A Look Inside & Component Analysis

Before reading this page, we strongly suggest a look at this article, which will help you understand the internal components of a PSU much better. Our main tool for the disassembly of the PSU is a Thermaltronics TMT-9000S soldering and rework station. It is of extreme quality and is equipped with a matching de-soldering gun. With such equipment in hand, breaking apart every PSU is like a walk in the park!


As you can easily figure out by taking a look at the photograph above (tip: the three thermal pads), the chassis plays a key role in keeping the unit's componentry cool.




This PSU's OEM is Seasonic, and the unit is based on a modified version of the same platform their budget G series units utilize. The APFC heatsink is small, and both DC-DC converters are installed on two small daughter-boards that are cooled by two equally small dedicated heatsinks. All the regulation fets but those responsible for the minor rails are on the solder side of the main PCB, which has the PSU chassis take care of their cooling. The PCB is pretty small and not densely populated. Seasonic used a half-bridge topology and an LLC resonant converter in the primary side and a synchronous design and two VRMs to generate the minor rails in the secondary side. This is a typical modern platform, which looks promising.


A sealed PCB holds the first part of the transient/EMI filtering stage, two Y caps and an X cap. The same filter continues on the main PCB with four Y caps, one X cap, two CM chokes, and an MOV. All in all, the EMI filter is complete.


There is an NTC thermistor for protection against large inrush currents. It is supported by an electromagnetic relay that isolates it from the circuit when the start-up phase finishes, which allows it to cool down.


A dedicated heatsink is used to cool down the only bridge rectifier, a GBU10V08.


The APFC fets, a pair of Infineon IPD65R225C7s, and the boost diode, an Infineon IDH08SG60C, are installed on the solder side of the main PCB. The heatsink on top of these and the chassis itself cool these parts down. The bulk cap is by Chemi-Con (420V, 560uF, 2000h @ 105 C, KMR), and it is big enough to ensure a hold-up time above 16 ms.


The main fets are a pair of Infineon IPD50R280CE. Arranged in a half-bridge topology, Seasonic installed these to the solder side of the main PCB. An LLC resonant controller is also used to boost efficiency.


This daughter-board hods the APFC and resonant controller combination and an NCP1910 IC. On the same PCB is also the protections IC, an HY-510N that only provides OVP, UVP, and SCP.


In the secondary side, four NXP PSMN2R6-40YS fets and SBR10U45S SBRs regulate the +12V rail. The SBRs replace the fets' embedded diodes, which increases efficiency. Among these fets and SBRs is an MP6922A rectifier IC.


We decided to desolder one of the VRMs that regulate the minor rails in order to identify its components. On it are an APW7164 PWM controller and a FDE15AJ fet.


On the main PCB, several electrolytic and polymer caps by Chemi-Con filter the rails. All electrolytics are rated at 105°C.


Toward the front of the modular PCB are several NIC and Enesol polymer caps and an electrolytic cap from Chemi-Con.


The standby PWM controller is an FSQ0165R IC, and the SBR that rectifies the 5VSB rail is an SBR10U45S on the solder side of the main PCB.


Overall soldering quality is good, although definitely not the best we have seen from Seasonic.


The fan that handles this unit's cooling uses a teflon-coated bearing, which, due to air pressure, provides better characteristics and lasts longer than a sleeve-bearing fan. Its official specifications also state it to be quieter, with a lifetime that exceeds 80,000 hours at 40°C. The bearing's lack of lubricant (oil) means this fan isn't prone to leakage, which makes it ideal for horizontal installation, contrary to sleeve-bearing fans that are designed for vertical installation since most of them don't use gaskets to contain the lubricant inside their bearing compartment.