Primary Analysis
Contents
This power supply uses one KBL406 rectifying bridge in its primary, which can deliver up to 4 A (rated at 50° C). No heatsink was used to cool down this component. This is the most low-end rectifier we’ve seen on a power supply to date. With this 4 A limit the power supply would only be able to pull up to 460 W from the power grid at 115 V. Assuming a typical efficiency of 80%, this means that this unit would be able to deliver only up to 368 W on its outputs without burning this component. And this unit was labeled as a "550 W" model! Of couse to truly test this power supply we would need a load tester, equipment that we still don’t have.
On the switching section two 2SC2625 NPN power transistors are used using the half-bridge configuration, which is the most common configuration for power supplies without active PFC. Each transistor has a maximum rated current of 10 A @ 25° C (or 20 A peak current). Of course maximum current at real-world temperatures will be lower.
Figure 11: Two power NPN transistors are used on the switching section.
