Eps power supplies: ATX, EPS, and 80 PLUS Specifications

– EPS Explained

Entry-Level Power Supply Specification, otherwise known as EPS, is a PSU standard that provides critical-based applications and systems with a stable environment while cranking up their power.

EPS power supplies are often designed with an eight-pin 12V connector and a 24-pin motherboard power connector.

In theory, EPS power supplies are compatible with ATX12V and ATX motherboards found in offices and homes.

However, there may be mechanical problems when you connect an EPS12V PSU to an ATX board, especially if the board is from an older generation.

You risk the board’s connector overhanging the socket. To overcome this issue, many PSU vendors utilize connectors in areas where possible to unclip the extra sections. There is no -5V rail for the EPS standard.

– Using Eight-pin EPS + 12V Power Cable

The eight-pin EPS12V power cable was originally designed for workstations so they could provide multiple CPUs with 12 volts of power. However, thanks to the advancement in technology, many CPUs now require more 12-volt power, thereby making the eight-pin 12-volt cable the ideal choice instead of the four-pin 12V cable. The eight-pin EPS12V comes in two variants depending on the power supply.

There’s the variant where only one 12-volt rail is included in all eight pins and a different variant where two 12-volt rails come in four pins apiece.

Thanks to the fact that the eight-pin 12V cable is polarized, you can connect it directly to your motherboard’s 8-pin connector.

– EPS12V Pinout Shapes and Arrangement

Of these eight pins, four pins often have a square shape while the remaining four have rounded corners. Your motherboard connector should also have the same shapes and arrangement so the cable can fit in correctly.

While these correct shapes and arrangements are usually the case, you can plug an incorrect arrangement into the connector with a little bit of force, though it’s not guaranteed to work.

The eight-pin cable comes with enough pins to make sure you don’t connect it to your motherboard the wrong way.

You should make sure the square and rounded patterns match the exact same patterns on your motherboard.

While some of your motherboard connectors, such as the 24-pin main power connector and the 20-pin main power connector, may have the same type of patterns as the EPS12V header, the eight-pin EPS cable should be plugged in its correct socket to make sure none of your components get fried.

– Connecting Eight-pin EPS12V Cable to a Four-Pin Motherboard Connector

You can also connect the eight-pin 12 volts cable to a four-pin 12-volt motherboard connector. In this situation, only four of the pins on your eight-pin cable will fit into the four-pin MOBO connector, while the remaining four pins that are unconnected will hang off the end of the connector.

Note that you can only fit one end of the eight-pin cable into the four-pin connector on your motherboard.

There’s usually a component that helps you block off the area where the remaining four-pin will hang off.

And there are cases where the plastic end of the four-pin connector on your motherboard would be just too thick, so you won’t need the component to sit between the pins of the eight-pin cable.

– Using 4-pin Peripheral Adapters

If you’re unable to get an eight-pin EPS cable, you can use a four-pin peripheral adapter instead.

This adapter helps you convert two four-pin peripheral power cables into an eight-pin 12V cable.

However, if you choose to use this adapter, make sure to plug the four-pin peripheral connectors into different power supply cables.

If you connect both four-pin peripheral power cables into the same PSU cable, you’ll be pulling the power needed for an entire 8-pin 12 volts connector through one 18-gauge wire.

While there may be no immediate effects, it may not be the safest method in the long run.

– EPS12V and PCIe Connectors

While the EPS connector is designed to provide the motherboard’s CPU socket with power, the PCI Express connector is built to provide power to the GPU.

Make sure you never try to connect an eight-pin EPS cable to a video card’s eight-pin PCIe power connector.

While the cables for both components may look very similar, they don’t work well with each other. Many people get both cables confused and end up frying their PC components.

The eight-pin PCIe cable is often labeled to make sure that it is not mistaken for the eight-pin EPS cables.

The PCIe cables usually come with a label that says “PCI-E” on their connectors.

If you’re unable to find any label on the connector, you can use the color-coded wires to tell whether or not they are EPS cables or PCIe cables.

A typical eight-pin EPS cable features yellow wires on the side that has the connector clip, while an eight-pin PCI Express cable would have black wires on the side with the connector clip.

– EPS12V vs PCIe Connection

Besides their appearance, the way both cables are keyed into their connectors is also different, so it would be difficult for you to plug a PCIe cable into an EPS connector or vice versa, except you force the cables. The square and rounded-off connectors of both cables and motherboard connectors are designed so you won’t be able to connect one to the other.

While forcing the cables may allow you to plug the wrong cable into the wrong connector, it’s important to note that both the PCIe and EPS cables and connectors are not compatible with each other and can cause serious damage to your rig.

Both power connectors may offer 12 volts of power, but the row of pins close to the clip of the PCI express connector is ground, while the bottom offers the 12 volts of power.

On the EPS connector, the arrangement is the opposite, with the bottom being ground and the clip side being 12V.

– Using the ATX12V

Before the introduction of the newer 12V power cable, only one 12-volt line was used to provide power to the motherboard.

With the advent of a newer 12 volts cable, there were now two power cables, which allowed more load to be moved to 12 volts.

Most of the power coming from the 12V connector is often used to power the CPU. However, some motherboards dedicate the power to other things as well.

Having the new 12V connector on a motherboard meant that your motherboard was an ATX12V motherboard.

If your motherboard is designed with an ATX12V connector, then you’ll need to plug an ATX power cable into the connector, or else your processor would get no power. There was one exception, however.

When the connector was newly made, some motherboards featured an alternative in the form of a socket that allowed you to plug in a four-pin peripheral power cable.

This solution allowed and still allows people with older power supplies that didn’t and don’t have the four-pin 12-volt cable to power their components.

– ATX12V Shapes and Arrangement

The four-pin 12-volt cable comes in a polarized design, so you can’t plug it into any other connector except a four-pin motherboard connector. There are two pins with rounded corners and two pins with a square shape.

The motherboard connectors they connect to also come with the same design and arrangement, so you can only connect the cable correctly as long as you don’t forcefully connect it the wrong way.

While the square and rounded pattern arrangement on the ATX12V pins may match various arrangements on other motherboard connectors, such as the 24-pin main power connector and the 20-pin main power connector.

It’s recommended that you only plug it into the rightful four-pin connector on your motherboard if you don’t want to fry your components.

You can also use a four-pin peripheral adapter to connect a four-pin 12 volts cable to your power supply if your PSU doesn’t have a four-pin 12V cable.

EPS12V vs ATX12V

While it’s possible to plug the four-pin 12 volts of an ATX12V cable into an eight-pin EPS motherboard, there’s no guarantee that the former would work.

If one 12-volt rail is what the motherboard is designed to take, then the four-pin 12-volt cable of an ATX12V may work.

However, if the motherboard is supposed to take up two 12-volt rails, then the four-pin cable won’t work.

Keep in mind that many double CPU motherboards need one 12 volt rail per processor for them to function properly.

Even if the motherboard ends up working with the four-pin 12-volt cable, you’ll only be providing half the current-carrying capacity the eight-pin EPS cable is capable of providing.

The lack of power can cause your motherboard’s connector and the four-pin cable to overheat, leading to melted or scorched connectors.

Motherboards with eight-pin EPS connectors expect a significant amount of power. You’ll be taking a great risk by plugging in a four-pin cable.

Besides the fact that the four-pin cable won’t supply enough power, it can only sit on one end of the eight-pin connector.

And sometimes, the pin arrangement won’t align with how the connector pins are arranged.

Conclusion

With this post, you’ve learned EPS12V meaning as well as the difference between EPS modular power and other power supply units.

Here’s a summary to make sure you have all you need:

• EPS12V comes with eight-pin connectors that require an eight-pin cable with the same pin arrangement
• You cannot connect an EPS cable into a PCIe connector or vice versa
• Connecting an ATX12V cable into an EPS12V motherboard connector isn’t recommended and may not work
• ATX12V features a four-pin connector that requires a four-pin cable with the same pin arrangement

Always make sure you plug in the right power supply cable into the right motherboard connector to avoid damaging your PC components.

Remember that the EPS12V doesn’t have a label, while the PCI Express tends to have a label depicting that it’s a PCIe connector or cable.

EPS-45S-48

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Specifications

Output:
DC voltage	48V
Rated current	0. 94A
Rated power	45.1W
Output noise level	300mVp-p
Voltage adjustment range	45. 6-52.8V
Voltage tolerance	±1.0%
Mains output voltage instability	±0.5%
Load instability	±0. 5%
Settling time, rise time	500ms, 30ms / 230VAC 500ms, 30ms / 115VAC at full load
retention time	30ms / 230VAC 12ms / 115VAC at full load

Input:
Input voltage range	85-264VAC 120-370VDC
Frequency range	47~63Hz
efficiency	9one%
Alternating current	1. 2A/115VAC 1A/230VAC
Withstand voltage	l/P-0/P:3KVAC l/P-FG:2KVAC O/P-FG:0.5KVAC
Starting current	OLD STAR 30A/115VAC 60A/230VAC

Ambient conditions Wednesdays:
Operating temperature range	-30 ~ +70°C
Operating Humidity	20 ~ 90% RH non-condensing
Temperature coefficient	±0. 03%/°C (0 ~ 45°C)
Vibration	10 — 500Hz, 2G 10min./1 cycle, period for60min. each along X, Y, Zaxes
Temperature and humidity conditions of storage	-40 ~ +85°C, 10 ~ 95% RH

Other:
MTBF (Mean Time Between Failures)	726. 2Khrs min. MIL-HDBK-217F (25℃)
dimensions	76.2*50.8*24mm (L*W*H)
Package	0.11Kg; 120pcs/14.2Kg/0.97CUFT

EPS-35-5 for 1 336.

32 ₽ in stock manufactured by MEAN WELL

You can buy a pulse power supply unit 30W EPS-35-5 from the manufacturer MEAN WELL wholesale and retail with delivery throughout Russia, Kazakhstan, the Republic of Belarus and Ukraine, as well as to other countries of the Customs Union (Armenia, Kyrgyzstan, etc.).

In order to buy this product at the base price at retail, put it in the shopping cart and place an order following the detailed instructions. Please note that depending on the increase in the volume of products, the retail price will be recalculated automatically. The wholesale price for a switching power supply 30W 120-370Vdc 85-264Vac EPS-35-5 is set only after sending a commercial request to e-mail: [email protected] or [email protected]

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Open power supplies of almost all well-known world brands are represented by our company. If the product you are interested in was not found on our website, contact the technical support service or your manager and our engineers will select analogues for your equipment. Thus, it is possible to reduce the cost of equipment maintenance by up to 20% and optimize your costs. The SUPPLY24.ONLINE company takes full responsibility for the correct selection of the analogue. Our company offers only a reasonable approach, if, according to a number of criteria, the requested product does not imply a replacement for an analogue, we do not offer a replacement.
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Attention!

• Characteristics, appearance and complete set of goods can be changed by the manufacturer without notice.
• Product image is for illustration purposes only and is subject to change without notice.
• See Specifications tab for exact specification.
• If you need to install software and use third-party accessories, please check their compatibility with the device by studying the documentation on the manufacturer’s website MEAN WELL
• It is forbidden to violate the factory settings and adjustments without the involvement of specialists from certified service centers.

Features

Manufacturer

MEAN WELL

Dimensions

see

Installation

Open execution

Power

EPS-35

Operating temperature

-30 . .. 70 ° C

power voltage

85 … 264V AC,

Related goods

BVHH- 21t-P1.1,

Outpatus current

Protection

from KZ,

Outputs

Outpatient voltage

4.75 … 5.5V DC,

External dimensions

76.2×50.8x24mm

Power supply type

pulsed

Type of power supply

without housing

Electrical connection

plug with a pitch of 3.96 mm

DELIVERY IN RUSSIA

goods in a warehouse in the Russian Federation. In some cases, with a large remoteness of your region, the delivery time may be increased.

• A complete list of cities to which delivery is carried out, see below.

DELIVERY TO THE COUNTRIES OF THE CUSTOMS UNION

Delivery is carried out within 3-5 days from the moment the funds are credited to the account of the company to the following countries.

• Kazakhstan
• Armenia
• Belarus
• Kyrgyzstan

Please note that the terms of delivery of goods directly depend on the availability of goods in the Russian warehouse of the company.

If the selected items are located in one of the external warehouses in Europe or the USA, then the delivery time of the goods can be up to 3-4 weeks. To avoid misunderstandings, we recommend that you clarify the current delivery time in the logistics department or with the company manager.

In this case, as a rule, 90% of orders are delivered to customers within the first 2 weeks.

If any part of the goods from your order is not in stock, we will ship all available goods, and after receiving the rest of the order from the external warehouse, we will send it to you at our company’s expense.

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Mean Well EPS-65S-24 power supply, third of six. Overview and test of the power supply for 24 Volts. Power supply 24V Mean Well

$9.97

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And so, today I have in my hands the third power supply and six sent to me by one of my readers. In this case, we will talk about a relatively compact and inexpensive power supply, I would even say that this unit belongs to the budget series, since to some extent it is noticeably simpler than the previous ones. But simpler does not always mean worse, and I will try to show and explain all this in the course of the review.
In general, who are interested in branded power supplies, I think they will find something new for themselves.

In fairness, this review is the third only conditionally, since before that I had already reviewed the power supply from this company, but since there are reviews from one batch of six pieces, the review is called — the third of six 🙂
More I would like to thank Vladimir, without whom this series would not have been possible. Anyway, I somehow thought that there are a lot of reviews of «Chinese» power supplies, but there is a failure with branded ones, but they are also of interest, not only for the quality of work, but also for circuitry solutions different from Chinese «comrades». That’s why I think that reviews of branded power supplies are also very useful and I’m glad that I can fill this gap.

The power supply was bought on Taobao, but if the previous two were bought from one seller, then the one being reviewed is already from another.
The packaging is simple, of course worse than a cardboard box, but better than bubble wrap.

Externally, the power supply looks great, no damage. However, the manufacturer fills its power supplies with sealant in such a way that nothing moves in it at all and it is also very problematic to break off anything.

High efficiency, up to 91% depending on the output voltage, as well as power consumption without load, only 0.1 watts.
In addition, there is protection against overload, short circuit and overvoltage.
The power supply is designed for passive cooling and operation in the temperature range from -30 to +70.

Full specifications are available on the datasheet, but I’ll just quote some key pages from it.
Judging by the description, the power supply is available with seven output voltage options, but I will review the 24 Volt version.
You can also notice that the power supply works out the declared power only in the version with voltages of 12 volts and higher. At lower voltages, the power can even be two times lower than the declared one, for example, for the 3.3 Volt version.

This power supply is a variation of the EPS-65 version, which has a slightly different design.

The power supply is made in the form factor 2×3 inches, or about 50x75mm and belongs to the compact series.

For comparison, I put a pair of Minvel power supplies with a power of 100 and 120 watts on the left, and on the left a Chinese version with a declared power of 72-96 watts, the so-called «folk».

Dimensional drawing of power supplies of this series. It can be seen that the power supply is very compact, for example, the total height is only 27mm.

But let’s move on to a more detailed examination.
At the input there is an almost full-fledged filter, perhaps only a protective varistor is missing.

As expected, there is a thermistor to limit the inrush current and an X type capacitor. There are two two-winding chokes, a small one is turned on immediately after the power input, a large one is between the X capacitor and the diode bridge.
The input capacitor has a specification sticker. The capacitance of the input capacitor is 82 microfarads, taking into account the output power of 65 watts and the full range of input voltage, I would say that this is not enough.

I thought I saw a lot of different power supplies, but they still never cease to amaze me. In this case, I came across a very unusual choke. The fact is that it is wound not with an ordinary wire, but with a thin tire, a very unusual solution.
No, of course I have seen transformers whose windings are wound with a busbar or thick foil, but here the busbar is laid perpendicular to the frame. ..

the power of the power supply.
2. Output diode assembly MBR20200, 200 Volt 20 Amp, which is very good for an output current of 2.7 Ampere. To the right you can see a place for another diode assembly, it is presumably installed in low-voltage versions of power supplies.
3. There is also a pair of feedback optocouplers, one is responsible for voltage stabilization, the other for overvoltage protection.
4. Another unusual thing I saw in this block. Interwinding capacitors are not one or even two, but four.
The bottom pair is included as standard, between the minus of the input filter capacitor and the common output wire. But the second pair is connected at one end between the noise suppression chokes, while the other side also goes to the common output wire.
The solution is somewhat extraordinary, I have not seen this before.

Above, I wrote that a 13N60M2 transistor was used. By and large, the most common high-voltage transistor, if not for what case it comes in. The most common isolated TO-220 is installed here, but it turns out that there is also a shortened version, which I also did not come across before.

And here the designers surprised me once again, but this time not very pleasantly. The fact is that a diode assembly is installed at the output of the power supply and it is quite logical that it is installed on a radiator. Since the power supply has modifications with a large output current, the designers have installed a very decent radiator, which is good.
But the fact that it not only goes to the «hot» side, but also has insulation only in the form of adhesive tape, surprised me greatly, especially considering the scrupulous attitude of this company to the safety of its products.
The radiator is fixed with a special sealant and installed very rigidly, but in my opinion this solution is closer to «Chinese» crafts than to a proprietary device.

1. After the diode assembly, there is a pair of 390 microfarad capacitors at 35 Volts, manufactured by Rubicon, however this was predictable: There is also a choke to reduce the level of output ripple.
2. To the left, another capacitor is installed, with a capacity of 100 μF, which is connected after the inductor, as well as an LED and a tuning resistor for setting the output voltage.

Another couple of photos of the power supply in the top view.

Everything is neat from below, although I did not doubt it. The board is clean, there are protective slots in the «narrow» places.

1. Controls the operation of the PWM controller 46BL065. This is a quasi-resonant PWM controller, but what is curious, although it has a different name, according to the conclusions, it completely coincides with the NCP1239 PWM controller, which is installed in the RPS-120-27 power supply. But at the same time, NCP1239 is not quasi-resonant.
2. Another place that surprised me in this power supply. The
PWM controller is often able to monitor the input voltage in order to protect against operation when the input voltage is too low. But usually the voltage across the input capacitor of the filter is measured. But here the alternating voltage is controlled, up to the diode bridge. To do this, there are two diodes on the board, the cathodes of which are connected and go to the PWM controller.
Everything would be fine, but this feature gave rise to at least two problems:
1. When the PWM input voltage fails, the controller immediately blocks the operation, and does not wait until the capacitor is discharged. Therefore, this PSU is worse for a short-term loss of power at the input. In fact, everything is given «at the mercy» of the output capacitors.
2. Since the PWM controller is immediately blocked, and there is no one to discharge the capacitor, it remains energized even after the power is turned off. And even after 12 hours, there is a residual voltage of 250-260 Volts on it!
I found out about this by accident when I decided to discharge the capacitor before measuring its capacitance. The result for me was somewhat …. unexpected.

There is a third problem. The fact is that there is no one to discharge the input X capacitor either, so if you remove the power plug from the network and immediately touch its contacts, you can “pinch” a little

In general, the developers surprised me once again. The above features do not affect the quality of work, but in my opinion they are unpleasant.

Another small observation, the capacitor after the output choke is connected somewhat incorrectly, since there is a rather long path in series with it. In theory, it should be closer to the output connector.
But as the tests showed, everything worked fine, although this can usually increase the amplitude of the ripple and the noise level a little.

The block diagram is present in the instructions for the power supply and it basically differs from the same RPS-120-27 in the absence of a thermal protection circuit.
Yes, this power supply does not have overheating protection, which is also unusual for Minwell products.

Since the power supply is relatively simple, I drew a complete circuit diagram of it. Of course, there may be some errors, but I tried to transfer it carefully up to the positional designations of the components.
At a cursory glance, we can say that we have before us the most common power supply circuit, if not for one more minor nuance. Not only is there no output load resistor, but for modern power supplies it is not really needed. But the value of the resistor in series with the power-on indication LED is as much as 680 kOhm, when 2-10 kOhm is usually set. Apparently again the struggle for low energy consumption at idle.

Before proceeding to the tests, a small photo to explain what and where is located in this power supply.

The output voltage adjustment range is very decent. at the base 24 Volts, you can set the output voltage from 21.1 to 28.4, while the adjustment is smooth.

The first test with which I will check the dependence of the output voltage on the load current, as well as measure the efficiency of the power supply and power factor.
The test used one of my electronic loads, a wattmeter and two multimeters to measure current and voltage simultaneously.
In this case, the test was carried out both at a voltage of 225-230 Volts, and at a voltage of about 108-110.

Judging by the results, the power supply has not only high efficiency, but also quite good output voltage stability. The output voltage difference over the full load range is only about 30mV.
Efficiency measurement results at 110 volts may not be very accurate, since the Wattmeter does not work quite correctly in this mode.

The next test is to measure the ripple level at the output of the power supply.

First, what does the idle output look like. A small low-frequency saw is visible, since the controller is in «green mode», but unlike the RPS-120-27, this power supply is quiet, the noise is noticeable only in the current range from 50 to 150 mA.

I will hide the main part of the waveforms under the spoiler, since they are given simply as an addition.

Waveforms

Summary of RF and LF ripple at 230/110 V input and 100% load.
1.2 — 230 Volts
3, 4 — 110 Volts

I can note a low ripple range, especially against the background of what was stated in the description for the power supply.
For a 24 Volt model, a swing of no more than 240 mV is declared, in fact the result was about four times less.

As usual, at the end of the review, I present the results of the thermal run. The tests were carried out classically, for 20 minutes each, followed by temperature measurement and an increase in the load current. The power supply was covered with a lid to simulate a closed volume.

Here I will digress a little. The instruction indicates rather severe restrictions in terms of the operating conditions of the power supply. For example, when the ambient temperature exceeds 50 degrees, it is necessary to reduce the load current. But in addition, such restrictions also apply when the input voltage is reduced. For example, with my test voltage of 108-110 Volts, the output power should be reduced to 90% of the maximum continuous. In this case, at a level of about 60 watts.

In fact, I did not reduce the load power, moreover, when powered by 230 Volts, I even loaded it with a current of 3 Amperes, and not 2. 7, as stated by the manufacturer. And in my opinion, the power supply normally survived all this, starting to give up only at extreme operating conditions.
At a voltage of 230 volts, the high-voltage transistor was the first to overheat, although it is still far from a critical state.
When the voltage was reduced to 110 volts, the heating of the diode bridge predictably increased, as the current through it increased.
The rest of the components did not have very high temperatures, so I believe that by increasing the area of ​​​​the radiator in the «hot» part, you can get more power output without overheating.

Thermal photo after run at 230 Volts

And after run at 110 Volts.

As before, I ran a DC test to determine the maximum output current.
1, 2. With an input voltage of 230 Volts, the PSU turned off at 3.878 Amps.
3, 4. At 110 volts, the shutdown was a little earlier, 3.569Ampere.

In both cases, the power supply turned off abruptly, and the output voltage until the moment of shutdown was the original 24 Volts, this can be seen not in the first and third photos.
After the overload was removed, the power supply automatically restored operation.

Just for fun, I made a GIF for checking for a short circuit.

Let me sum up the results of the tests.
The power supply passed all tests, showed good quality of output voltage stabilization, low heating, small ripple range, and high efficiency.
By and large, in terms of work, I really have nothing to complain about, but in terms of «features» there are some comments.
Firstly, the absence of discharge circuits in parallel with the input capacitor, this does not affect operation, but it does affect safety.
Secondly, the design of the heatsink of the output diode assembly is not very good, also a note on safety.
And thirdly, the lack of thermal protection, which is also not very good, although the power supply does not overheat in operation.

Personally, in my opinion, such a Bp is perfect for building compact soldering stations with T12 soldering irons.

That’s all for me, I will be glad to ask questions and just comments, I hope that the review was useful.

$9.97

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MeanWell EPS-65S-24 power supply, third of six

And so, today I have in my hands the third power supply and six sent to me by one of my readers. In this case, we will talk about a relatively compact and inexpensive power supply, I would even say that this unit belongs to the budget series, since to some extent it is noticeably simpler than the previous ones. But simpler does not always mean worse, and I will try to show and explain all this in the course of the review.
In general, who are interested in branded power supplies, I think they will find something new for themselves.

In fairness, this review is the third only conditionally, since before that I had already reviewed the power supply from this company, but since there are reviews from one batch of six pieces, the review is called the third of six 🙂
Once again, I would like to thank Vladimir, without whom this series would not have been possible. Anyway, I somehow thought that there are a lot of reviews of “Chinese” power supplies, but there is a failure with branded ones, but they are also of interest, not only for the quality of work, but also for circuitry solutions different from Chinese “comrades”. That’s why I think that reviews of branded power supplies are also very useful and I’m glad that I can fill this gap.

The power supply was bought on Taobao, but if the previous two were bought from one seller, then the one being reviewed is already from another.
The packaging is simple, of course worse than a cardboard box, but better than a bubble wrap.

Externally, the power supply looks great, no damage. However, the manufacturer fills its power supplies with sealant in such a way that nothing moves in it at all and it is also very problematic to break off anything.

High efficiency, up to 91% depending on the output voltage, as well as power consumption without load, only 0. 1 watts.
In addition, there is protection against overload, short circuit and overvoltage.
The power supply is designed for passive cooling and operation in the temperature range from -30 to +70.

Full specifications are available on the datasheet, but I’ll just quote some key pages from it.
Judging by the description, the power supply is available with seven output voltage options, but I will review the 24 Volt version.
You can also notice that the power supply works out the declared power only in the version with voltages of 12 volts and above. At lower voltages, the power can even be two times lower than the declared one, for example, for the 3.3 Volt version.

This power supply is a variation of the EPS-65 version, which has a slightly different design.

The power supply is made in the form factor 2×3 inches, or about 50x75mm and belongs to the compact series.

For comparison, I put a pair of Minvel power supplies with a power of 100 and 120 watts on the right, and on the left a Chinese version with a declared power of 72-96 watts, the so-called «folk».

Dimensional drawing of power supplies of this series. It can be seen that the power supply is very compact, for example, the total height is only 27mm.

But let’s move on to a more detailed examination.
At the input there is an almost full-fledged filter, perhaps only a protective varistor is missing.

As expected, there is a thermistor to limit the inrush current and an X type capacitor. There are two two-winding chokes, a small one is turned on immediately after the power input, a large one is between the X capacitor and the diode bridge.
There is a sticker with technical characteristics on the input capacitor. The capacitance of the input capacitor is 82 microfarads, taking into account the output power of 65 watts and the full range of input voltage, I would say that this is not enough.

I thought I saw a lot of different power supplies, but they still never cease to amaze me. In this case, I came across a very unusual choke. The fact is that it is wound not with an ordinary wire, but with a thin tire, a very unusual solution.
No, of course I have seen transformers whose windings are wound with a busbar or thick foil, but here the busbar is laid perpendicular to the frame …

.
2. Output diode assembly MBR20200, 200 Volt 20 Amp, which is very good for an output current of 2.7 Ampere. To the right you can see a place for another diode assembly, it is presumably installed in low-voltage versions of power supplies.
3. There is also a pair of feedback optocouplers, one is responsible for voltage stabilization, the other for overvoltage protection.
4. Another unusual thing that I saw in this block. Interwinding capacitors are not one or even two, but four.
The bottom pair is included as standard, between the minus of the input filter capacitor and the common output wire. But the second pair is connected at one end between the noise suppression chokes, while the other side also goes to the common output wire.
The solution is somewhat extraordinary, I have not seen this before.

Above, I wrote that the 13N60M2 transistor was used. By and large, the most common high-voltage transistor, if not for what case it comes in. The most common isolated TO-220 is installed here, but it turns out that there is also a shortened version, which I also did not come across before.

And here the designers surprised me once again, but this time not very pleasantly. The fact is that a diode assembly is installed at the output of the power supply and it is quite logical that it is installed on a radiator. Since the power supply has modifications with a large output current, the designers have installed a very decent radiator, which is good.
But the fact that it not only enters the “hot” side, but also has insulation only in the form of adhesive tape, surprised me greatly, especially considering the scrupulous attitude of this company to the safety of its products.
The radiator is fixed with a special sealant and installed very rigidly, but in my opinion, this solution is closer to «Chinese» crafts than to a proprietary device.

1. After the diode assembly, there is a pair of 390 microfarad capacitors at 35 Volts, manufactured by Rubicon, however, this was predictable: There is also a choke to reduce the level of output ripple.
2. To the left, another capacitor is installed, with a capacity of 100 microfarads, which is connected after the inductor, as well as an LED and a tuning resistor for setting the output voltage.

Another couple of photos of the power supply in the top view.

Everything is neat from below, although I did not doubt it. The board is clean, there are protective slots in the «narrow» places.

1. Controls the operation of the PWM controller 46BL065. This is a quasi-resonant PWM controller (presumably), but what is curious, although it has a different name, according to the conclusions, it completely matches the NCP1239 PWM controller, which is installed in the RPS-120-27 power supply.
2. Another place that surprised me in this power supply.
The PWM controller is often able to monitor the input voltage in order to protect against operation when the input voltage is too low. But usually the voltage across the input capacitor of the filter is measured. But here the alternating voltage is controlled, up to the diode bridge. To do this, there are two diodes on the board, the cathodes of which are connected and go to the PWM controller.
Everything would be fine, but this feature gave rise to at least two problems:
1. When the PWM input voltage fails, the controller immediately blocks the operation, and does not wait until the capacitor is discharged. Therefore, this PSU is worse for a short-term loss of power at the input. In fact, everything is given «at the mercy» of the output capacitors.
2. Since the PWM controller is immediately blocked, and there is no one to discharge the capacitor, it remains energized even after the power is turned off. And even after 12 hours, there is a residual voltage of 250-260 Volts on it!
I found out about this by accident when I decided to discharge the capacitor before measuring its capacitance. The result for me was somewhat … unexpected.

There is a third problem. The fact is that there is no one to discharge the input X capacitor either, so if you remove the power plug from the network and immediately touch its contacts, you can “pinch” a little

In general, the developers surprised me once again. The above features do not affect the quality of work, but in my opinion they are unpleasant.

Another small observation, the capacitor after the output choke is connected somewhat incorrectly, since there is a rather long path in series with it. In theory, it should be closer to the output connector.
But as tests showed, everything worked fine, although usually this can slightly increase the range of ripples and the level of interference.

The block diagram is present in the instructions for the power supply and it basically differs from the same RPS-120-27 in the absence of a thermal protection circuit.
Yes, this power supply does not have overheating protection, which is also unusual for Minwell products.

Since the power supply is relatively simple, I drew a complete circuit diagram of it. Of course, there may be some errors, but I tried to transfer it carefully up to the positional designations of the components.
At a cursory glance, we can say that we have before us the most common power supply circuit, if not for one more minor nuance. Not only is there no output load resistor, but for modern power supplies it is not really needed. But the value of the resistor in series with the power-on indication LED is as much as 680 kOhm, when 2-10 kOhm is usually set. Apparently again the struggle for low energy consumption at idle.

Before proceeding to the tests, a small photo to explain what and where is located in this power supply.

The output voltage adjustment range is very decent. at the base 24 Volts, you can set the output voltage from 21.1 to 28.4, while the adjustment is smooth.

The first test with which I will check the dependence of the output voltage on the load current, as well as measure the efficiency of the power supply and power factor.
The test used one of my electronic loads, a wattmeter, and two multimeters to measure current and voltage simultaneously.
In this case, the test was carried out both at a voltage of 225-230 Volts, and at a voltage of about 108-110.

Judging by the results, the power supply has not only high efficiency, but also quite good output voltage stability. The output voltage difference over the full load range is only about 30mV.
The results of measuring the efficiency at a voltage of 110 volts may not be very accurate, since the Wattmeter does not work quite correctly in this mode.

The next test is to measure the ripple level at the output of the power supply.
First, what does the idle output look like. A small low-frequency saw is visible, since the controller is operating in “green mode”, but unlike the RPS-120-27, this power supply is quiet, the noise is noticeable only in the current range from 50 to 150 mA.

I will hide the main part of the waveforms under the spoiler, since they are given simply as an addition.

Waveforms

All waveforms were taken at 25%, 50%, 75% and 100% load.
HF ripple at 230V input voltage

LF ripple

Supply voltage 110V
HF ripple

LF ripple

Combined pattern of HF and LF ripple at 230/110 Volts input voltage and 100% load.
1.2 — 230 Volt
3, 4 — 110 Volts

I can note a low ripple range, especially against the background of what was stated in the description for the power supply.
For a model with a voltage of 24 Volts, a swing of no more than 240 mV is declared, in fact, the result was about four times less.

As usual, at the end of the review, I present the results of the thermal run. The tests were carried out classically, for 20 minutes each, followed by temperature measurement and an increase in the load current. The power supply was covered with a lid to simulate a closed volume.

Here I will make a small digression. The instruction indicates rather severe restrictions in terms of the operating conditions of the power supply. For example, when the ambient temperature exceeds 50 degrees, it is necessary to reduce the load current. But in addition, such restrictions also apply when the input voltage is reduced. For example, with my test voltage of 108-110 Volts, the output power should be reduced to 90% of the maximum continuous. In this case, at a level of about 60 watts.

In fact, I did not reduce the load power, moreover, when powered by 230 Volts, I even loaded it with a current of 3 Amperes, and not 2.7, as stated by the manufacturer. And in my opinion, the power supply normally survived all this, starting to give up only at extreme operating conditions.
At a voltage of 230 volts, the high-voltage transistor was the first to overheat, although it is still far from a critical state.
When the voltage was reduced to 110 volts, the heating of the diode bridge predictably increased, as the current through it increased.
The remaining components did not have very high temperatures, so I believe that by increasing the area of ​​​​the radiator in the «hot» part, you can get more power output without overheating.

Thermal photo after run at 230 Volts

And after run at 110 Volts.

As before, I ran a DC test to determine the maximum output current.
1, 2. With an input voltage of 230 Volts, the PSU turned off at 3.878 Amps.
3, 4. At 110 volts, the shutdown was a little earlier, 3.569 Amperes.

In both cases, the power supply turned off abruptly, and the output voltage until the moment of shutdown was the original 24 Volts, this can be seen not in the first and third photos.
After removing the overload, the power supply automatically restored work.

Short circuit test.

A small video on this PSU.

Let me sum up the results of the tests.
The power supply passed all tests, showed good quality of output voltage stabilization, low heating, small ripple range, and high efficiency.
By and large, in terms of work, I don’t really have anything to complain about, but in terms of “features”, there are some comments.
Firstly, the absence of discharge circuits in parallel with the input capacitor, this does not affect operation, but it does affect safety.
Secondly, the design of the radiator of the output diode assembly is not very good, also a note on safety.
And thirdly, the lack of thermal protection, which is also not very good, although the power supply does not overheat in operation.

I think that such a PSU would be well suited for building compact soldering stations with T12 soldering irons.

That’s all for me, I will be glad to ask questions and just comments, I hope that the review was useful.

Vanguard

Emma Young
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