A Look Inside And Component Analysis
Before proceeding with this page, we strongly encourage you to a look at our PSUs 101 article, which provides valuable information about PSUs and their operation, allowing you to better understand the components we're about to discuss. Our main tools for disassembling PSUs are a Thermaltronics soldering and rework station, and a Hakko FR-300 desoldering gun.
|Transient Filter||4x Y caps, 2x X caps, 2x CM chokes, 1x MOV|
|Inrush Protection||NTC Thermistor & Diode|
|Bridge Rectifier(s)||2x GBU1006 (600V, 10A @ 100°C)|
|APFC MOSFETs||2x Infineon IPW50R280CE (550V, 11.4A @ 100°C, 0.28Ω)|
|APFC Boost Diode||1x Power Integrations QH08TZ600 (600V, 8A @ 150°C)|
|Hold-up Cap(s)||1x Nichicon (400V, 390uF, 2000h @ 105°C, GG)|
|Main Switchers||2x Vishay SiHG20N50C (560V, 11A @ 100°C, 0.27Ω)|
|Combo APFC/PWM Controller||Champion CM6800TX & CM03X Green PFC controller|
|Topology||Primary side: Double-Forward Secondary side: Synchronous Rectification & DC-DC converters|
|+12V MOSFETs||4x APEC AP9990GH-HF (60V, 100A @ 25°C, 6mΩ)|
|5V & 3.3V||DC-DC Converters: 6x APEC AP72T03GP (30V, 47A @ 100°C, 9.5 mΩ) PWM Controller: ANPEC APW7159C|
|Filtering Capacitors||Electrolytics: Nippon Chemi-Con (1-5,000 @ 105°C, KZE), Su'scon (2-5,000h @ 105°C, MF), 1x Taicon (105°C) Polymers: APAQ, EneSol|
|Supervisor IC||Weltrend WT7502 (OVP, UVP, SCP, PG)|
|Fan Model||Yate Loon D14SH-12 (140mm, 12V, 0.70A, 2100RPM, 140CFM, 48.5 dB(A), Sleeve Bearing)|
|Rectifier||1x MBR2045CT SBR (45V, 20A) & CEF04N7G (700V, 4A, 3.3Ω)|
|Standby PWM Controller||On-Bright OB5269CP|
The CX750M is based on a slightly modified PUQ-B CWT platform (a big thanks to the members of a well known PSU forum for reminding me of this), with the number of small changes being dictated by Corsair's engineers in order to improve performance. The design is much more sophisticated than we expected given an 80 PLUS Bronze rating. It employs a double-forward topology on the primary side and a synchronous design on the secondary, with both VRMs installed on the modular PCB for lower voltage drops and minimal energy losses. Moreover, there are no heat sinks on the secondary side, despite a relatively mainstream efficiency certification. CWT seems to be avoiding heat sinks on the secondary side lately, and although this doesn't raise any concerns in high-efficiency Gold, Platinum, and Titanium platforms, it can affect the lifetime of Bronze-rated units under higher thermal loads. CWT's engineers are nevertheless confident in this design, otherwise Corsair wouldn't stand behind it for five years.
The first part of the transient filter is on the AC receptacle with a pair of Y caps. The second part is on the main PCB and consists of two Y and two X caps, two CM chokes, and an MOV.
The bridge rectifiers are a couple of GBU1006s bolted to a dedicated heat sink. Combined, they can handle up to 20A of current.
In the APFC converter we meet two Infineon IPW50R280CE FETs and a single QH08TZ600 boost diode provided by Power Integrations. The bulk cap is sourced from Nichicon and its capacity is low for a 750W PSU. As a result, we don't expect the unit's hold-up time to reach 17ms, per the ATX specification's requirement.
The primary switching FETs are two Vishay SiHG20N50Cs arranged into a double-forward topology. In addition, the combo PFC/PWM controller is a Champion CM6800TX IC, which is quite popular among Bronze-rated PSUs. We've even found it in several low-cost Silver and Gold units.
A vertical daughterboard holds the +12V FETs: four AP9990GH-HFs from APEC. Several bus bars are used to cool the FETs and main PCB. Although the cooling appears insufficient for a not-so-efficient 80 PLUS Bronze power supply, we didn't encounter any problems during our extra-tough tests conducted at very high ambient temperatures.
In a Bronze-class PSU, the last thing we'd expect to see would be DC-DC converters, responsible for generating the minor rails, installed directly on the modular board to limit energy losses. This technique is usually reserved for more efficient platforms. Both VRMs use six APEC AP72T03GP FETs, and the common PWM controller is an Anpec APW7159C.
The electrolytic filtering caps are provided by Chemi-Con (105°C, KZE) and Su'scon (105°C, MF). We also spotted a single Taicon (105°C) capacitor.
The supervisor IC is a Weltrend WT7502, which provides only the absolute necessary protections. It doesn't offer over-temperature protection and that's a great shame.
Several polymer APAQ and EneSol polymer caps on the modular board provide extra filtering. Some of them are used by the VRMs of the minor rails, too.
Two copper EMI shields don't offer adequate protection since they aren't grounded.
Here we have a general view of the secondary side and a close photo of the +12V island.
The soldering quality on the main PCB is decent. Still, we've seen much better implementations from CWT. On this side, we spot an LM393 dual-voltage comparator.
The fan is made by Yate Loon and its model number is D14SH-12 (140mm, 12V, 0.70A, 2100 RPM, 140 CFM, 48.5 dB[A]). This is a fairly strong fan that employs a sleeve bearing specified for a shorter lifetime than most double-ball bearing or fluid-dynamic bearing designs. We can't be too picky in this price range though, particularly since higher-quality fans significantly affect production costs.