As we mentioned on other articles, 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.

Even though this power supply from GlacialPower has one more component than the necessary – one extra X capacitor –, it doesn’t have a MOV, which is a sin.

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Figure 5: Transient filtering stage (part 1).

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Figure 6: Transient filtering stage (part 2).