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.

This power supply has one X capacitor, one coil and two Y capacitors more than the minimum required plus two Y capacitors and one X capacitor after the rectification bridges, but it doesn’t come with a MOV, which is a sin. This component is in charge of surge protection. We expected it to have one, since it carries the name ASUS.

click to enlarge
Figure 7: Transient filtering stage (part 1).

click to enlarge
Figure 8: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion of the components used in the ASUS P-50GA.