Common phenomena in daily use of digital oscilloscopes

1. There is often no light spot or the waveform
    power supply is not turned on.
    The brightness knob is not adjusted properly.
    X, Y axis shift knob position adjustment.
    The Y-axis balance potentiometer is improperly adjusted, causing a serious imbalance in the DC amplifier circuit.
2. If
    the trigger source selection switch cannot be deployed in the horizontal direction and is set to the outer position, and there is no external trigger signal input, no sawtooth wave will be generated.
    The level knob is improperly adjusted.
    The stability potentiometer is not adjusted to keep the scan circuit in a critical state to trigger.
    The X-axis selection is mistakenly placed in the X external position, and there is no signal input on the external socket.
    If the two-trace oscilloscope only uses channel A (channel B has no input signal) and the internal trigger switch is placed in the YB position, no sawtooth wave will be generated.
3. There is no display of
    the input coupling mode in the vertical direction. The DC-ground-AC switch is mistakenly placed in the ground position.
    The high and low potential terminals of the input terminal are reversely connected to the high and low potential terminals of the circuit under test.
    The input signal is small, and V/div is mistakenly placed in the low sensitivity level.
4. The waveform is unstable and
    the stability potentiometer rotates excessively clockwise, causing the scanning circuit to be in a self-excited scanning state (not in a critical state to be triggered).
    The trigger coupling mode AC, AC (H), and DC switch failed to correctly select the corresponding level according to different trigger signal frequencies.
    When selecting the high-frequency trigger state, the trigger source selection switch is mistakenly placed in the outer position (it should be in the inner position.)
    When some oscilloscope scans are in the automatic position (continuous scan), the waveform is unstable.
5. The vertical lines are dense or appear as a rectangle.
    The t/div switch is improperly selected, resulting in f scan << f signal.
    The horizontal lines are densely packed or form a sloping horizontal line.
    The t/div switch is improperly selected, resulting in f scan>>f signal.
6. The voltage reading in the vertical direction is inaccurate and
    the deflection sensitivity (v/div) in the vertical direction has not been calibrated.
    When performing v/div calibration, the v/div fine-tuning knob is not in the correction position (that is, it is not turned fully clockwise).
    During the test, the v/div fine-tuning knob was moved away from the correction position (that is, away from the full clockwise position).
    Using a l0:1 attenuation probe, the voltage was not multiplied by 10 times when calculating the voltage.
    The frequency of the signal being measured exceeds the maximum operating frequency of the oscilloscope, and the oscilloscope reading is smaller than the actual value.
    What is measured is peak-to-peak value, and the sine effective value needs to be converted to obtain it.