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, yellow component on the pictures below) 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 is flawless on this stage, having one more ferrite coil, four more Y capacitors (two of them can’t be seen in Figure 9), one more X capacitor and one more MOV than necessary. On this power supply the two MOV’s are locate after the rectifying bridge and not before as is the most common location today.

click to enlarge
Figure 9: Transient filtering stage (part 1).

click to enlarge
Figure 10: Transient filtering stage (part 2).

click to enlarge
Figure 11: MOV’s.

In the next page we will have a more detailed discussion of the components used in the TOP-1100P10.