Introduction
This is the fifth power supply from Huntkey that we reviewed and so far most power supplies from this manufacturer have the bad reputation of exploding when you try to pull their labeled power. Will this also happen with Green Star 350 W? Let’s see.
By the way, the only power supply from Huntkey we tested and didn’t explode was Titan 650 W (sold in the US as Rocketfish 700 W), which uses a completely different project.
Funny enough Huntkey removed all Green Star models from their website, but they continue to be sold, especially in developing countries.
If you paid attention you saw that the part number used on this model is a little bit different from other Huntkey power supplies we've already tested (HG vs. SG). Digging a little bit further on Huntkey's website we discovered that these two letters indicate the size of the fan: HG for 120 mm and SG for 140 mm.
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Figure 1: Huntkey Green Star 350 W (LW-6350HG).
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Figure 2: Huntkey Green Star 350 W (LW-6350HG).
This power supply is very small, being 5 ½” (14 cm) deep, features a 120-mm fan on its bottom and doesn’t have active PFC circuit, so Huntkey can’t sell this product in Europe. On Figure 1 you can see that it has a voltage selection switch, feature usually present on models without this circuit.
The main motherboard cable, which uses a 20/24-pin connector, is the only one using a nylon protection, which doesn’t come from inside the power supply housing. Green Star 350 W also comes with one ATX12V cable.
Green Star 350 W comes with one cable with three standard peripheral power plugs, one cable with two standard peripheral power plugs and one floppy disk drive power plug and one cable with two SATA power connectors.
The number of power plugs is simply not enough. With only two SATA power plugs you will need to use an adaptor to install more than one hard disk drive (assuming that you have a SATA optical drive) and this unit doesn’t come with any auxiliary power connectors for video cards! So you will also need to use adaptors to convert peripheral power plugs into video card auxiliary power plugs.
The peripheral and SATA cables use 20 AWG wires (i.e. thinner than we’d like to see), while the wires on the ATX12V cable and on the main motherboard cable are 18 AWG.
Let’s now take an in-depth look inside this power supply.
A Look Inside Green Star 350 W (LW-6350HG)
We decided to disassemble this power supply to see how it looks like inside, what is the design used and what components are used. Please read our Anatomy of Switching Power Supplies tutorial to understand how a power supply works inside and to compare this power supply to others.
The first thing we noticed is that Green Star 350 W uses a different internal design compared to other Huntkey units we’ve reviewed to date. Let’s see if this different design will allow it to deliver its labeled power.
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Figure 3: Overall look.
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Figure 4: Overall look.
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Figure 5: Overall look.
Transient Filtering Stage
As we mentioned on other articles and reviews, the first place we like to take a look when opening a power supply to have a hint about its quality is its filtering stage. The recommend 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 than that, usually removing the MOV and the first coil.
This power supply uses an adequate transient filtering stage, with two extra Y capacitors.
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Figure 6: Transient filtering stage (part 1).
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Figure 7: Transient filtering stage (part 2).
Now let’s have a more detailed discussion on the components used on LW-6350HG.
Primary Analysis
Let’s now take an in-depth look on the primary stage from Green Star 350 W (LW-6350HG). For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses one T15XB80 rectifying bridge on its primary, capable of delivering up to 15 A at 100º C if a heatsink is used – which is not the case – but only 3.2 A at 25º C if a heatsink is not used. The difference is outrageous and Huntkey should have added a heatsink on this component. The current limit for this component is simply too low (3.2 A). At 115 V this unit would be able to pull only up to 368 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver only up to 294 W without burning this component. Of course we are only talking about this component and the real limit will depend on all other components from the power supply. This is the same component used on Huntkey V-Power 550 W and Huntkey Titan 650 W (Rocketfish 700 W), but at least Titan 650 W had a heatsink attached to it, which increased the current limit.
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Figure 8: Rectifying bridge.
LW-6350HG uses two FJP13009 power NPN transistors on its switching section using the half-bridge design, supporting up to 12 A in continuous mode or 24 A in pulse mode, both currents measured at 25º C (unfortunately the manufacturer from these transistors do not say how much they can deliver at higher temperatures). These are the same transistors used on Huntkey Green Star 400 W (Dynex 400 W) and Huntkey Green Star 450 W. Even though the transistors have the same specs on these other two power supplies they use a bigger packaging (called TO-247, while the packaging you can see on Figure 9 is called TO-220), which allow them to dissipate heat better.
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Figure 9: The two switching transistors.
The primary is controlled by an AZ7500B PWM controller, which is physically located on the secondary section of the power supply.
The two big electrolytic capacitors from the primary are from Teapo (a Taiwanese company) and rated at 85º C.
Secondary Analysis
Huntkey LW-3550HG has four Schottky rectifiers on its secondary, two for the +12 V output, one for the +5 V output and one for the +3.3 V output.
Since this power supply uses a half-bridge configuration to calculate the maximum theoretical current each output can deliver is easy: all we need to do is to add the maximum current supported by all diodes.
The +12 V output is produced by two BYQ30E200 Schottky rectifiers connected in parallel, each one capable of handling up to 16 A at 104º C (8 A per internal diode). So the maximum theoretical current the +12 V output from this power supply can deliver is of 32 A or 384 W. Of course this math is just an exercise and the actual limit depends on several other factors. These rectifiers have a lower current limit compared to the ones used on the 400 W and 450 W Green Star models.
The +5 V output is produced by one S30D40C Schottky rectifier, which is capable of handling up to 30 A at 80º C (15 A per internal diode). So the maximum theoretical current the +5 V output from this power supply can deliver is of 30 A at 80º C or 150 W. This is the same component used on the 400 W and 450 W models.
The +3.3 V output is produced by one STPS3045CT Schottky rectifiers, which is capable of delivering up to 30 A at 155º C (15 A per internal diode). So the maximum theoretical current the +3.3 V output from this power supply can deliver is of 30 A at 155º C or 99 W. The 400 W and 450 W models use a different component with a higher dissipation area (TO-247 packaging instead of TO-220 as used on this power supply) but with the same current limits.
It is always good to remember that the real current/power limit for each output will depend on other factors, like the coils and the width of the printed circuit board traces.
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Figure 10: +5 V rectifier and +12 V rectifier.
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Figure 11: +12 V rectifier and +3.3 V rectifier.
On Figure 12 you can see the thermal sensor available below the secondary heatsink, in charge of changing the fan speed according to the power supply internal temperature.
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Figure 12: Thermal sensor.
Instead of using a monitoring integrated circuit, the protections from this power supply are implemented discretely, using two LM339 voltage comparators. On Figure 13 you can also see the AZ7500B PWM controller, which is in charge of controlling the switching transistors.
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Figure 13: Monitoring circuit.
The electrolytic capacitors from the secondary are from Teapo and Fcon and labeled at 105º C, as usual.
Power Distribution
On Figure 14 you can see this power supply label containing all its power specs.
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Figure 14: Power supply label.
This power supply features two +12 V virtual rails distributed like this:
- +12V1 (solid yellow wire): All cables but the ATX12V.
- +12V2 (yellow with black stripe wire): ATX12V connector.
Let’s now see if this power supply can really deliver 350 W.
Load Tests
We made 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 loads patterns, trying to pull around 20%, 40%, 60%, 80% and 100% of its labeled maximum capacity (under “% Max Load” we list the actual percentage that was used), watching how the reviewed unit behaved under each load. On the table below we list the load patterns we used and the results for each load.
If you add all the powers listed for each test you may find a value different from what posted under “Total” below. Since each output can have a slight variation (e.g. +5 V output working at 5.10 V) the actual total amount of power being delivered is slightly different from the calculated value. On “Total” row we are using the real amount of power being delivered, as measured by our load tester.
+12V1 and +12V2 are the two independent +12V inputs from our load tester and during out tests the +12V1 input was connected to the power supply +12V1 (main motherboard cable and peripheral power connectors), while the +12V2 input was connected to the power supply +12V2 rail (ATX12V connector). Thus on this review+12V1 and +12V2 really represent the power supply rails with the same name.
Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
+12V1 | 2 A (24 W) | 4.5 A (54 W) | 7 A (84 W) | 9 A (108 W) | 11 A (132 W) |
+12V2 | 2 A (24 W) | 4.5 A (54 W) | 7 A (84 W) | 9 A (108 W) | 11 A (132 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 A (5 W) | 1.5 A (7.5 W) | 2 A (10 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 | 67.3 W | 135.5 W | 212.1 W | 279.5 W | Fail |
% Max Load | 19.2% | 38.7% | 60.6% | 79.9% | Fail |
Room Temp. | 44.2º C | 43.3º C | 45.1º C | 43.4º C | 43.4º C |
PSU Temp. | 48.7º C | 47.6º C | 48.8º C | 49.1º C | 49.1º C |
Voltage Stability | Pass | Pass | Pass | Pass | Fail |
Ripple and Noise | Pass | Pass | Pass | Pass | Fail |
AC Power | 83 W | 161 W | 254 W | 344 W | Fail |
Efficiency | 80.7% | 84.2% | 83.5% | 81.3% | Fail |
Final Result | Pass | Pass | Pass | Pass | Fail |
This power supply exploded when we tried to pull 350 W from it (test number five). On the next page we posted the video of the explosion and detailed information about it.
If you pull up to 80% of this power supply labeled capacity (i.e. up to 280 W) it works very nice, presenting efficiency above 80% all the time, with a decent efficiency when you pull between 40% and 60% from the labeled power (between 140 W and 210 W).
Voltage was always between 3% of their nominal value, which is always good to see, including the -12 V output, which is usually more distant than its nominal value.
Ripple and noise level was the highlight from this product. Noise at +12 V achieved a maximum of 34 mV (right before the power supply explosion), noise at +5 V achieved a maximum of 17.6 mV and noise at +3.3 V achieved a maximum of 11 mV. Just to remind, the maximum admissible is 120 mV for +12V and 50 mV for +5 V and +3.3 V. All these values are peak-to-peak figures.
The Explosion
Below you can watch the video from test number five with Huntkey LW-6350HG. The knob on the left side of the load tester that we rotate from time to time is in charge of switching which output we want to see on our oscilloscope for the ripple and noise testing. This has no influence on the test (we are saying this because the explosion occurred right after we rotated the knob, but this was just a coincidence). You will see the explosion after around 2 minutes.
What exploded were the two switching transistors. When the power supply explodes this means that the primary side is under dimensioned. When the secondary side is under dimensioned the power supply dies silently, because when a rectifier burns the short-circuit protection enters immediately in action shutting down the power supply.
As you can see on the video, the explosion wasn’t big as the one we’ve see with V-Power 550 W and the transistors didn’t crack like happened with this other power supply, but they were shorted.
Main Features
Huntkey Green Star 350 W (LW-6350HG) power supply main specs include:
- ATX12V 2.2
- Nominal labeled power: 350 W
- Measured maximum power: 280 W at 43.4º C.
- Labeled efficiency: N/A.
- Measured efficiency: Between 80.7% and 84.2% at 115 V.
- Active PFC: No.
- Modular Cabling System: No.
- Motherboard Power Connectors: One 20/24-pin connector and one ATX12V connector.
- Video Card Power Connectors: None.
- Peripheral Power Connectors: Five in two cables.
- Floppy Disk Drive Power Connectors: One.
- SATA Power Connectors: Two.
- Protections: Over voltage (OVP, not tested) and short-circuit (SCP, tested and working).
- Warranty: N/A.
- More Information: N/A.
- Average price in the US: We couldn’t find this product being sold in the USA.
Conclusions
Like other members from Green Star family, LW-6350HG exploded when we tried to pull its labeled power.
So far we’ve tested five power supply models from Huntkey and only one, Titan 650 W (a.k.a. Rocketfish 700 W) didn’t explode.
Even if it didn’t explode it would continue to be a bad product, as it has only two SATA power connectors and no auxiliary power connectors for video cards.
And even if it was labeled with its correct capacity (280 W according to our tests) we wouldn’t recommend it, as it would explode if you overload it and not shut down as good power supplies do.
As usual, the manufacturer assumes that the user won’t pull anywhere near the power supply maximum power. But if we are buying a 350 W power supply we want it to be able to deliver 350 W. Otherwise it is false advertisement!
With so many bad power supply reviews being done around the web simply because most websites don’t have the correct knowledge in electronics and don’t have the correct equipment to test power supplies, we are glad to expose this kind of scam.
Originally at http://www.hardwaresecrets.com/article/672
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