As we mentioned on other articles and reviews, the first place we like to take a look when opening a power supply to have a hint about its quality is its filtering stage. The recommend 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 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).

Now let’s have a more detailed discussion on the components used on Mach 1 ABT-700MA1S.