Oscilloscope: Non-contact Probing - Measure signal without physically touching the circuit

Oscilloscope: Non-contact Probing - Measure signal without physically touching the circuit.
The primary side of a switched-mode power supply (SMPS) circuit typically carries 120V or 220V AC high voltage.
The inductive method can detect the waveform without touching the circuit contacts; this method is both simple and safe.
If the DVD player can operate normally, and the probe is placed near the switching transformer, the oscilloscope should display the pulse signal waveform.
If the pulse signal waveform can be detected, the input stage and the power switching stage of the switched mode power supply are normal; otherwise, these stages of the circuit may be faulty.
Digital oscilloscope: Rigol DS1202Z-E

[@norbert.kiszka]

This is a "EMI measurement" by capacitance. Not by inductance. It will be better to use voltmeter to check this PSU instead.

[@xenoxaos1]

It's usually much easier to thread a bit of magnet wire through the transformer. Then you're actually measuring the flux through the single loop.

[@biniouhamoto1236]

very interesting 👍thanks

[@topQuark12]

Yep, looks like a healthy flyback transformer you've got there. This is a valid measurement method, but this is probing through capacitive coupling (dV/dt) not induction, as you don't have loop at the tip (e.g. clipping your ground lead to the probe tip).

[@richardbroman]

So, maybe you can show how it is done…

[@tpg3942]

Keep the probe tip close to the transformer, the oscilloscope can pick up the signal from within the transformer

[@richardbroman]

👍