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.

On this stage this power supply is flawless, providing two extra Y capacitors, one extra X capacitor and a ferrite bead attached to the main AC cable. This power supply also provides an X capacitor after the rectifying bridges.

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Figure 6: Transient filtering stage (part 1).

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Figure 7: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion of the components used in the iPower 660.