A Look Inside & Component Analysis

Before reading this page, we strongly suggest a look at this article, which will help you understand the internal components of a PSU much better. Our main tool for the disassembly of the PSU is a Thermaltronics TMT-9000S soldering and rework station. It is of extreme quality and is equipped with a matching de-soldering gun. With such equipment in hand, breaking apart every PSU is like a walk in the park!


We were pretty sure we had come across the design once we took this PSU apart, and we found the PSU in question after only a short search. The semi-digital High Power Astro GD 750 W uses the same platform, so the SM1-700 is based on a non-digital version of High Power's topnotch platform. The platform utilizes an LLC resonant converter in its primary side for loss-less switching and increased efficiency and a synchronous design with DC-DC converters in the secondary side. Overall a high-end platform, SilentiumPC did well to use it in their top model, although SilentiumPC doesn't use any of the digital components native to the Astro GD to keep costs down.


The transient filtering stage starts with one X cap and a pair of Y caps at the AC receptacle. A CM02X mounted to the X cap is to block current through the cap discharge resistor when AC voltage is connected. It also automatically discharges the aforementioned cap through the discharge resistor when AC is disconnected. This increases efficiency since X caps tend to keep their charge for quite a long time once AC power is cut off, which is why bleeding resistors have to be used as a safety precaution. While some energy is still lost on such resistors while the PSU is operating, the CM02X takes care of that by cutting the bleeding resistor off the circuit. The second part of the transient filter is located on the main PCB and includes two CM chokes, a single X cap, and two Y caps. An MOV is also present, and we located an NTC thermistor responsible for high inrush current protection, along with a relay that isolates it from the circuit once the start-up phase finishes.


The two parallel bridges (GBU1005) are bolted to the primary heatsink. They can handle up to 20 A of current combined, which should easily cover the needs of this unit.


A single fet, an Infineon IPW60R070C6, chops the full wave rectified signal in the APFC circuit into constant pulse sequences. A CREE C3D08060A boost diode also helps in raising the voltage to around 380 VDC. The bulk cap is provided by Panasonic (400 V, 680 µF, 105°C) and its capacity is high enough to cover the needs of this PSU.


The PFC controller is installed on the main PCB. It is a Champion CM6502 that its manufacturer says to meet the 90+ specification.


Below the CM6502 is the standby controller, a Power Integrations TNY278PN IC.


Two IPP60R125C6 fets are used as main switchers and an LLC resonant controller helps in minimizing their energy losses.


The LLC resonant controller is a Champion CM6901. It is installed on a small vertical daughterboard.


We had to de-solder the secondary heatsink to clear things out for a better look at the DC-DC modules. This wasn't an easy task as our sample was an early production model, so soldering quality wasn't at its best. We found eight fets in total (IPD060N03L) and a single PWM controller, an APW7159, on the vertical PCB that holds both VRMs which generate the minor rails.


The secondary heatsink holds four IPP015N04N fets that generate +12V and a single PFR30L45CT SBR that rectifies 5VSB. There are also several polymer filtering capacitors on the secondary side, with a few electrolytic ones. All are provided by Nippon Chemi-Con.


A side view of the unit's secondary side.


The protections IC is a SITI PS223.


Several cables transfer power to the modular board, and a plastic shield on its back has been put there to prevent shorts.


Soldering quality on the main PCB was most likely mediocre because the sample we had on hand was a pre-production model. However, the High Power Astro GD 750 W unit we reviewed was a pre-production model as well.


We found a Silicon Labs Si8233BD isolator interface on the solder side of the PCB. Its task is to isolate the primary from the secondary side.


The cooling fan is by Globe Fan, and its model number is RL4Z S1352512M (12 V, 0.28 A). It uses a sleeve bearing and is a low-RPM fan, so we expect it to be silent enough.