which will be indicated by the LED lighting up. The signal present at the input BNC connector cannot influence the trace. In Yt-mode with auto trigger an un-deflected trace will be visible (zero-volts trace position) .In XY-mode there will be no deflection in X and Y directions respectively.

26. INV – LED button for CH 2

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

27. HOLD-OFF/ON – LED button

By shortly pressing this button, adjustment of the hold-off time by turning the knob /TIME/DIV 15 will be activated which will be indicated by the LED lighting up. Refer to item 15 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 27 , the hold-off time will be automatically reset to its minimum value. By shortly pressing the TIME/DIV knob while 27 is activated, it is possible to alternate between setting the time/div. and hold-off time adjustment. See also under “Hold-off time adjustment”.

28. Z-INP – LED button

By shortly pressing this button, the function of the input EXT.TRIG /Z-INP 31 is changed from external trigger input to external intensity modulation input which will be indicated by the LED lighting up. If external 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.

29. 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 24, GND 25 and INV 26 (CH2 only) correspond to this input.

30. PROBE ADJUST – Contact

At this contact a square wave signal of 1 kHz or 1 MHz with a rise time of <5 ns and an output impedance of 50 Ω is available for the adjustment of probes other than 1:1, the amplitude is approximately 0.2 Vpp (peak to peak). 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 15 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 ADJUSTS: This contact is the ground connection for the probe.

31. 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 connector is connected to the chassis and thus to the mains safety earth. By shortly pressing the Z-INP 28 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 16 to 19 ; if external triggering is selected, the Z input will be automatically disabled.

Z-INP: Z modulation is only possible if the Z-INP 28 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 influenced, with 5 V TTL level the trace will be fully suppressed; do not apply higher voltages.

Fig: 3 Front Panel / Control Panel

32. 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 16 lighting up. The last function of the VOLTS/DIV 14 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 channelCH2 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 17 lighting up. The last function of the VOLTS/DIV 14 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 intentionally. 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 influenced 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 XY mode or it allows access to the settings memory 5. If XY 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 of time.

The existing trigger control settings before switching to XY are preserved, however.

Also all controls belonging to these displays/indicators will be disabled. The POSITION 1 5 and the TRIGGER LEVEL 10 knobs are disabled, too. The X position will remain to be controlled by the X-POSITION 13 knob.

COMP: This button has a dual function: it either selects the COMPONENT 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 2 , with their LEDs: INTENS, FOCUS, and TRACE 3

– X-POSITION knob 13

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

33. 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 and thus to the mains safety earth. For DC or low frequency measurements it may be used as a ground terminal.

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