Seasonic FOCUS SGX-650 650W (Page 3 of 4) | Reports

Page 3 - Physical Look - Inside

As always, we opened up our Seasonic FOCUS SGX-650 650W power supply to take a detailed look at what is going on inside. Please note that doing this at home will void your ten-year warranty, thanks to the warranty seal Seasonic applied over one of the attachment screws. But for the benefit of you, we cracked ours open so you do not need to, haha. There are no user serviceable parts inside.

Disassembling the Seasonic FOCUS SGX-650 650W is quite straightforward with the removal of eight to twelve screws, depending on how far you want to get. Our photo above shows an overhead view of its internal components. Its OEM is, of course, Seasonic themselves, one of the best manufacturers of power supplies in the world. This power supply is based off the FOCUS Plus Gold platform, which we have reviewed a model from back in September 2017. The NZXT E850 850W is also based off the same platform. One unique feature of the FOCUS series is that there are no power cables inside. At first glance, the build quality appears to be excellent. There are two main heatsinks inside, all of which are unpainted.

Pulling the enclosure apart, and we got straight to the internal inspection. The transient filter stage is the first input stage of a computer power supply, so we will take a look at that first. Seasonic has always done a great job in the past to make sure their power supplies met or exceeded the recommended requirements, and the FOCUS SGX-650 650W is no exception. The Seasonic FOCUS SGX-650 650W has one metal oxide varistor, two metalized polyester X-capacitors, four ceramic Y-capacitors, and two ferrite coils. This is twice times the amount of X and Y capacitors than recommended, and the metal oxide varistor is used to stabilize spikes from the AC line. A Champion CM6500 PFC controller can be spotted at the back of the PCB.

On the primary side, we can see one Japanese made Nichicon capacitor. 100% Japanese made capacitors are usually what we expect from something in this class, so this is nothing surprising. Our 650W version of Seasonic's latest FOCUS SGX-series power supply incorporates one 470µF x 400V capacitor. It is rated at 105c; whereas more value-oriented power supplies usually use 85c rated capacitors.

The active PFC circuit featured on the Seasonic FOCUS SGX-650 650W uses one Lite-On Semiconductor GBU1506 bridge rectifier attached to the first heatsink. At 115V, the maximum rectified forward current capacity with heatsink is 15A each, so you can theoretically pull up to 1725W (15A * 1 diode * 115V) from the bridge rectifier at 100% efficiency -- of course, this is limited by the fact that it is not 100% efficient, and also neglects the fact that not every component in the system are able to keep up. Further down the line, on the smaller heatsink, we can see two Infineon IPP60R190P6 power transistors. This MOSFET model is certified for up to 12.7A at 100c. A STMicroelectronics STTH8S06 boost diode is placed right next it. Two Greatpower GPT13N50DGN220FP power MOFSET transistors are used as the main switchers on the FOCUS SGX-650 650W power supply. Each Greatpower GPT13N50DGN220FP MOFSET can deliver up to 13A at 25 degrees Celsius continuously. These transistors present a maximum resistance of 0.49 ohm when turned on according to the manufacturer's data sheet. This on characteristic is called Static Drain-Source On-Resistance, or commonly abbreviated as RDS(on). The more efficient the component is, the lower the RDS(on) value, since it wastes less power with lower resistance.

On the secondary side, we can see more Japanese made capacitors from Nippon Chemi-Con and Nichicon rated at 105c. As with modern high efficiency power supplies, all rectifiers produce the +12V out -- while the +5V and +3.3V outputs are generated from the +12V output using a DC to DC converter within the power supply unit. These components are soldered located on a daughterboard behind the modular daughterboard, and I was unable to see what they are. My guess is they are Nexperia PSMN2R6-40 MOSFETs. The PSMN2R6-40's rated continuous drain current is 100A at 100c. It has a RDS(on) value of 0.0028 ohm maximum and 0.0020 ohm typical. Meanwhile, a Weltrend WT7527 monitoring IC provides over/under current and over/under voltage protection. Champion's CM6901 is the PWM switching controller, both of which are located at the bottom of the main PCB. The datasheets for all components mentioned in this review can be found on their respective manufacturer's websites.

At the back, we have a large daughterboard covering the entire rear panel for the modular cable sockets. All modular sockets at the bottom are soldered directly to the main PCB after the secondary stage to reduce power transmission loss. The output connector configuration can be seen on the previous page. Overall, the internal build quality of Seasonic's FOCUS SGX-650 650W power supply is excellent -- something we would expect from a Seasonic built unit. Components are arranged very well for optimal cooling with minimal wires running around inside, and solder points on its green PCB is quite clean in general. I would say the Seasonic FOCUS SGX-650 650W is generally very good with regards to the selection of components used under the hood; appropriate for its performance class.

Lastly, we see a 120mm fan that provides cooling to the Seasonic FOCUS SGX-650 650W's internal components. It is connected to the mainboard using a 2-pin connector. A 120mm fan is the largest fan you can possibly fit in an SFX power supply, and it is beneficial in most cases in providing lots of airflow at lower speeds for quiet operation. Globe is the fan OEM, with S1201512HB as the model number, as shown in our photo above. Further research indicates the S1201512HB is a sleeve bearing fan specified at 0.45A for a maximum of speed of 2200 RPM. Fans with sleeve bearings generally have much shorter lifespans compared to ball or fluid dynamic bearings bearing fans, but they are the quietest. Since the Seasonic FOCUS SGX-650 650W has a hybrid fan, the S1201512HB is probably off most of the time, rendering this an acceptable application.

Page Index
1. Introduction, Packaging, Specifications
2. Physical Look - Outside
3. Physical Look - Inside
4. Minor Tests and Conclusion