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 of this little fellow is Delta Electronics, one of the largest and most experienced PSU manufacturers. Despite the underpopulated PCB we removed the bridge rectifier's heatsink along with the secondary side one, in order to give you a better view of the internals. Although we have a special de-soldering gun (Hakko 808) at our disposal, the removal of the secondary heatsink was really difficult.


The transient filter starts right at the AC receptacle with two Y caps. Also the two cables that transfer power to the main PCB are wrapped around a ferrite ring. On the main PCB there are more transient filtering components, namely two CM chokes and two pairs of X and Y caps. Unfortunately there is no MOV (Metal Oxide Varistor) present so the PSU is susceptible to spikes coming from the power grid, unless you use a surge protector with it.


The bridge rectifier, a T6KB60, can handle up to six Amps, so more than enough for the VP550P, taking also into account that it is attached to a dedicated heatsink. There is space for another parallel bridge rectifier on the PCB. After the bridge rectifier, the full wave rectified signal with 100 Hz frequency is filtered by the PFC input capacitor which in this case is an X one.


The APFC uses only one mosfet, since there is no need for voltage doubling as the PSU works only with 230VAC input and on top of that the max output power is small. An SPP21N50C3 mosfet is up to the task of separating the full wave rectified signal into constant pulse sequences. The hold cap is a Samxon labeled at 85°C and with 270μF capacitance. Thankfully, although it is only 85°C rated and doesn't come from the best available manufacturer it is rated at 450V, significantly higher than the APFC 380V DC bus voltage.


The main switches are two SPP15N60C3.


The combo PFC/PWM controller is the well known CM6800AG and is soldered on the main PCB. Also the standby PWM controller is a TNY278PN which can deliver up to 16W at 5VSB with 230VAC input.


In the secondary side only passive components are used. The +12V rail is handled by one STPS30L60CT and a pair of STPS20L60CT SBRs while 5V are generated from two MBR2045CT SBRs and 3.3V from one MBR3045 SBR. The presence of three toroidal chokes indicates that independent regulation is used for the generation of the rails, something that greatly affects, positively of course, cross load performance. To our surprise, since this is a real budget unit, all caps in the secondary are Japanese and provided by Rubycon, Nippon Chemi-Con and Nichicon with an 105°C rating. This sounds really weird but of course we are not going to complain about it!


The protection's IC, a DWA107, is soldered on a large daughter-board on the side of the main PCB.


Soldering quality on the main PCB is very good, typical of Delta platforms. On the solder side of the PCB we located the 5VSB rectifier, an SBR10U45.


The PCB indeed supports two +12V rails and the shunt resistors are located on the component side.


The cooling fan is provided by Yate Loon Electronics and its model number is D12SH-12. With a maximum speed of 2200 RPM and 40 dBA noise output you can't call it quiet, for sure.