A Look Inside & Component AnalysisBefore reading this page, we strongly suggest a look at this article, which will help you understand the internal components of a PSU better.
This time, Kingwin picked Highpower/Sirfa over their favorite OEM, Super Flower, to build this unit since they wanted a budget PSU for the average user. The PF-850 is actually a re-badged Highpower Direct12 unit. The platform is not cutting edge, but nor is it outdated. The primary side holds a conventional double-forward topology, while the secondary side utilizes synchronous rectification and two DC-DC converters to handle the generation of the minor rails. To our surprise, all capacitors, both electrolytic and polymers, are Japanese, which significantly extends the unit's lifespan. This is why Kingwin is confident in offering a five-year warranty with this product.
The transient filtering starts at the AC receptacle with two Y caps and one X cap. We also found a CM02X on the AC receptacle. The CM02X blocks current through the X cap discharge resistor when AC voltage is connected and automatically discharges the X cap through the discharge resistor when AC is disconnected. This produces higher efficiency since X caps tend to keep their charge for quite a long time once AC power is cut off, so bleeding resistors are used for safety. However, some energy is lost on such resistors while the PSU is operating, something that the CM02X takes care of by isolating the bleeding resistor from the circuit. We have seen something similar in the FSP AURUM 92+ 650 W unit. The transient filter continues on the main PCB with two CM chokes, an MOV, one X cap, and two Y caps, with the latter having been installed after the bridge rectifiers.
The two parallel bridge rectifiers are bolted onto a dedicated heatsink, and their model number is GBU805. Each one can handle up to 8 A of current at 100°C, so they support up to 16A of current combined.
In the APFC, two IPW60R070C6 fets chop the intermediate DC voltage coming from the bridge rectifiers into constant pulse sequences. The hold-up cap is provided my Matsushita/Panasonic (560 μF, 400V, 105°C).
As main switchers, two FMP20N60S1 are used; they are configured in a double-forward topology.
The combo PFC/PWM controller is the usual suspect for Bronze efficiency units: a CM6800TX IC. The standby PWM controller, a TNY278PN IC, is close-by.
On the secondary side, synchronous rectification is used, and four AOT480 fets rectify the +12V rail. All filtering capacitors, both electrolytic and polymers, are provided by Nippon Chemi-Con.
Two VRMs generate the minor rails. We find an FP6329 PWM controller and four IPD060N03L G fets on each one. Chemi-Con polymer caps are also used on the VRMs to filter their outputs.
The 5VSB rail rectifies a single SIRECT SBL05L40C SBR; a PI filter cleans its output.
The small modular PCB doesn't have any space for extra filtering caps. Soldering quality on it is decent.
The supervisor IC is a SITI PS223. It supports IC for up to two +12V rails and includes OTP (Over Temperature Protection) amongst the protection features it supports.
This is the solder side of the main PCB. As you can see, soldering quality, although not great, is definitely above average. The good thing here is that we didn't spot any long component leads that could cause dangerous shorts. We found four shunts under the +12V islands. The shunts are normally used by OCP, but they are, in this case, all shorted together.
The cooling fan is provided by Globe Fan, and its model number is RL4Z S1352512HH. This fan has 1800 RPM max speed, so we don't expect it to be very quiet. It is also equipped with sleeve bearings, which is inferior to ball-bearings.