As we have mentioned in other articles and reviews, the first place we look when opening a power supply for a hint about its quality, is its filtering stage. The recommended 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, usually removing the MOV and the first coil.

In the transient filtering stage, this power supply has two X capacitors and two Y capacitors more than the minimum required. However, it doesn’t have an MOV, a component that is in charge of removing spikes coming from the power grid.

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Figure 8: Transient filtering stage

On the next page, we will have a more detailed discussion about the components used in the Rosewill SilentNight 500 W.