A Look Inside

Before reading this page we strongly suggest to take a look at this article, which will help you understand the internal components of a PSU much better.


The OEM is Seasonic and the platform that HCG-520 uses is the Seasonic S12 II, which unfortunately is group regulated.


Right behind the AC receptacle there is a small PCB with some transient filtering parts, one X, four Y caps and a coil. On the main PCB we also find one X and two Y caps, two coils and an MOV.


The bridge rectifier is a GBU806 which is bolted on a heatsink. In the APFC section two FDP18N50 mosfets along with a boost diode and a choke shape the current waveform in order to be proportional to the AC main waveform. The smoothing/reservoir capacitor is provided by Nippon Chemi-Con (SMQ series, 400V, 390μF, 85C). As primary switches two FDP18N50 are used again. Behind the APFC capacitor there is a vertical daughter-board which holds the combo PFC/PWM controller, an Infineon ICE1CS02.


In the secondary side passive design is used, meaning that all rails are regulated by Schottky Barrier Diodes (SBRs) and not by mosfets. For +12V three 30A50CT are used while 5V are generated by a 40U45CT and 3.3V by an STPS30L30C. All filtering caps in the secondary stage are from Nippon Chemi-Con and rated at 105°C. Also the presence of only two coils means that the outdated, but cheap to implement, group regulation method is used, so in cross load tests don't expect breath taking results. The bigger choke is for 12V&5V and the smaller one for 3.3V. Finally, the protections IC is a PS223 and is housed on a small vertical PCB, in the secondary side.


Soldering quality is decent, taking into account the price and the category of the PSU. However we found several quite long component leads which is something that always concern us, because they may cause unexpected shorts.


Under the thermal pad an SBR10U45 is hiding. It is responsible for 5VSB regulation.


The cooling fan is provided by Adda, the favorite choice of Seasonic. Its model number is ADN512MB-A90 (135mm, 12V, 0.27A, 1700RPM max, 30 dBA)