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!

The OEM of all three V units, including the V850, is Seasonic. One of the best PSU manufacturers, Seasonic keeps on impressing us with their products and designs. Some OEMs follow a conservative strategy and avoid new designs and innovations that could harbor problems; that is, until the design is finalized and all problems of a fresh platform are resolved. Seasonic takes these risks and doesn't stick to old designs and beliefs. Their R&D teams continuously thrive to achieve the best possible performance through new implementations and ideas. Although some of their fresh designs had problems, especially with coil whine, they stand by their ideas, provide great product support, and resolve problems posted by regular users and reviewers. It is their philosophy and conduct that makes this company worthy of a good reputation and the respect of most reviewers and users, yet they aren't as big as Delta or FSP and, unwilling to lower their quality standards, Seasonic product prices are, as such, a little stiff. CM, though, either managed to get a pretty good deal, since they sell the V units for highly competitive prices, or simply reduced the profit margin greatly to make an impression on the PSU market.


The platform this unit uses is based on Seasonic's fresh KM3 design, though it is offered in a lower efficiency than the original Platinum to restrict production cost a little bit. The primary side has a full-bridge topology and an LLC resonant converter for loss-less switching, and the secondary side uses synchronous rectification along with DC-DC converters that generate the minor rails. The latter are installed directly onto the modular PCB for decreased power losses.


There is a sealed PCB for EMI reduction behind the AC receptacle. It holds a few of the transient filtering stage components—namely, four Y caps, a CM choke, and a single X cap. The other transient filtering components can be found on the main PCB: two pairs of X and Y caps, two CM chokes, and an MOV. There is also a thermistor that provides protection against large inrush currents and the corresponding electromagnetic relay that isolates it from the circuit once the APFC caps are fully charged.


Two GBJ 1506s are used as bridge rectifiers. Each one can handle up to 15 A of current for a combined total of 30 A.


In the APFC section, two Infineon IPP50R199CP fets and a single STPSC606D boost diode are used. The two parallel hold-up caps are provided by Nippon Chemi-Con (420 V; 330 μF each or 660 μF combined; 105°C; KMR series).


A small daughter-board houses the PFC controller: an NPC1654 IC.


The full bridge topology uses four Infineon IPP50R399CP fets. An LLC resonant converter is also used to boost efficiency.


A Champion CM6901 LLC resonant controller can be found on the above daughter-board. The same PCB also houses the fets that regulate the +12V rail, and two heatsinks cool down them. We found a thermistor that provides temperature data to the fan-control circuit attached to the top heatsink. We also noticed that Seasonic didn't apply any thermal paste to provide better heat conductivity between the two heatsinks after removing the top heatsink. It appears as though they didn't think it necessary, but we would still like to see some. Several high-quality Chemi-Con polymer caps filter the +12V rail under the bottom heatsink, with electrolytic ones provided by the same company also filtering the same rail.


The VRMs generating the minor rails are installed on the modular PCB, and their common PWM controller is an APW7159 IC. Each one uses three K0332 fets. At the front of the same PCB are several polymer caps by Chemi-Con. These filter the DC outputs.


This board hosts a Weltrend WT7257V supervisor IC and an AS393 dual-voltage comparator. This supervisor IC supports OCP for up to two +12V virtual rails, but only one exists in the
V850.


The standby PWM controller is an ICE2QR4765 IC.


Soldering quality is great, as is the norm for a high-end Seasonic implementation. The only strange thing here is that this side of the PCB is green and not red like the top PCB.


The fan is the same as in the V1000. It is of high quality since it uses a Fluid Dynamic Bearing (FDB). These bearings last much longer than ball-bearings and even produce less noise. The fan is made by Protechnic, one of the best fan manufacturers, and its model number is MGA13512XF-025. CM made an excellent choice by using this fan, which is one of the best fans for PSU usage. We can't but wonder how they managed to use such high-end components while keeping the unit's price at these levels.