Let’s now take an in-depth look on the primary stage from Dynex 400 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses one RS806 rectifying bridge on its primary, capable of delivering up to 8 A at 100º C. The Green Star 450 W sample we reviewed used a different bridge, D15XB80, which is capable of providing only up to 3.2 A at 25º C if no heatsink is used (installing a heatsink its current limit grows to 15 A).
click to enlarge Figure 9: Rectifying bridge.
The switching section from Green Star 450 W and from Green Star 400 W (aka Dynex 400 W) is identical. Both use a very old design using regular power NPN transistors instead of MOSFET components. Here two FJP13009 NPN power transistors are used. 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.
click to enlarge Figure 10: Switching transistors (the second transistor is on the other side of the heatsink).
The two electrolytic capacitors used on the voltage doubler are Chinese from Jianghai and rated at 85º C. The capacitors from the Green Star 450 W sample we reviewed were from Teapo, a Taiwanese company.
