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.

The transient filtering stage from this power supply is flawless, providing two Y capacitors and one ferrite coil more than required, plus one X capacitor after the rectifying bridge. The MOV is located after the bridge and not before as usual.

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Figure 8: Transient filtering stage (part 1).

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Figure 9: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion of the components used in the Enermax ECO80+ 620 W.