A Look Inside EarthWatts 500 W

We decided to disassemble this power supply to see how it looks like inside, what is the design used and what components are used. Please read our Anatomy of Switching Power Supplies tutorial to understand how a power supply works inside and to compare this power supply to others.

In this page we will have an overll look, while on the next page we will discuss in details the quality and rating of the components used.

We can point out several differences between this power supply and a low-end (a.k.a. “generic”) one: the construction quality of the printed circuit board (PCB); the use of more components on the transient filtering stage; the active PFC circuitry; the power rating of all components; the design; etcetera.

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Figure 3: Overall look.

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Figure 4: Overall look.

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Figure 5: Overall look.

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, which is essential for cutting spikes coming from the power grid, and the first coil.

On this section this power supply is flawless, as it has more components than the necessary – one extra X capacitors, one extra coil and a ferrite bead on the main AC cable. It also provides one X capacitor and two Y capacitors after the rectifying bridge.

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Figure 6: Transient filtering stage (part 1).

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Figure 7: Transient filtering stage (part 2).

Now let’s have a more detailed discussion on the components used on EarthWatts 500 W.

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