Let’s now take an in-depth look on the primary stage from Kingwin Mach 1 ABT-700MA1S (a.k.a. Super Flower Aurora 700 W). For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses one PBU1005 rectifying bridge on its primary, which support up to 10 A at 100º C. This bridge is attached to an individual heatsink. This is more than adequate rating for a 700 W power supply. The reason why is that at 115 V this unit would be able to pull up to 1,150 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 920 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.
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Figure 11: Rectifying bridge.
On the switching section this power supply uses two traditional bipolar power transistors (BJT) in half-bridge configuration instead of two power MOSFET transistors in forward configuration. This is normal on power supplies without active PFC. Traditionally power supplies based on BJT present a lower efficiency. This power supply uses two 2SC4140, which can deliver up to 18 A in pulse mode at 25º C.
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Figure 12: Switching transistors.
As we already mentioned, this unit does not feature active PFC circuit. The primary is controlled by a KA7500C integrated circuit, which is physically present on the secondary side of the power supply.
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Figure 13: PWM controller.
The two electrolytic capacitors used on the voltage doubler circuit are rated at 105º C, which is great (usually power supplies use capacitors rated at 85º C here). They are from Fuhjyyu, a Taiwanese company.
