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.


Once we removed the casing we looked at a familiar platform, the M12II of Seasonic on which this unit is based on. This platform doesn't use cutting edge technology, on the contrary, but it still manages to provide good performance overall. The PCB is small compared to the casing it uses and the same applies to the heatsinks, regardless the fact that efficiency is not as high as 80 PLUS Gold or Platinum, so energy losses are not insignificant. However the maximum capacity of the unit is not high so with the help of the powerful 120 mm fan the heatsinks efficiently remove the heat from the mosfets/SBRs.


The first part of the transient filtering stage resides on a small PCB right behind the AC receptacle. It houses four Y caps, one X and a CM choke. On the main PCB we find the remaining components of the transient filter, two Y and one X caps, two CM chokes and an MOV. All in all the transient filtering stage is more than complete.


The lonely bridge rectifier is bolted on a dedicated heatsink. Its model number is GBU1006 and can handle up to 10A.


In the APFC two SPP20N60C3 mosfets are used along with an STTH8S06D boost diode. The hold up cap is provided by Nippon Chemi-Con (560μF, 400V, 105°C, KMR series). We would like to see a higher voltage rating cap here since 400V are very close to the APFC's DC bus of 380V.


On a vertical PCB the combo PFC/PWM controller is soldered, an ICEICS02.


As primary switches two SPP20N60C3 are used.


In the secondary side group regulation is utilized so the bigger toroidal choke is used by +12V and 5V regulators and the smaller one by 3.3V. We wanted to see independent regulation here for all rails but unfortunately a significant price cut demands sacrifices. Thankfully all filtering caps in the secondary are Japanese (Chemi-Con and we spotted a lonely Rubycon too).


The generation of the DC rails is done via passive components (Schottky Barrier Rectifiers). The +12V rail handle three 30A50CT and the 3.3V an MBR30H30CTG. Unfortunately we couldn't make out the markings on the single SBR used by 5V and we didn't want to desolder the whole secondary heatsink only to identify this particular SBR. Finally the diode, an SBR10U45, used by 5VSB is soldered on the back of the main PCB; a usual tactic which Seasonic uses in most of their designs.


The protections IC is housed on a vertical PCB in the secondary side. It's an HY-510N which provides only the basic protections, overvoltage and undervoltage protection.


Soldering quality on the main PCB is fairly good but surely not the best we have seen from Seasonic. The most significant point here is that we didn't spot any long component leads that could cause dangerous shorts. The small modular PCB also features good soldering quality and on the front of it there are some Nippon caps for extra ripple filtering.


Responsible for cooling the unit is a ball bearings fan from Adda with model number AD1212HB-A71GL (120mm, 85.2CFM, 2200RPM, 39.1dBA). Not the quietest fan on the market but on the other hand it is very reliable.