We were very curious to check what components were chosen for the power section of this power supply and also how they were set together, i.e., the design used. We were willing to see if the components could really deliver the power announced by Huntkey.

This power supply uses one D15XB80 rectifying bridge in its primary stage, which can deliver up to 3.2 A (rated at 25º C) without a heatsink installed, which was the case. If Huntkey had attached a heatsink to this bridge its maximum current would be 15 A at 100º C. This is definitely something Huntkey should have done, because this bridge is limiting the maximum amount of current this power supply can deliver. At 115 V this unit would be able to pull only up to 368 W (115 V x 3.2 A) from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver only up to 294 W without burning this component. This is ridiculous and a hint that something is wrong with the project from this power supply.

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Figure 9: Rectifying bridge.

In the switching section, two FJP13009 NPN power transistors are used in a half-bridge configuration. They can deliver up to 12 A continuous mode or up to 24 A in pulse mode, which is the case. Both values are given at 25º C. This old configuration is typical on power supplies without active PFC and usually power supplies based on this topology present lower efficiency.

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Figure 10: Switching transistors (the second transistor is on the other side of the heatsink).