1. The main control parts of the display part are:
(1) power switch.
(2) power indicator.
(3) brightness adjustment spot brightness.
(4) focus to adjust the light spot or waveform clarity.
(5) auxiliary focus is matched with the "focus" knob to adjust the clarity.
(6) the brightness of the scale line on the brightness level coordinate of the ruler.
(7) Tracking When the key is pressed down, the light spot deviated from the fluorescent screen returns to the display area, and the position of the light spot is found.
(8) The standard signal outputs a 1kHz, 1V square wave calibration signal, which leads to it. It is added to the Y-axis input terminal to calibrate the Y-axis input sensitivity and the X-axis scanning speed.
2. Y-axis plug-in part
(1) The display mode selection switch is used to switch the working states of two Y-axis preamplifiers YA and YB, and it has five different display modes:
Alternating: when the display mode switch is set to Alternating, the electronic switch is controlled and switched by the scanning signal, and the YA or YB signal is turned on in turn every scanning. When the frequency of the measured signal is higher, the frequency of the scanning signal is also higher. The faster the switching rate of the electric
sub-switch is, there will be no flicker. This working state is suitable for observing two signals with higher working frequency.
"Intermittent": When the display mode switch is set to "Intermittent", the electronic switch is not controlled by the scanning signal, and generates a square wave signal with a fixed frequency of 2kHz, so that the electronic switch can quickly turn on YA and YB alternately. Because the switching frequency is higher than the frequency of the measured signal, the waveforms of the two channels displayed on the screen are intermittent. When the frequency of the measured signal is high, the intermittent phenomenon is very obvious and even impossible to observe; When the frequency of the measured signal is low, the intermittent phenomenon is covered up. Therefore, this working state is suitable for observing two signals with lower working frequency.
"YA" and "YB": when the display mode switch is set to "YA" or "YB", it means that the oscilloscope is working in a single channel. At this time, the working mode of the oscilloscope is equivalent to a single-track oscilloscope, that is, the signal waveform of the "ya" or "YB" channel can only be displayed separately.
"YA+YB": when the display mode switch is set to "YA+YB", the electronic switch does not work, and both signals of ya and Yb pass through the amplifier and gate circuit, and the oscilloscope will display the waveform of the superposition of the two signals.
(2) the "DC-⊥-AC" Y-axis input selector switch is used to select the coupling mode of the measured signal connected to the input terminal. Setting "DC" is a direct coupling, which can input AC signal with DC component; Put it in "AC" position to realize AC coupling and only input AC components; When placed in the "⊥" position, the Y-axis input terminal is grounded, and the displayed time baseline is generally used as the reference baseline for testing the zero level of DC voltage.
(3) "Fine-tuning V/div" sensitivity selector switch and fine-tuning device. The sensitivity is selected with an open-relation sleeve shaft structure, and the black knob is a Y-axis sensitivity coarse adjustment device, which is divided into 11 grades from 1mv/div to 2v/div. The red knob is a fine adjustment device, and it is a calibration position when it is increased to full scale clockwise. The amplitude of the measured signal can be read according to the value indicated by the coarse knob. When the knob is turned counterclockwise to full scale, its range of change should be more than 2.5 times. Continuously adjusting the "fine-tuning" potentiometer can realize the sensitivity coverage among all steps. When making quantitative measurement, the knob should be placed in the "calibration" position of clockwise full scale.
(4) "Balance" When the input circuit of the Y-axis amplifier is unbalanced, the displayed light spot or waveform will shift in the Y-axis direction with the "fine adjustment" rotation of the "V/div" switch. Adjusting the "balance" potentiometer can minimize this shift.
(5) Y-axis displacement potentiometer to adjust the vertical position of the waveform.
(6) Push-pull switch for polarity conversion of "polarity, pull ya" ya channel. When pulling out, the YA channel signal is displayed in phase inversion, that is, when the display mode is (YA+ YB), the displayed image is YB-YA.
(7) "internal trigger, YB pull" trigger source selection switch. In the pressed position (normal), the scanning trigger signal is taken from the input signals of YA and YB channels respectively, which is suitable for single-trace or double-trace display, but it is impossible to compare the time of double-trace waveforms. When the switch is pulled out, the trigger signal of scanning is only taken from the input signal of YB channel, so it is suitable for comparing the time and phase difference of two waveforms in double trace display.
(8) The Y-axis input socket adopts BNC socket, from which the measured signal is input directly or through the probe.
3. X-axis plug-in part
(1) "T/div" scanning speed selector switch and fine-tuning knob. The moving speed of the X-axis light spot is determined by it, and it is divided into 21 steps from .2 μ s to 1s * * *. When the switch "fine-tunes" the potentiometer clockwise to the end and the switch is connected, it is the "calibration" position. At this time, the indicated value of "t/div" is the actual value of the scanning speed.
(2) "expand, pull× 1" scanning speed expansion device. It is a pull switch, which can be used normally in the pressed state, and the scanning speed of the pull position is increased by 1 times. The indicated value of "t/div" should also be calculated accordingly. Using "extended pull× 1" is suitable for observing waveform details.
(3) "→←" X-axis position adjustment knob. It is a horizontal position adjustment potentiometer with X-axis light trace, which is a sleeve shaft structure. The outer ring knob is a coarse adjustment device. When rotating clockwise, the baseline moves to the right, and when rotating counterclockwise, the baseline moves to the left. The small knob placed on the sleeve shaft is a fine adjustment device, which is suitable for adjusting the expanded signal.
(4) BNC socket is used for "external trigger and external X connection". When the external trigger is used, it is used as a socket for connecting the external trigger signal. It can also be used as a signal input socket when the X-axis amplifier is connected externally. Its input impedance is about 1 mω. When external connection is used, the peak value of input signal should be less than 12V.
(5) the "trigger level" knob triggers the level adjustment potentiometer knob. Used to select the trigger point of the input signal waveform. Specifically, it is to adjust the start time of scanning and decide at which point of the trigger signal waveform the scanning is triggered. When turning clockwise, the trigger point tends to the positive part of the signal waveform, and when turning counterclockwise, the trigger point tends to the negative part of the signal waveform.
(6) Stability triggers the stability fine-tuning knob. Used to change the working state of the scanning circuit, which should be in the state to be triggered. The adjustment method is to set the Y-axis input coupling mode selection (AC- ground -DC) switch to the ground gear, and set the V/div switch to the gear with the highest sensitivity. When the level knob is out of the self-excited state, turn the stability potentiometer clockwise to the end with a small screwdriver, and the scanning circuit will generate self-excited scanning, and scanning lines will appear on the screen at this time. Then slowly turn counterclockwise, so that the scanning line just disappears. At this time, the scanning circuit is in the state of being triggered. In this state, when measuring with an oscilloscope, a stable waveform can be obtained on the screen as long as the level knob is adjusted, and the starting point position of the waveform on the screen can be adjusted and selected at will. A few oscilloscopes, when the stability potentiometer is turned counterclockwise to the end, scanning lines appear on the screen; Then slowly rotate clockwise, so that the scanning line on the screen just disappears, and at this time, the scanning circuit is in the state of being triggered.
(7) "inside and outside" trigger source selection switch. When placed in the "inside" position, the scanning trigger signal is taken from the measured signal of the Y-axis channel; When placed in the "external" position, the trigger signal is taken from the external trigger signal introduced by the "external trigger X external" input terminal.
(8) "AC", "AC (h)" and "DC" trigger the coupling mode switch. "DC" gear is in DC coupling state, which is suitable for trigger signals with slow change or very low frequency (such as below 1Hz). The "AC" gear is in AC coupling state, and the trigger performance is not affected by the DC component because it cuts off the DC component in the trigger. The "AC(H)" file is in the AC coupling state of low frequency suppression. When observing the high frequency composite wave containing low frequency components, the trigger signal is coupled through a high-pass filter, which suppresses low frequency noise and low frequency trigger signal (low frequency components below 2MHz) and avoids waveform flicker caused by false triggering.
(9) "High frequency, normal, automatic" trigger mode switch. It is used to select different trigger modes to adapt to different tested signals and test purposes. "High frequency" range, when the frequency is very high (such as higher than 5MHz) and there is not enough amplitude to make the trigger stable, select this range. At this time, the scanning is in high-frequency trigger state, and the measured signal is synchronized by the high-frequency signal (2kHz signal) generated by the oscilloscope itself. There is no need to adjust the level knob frequently, and a stable waveform can be displayed on the screen, which is convenient to operate and beneficial to observing the waveform of high-frequency signals. "Normal" file, which uses the input signal from Y axis or external contact source to trigger scanning, is a commonly used trigger scanning method. "Auto" gear, the scanning is in an automatic state (similar to the high-frequency trigger mode), but stable waveform can be observed without adjusting the level knob, which is convenient to operate and beneficial to observe signals with lower frequency.
(1) "+,-"triggers the polarity switch. In the "+"position, the rising part of the trigger signal is selected, and in the "-"position, the falling part of the trigger signal is selected to trigger the scanning circuit.
(2) Inspection, adjustment and calibration before use
Before the oscilloscope is used for the first time or when it is reused for a long time, it is necessary to conduct a simple inspection of whether it can work and adjust the stability of the scanning circuit and the DC balance of the vertical amplifier circuit. When measuring the voltage and time quantitatively, the oscilloscope must also calibrate the gain of the vertical amplifier circuit and the horizontal scanning speed. The methods of checking whether the oscilloscope can work normally and calibrating the gain of vertical amplification circuit and horizontal scanning speed are slightly different because of the different parameters such as amplitude and frequency of calibration signals of various models of oscilloscopes.
(III) Using Step
The oscillograph can be used to observe the waveform curves of different electric signal amplitudes changing with time. On this basis, the oscillograph can be used to measure electrical parameters such as voltage, time, frequency, phase difference and amplitude modulation. The following introduces the use steps of observing the waveform of electric signal with oscilloscope.
1. Select Y-axis coupling mode
According to the frequency of the signal to be measured, set the "AC- ground -DC" switch for selecting Y-axis input coupling mode to AC or DC.
2. Select Y-axis sensitivity
according to the approximate peak-to-peak value of the measured signal (if an attenuation probe is used, it should be divided by the attenuation multiple; When the coupling mode takes DC gear, the superimposed DC voltage value should also be considered), and the Y-axis sensitivity selection V/div switch (or Y-axis attenuation switch) should be placed in an appropriate gear. In actual use, if it is not necessary to read the voltage value, you can adjust the Y-axis sensitivity fine-tuning (or Y-axis gain) knob appropriately to make the waveform with the required height appear on the screen.
3. Select the source and polarity of the trigger (or synchronization) signal
Usually, put the trigger (or synchronization) signal polarity switch in the "+"or "-"position.
4. Select the scanning speed
According to the approximate value of the period (or frequency) of the measured signal, put the X-axis scanning speed t/div (or scanning range) switch at an appropriate level. In actual use, if it is not necessary to read the time value, the scanning speed t/div fine-tuning (or scanning fine-tuning) knob can be adjusted appropriately, so that the waveform of the number of cycles required for the test can be displayed on the screen. If you need to observe the edge of the signal, the scan speed t/div switch should be set to the fastest scan speed.
5. Input the measured signal
After the measured signal is attenuated by the probe (or directly input by the coaxial cable without attenuation, but the input impedance decreases and the input capacitance increases at this time), it is input into the oscilloscope through the Y-axis input terminal.
The phenomenon is
The original reason is
1. There is no light spot or waveform
The power supply is not connected.
the brightness knob is not adjusted properly.
the position of the x and y axis shift knob is adjusted.
improper adjustment of Y-axis balance potentiometer causes serious imbalance of DC amplifier circuit.
2. It can't be unfolded in the horizontal direction
If the trigger source selection switch is placed in the external gear and there is no external trigger signal input, there will be no sawtooth wave.
the level knob is not adjusted properly.
the stability potentiometer is not adjusted to make the scanning circuit in the critical state to be triggered.
the x-axis selection is wrongly placed in the x external position, and there is no signal input on the external socket.
if only channel a (channel b has no input signal) is used in the two-trace oscilloscope, and the internal trigger switch is set to YB position, no sawtooth wave will be generated.
Third, there is no display in the vertical direction
The DC- grounding -AC switch with input coupling mode is wrongly placed in the grounding position.
the high and low potential terminals of the input terminal are connected with the high and low potential terminals of the circuit under test.
the input signal is small, and the V/div is wrongly placed in the low sensitivity file.
fourth, the waveform is unstable.
the stability potentiometer rotates excessively clockwise, which makes the scanning circuit in the self-excited scanning state (not in the critical state to be triggered).
the trigger coupling modes AC, AC(H) and DC switches failed to correctly select the corresponding gears according to different trigger signal frequencies.
when selecting the high-frequency trigger state, the trigger source selection switch is mistakenly placed in the outer gear (it should be placed in the inner gear. )
when some oscilloscopes are scanned in automatic mode (continuous scanning), the waveform is unstable.
5. The vertical lines are dense or present a rectangle.
Improper selection of T/div switch causes F scanning < < f signal.
VI. The horizontal lines are dense or an inclined horizontal line
The T/div switch is not properly selected, resulting in F scanning > > F signal.
VII. The voltage reading in the vertical direction is not allowed
The deflection sensitivity (v/div) in the vertical direction has not been calibrated.
during v/div calibration, the v/div fine-tuning knob was not placed in the calibration position (that is, it was not turned clockwise).
during the test, the v/div fine-tuning knob was moved out of the calibration position (that is, moved out of the clockwise position).
using l: 1 attenuation probe, the voltage is not multiplied by 1 times.
The frequency of the measured signal exceeds the maximum frequency of the oscilloscope, and the reading of the oscilloscope is smaller than the actual value.
the measured value is peak-to-peak, and the sine effective value needs to be converted.
VIII. Reading in the horizontal direction is not allowed
Deflection sensitivity (t/div) calibration in the horizontal direction is not performed.
during t/div calibration, the t/div fine-tuning knob was not placed in the calibration position (that is, it was not turned clockwise).
during the test, the t/div fine-tuning knob moved out of the calibration position (i.e.