Disassembly
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The input filtering consists of just two 2kV ceramic capacitors, which is completely inadequate. There are no X capacitors, coils or MOVs. Four 3A diodes are used in place of a bridge rectifier. The two primary capacitors are 470µF parts from Anodia. The switching transistors are SI Semiconductors MJE13007s, rated at 8A. Just to the left of them is a Silan Micro SVF2N65F Transistor rated at 2A, which is used as the main 5Vsb switcher. The smaller drive transistor for it is a SemTech ST2N2222A. These two-transistor circuits really need to be coupled with high quality capacitors, because if a small capacitor in this circuit fails, the 5vsb voltage will go through the roof and fry the motherboard. Unfortunately, the critical capacitor is made by a Chinese company called Yang-Chun, which is not one of the few high quality capacitor brands.
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The secondary output filtering capacitors are also from Yang-Chun. The other problem with the output filtering is that there is only a single 1000µF capacitor on each rail with no PI coils. The small capacitors used are simply not up to the job, as we saw from the ripple results. This will also increase the stress on the capacitors and reduce their already short lifespan.
The 12V rectifier is a Lite-On SBL1060CTW, which is rated for a pathetic 10A. Considering that the label claims up to 14A on the 12V rail, a higher rated part should have been used. The rectifier just to the left of it is for the 3.3V rail. It’s an SBL1045CTW, also rated at 10A. This rail is supposed to be capable of up to 16A, so again, a 16A or higher rectifier should have been used. The 5V rectifier is an SBL3045PT, which is rated at 30A. It’s the only rectifier which is good enough for what the label claims, but even this is diminished by the circuit arrangement which stacks the 12V winding on top of its cathode (so the 5V rectifier here actually has to pass the combined current of the 5V and 12V outputs).
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The soldering is generally OK, but the legs on the toroid coils and 5vsb output diode could have been cut far shorter. This probably won’t cause problems, though, since they still aren’t long enough to short on the case, despite the lack of a plastic insulation sheet.
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Keen eyed viewers may notice that the fan’s shroud is slightly warped. This is because it is quite thin and easy to bend. Even the blades are somewhat flexible. After removing the sticker and plug, I also found that the lubricant in the bearing housing was insufficient, which means that the fan would probably not last long. The fan is wired straight to 12V, and was easily audible. The heat sinks aren’t quite as bad as the ones in the A-Power in the El-Cheapo Power Supply Roundup, but they are still quite small.
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