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 than that, usually removing the MOV, which is essential for cutting spikes coming from the power grid, and the first coil.

On this section this power supply is flawless, as it has more components than the necessary – one extra X capacitor, two extra Y capacitors and a ferrite bead on the main AC cable. It also provides a traditional fuse holder for its fuse, a feature hard to see nowadays, as most manufacturers solder the fuse directly to the printed circuit board.

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Figure 7: Transient filtering stage (part 1).

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Figure 8: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion of the components used in the StarTech.com WattSmart 650 W.