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 we already mentioned, the OEM of this unit is Seasonic. The platform is rather outdated, but the DC-DC converters utilized in the secondary side will easily allow the unit to pass Intel's new Haswell compliance test, which many older PSUs fail to do. Finally, the construction quality is good enough and, like in all Seasonic products, very good components were used, including Nippon Chemi-Con electrolytic caps, Enesol polymer ones, Infineon fets etc.


The first part of the transient filtering stage starts right at the AC receptacle. It is, in this case, sealed inside of a metallic enclosure to protect it against EMI. It consists of two Y caps, a single X cap, and a CM choke. The transient filter continues on the main PCB with two CM chokes, one X cap, a pair of Y caps after the bridge rectifiers, and an MOV.


The bridge rectifiers are bolted onto a leaning heatsink, and their model number is GBU806. Exactly the same ones are used in the HCG-750M.


The APFC has three Fairchild FDP18N50 fets along with an STTH8S06D boost diode. The latter is installed on the heatsink that holds the primary switchers. The two parallel hold-up caps are provided by Chemi-Con (400 V, 105°C, 330 μF each and 660 μF combined, KMR series). Finally, we had to remove the PFC choke in order to clear the view for you.


We spotted the first crucial difference between the HCG-750M and the HCG-850M in the main switching section. While the first uses two Infineon SPP20N60C3 fets, the second uses two SPP24N60C3s that are provided by the same manufacturer. The SPP20N60C3 fets have an Rds(on) value of 0.19 Ohm. The two on the second have 0.16 Ohm, which translates into less energy lost on them during switching, so the HCG-850M will have a better efficiency than its smaller brother, since all other components up to this point are exactly the same and the differences in the secondary side are minimal, as you will see later on.


The combo PFC/PWM controller is a CM6802TBHX IC. Housekeeping duties are handled by a SITI PS223 IC that supports OCP for up to two +12V rails. It is also one of the very few ICs that supports OTP (Over Temperature Protection) without the need of external circuits and controllers.


The standby PWM controller is an Infineon ICE2QR4765 IC, and the 5VSB circuit is filtered by a single Rubycon cap. The diode that rectifies this rail, an SBR10U45, is located on the solder side of the main PCB.


In the secondary side, six SBR30A50CT diodes rectify the +12V rail, while only five were utilized in the 750 W model. The minor rails are generated through +12V with the help of two DC-DC converters that are installed on the same PCB. Finally, all filtering caps are provided by Chemi-Con and are rated at up to 105°C.


The front of the modular PCB has several Enesol polymer caps along with some Chemi-Con electrolytic ones for some extra ripple filtering. The rear side of the modular PCB is protected by a plastic shield.


Soldering quality is good although not as top-notch as on Seasonic's high-end implementations. We also spotted some long but bent component leads. These will not cause problems, but are a sore sight to us reviewers.


The fan is provided by ADDA, and its model number is ADN512UB-A90LD. It is equipped with double ball-bearings and has LED lighting. It may be a good and reliable fan but is noisy, especially at high speeds.