Amacrox Free Earth 85PLUS 650 W Power Supply Review
By Gabriel Torres on March 29, 2010


Introduction

Hardware Secrets Golden Award

We’ve already reviewed a  power supply from the newcomer Amacrox (Free Style 85PLUS 650 W), which proved to be a product with an outstanding cost/benefit ratio. Let’s see if their Free Earth 85PLUS 650 W model is also a good buy.

As you can infer from the product name, this unit promises efficiency of at least 85%, being 80 Plus Bronze certified. Like the other model we reviewed, Free Earth 85 PLUS is manufactured by FSP.

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 1: Amacrox Free Earth 85PLUS 650 W power supply.

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 2: Amacrox Free Earth 85PLUS 650 W power supply.

Amacrox Free Earth 85PLUS 650 W is a short 5 ½” (140 mm) deep unit, having a 120 mm fan on its bottom , active PFC but no modular cabling system. Models from Free Style 85PLUS series have this feature, and this is the main difference between models from Free Style 85PLUS and Free Earth series (of course since we reviewed the 650 W model from Free Style 85PLUS series, we will see if there is any other internal difference).

All cables have nylon sleevings that come from inside the unit. All wires are 18 AWG, which is the recommended gauge to be use. The cables included on Free Earth 85PLUS 650 W are:

The number of cables may be adequate for a 650 W product, but we wish it had more SATA power connectors “just in case.” We also would like to see a greater distance between connectors on cables that carry more than one connector.

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 3: Cables.

Now let’s take an in-depth look inside this power supply.

A Look Inside The Free Earth 85PLUS 650 W

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.

This page will be an overview, and then in the following pages we will discuss in detail the quality and ratings of the components used. Here we could clearly see that Free Earth 85PLUS 650 W uses the exact same printed circuit board used on Free Style 85PLUS 650 W. Let’s see if there is any difference on the components used.

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 4: Overall look.

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 5: Overall look.

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 6: Overall look.

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. 

This power supply has two X capacitors and two Y capacitors more than the minimum required plus two X capacitors and one ferrite coil after the rectification bridge, but it doesn’t come with a MOV, which is a sin. This component is in charge of surge protection.

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 7: Transient filtering stage (part 1).

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 8: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion about the components used in the Amacrox Free Earth 85PLUS 650 W.

Primary Analysis

On this page we will take an in-depth look at the primary stage of Amacrox Free Earth 85PLUS 650 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two GBU606 rectifying bridges connected in parallel in its primary, each one being able to deliver up to 6 A at 100° C if a heatsink is used (which is the case) or up to 2.8 A at 100° C is a heatsink is not used. So in theory you would be able to pull up to 1,380 W from the power grid; assuming 80% efficiency, these bridges would allow this unit to deliver up to 1,104 W without burning themselves out. Talk about overspecification! Of course, we are only talking about these components, and the real limit will depend on all the other components in this power supply. These are the same components used on Free Style 85PLUS 650 W.

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 9: Rectifying bridges.

Two FCPF21N60 power MOSFETs are used on the active PFC circuit, each one capable of delivering up to 20 A at 25° C or 12.5 A at 100° C in continuous mode (note the difference temperature makes) or up to 60 A at 25° C in pulse mode. These transistors present a maximum resistance of 150 mΩ when turned on, a characteristic called RDS(on). This number indicates the amount of power that is wasted, so the lower this number the better, as less power will be wasted thus increasing efficiency. These are the same components used on Free Style 85PLUS 650 W.

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 10: Active PFC transistors and diode.

The electrolytic capacitor is charge of filtering the active PFC output is Japanese from Hitachi and labeled at 105° C, which is great. This is the same component used on Free Style 85PLUS 650 W.

In the switching section, two SPA20N60C3 power MOSFET transistors are used, each one capable of delivering up to 20.7 A at 25° C or 13.1 A at 100° C in continuous mode, or up to 62.1 A in pulse mode at 25° C, with an RDS(on) of 190 mΩ. These are the same components used on Free Style 85PLUS 650 W.

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 11: Switching transistors.

This power supply uses the omnipresent CM6800 PFC/PWM combo controller.

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 12: PFC/PWM controller.

So far Free Earth 85PLUS 650 W is identical to Free Style 85PLUS 650 W. Let’s see if anything changed on the secondary.

Secondary Analysis

Amacrox Free Earth 85PLUS 650 W uses eight Schottky rectifiers on the secondary.

The maximum theoretical current each line can deliver is given by the formula I / (1 - D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode. Just as an exercise, we can assume a typical duty cycle of 30%.

The +12 V output is produced by four SBR40U60CT Schottky rectifiers (40 A, 20 A per internal diode at 100° C, 0.60 V maximum voltage drop) connected in parallel, giving us a maximum theoretical current of 114 A or 1,371 W for the +12 V output. Talk about overspecification! These are the same components used on Free Style 85PLUS 650 W.

The +5 V output is produced by two SBR30U30CT Schottky rectifiers (30 A, 15 A per internal diode at 140° C, maximum forward voltage of 0.54 V) connected in parallel. This gives us a maximum theoretical current of 43 A or 214 W for the +5 V output. These are the same components used on Free Style 85PLUS 650 W.

The +3.3 V output is produced by another two SBR30U30CT Schottky rectifiers, giving us a maximum theoretical current of 43 A or 141 W for the +3.3 V output. These are the same components used  on Free Style 85PLUS 650 W.

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 13: Rectifiers.

The secondary is monitored by two integrated circuits, a PS223, which supports OCP (over current protection), OVP (over voltage protection), UVP (under voltage protection) and OTP (over temperature protection, not implemented on this power supply), and a WT7518, which provides four individual over current sensors.

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 14: Monitoring circuit.

Electrolytic capacitors from the secondary are from Teapo and labeled at 105° C, as usual.

So Free Earth 85PLUS 650 W and Free Style 85PLUS 650 W are identical units, the only difference between them being the presence of a modular cabling system on the Free Style 85PLUS version.

Power Distribution

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

Amacrox Free Earth 85PLUS 650 W power supply
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Figure 15: Power supply label.

This power supply has four virtual rails (this unit has really four OCP circuits, as mentioned in the previous page), distributed like this:

This distribution is perfect, as it separates the CPU (ATX12V/EPS12V), the video card and all the rest on different rails.

Now let’s see if this power supply can really deliver 650 W.

Load Tests (Sample 1)

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

First we tested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching how the reviewed unit behaved under each load. In the table below we list the load patterns we used and the results for each load.

If you add all the power listed for each test, you may find a different value than what is posted under “Total” below. Since each output can vary slightly (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. On 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 and during all tests the +12VA input was connected to the power supply +12V1 and +12V3 rails while the +12VB input was connected to the power supply +12V2 rail.

Input

Test 1

Test 2

Test 3

Test 4

Test 5

+12VA

5 A (60 W)

10 A (120 W)

15 A (180 W)

20 A (240 W)

26 A (312 W)

+12VB

5 A (60 W)

10 A (120 W)

14 A (168 W)

20 A (240 W)

23 A (276 W)

+5V

1 A (5 W)

2 A (10 W)

4 A (20 W)

6 A (30 W)

8 A (40 W)

+3.3 V

1 A (3.3 W)

2 A (6.6 W)

4 A (13.2 W)

6 A (19.8 W)

8 A (26.4 W)

+5VSB

1 A (5 W)

1 A (5 W)

1.5 A (7.5 W)

2 A (10 W)

2.5 A (12.5 W)

-12 V

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

Total

137.4 W

262.8 W

386.7 W

531.7 W

654.0 W

% Max Load

21.1%

40.4%

59.5%

81.8%

100.6%

Room Temp.

41.3° C

41.9° C

43.5° C

43.9° C

30.3° C

PSU Temp.

46.1° C

46.6° C

46.6° C

49.2° C

32.4° C

Voltage Stability

Pass

Pass

Pass

Pass

Pass

Ripple and Noise

Pass

Pass

Pass

Pass

Pass

AC Power

162.0 W

305.5 W

452.5 W

634.0 W

797.0 W

Efficiency

84.8%

86.0%

85.5%

83.9%

82.1%

AC Voltage

115.8 V

114.7 V

112.8 V

109.3 V

105.6 V

Power Factor

0.971

0.986

0.992

0.996

0.996

Final Result

Pass

Pass

Pass

Pass

Fail

For some reason the reviewed unit couldn’t deliver its labeled power at high temperatures. When the unit was hot with us pulling 650 W from it, it shut down. At a room temperature of only 30° C, it would deliver 650 W for only 45 seconds.

Because of this problem, we requested a second sample from Amacrox, so we could re-test this power supply. The results for this second sample are published on next page.

We also saw over current protection (OCP) kicking in during test five, which is good. Usually with 650 W power supplies we try to pull 24.5 A from +12VA and 24.5 A from +12VB during our 650 W test, but pulling 24 A or more from +12VB (which was connected to the power supply +12V2 rail) the unit wouldn’t turn on, so we had to configure +12VB with 23 A and +12V1 with 26 A.

Voltages were always within their required range and ripple and noise were always low. Below you can see noise and ripple levels during test five.

Amacrox Free Earth 85PLUS 650 W Power Supply
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Figure 16: +12VA input from load tester during test five at 654.0 W (43.2 mV).

Amacrox Free Earth 85PLUS 650 W Power Supply
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Figure 17: +12VB input from load tester during test five at 654.0 W (38.6 mV).

Amacrox Free Earth 85PLUS 650 W Power Supply
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Figure 18: +5V rail during test five at 654.0 W (21.4 mV).

Amacrox Free Earth 85PLUS 650 W Power Supply
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Figure 19: +3.3 V rail during test five at 654.0 W (25.2 mV).

Load Tests (Sample 2)

Since the sample we received from Amacrox presented the problems described in the previous page, we requested a second sample from them. The results for this new sample were quite different during test five: we could pull 650 W continuously and with the current configuration we wanted. 

Input

Test 1

Test 2

Test 3

Test 4

Test 5

+12VA

5 A (60 W)

10 A (120 W)

15 A (180 W)

20 A (240 W)

24.5 A (294 W)

+12VB

5 A (60 W)

10 A (120 W)

14 A (168 W)

20 A (240 W)

24.5 A (294 W)

+5V

1 A (5 W)

2 A (10 W)

4 A (20 W)

6 A (30 W)

8 A (40 W)

+3.3 V

1 A (3.3 W)

2 A (6.6 W)

4 A (13.2 W)

6 A (19.8 W)

8 A (26.4 W)

+5VSB

1 A (5 W)

1 A (5 W)

1.5 A (7.5 W)

2 A (10 W)

2.5 A (12.5 W)

-12 V

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

Total

136.8 W

261.7 W

384.9 W

529.1 W

648.3 W

% Max Load

21.0%

40.3%

59.2%

81.4%

99.7%

Room Temp.

44.7° C

43.8° C

44.0° C

45.1° C

47.5° C

PSU Temp.

49.7° C

49.7° C

49.9° C

51.0° C

53.6° C

Voltage Stability

Pass

Pass

Pass

Pass

Pass

Ripple and Noise

Pass

Pass

Pass

Pass

Pass

AC Power

162.3 W

304.2 W

450.6 W

632.0 W

793.0 W

Efficiency

84.3%

86.0%

85.4%

83.7%

81.8%

AC Voltage

115.4 V

113.8 V

112.4 V

110.5 V

108.3 V

Power Factor

0.977

0.989

0.993

0.996

0.998

Final Result

Pass

Pass

Pass

Pass

Pass

This time Amacrox Free Earth 85PLUS 650 W passed with flying colors. Efficiency was always above 81.8%, peaking 86%.

Voltages were always inside the allowed range.

Noise and ripple, which were already low on the first sample, decreased a lot on the second sample, as you can see below. The maximum allowed is 120 mV on +12 V and 50 mV on +5 V and +3.3 V. All these numbers are peak-to-peak figures.

Amacrox Free Earth 85PLUS 650 W
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Figure 20: +12VA input from load tester during test five at 648.3 W (28.6 mV).

Amacrox Free Earth 85PLUS 650 W
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Figure 21: +12VB input from load tester during test five at 648.3 W (32.2 mV).

Amacrox Free Earth 85PLUS 650 W
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Figure 22: +5V rail during test five at 648.3 W (13.6 mV).

Amacrox Free Earth 85PLUS 650 W
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Figure 23: +3.3 V rail during test five at 648.3 W (26.4 mV).

Now let’s see if we can pull more than 650 W from this unit.

Overload Tests

Below you can see the maximum we could pull from the second sample from this power supply with it still working correctly. If we tried to pull more power the unit would shut down, showing that one of the power supply protections was entering in action.

Input

Overload Test

+12VA

27 A (324 W)

+12VB

27 A (324 W)

+5V

10 A (50 W)

+3.3 V

10 A (33 W)

+5VSB

2.5 A (12.5 W)

-12 V

0.5 A (6 W)

Total

721.8 W

% Max Load

111.0%

Room Temp.

44.8° C

PSU Temp.

50.5° C

AC Power

898.0 W

Efficiency

80.4%

AC Voltage

107.6 V

Power Factor

0.998

Main Specifications

Amacrox Free Earth 85PLUS 650 W power supply specs include:

Conclusions

Amacrox Free Earth 85PLUS 650 W is a version of Free Style 85PLUS 650 W without a modular cabling system. During our tests it provided high efficiency between 81.8% and 86.0%, voltages within the allowed range and very low ripple and noise levels.

The first sample we've got from this unit couldn’t deliver its labeled power at high temperatures for long: after a few seconds the power supply shut down.

We requested a second sample from the manufacturer and this second sample worked terrifically well, not showing any of the symptoms of the first sample we tested. Since this unit should arrive on the market at a very affordable price and the manufacturer promised us that the products that will reach the market are the ones based on the second sample, we are upgrading our recommendation for this unit, giving it our Golden Award.

By the way, internally both samples were absolutely identical, so we either got a defective sample at first or the manufacturer changed the configuration of the protections.

The only drawback we saw on this unit is its reduced number of SATA power connectors. Also the SATA and peripheral power connectors are too close to each other, they should be more spaced out.

Originally at http://www.hardwaresecrets.com/article/Amacrox-Free-Earth-85PLUS-650-W-Power-Supply-Review/941


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