Seventeam ST-620PAF Power Supply Review
Transient Filtering Stage
Contents
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.
The transient filtering stage from this power supply is flawless, providing two Y capacitors, one ferrite coil and one X capacitor more than required, plus one X capacitor after the rectifying bridge. The MOV is located behind the fuse in Figure 8 and that’s why we can’t see it on this picture.
Figure 7: Transient filtering stage (part 1).
Figure 8: Transient filtering stage (part 2).
In the next page we will have a more detailed discussion about the components used in the Seventeam ST-620PAF.