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 platform is the same as in the SS-1200XP3, with some minor changes in parts resulting in slightly lower overall efficiency. The primary side consists of a full-bridge topology with an LLC converter for lossless switching, while the secondary side employs a synchronous design with the +12V fets installed on the main PCB's solder side. Both DC-DC converters are on the modular PCB to reduce power losses.


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


Two bridge rectifiers (GBJ2506) are bolted to a dedicated heatsink.


The APFC converter uses three Infineon IPP50R140CP 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 IPP50R250CP fets and an LLC resonant converter to boost efficiency.


The LLC resonant controller, a Champion CM6901 IC, is on a vertical PCB right behind the bulk-cap in the middle.


A large heatsink in the secondary side helps cool the +12V fets below it, on the solder side of the mainboard. The latter are eight NXP 2R640 fets. The above heatsink and the enclosure itself keep these fets cool.


All capacitors in the secondary side, polymer and electrolytic, are provided by Nippon Chemi-Con.


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


Many polymer caps on the front of the modular PCB are used for filtering purposes, and we also found two coils both DC-DC converters use.


The lower sockets of the modular PCB are directly soldered to the main board for decreased energy losses on power transfers at, in particular, higher loads.


This PCB 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 X-1250 only has one.


The standby PWM controller is an ICE2QR4765 IC.


Soldering quality is very good, which we have come to expect from high-end Seasonic products.


The cooling fan with model number 9S1212H403 is by Sanyo Denki and uses a pair of ball-bearings, which will have it last a long time (40,000 hours according to its manufacturer). Unfortunately, it is noisy, especially at high speeds.