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.


Like all ZS units the OEM of the ZS 650W is Sirfa. The platform utilizes the classic double forward topology and in the secondary side it has independent regulation.


In the AC receptacle we find some parts of the transient filtering stage, two Y and one X caps. On the main PCB we find the remaining parts of the transient filter, two chokes, an MOV, two Y and one X caps.


The bridge rectifier is a GBU805 which is cooled by a dedicated heatsink. Here we should note that while the universal input (100-240 VAC) ZS 650W uses two GBU805 bridges, in the EU/UK version a single bridge is enough.


In the APFC we find only one mosfet (IPW6R190C6) (the universal input model has two) and the necessary boost diode. The APFC cap is provided by Matsushita/Panasonic (330µF,400V, 85°C). The combo PFC/PWM controller, a CM6800TX is soldered on a vertical daughter-board in the primary side. The main switches are two Fuji Electric 19N60E mosfets.


The standby PWM controller is a TNY278PN IC which incorporates a 700 V power MOSFET.


In the secondary side only passive components (Schottky Barrier Rectifiers) are used for the regulation of the rails. For +12V two MOSPEC S30D45C are used while two pairs of PFR30L45CT handle 5V and 3.3V. Finally the three toroidal chokes mean that each rail is regulated independently.


In the secondary side only Japanese caps are used (Nippon Chemi-Con rated at 105°C).


All protections are handled by an ST9S423 IC for which we found nothing on the web so we can't verify the protections it supports.


Soldering quality isn't top notch but you can't call it bad either. In addition we did not spot any long component leads which are very dangerous for the health of the PSU and the system it powers.


The cooling fan is the same as on the ZS 750W. It's provided by Globe Fan and its model number is RL4Z B1352512M (12V, 0.28A, dual ball bearing).