The 2013 El-Cheapo Power Supply Round-up

Aozhong ATX-400A

Well, it zeems like zomebody has been zinging ao-zhong. That’s the only conclusion I can come to from looking at this power supply. Bad puns aside, I have never heard of this brand before.

az-label_az

Again, this is another 5V-heavy design.

Load Testing

Test 1 (112.23W Load)

Rail Load Voltage Ripple
12V 4.5A 12.21V 41.2mV
5V 5.01A 5.01V 45.4mV
3.3V 10.06A 3.32V 85.2mV
−12V 0A −11.96V 45.0mV
5Vsb 0A 5.03V 29.6mV
AC Power 150.3W
Efficiency 74.67%
Power Factor 0.64

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Test 2 (194.3W Load)

Rail Load Voltage Ripple
12V 9.0A 11.84V 66.8mV
5V 9.9A 4.95V 60.2mV
3.3V 9.94A 3.28V 78.0mV
−12V 0.1A −12.17V 82.0mV
5Vsb 0.99A 4.95V 34.6mV
AC Power 255.1W
Efficiency 76.17%
Power Factor 0.62

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Test 3 (241.74W Load)

Rail Load Voltage Ripple
12V 13.2A 11.65V 85.0mV
5V 9.92A 4.96V 68.6mV
3.3V 9.94A 3.28V 78.0mV
−12V 0.1A −12.45V 101.8mV
5Vsb 0.99A 4.93V 38.6mV
AC Power 325.3W
Efficiency 74.31%
Power Factor 0.61

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The 12V rail started at 12.21V, and wound up at 11.65V in test 3. This gives us 0.35V (2.92%) worst-case regulation and a drop of 0.56V (4.66%) – a poor result. The other two rails fared much better, with drops of 1.2% for both the 5 and 3.3V rail.

The efficiency was also very poor, only making it up to 76.1% during test 2. The power supply was also unable to deliver any more than 240W. When I asked for 300W, its fuse popped after 30 seconds or so. The cause was more than likely a failed switching transistor.

Rail Test 2 (194.3W) Test 3 (241.74W)
12V  az-test2-12v  az-test3-12v
5V  az-test2-5v  az-test3-5v
3.3V  az-test2-3.3v  az-test3-3.3v
−12V  az-test2--12v  az-test3--12v
5Vsb  az-test2-5vsb  az-test3-5vsb

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The ripple suppression was unacceptable. The 3.3V was out of spec the whole time, and the 5V rail was out of spec for all but the first test. The other rails fared a little better, but were still above half the maximum allowed. This will cost the unit all 10 points from the final score.

Disassembly

az-primary_az-secondary

The input filtering consists of an X capacitor, a common-mode choke and two ceramic capacitors. There should be another choke and X cap installed, and the ceramic capacitors are not safety rated. Like on the Infinity, there is no bridge rectifier, although the diodes are rated at 3A this time around. The two primary capacitors are rated for 560µF and are supplied by a company called Cheng. The switching transistors are ST Morocco ST13009s, which are rated at 12A. The plastic washers on them are melted from overheating, which is probably why they failed.

Moving on to the secondary side, the 12V rail uses a MOSPEC F16C20 rectifier, which is rated for 16A, The 5V rectifier is a PanJIT SB3040PT Schottky rectifier, which is rated at 30A and the 3.3V rail uses an SB2040CT, which is rated for 20A. Ideally, higher rated parts should be used on all of the rails, since these rectifiers are all under-spec’d for what the label claims the rails to be capable of. The capacitors on the secondary side are also branded Cheng. This is a brand I am largely unfamiliar with, but in all likelihood, they are a cheap Chinese brand. There is only one capacitor installed for each rail, and there are no PI coils, which explains why the ripple suppression was so poor.

az-fan_az-internals

The fan is branded Ning Jie. This is another brand which I have never heard of, and no one seems to know much about. It is wired directly to the 12V output, and it was loud. In fact, I think this one would have to be the loudest power supply I have ever reviewed – being the only one I have tested thus far which I could notice through the load tester’s fans (normally, I have to turn the load tester’s fans off to gauge the fan noise). There was some grease in the bearing, but oil would be much better, as it doesn’t get pushed out like grease. The heat sinks aren’t great, but I have seen worse.

Specifications and Conclusions

Real Wattage 0W
OEM Unknown
PFC None
Price Unknown
ATX Connector type 20+4 pin
Worst-case voltage regulation (12v, 5v, 3.3v) 2.92%, 1%, 0.6%
Worst-case ripple (12v, 5v, 3.3v) 85.0mV, 85.2mV, 68.6mV
Worst-case efficiency 74.31%
Input filtering Inadequate
CPU Connector ATX12V (4 pin)
PCIe Connectors None
Molex (Peripheral) Connectors 4
FDD Power connectors 1
SATA Power connectors 1

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Pros: None

Cons: Can’t deliver anything with ripple in spec (−10), Mediocre 12V voltage regulation, Questionable capacitor choice, Fan could be better, Old 5V-Heavy design, Very loud, Inefficient.

Score: 0/10

HWIFail

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