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.


It was quite hard to fully disassemble the unit since we had to remove about 20 screws! Once we managed to remove the whole casing we looked at a design that shares many similarities, at least visually, with the X series platform. This is natural since the X Series uses cutting edge technology so it can provide many solutions/ideas for increased efficiency along with tight voltage regulation. Briefly, the SS-1000XP utilizes a full-bridge topology along with an LLC resonant converter for zero voltage switching which greatly reduces energy losses on the primary mosfets. Also another interesting feature, which Seasonic utilized in X series PSUs too, is that the VRMs are responsible for the minor rails generation are integrated into the modular PCB, so efficiency gets a noticeable boost since impedance along with current losses are minimized.


The AC receptacle incorporates an EMI line filter which includes all necessary components (one X, two Y capacitors and two coils). On the main PCB we find more transient filtering components, two CM chokes, four Y and one X caps and an MOV.


Right in front the Y caps, shown above, we find a thermistor wrapped in heatshrink which is responsible for inrush current protection. The orange component in front of it is an electromagnetic relay which bypasses the thermistor once the PSU completes the start up phase and the PFC caps are fully charged.


The two bridge rectifiers are bolted on a dedicated heatsink. After them the PFC input capacitor filters the high frequency ripple.


In the APFC two IPW60R199CP mosfets along with a C3D10060 boost diode are used to shape the current waveform. The three parallel hold up capacitors are provided by Nippon Chemi-Con (330μF each or 990μF total, 420V, 105°C, KMR series). In order to provide a better view to the resonant controller (CM6901) we removed the middle one.


The four switching IPP60R190C6 mosfets are bolted on a dedicated heatsink.


In the secondary side, on the top side of the PCB, there are only some small heatsinks and a great number of polymer filtering capacitors along with several electrolytic ones. All are Japan-made (Nippon Chemi-Con) and the electrolytic ones are rated at 105°C. Here you should be wondering where the components are that generate +12V. But of course, on the solder side of the PCB. The eight BSC018N04LS mosfets, which regulate +12V, are cooled passively by the casing itself and the heatsinks on the PCB's components side also help with heat removal.


To minimize the distance the minor rails had to travel, along with the impedance, the VRMs (Voltage Regulation Modules) that handle 5V and 3.3V are incorporated into the modular PCB. Each VRM has three mosfets and one APW7159 PWM controller handles both VRMs. By taking a better look at the solder side of the modular PCB we noticed that one thick +12V wire feeds the VRMs and two smaller ones feed the peripheral sockets and the EPS/PCIe socket located on the top right corner. Finally all five bottom modular sockets are soldered directly to the main PCB through thick metal conductors, so energy losses are minimized here.


On a vertical PCB on the side of the main PCB, the protections IC, a PS232F, along with an LM393 Dual Voltage Comparator are installed.


The duties of the standby PWM controller handles an ICE2QR4765 IC. Near this IC we spotted the only cap used in this unit that is not provided by Nippon but by another major manufacturer, Rubycon.


The solder side of the main PCB features a very nice, clean, design and well made solder joints. In addition we didn't find any long component leads.


The cooling fan, a San Ace 120, is provided by Sanyo Denki and its model number is 9S1212F404. At full speed it's noisy but in this unit most of the times it will work at middle-low RPMs and if you choose Hybrid operation then it won't work at all at low loads. The same fan is used in all X series PSUs (except the two fanless models of course!)