Fractal Design Edison M Series 750W Power Supply Review

A Look Inside And Component Analysis

Our main tools for disassembling PSUs are a Thermaltronics soldering and rework station and a Hakko 808 desoldering gun.

Parts Description

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Fractal Design's Edison M units are based on the same platform as Seasonic's G-series PSUs. The platform uses a half-bridge topology in the primary side along with an LLC resonant converter, while in the secondary side a synchronous design is utilized for the rectification of the +12V rail along with two DC-DC converters for generating the minor rails. The quality of components is very high and all capacitors are provided by Chemi-Con, a highly reliable Japanese manufacturer.

A small PCB behind the AC receptacle hosts the first part of the EMI filter, which includes four Y caps, a single X cap and a CM choke. The rest of the components of the EMI filter are located on the main PCB and consist of two CM chokes, two Y caps along with a single X cap and an MOV (metal oxide varistor).

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The single bridge rectifier (model number GBU1506) is bolted on a dedicated heat sink. After the bridge rectifier, the fully rectified voltage enters the APFC converter, which in this PSU uses two Infineon FETs (model number SPP20N60C3) and a boost diode (model STTH8S06D) to shape the current waveform and make it identical to the mains voltage in order to bring the power factor as close as possible to unity. Finally, close to the bulk cap is the NTC thermistor, which is responsible for protecting against large inrush currents. The only problem here is that, once the start-up phase finishes, there is no bypass relay for the thermistor, allowing it to cool down and regain its original resistance. We also didn't see a diode, which in some cases plays the same role as the relay mentioned above.

The main switchers are two Infineon (IPP50R250CP) FETs, arranged into a half-bridge topology.

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The resonant controller (the large IC on the left, model number ICE2HS01G) and the PFC controller (the small IC on the right, model number ICE3PCS01) are installed on a daughter board located in the primary side. The resonant controller operates in pulse-frequency modulation (PFM) mode, in which the repetition rate (or frequency) of fixed-duration pulses varies, unlike with PWM where the width of square pulses is varied at a constant frequency. In order to avoid high-frequency switching, the resonant controller employs missing cycle mode at light loads and burst mode with no load.

The four +12V FETs (model number PSMN2R6-40YS) are located on the solder side of the main PCB and are cooled by the heat sink above them and by the PSU's chassis as well. We also found two Schottky diodes (model number SBR10U45) on the sides of the FETs, which further increase efficiency by reducing switching loss, since they actually replace the body diodes of the slower FETs that have higher forward-voltage drops.

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Both minor rails are generated by an equal number of DC-DC converters, which are hosted on the same vertical board. Unfortunately, there was no way to identify their PWM controller and FETs without completely disassembling the board.

Housekeeping is handled by a SITI (PS223), which is among the few supervisor ICs that support OTP (over-temperature protection) out of the box.

The standby PWM controller is an Infineon (model number ICE2QR4765); the Schottky diode responsible for 5VSB rectification (model number SBR10U45) is located on the solder side of the main PCB.

Several polymer caps along with some electrolytic caps filter the rails in the secondary side. All are provided by Chemi-Con, so they are of high quality. The electrolytic caps are rated at up to 105 degrees Celsius and they belong to the KY and KZH series. Given the high quality of the caps used in this unit, we see no reason that the PSU should not be able to deliver full power continuously at 50 degrees C. It seems that Seasonic was being cautious in this regard, or perhaps the company was afraid that the +12V FETs on the solder side of the main PCB would be exposed to excess heat in a worst-case scenario, which would affect their lifespan.

At the front side of the small PCB we also found several Chemi-Con electrolytic caps for some extra ripple filtering.

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Soldering quality is definitely satisfactory. We didn't expect anything less from Seasonic.

 The cooling fan is provided by Hong Hua, Seasonic's preferred fan manufacturer for its affordable designs. The fan's model number is HA1225M12F-Z (12V, 0.22A, 2000 RPM, fluid dynamic bearing) and it will last for quite a long time thanks to the quality bearing that it uses. The only problem we see is the fan's small diameter, which forces it to spin at a high RPM in order to push a decent amount of air, leading to increased noise under stressful conditions.