What should I do if my oscilloscope has no scanline fault?

In the event of a non-scan line fault, check whether the power supply circuit, oscilloscope tube circuit, trigger scanning circuit, X-axis amplifier, etc. are working properly. If these parts are working properly, it may be a fault of the brightening channel (z-channel), because the gate potential of the oscilloscope tube is usually minus 60-70 volts compared to the cathode potential, and in general, the cathode emitted electrons can reach the phosphor screen very little suppressed by the negative gate voltage. The X-axis channel generates a scanning voltage and also produces a brightness signal, which is sent to the oscilloscope gate level through the Z channel, so that the gate potential is increased by about 30 volts, and the cathode electrons will be emitted to the phosphor screen to form a brighter scan line.

If there is no brightening pulse or the brightening pulse amplitude is insufficient, it will inevitably cause a no-scan line failure.

1. The baseline shift of the channel is too large, that is, the current 0 level is not in the center of the screen! In this case, you can turn the coupling of the oscilloscope to GND, and the trigger mode is Auto, and then adjust the vertical displacement knob to adjust the baseline to the middle of the screen to measure the signal.

2. Similarly, if your vertical sensitivity is too low at this time, the DC level of the signal is too large, and the signal cannot be observed, you can adjust the vertical displacement to see if you can adjust the signal to the display position of the screen, or adjust the baseline to the center, and the input coupling is played to AC mode to see if there is a signal.

3. The trigger level is wrong, that is, the signal is not triggered, adjust the trigger level to see if there is a display.

Turn on the scope.

After the power switch, the scan line and light spot are not visible on the screen for the following reasons:

1. The center of the horizontal axis and the vertical axis are offset.

2. Brightness adjustment potentiometer.

Position offset. 3. The oscilloscope tube is damaged.

4. The oscilloscope circuit is faulty. The horizontal scan circuit is damaged.

Here's how to fix it:

1. Try to adjust the vertical and horizontal position buttons of the oscilloscope, and the waveform can be moved outside the phosphor screen.

2. Adjust the brightness appropriately, if the brightness is adjusted to the minimum, of course, you can't see the scan line.

3. If the scanning method is selected as normal to change the mode, no trigger will not be scanned, no signal will be added or the trigger bar will not be reached, and the scan line will not be seen.

4. Restore the instrument to factory settings, and then select Auto Set Oscilloscope At this time, you can see a 1kHz square wave, if you can't see it, check all connections If you still can't see it, run the oscilloscope's possible self-diagnostic program.

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If you turn on the power switch of the oscilloscope, you can't see the scan line and the light spot cause analysis on the screen

The horizontal axis and vertical axis are offset from the center.

Brightness adjustment potentiometer position offset.

The oscilloscope tube is damaged.

The oscilloscope circuit is faulty. The horizontal scan circuit is damaged.

Adjust the brightness first, hit it to about 80%, then adjust the up and down displacement, put it in the middle of the twist, put the input coupling on the ground, use auto (automatic) for the trigger mode, select CH1 for the trigger source, and shift the horizontal displacement, and then you can't find it, the oscilloscope is broken.

If you are sure that your oscilloscope picture tube is not faulty, you can slowly adjust the frequency level and voltage level. If there is flickering, it proves that the scan deviates first, you can adjust the up and down knobs of the scan line to adjust it, at the beginning it is also to adjust it slowly, and when you have experience, you can quickly adjust it!

It may be that the scan has been turned up too large and out of the range of the screen.

There are several reasons for this:

1. If the brightness is too low, adjust the brightness (brightness) knob.

2. The scan line is up or down, or left or right, and is not displayed on the screen. Adjust the vertical position knob (i.e., y-axis position) and the horizontal position knob (x-axis position).

3. The wrong triggering method may also cause this phenomenon. Select a trigger method.

If you open the scope.

After the power switch, the scan line and light spot are not visible on the screen. Cause Analysis:

The center of the wax is offset in the horizontal axis and the vertical axis.

Brightness adjustment potential intellectualizer. Position offset.

The oscilloscope remnant tube is damaged.

The oscilloscope circuit is faulty. The horizontal scan circuit is damaged.