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 and one extra X capacitor. Since this power supply does not have active PFC circuit the two MOVs are installed after the rectifying bridge and physically located between the two electrolytic capacitors from voltage doubler, as this is the usual configuration with power supply without active PFC.

It also interesting to note that this power supply uses a fuse holder, which is a rarity nowadays.

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Figure 9: Transient filtering stage (part 1).

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Figure 10: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion of the components used in the Mach 1 ABT-700MA1S.