Rosewill Performance 650 W Power Supply Review

Primary Analysis

As mentioned, the problem was that the manufacturer did the favor of scratching off the markings from all semiconductors used in this power supply, preventing us from making a more in-depth analysis about the used components. We wonder why a manufacturer would do that. To prevent other companies from copying the project? As if anyone would copy a project from a manufacturer that is not even on the radar screen.

On the primary we could identify only the rectifying bridge and the PFC/PWM combo controller.

This power supply uses one KBU8K rectifying bridge in its primary, which supports up to 8 A at 100° C. This component is correctly dimensioned: at 115 V this unit would be able to pull up to 920 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 736 W without burning this component. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

Figure 8: Rectifying bridge.

This unit has four power transistors on the primary, two for the active PFC circuit and two for the switching circuit, which uses the traditional two-transistor forward configuration. As mentioned we couldn’t identify them as they had their markings scratched.

Figure 9: Primary transistors with their markings scratched off.

The electrolytic capacitor used on the active PFC circuit is from Teapo, a Taiwanese company, and labeled at 85° C.

Even though the PWM/PFC controller integrated circuit had also its markings scratched, we could read them: this power supply uses the omnipresent CM6800 controller.

Figure 10: PWM/PFC controller.

Now let’s take a look at the secondary from Rosewill Performance 650 W.