Transient Filtering Stage

As we mentioned on other articles and reviews, the first place we like to take a look when opening a power supply to have a hint about its quality is its filtering stage. The recommend components for this stage are two ferrite coils, two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor) and one MOV (Metal-Oxide Varistor). Very low-end power supplies use fewer components than that, usually removing the MOV and the first coil.

Even though this power supply has two additional Y capacitors on its transient filtering stage and two additional X capacitors and one additional ferrite coil after the rectifying bridge, it doesn’t have a MOV, which is essential to cut spikes coming from the power grid.

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Figure 9: Transient filtering stage (part 1).

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Figure 10: Transient filtering stage (part 2).

Now let’s have a more detailed discussion on the components used on ZM360B-APS.

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