Logisys PS600A12 Power Supply Review
By Gabriel Torres on March 2, 2011


Introduction

We decided to buy several power supplies that are sold for less than USD 40 at Newegg.com to see if they are good options for users on budget. Our first victim is the Logisys PS600A12, a “600 W” power supply that comes with a fake 80 Plus logo. Let’s check it out.

The product box comes with a completely fake 80 Plus logo, see Figure 1. We can tell this is a fake right away because one of the requirements for getting the standard 80 Plus certification is to present power factor of at least 0.90, and therefore it is impossible for power supplies without PFC circuit (like this one) to get any kind of 80 Plus certification.

Logisys PS600A12 power supply
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Figure 1: Fake 80 Plus badge

Half of the power supply casing is green, and the nylon sleeves used on the cables are lime green, making this probably the ugliest power supply we’ve ever seen.

Logisys PS600A12 power supply
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Figure 2: Logisys PS600A12 power supply

Logisys PS600A12 power supply
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Figure 3: Logisys PS600A12 power supply

The Logisys PS600A12 is 5 ½” (14 cm) deep, using a 120-mm sleeve bearing fan on its bottom (BaoDiKai BDH12025S). This unit doesn’t have an active PFC, being based on the outdated half-bridge topology.

The cables included are:

On the good side, this unit has two connectors for video cards. On the bad side, there are only four SATA connectors. The wires used with the peripheral power connectors are 20 AWG, i.e., thinner than recommended. All other wires are 18 AWG. As a curiosity, the main motherboard connector has a -5 V (white) wire. This wire was removed from the ATX12V specification in January 2002, meaning that this unit uses a complete obsolete design.

Logisys PS600A12 power supply
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Figure 4: Cables

Let’s now take an in-depth look inside this power supply.

A Look Inside The Logisys PS600A12

We decided to disassemble this power supply to see what it looks like inside, how it is designed, and what components are used. Please read our Anatomy of Switching Power Supplies tutorial to understand how a power supply works and to compare this power supply to others.

On this page we will have an overall look, and then in the following pages we will discuss in detail the quality and ratings of the components used.

Logisys PS600A12 power supply
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Figure 5: Top view

Logisys PS600A12 power supply
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Figure 6: Front quarter view

Logisys PS600A12 power supply
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Figure 7: Rear quarter view

Transient Filtering Stage

As we have mentioned in other articles and reviews, the first place we look when opening a power supply for a hint about its quality, is its filtering stage. The recommended components for this stage are two ferrite coils, two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor), and one MOV (Metal-Oxide Varistor). Very low-end power supplies use fewer components, usually removing the MOV and the first coil. 

In the transient filtering stage, the Logisys PS600A12 has all the required components, including one additional X capacitor, but it doesn’t have the MOVs. There is space for installing two MOVs between the electrolytic capacitors of the voltage doubler circuit, but the manufacturer decided not to add them.

Logisys PS600A12 power supply
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Figure 8: Transient filtering stage (part 1)

Logisys PS600A12 power supply
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Figure 9: Transient filtering stage (part 2)

In the next page we will have a more detailed discussion about the components used in the Logisys PS600A12.

Primary Analysis

On this page we will take an in-depth look at the primary stage of the Logisys PS600A12. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

Instead of a using a ready-made rectifying bridge, the reviewed unit uses four discrete diodes. This is another evidence that we are dealing with a very low-end power supply. Four 1N5408 diodes are used, each one supporting up to 3 A at 75° C. Therefore, this unit would be able to pull up to 345 W from a 115 V power grid; assuming 80% efficiency, the diodes would allow this unit to deliver up to 276 W without burning themselves out. Of course we are only talking about these components and the real limit will depend on all other components from the power supply. Here you can tell that it is simply impossible for this power supply to be a 600 W unit.

Logisys PS600A12 power supply
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Figure 10: Rectifying bridge

The electrolytic capacitors used in the voltage doubler circuit are Japanese, from Chemi-Con, and labeled at 105° C. But we wonder if they are not counterfeit parts.

The Logisys PS600A12 uses the obsolete half-bridge configuration, using two 2SD209L power NPN transistors, each one supporting up to 12 A at 25° C in continuous mode (unfortunately the manufacturer doesn’t say the limit at 100° C).

Logisys PS600A12 power supply
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Figure 11: Switching transistors

The switching transistors are driven by a TL494 PWM controller, which is physically located in the secondary.

Logisys PS600A12 power supply
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Figure 12: PWM controller

Now let’s take a look at the secondary of this power supply.

Secondary Analysis

The +12 V output uses one BYW51-200 rectifier, which supports up to 16 A (8 A per internal diode at 156° C, 0.97 V maximum voltage drop), giving us a maximum theoretical current of 16 A or 192 W for the +12 V output. It is important to understand that this rectifier is of the “ultra fast” type, not “Schottky.”

The +5 V output uses one ESAD83-004 (“D83-004”) Schottky rectifier, which supports up to 30 A (15 A per internal diode at 90° C, 0.55 V maximum voltage drop), giving us a maximum theoretical current of 30 A or 150 W for the +5 V output.

The +3.3 V output uses another ESAD83-004 Schottky rectifier, giving us a maximum theoretical current of 30 A or 99 W for the +3.3 V output.

All these numbers are theoretical. The real amount of current/power each output can deliver is limited by other components, especially by the coils used on each output.

Here you can clearly see three things. First, the +5 V output is “stronger” than the +12 V output, which is a typical scenario for power supplies projected more than 10 years ago. Nowadays the most current/power is pulled from the +12 V output (because there is where the CPU and the video cards are connected to) and, therefore, this output should be the “strongest.” Second, the +12 V rectifier is an “ultra fast” model, not a “Schottky” model, also showing how obsolete this unit it. And, third, if we add up all the maximum theoretical powers we get 441 W, so it is simply impossible for this power supply to be a 600 W model.

Logisys PS600A12 power supply
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Figure 13: +3.3 V, +12 V and +5 V rectifiers

The protections of this unit are built discretely using an LM339 voltage comparator. We couldn’t figure out which protections are really implemented.

Logisys PS600A12 power supply
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Figure 14: Voltage comparator

Power Distribution

In Figure 15, you can see this power supply label containing all its power specs.

Logisys PS600A12 power supply
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Figure 15: Power supply label

The label is, of course, a bad-taste joke. The manufacturer says this power supply is a 600 W unit with 630 W peak power. Right.

Let’s now see how much power this unit can really deliver.

Load Tests

We conducted several tests with this power supply, as described in the article Hardware Secrets Power Supply Test Methodology.  

Since with very low-end power supplies we can’t tell beforehand whether they will be able to deliver their labeled wattage or not, we test them using a different methodology. We increase load little by little, until we find out the maximum the power supply is capable of delivering. As usual, we pull more current/power from the +12 V outputs, as this better reflects the usage of a modern PC, since the CPU and the video cards are connected to these outputs.

If you add all the powers listed for each test, you may find a different value than what is posted under “Total” below. Since each output can have a slight variation (e.g., the +5 V output working at +5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. In the “Total” row, we are using the real amount of power being delivered, as measured by our load tester.

The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. During our tests, the +12VA and +12VB input were connected to the power supply single +12 V rail (the ATX12V connector was installed on the +12VB input of our load tester).

Input

Test 1

Test 2

Test 3

Test 4

+12VA

3 A (36 W)

3.5 A (42 W)

4.5 A (54 W)

5.5 A (66 W)

+12VB

2.5 A (30 W)

3.25 A (39 W)

4 A (48 W)

5 A (60 W)

+5V

1 A (5 W)

1 A (5 W)

1.5 A (7.5 A)

1.5 A (7.5 A)

+3.3 V

1 A (5 W)

1 A (5 W)

1.5 A (4.95 W)

1.5 A (4.95 W)

+5VSB

1 A (5 W)

1 A (5 W)

1 A (5 W)

1 A (5 W)

-12 V

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

Total

85.6 W

100.4 W

125.9 W

149.4 W

% Max Load

14.3%

16.7%

21.0%

24.9%

Room Temp.

40.7° C

40.3° C

39.9° C

39.7° C

PSU Temp.

41.7° C

43.3° C

44.1° C

44.5° C

Voltage Regulation

Fail on +5 V

Fail on +5 V

Fail on +5 V

Fail on +5 V

Ripple and Noise

Pass

Pass

Pass

Pass

AC Power

112.8 W

130.7 W

161.4 W

190.4 W

Efficiency

75.9%

76.8%

78.0%

78.5%

AC Voltage

120.5 V

119.9 V

118.3 V

118.4 V

Power Factor

0.608

0.618

0.636

0.648

Final Result

Fail

Fail

Fail

Fail


Input

Test 5

Test 6

Test 7

Test 8

+12VA

6.25 A (75 W)

7.5 A (90 W)

8.25 A (99 W)

9.25 A (111 W)

+12VB

6 A (72 W)

7 A (84 W)

8 A (96 W)

9 A (108 W)

+5V

2 A (10 W)

2 A (10 W)

2.5 A (12.5 W)

2.5 A (12.5 W)

+3.3 V

2 A (6.6 W)

2 A (6.6 W)

2.5 A (8.25 W)

2.5 A (8.25 W)

+5VSB

1 A (5 W)

1 A (5 W)

1 A (5 W)

1 A (5 W)

-12 V

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

Total

174.5 W

200.6 W

225.4 W

248.4 W

% Max Load

29.1%

33.4%

37.6%

41.4%

Room Temp.

39.7° C

40.0° C

40.7° C

41.7° C

PSU Temp.

44.8° C

45.3° C

46.0° C

47.0° C

Voltage Regulation

Fail on +5 V

Fail on +5 V

Fail on +5 V

Fail on +5 V

Ripple and Noise

Pass

Pass

Pass

Pass

AC Power

222.6 W

256.2 W

290.3 W

321.2 W

Efficiency

78.4%

78.3%

77.6%

77.3%

AC Voltage

118.1 V

118.5 V

118.1 V

117.7 V

Power Factor

0.660

0.670

0.679

0.686

Final Result

Fail

Fail

Fail

Fail


Input

Test 9

Test 10

Test 11

Test 12

+12VA

10 A (120 W)

11 A (132 W)

12 A (144 W)

13 A (156 W)

+12VB

10 A (120 W)

11 A (132 W)

11.75 A (141 W)

12.75 A (153 W)

+5V

3 A (15 W)

3 A (15 W)

3.5 A (17.5 W)

3.5 A (17.5 W)

+3.3 V

3 A (9.9 W)

3 A (9.9 W)

3.5 A (11.55 W)

3.5 A (11.55 W)

+5VSB

1 A (5 W)

1 A (5 W)

1 A (5 W)

1 A (5 W)

-12 V

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

Total

272.3 W

295.3 W

319.9 W

341.1 W

% Max Load

45.4%

49.2%

53.3%

56.9%

Room Temp.

42.9° C

43.2° C

41.9° C

43.6° C

PSU Temp.

48.3° C

44.4° C

42.5° C

44.2° C

Voltage Regulation

Fail on +5 V

Fail on +5 V

Fail on +5 V

Fail on +5 V

Ripple and Noise

Pass

Pass

Pass

Pass

AC Power

358.2 W

392.4 W

432.8 W

475.0 W

Efficiency

76.0%

75.3%

73.9%

71.8%

AC Voltage

117.2 V

117.1 V

117.3 V

116.9 V

Power Factor

0.693

0.699

0.706

0.716

Final Result

Fail

Fail

Fail

Fail

As expected, the Logisys PS600A12 can’t deliver its labeled wattage: it burned when we tried to pull around 375 W from it. It can only deliver up to 350 W without burning. The component that burned was the +12 rectifier.

Efficiency was always below 80%, between 72% and 78%.

The +5 V output presented voltages above the maximum allowed all the time: the maximum allowed is +5.25 V but this output was always between +5.26 V and +5.38 V. The +12 V and +3.3 V outputs, on the other hand, presented voltages within 3% of their nominal values. The ATX12V specification allows voltages to be up to 5% from their nominal values (10% for the -12 V output).

Noise and ripple levels were always below the maximum allowed. During the test 12, the noise level on the +12VA input was 72.8 mV, on the +12VB input was 72.4 mV, on the +5 V input was 16.6 mV and on the +3.3 V input was 22.4 mV. The maximum allowed is 120 mV for the +12 V and -12 V outputs, and 50 mV for the +5 V, +3.3 V, and +5VSB outputs. All values are peak-to-peak figures.

Main Specifications

The main specifications for the Logisys PS600A12 include:

* Researched at Newegg.com on the day we published this review.

Conclusions

We were surprised to discover that power supplies with fake wattages and fake 80 Plus logos were being sold in the United States and, of all places, at Newegg.com. We thought it was illegal to sell this kind of junk in America.

The Logisys PS6000A12 has “garbage” written all over it. It is labeled as 600 W continuous and 630 W peak, but it burned when we tried to pull 375 W from it. It has a fake 80 Plus logo (power supplies without PFC circuit can’t be certified, since the 80 Plus certification requires a minimum of 0.90 power factor). Efficiency was between 72% and 78%, and the +5 V output presented voltages above the maximum allowed all the time, which can lead to computer malfunction. It has an ugly color. It has an obsolete design. And the worst part: it is too expensive.

For the same USD 40 you can buy the Corsair CX430, which is a far better power supply and is the product we recommend if you are on budget.

Originally at http://www.hardwaresecrets.com/article/Logisys-PS600A12-Power-Supply-Review/1211


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