Coolmax V-500 Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of the Coolmax V-500. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

Instead of using a ready-made rectifying bridge, this power supply uses four discrete diodes. Four RL207 diodes are used, each one supporting up to 2 A at 75° C. So, in theory, you would be able to pull up to 230 W from a 115 V power grid. Assuming 80% efficiency, these diodes would allow this unit to deliver up to 184 W without burning themselves out. Of course, we are only talking about these particular components. The real limit will depend on all the components combined in this power supply. Here we can clearly see that it is impossible for this power supply to be a 500 W product.

Figure 9: Rectifying bridge

The electrolytic capacitors of the voltage doubler circuit are Chinese, from Tongjia, and labeled at 105° C.

In the switching section, two AT350 NPN transistors are used in the obsolete half-bridge configuration. Unfortunately, we couldn’t find the datasheet for these components.

Figure 10: Switching transistors

The primary is controlled by an ATX2005 PWM controller, which is a very popular controller among “generic” power supplies (i.e., power supplies with fake wattages). This integrated circuit is physically located in the secondary of the power supply.

Figure 11: PWM controller

Let’s now take a look at the secondary of this power supply.