On this page we will take an in-depth look at the primary stage of Nexus RX-6300. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBU1006 rectifying bridge, which supports up to 10 A at 100º C, if a heatsink is used, which is the case (without a heatsink the current limit drops to 3.2 A). So in theory you would be able to pull up to 1,150 W from a 115 V power grid; assuming 80% efficiency, this bridge would allow this unit to deliver up to 920 W without burning. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

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Figure 9: Rectifying bridge.

The active PFC circuit uses two IXTQ26N50P power MOSFET transistors, each one capable of delivering up to 26 A at 25º C in continuous mode (unfortunately the manufacturer does not publish the maximum current at 100º C) or 78 A in pulse mode at 25º C. These transistors present a 230 mΩ resistance when turned on, a characteristic called RDS(on). The lower this number the better, meaning that the transistors will waste less power and the power supply will achieve a higher efficiency.

The electrolytic capacitor in charge of filtering the output from the active PFC circuit is Taiwanese from Teapo and labeled at 85º C.

In the switching section, two SPW16N50C3 power MOSFET transistors are used on the traditional two-transistor forward configuration. Each transistor supports up to 16 A at 25º C or 10 A at 100º C (note the difference temperature makes) or 48 A in pulse mode at 25º C, presenting an RDS(on) of 280 mΩ.

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Figure 10: +5VSB switching transistor, one of the active PFC transistors and switching transistors.

This power supply uses the famous CM6800 active PFC/PWM combo controller soldered on the solder side of the printed circuit board.

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Figure 11: Active PFC/PWM combo controller.

Now let’s take a look at the secondary of this power supply.