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.


Once we removed the casing we found that the main PCB actually is quite small compared to the length of the PSU. However the long heatpipes required an equally long case. Each of the two heatpipes is connected to one of the two heatsinks that reside in the primary and the secondary side. The OEM of ZM850-HP Plus is Enhance Electronics.


The first part of the transient filter can be found on the AC receptacle and has two X and two Y capacitors. The second part is on the main PCB and consists of two 2 coils, an MOV, two X and two Y capacitors.


The bridge rectifier is cooled by a heatsink. In the APFC stage we find two STW25NM50N mosfets and a boost diode. The filtering capacitors are provided by Rubycon (270μF, 420V, 85°C). As main switches two STW25NM50M mosfets are used.


In the secondary side for the generation of +12V synchronous design is used and for the minor rails passive design, so four AOT480 mosfets regulate the +12V rail and two STPS60L45CW SBRs the minor ones. On the secondary heatsink two thermistors are attached. One for OTP and one for the fan control. In the edge of the secondary heatsink there is also an MBR1060 SBR that regulates 5VSB. For the later a Nippon Chemi-Con filtering capacitor is used and for the filtering of all other DC outputs Teapo capacitors are utilized. Now some of you may wonder if this PSU has group regulation since only two coils are present in the secondary side. Well it doesn't since the +12V rails have their own toroidal choke and the 5V/3.3V rails share the other one, which is unlikely for group regulation designs.


The combo PFC/PWM controller, an CM6802, and the protections IC, an PS232S, reside on the same daughter-board with two optocouplers isolating the two circuits. As standby PWM controller an A6062H is used. The latter is located on the main PCB.



On the modular PCB there are three electrolytic capacitors (two Teapos and one Chemi-Con) that further reduce output ripple.


Soldering quality and workmanship on the main and the modular PCBs are very good. Also in the area where the +12V wires leave the main PCB we located four shunt resistors, so indeed the PSU has four virtual +12V rails.


The cooling fan is provided by Zalman and its model number is ZF1425ATF (1740 RPM, 94.3 CFM, 31.6 dBA).