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 an underpopulated, red PCB which most likely is made by Sirfa. The design is very clear and nice and all heatsinks are rather small, probably because the fan is strong enough to cool the internals easily and on top of that the Gold efficiency reduces energy/heat dissipation. In the primary side no exotic topology is used neither an LLC resonant converter, for loss less switching. On the contrary in the secondary side synchronous design is used for the regulation of +12V and two DC-DC converters generate the minor rails directly on the modular PCB, for minimized energy losses and lower voltage drops at high current. Initially this technique was used by Enermax and Seasonic but as it seems more companies start to realize its benefits and exploit it.


As usual we will start the internals description by the transient filtering stage. The first part is located on the AC receptacle and includes two Y and a single X caps. The latter has a bleeding resistor across its leads to quickly discharge once the power is cut off (X caps tend to keep charge for quite long). The secondary part is located on the main PCB and consists of two CM chokes, one X and two Y caps and an MOV.


The two parallel bridge rectifiers are bolted on a dedicated heatsink and sandwiched among two metal plates for extra passive cooling. Unfortunately we weren't able to recognize them without taking apart the whole thing.


The APFC uses two SPW35N60C3 fets to chop the incoming signal along with two boost diodes (C3D06060) which are installed in a separate heatsink. To clear the view for you we removed the heatsink that holds the latter. Right in front the PFC fets and next to the main switchers we find the thermistor, responsible for large inrush current protection and the relay that bypasses it once the start up phase completes. The two parallel hold up caps are provided by Nippon Chemi-Con (400V, 390μF, 105°C, KMR series). Finally the primary choppers are two SPW35N60C3 fets.


The combo PFC/PWM controller sits on a vertical PCB. It is a Champion CM6802IC which usually is used in lower efficiency units, but apparently Sirfa was quite confident that even with this controller they would achieve the desired Gold efficiency.


The 5VSB converter resides right next to the main transformer. It uses an MBR2045CT SBR which can handle up to 20A so there is quite some headroom here.


The secondary heatsink houses seven IPP037N08N fets which regulate the +12V rail. There is also a huge toroidal choke which takes part in the filtering and the rectify process of +12V and all the caps that surround it are provided by Chemi-Con (KZE series) and rated at 105°C. Among the crowd of electrolytic caps we also spotted two lonely polymer ones.


The supervisor IC is a SITI PS113 which doesn't support OCP while OCZ states that this unit has this protection. Apparently they mistakenly wrote this into the unit's specifications since in a single +12V rail that can output almost one kW, OCP is pretty much useless.


The VRMs responsible for the minor rails generation are located on the modular PCB, to minimize the distance these rails have to travel through PCB traces or wires till they reach the modular sockets. This design offers lower voltage drops especially when high loads are applied on the minor rails and at the same time EMI noise is greatly reduced. The main PWM controller for both VRMs is an APW7159 and for each rail two pairs of M3006D and M3004D fets are used. On the front side of the modular PCB besides the polymer caps used by the two VRMs we find several more for extra ripple filtering.


Most likely the excess heat coming from a soldering iron melted this heat shrink. Also the two solder joints on the modular PCB are sloppy and blobby. We are pretty sure that all above are an isolated event, right OCZ/Sirfa?


On the solder side of the main PCB soldering quality overall is good, however we spotted some hand made sloppy solder joints which spoil the whole picture a little bit. Apparently some last minute modifications had to be made, by hand of course.


The cooling fan is provided by HONG HUA, a company we never heard before. Its model number is HA1425H12B-Z (12V, 0.5A) and it uses double ball bearings. It is quite powerful and easily handles the heat load of this unit but at full speed is quite noisy. Finally it is equipped with red LED lighting for which unfortunately there is no turn off option.