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!


This unit uses Seasonic's current flagship platform, the XP3. Cooler Master was one of the first companies to use this platform, with slight differences resulting in a different fan and different bulk caps. The primary side uses a full-bridge topology and an LLC converter for lossless switching, and the secondary side employs a synchronous design with the +12V fets on the main PCB. Both DC-DC converters are also on the modular PCB to decrease power losses.


The sealed PCB behind the AC receptacle holds a CM choke, four Y caps, and a single X cap. The filter's other components, two pairs of X and Y caps, two CM chokes, and an MOV, are on the main PCB. There is also an NTC thermistor. It protects the unit against large inrush currents and has a relay that isolates it once it finishes its job.


Both parallel bridge rectifiers are bolted to a dedicated heatsink.


The APFC converter uses three Infineon IPP60R125CP fets and a single SCS110AG boost diode. The three parallel hold-up caps are provided by Nippon Chemi-Con (420 V; 390 μF each or 1170 μF combined; 105°C; KMR series).


The PFC controller, an NPC1654 IC, is on a small vertical PCB, right between the primary heatsinks and the APFC.


The full-bridge topology uses four Infineon IPP50R199CP fets. An LLC resonant converter is also used to boost efficiency.


The LLC resonant controller, a Champion CM6901 IC, is hiding behind the middle bulk-cap, but we desoldered the latter to clear the view.


A large heatsink in the secondary side. It, however, doesn't host any mosfets. The aforementioned heatsink is obviously there to cool the +12V fets on the main PCB's solder side. There are eight such Fairchild FDMS015N04B fets in total. This heatsink and the enclosure itself keep these fets cool.


All capacitors in the secondary side, polymer and electrolytic, are provided by Nippon Chemi-Con, so they are of very good quality.


Both VRMs responsible for generating the minor rails are on the modular PCB, which minimizes energy losses. Each VRM has three Infineon BSC0906NS fets, and one APW7159 PWM controller handles both regulators.


All lower modular sockets are directly soldered to the main PCB via thick metal conductors that reduce energy losses, which increases efficiency.


Many polymer caps on the modular PCB's primary side filter the rails, along with two coils which are used by both VRMs.


This board holds the supervisor IC, a Weltrend WT7257V and an AS393 dual-voltage comparator. The WT7257V supports OCP for up to two +12V virtual rails, but the Platinum-1200 only has one.


The standby PWM controller is an ICE2QR4765 IC, and it was buried under lots of glue in our sample.


Soldering quality is very good, but we don't expect anything less from Seasonic.


The cooling fan with model number 9S1212H403 is provided by Sanyo Denki and uses probably an improved (enhanced) sleeve-bearing, which will have it last a long time (40,000 hours according to its manufacturer).