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.


The OEM (Original Equipment Manufacturer) of the entire ZS series is Sirfa. The platform uses a double forward topology with a rather outdated secondary side which however uses independent regulation for the main rails. In order to provide you a clearer view we removed the secondary heatsink.


The first stage of the transient filter starts at the AC receptacle with two Y and one X capacitors. On the main PCB we also find two coils, an MOV, two Y and one X caps. As you can see the transient filter has all necessary components.


There is only one bridge rectifier bolted on a heatsink. Moving forward to the APFC section we meet one mosfet (SPW24N60C3) only along with a boost diode. The smoothing/reservoir capacitor is provided by Matsushita/Panasonic (390μF, 400V, 85°C). Right next to the APFC cap resides a vertical daughter-board which houses the combo PFC/PWM controller, a CM6800TX IC. Finally, the primary switches are two Fuji Electric 19N60E mosfets.


In the secondary side passive design is used so there are not mosfets present but only SBRs (Schottky Barrier Diodes). The +12V rail handle three MOSPEC S30D45C diodes and the 5V and 3.3V are generated by two pairs of PFR30L45CT. The presence of three toroidal chokes is an indication that independent regulation is used for the major rails. Finally all caps in the secondary side are provided by Nippon Chemi-Con and are rated at 105°C. Along with the electrolytics we also found a lonely polymer cap.


All protections are handled by an ST9S423 IC for which we didn't find anything on the web. Also the standby controller is a TNY278PN IC which incorporates a 700 V power MOSFET.


Soldering quality on the main PCB is fairly good, although not top notch. In the area where all +12V wires are connected to the main PCB we spotted two shunt resistors.


The cooling fan is provided by Globe Fan and its model number is RL4Z B1352512M (12V, 0.28A, dual ball bearing).