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.


As we already told you in the beginning of the review the OEM of the HM-650 is Channel Well Technology (CWT) and to be more precise the unit uses the PSH II platform. This can be easily figured out by the green colored transformers, the most notable characteristic of CWT platforms.


The transient filter starts at the AC receptacle with two Y and one X caps. Unfortunately we didn't find a ferrite core around the cables. On the main PCB the transient filtering stage continues with two coils, one X and two Y caps (there is space for additional two on the main PCB) an an MOV.


Near the transient filter, on the main PCB, there is the protections IC, a PS229 which doesn't support OTP (Over Temperature Protection) and doesn't have an additional protection input to support it via an external circuit (e.g. like the PS232S). So we seriously doubt that this PSU has OTP.


The bridge rectifier is a GBU1506 which is bolted on the APFC heatsink. This rectifier is overspec'd for the the merely 650W of the PSU. Opposite to the bridge rectifier resides a vertical daughter board that houses the combo PFC/PWM controller, a Champion CM6800TX.


In the APFC we find two SPW20N60C3 mosfets and of course a boost diode. The smoothing/reservoir capacitor is provided by Nippon Chemi-Con (KMR series, 400V, 390μF, 105°C). The primary switches are two IPW60R190C6.


In the secondary side passive design is used so all rails generated with the help of several Schottky Barrier Diodes (SBRs). The +12V rail is regulated by six 30A60CT SBRs while the minor rails are handled by two 40CPQ060. All filtering capacitors in the secondary side are provided by Chemi-Con and are labeled at 105°C. Also the three toroidal chokes indicate that independent (indi) regulation is used, a design with far better performance compared to group regulation.


On the front of the modular PCB we find two small polymer caps for further current ripple filtering.


Soldering quality on the main PCB is not the best we have seen from CWT. We spotted many sloppy solder jobs with excess amount of solder. The good thing is that we did not find any long component leads.


The cooling fan is made by Yate Loon Electronics and its model number is D14BH-12 (140x140x25, 12V, 2800 max RPM, 140.0 CFM, 48.5 dBA). It is equipped with three color LEDs which light on according to the load level that the PSU handles.