The uninterruptible power supply does not work on the computer, how to repair it. UPS malfunctions and their diagnosis

In this article, I will share with you a method for diagnosing and troubleshooting an uninterruptible power supply (UPS). So why might the uninterruptible power supply not turn on or not work from the network? one of the first reasons, a fuse has blown, perhaps the transformer or control board has failed, but in our case it’s a slightly different, but at the same time very basic problem...
Let's take a closer look...

We repair an uninterruptible power supply with our own hands

At the very beginning, before disassembling, we need to check whether the fuse is working, usually it is located on the back side of the UPS

We remove it and check it with a multimeter in dial mode.
In this case the fuse is good.

Let's move on to disassembling the uninterruptible power supply (UPS) itself.
I would like to note that the disassembly method may be distinguishable from your UPS model, but should not cause you any particular difficulties in disassembling.
Unscrew 4 screws and remove the lower part of the UPS housing.

After disassembly, carefully inspect the board for external damage to components. In our case, no damage was found.

The first step is to check the battery. Let's measure its voltage with a multimeter.
In our case, the battery is discharged to 2 volts, which is naturally not good and is a fairly deep discharge.

Let's check the battery for charge and discharge by connecting it to a laboratory power supply for recharging to eliminate the possibility of its breakdown.
As it turned out, the battery refused to accept the charge from the laboratory power supply, which means that there is a break somewhere and, accordingly, our battery is not working properly.

Let's take another battery to check. In my case it has a slightly larger capacity. Accordingly, the uninterruptible power supply should hold its charge longer and fits perfectly into the UPS case!

We connect the terminals - let's run it for a test without assembling the case. Started up.

We measure its voltage: - 12.4 volts.

To make sure that the battery is charging, measure the voltage at the battery terminals for a few seconds with the UPS connected to the network. The voltage should gradually rise.
12.9 volts tells us that the battery is charging, the uninterruptible power supply is working, it can be assembled and put into operation.

Failure of the battery or loss of its energy capacity is one of the most common failures among all types of UPS. So don’t rush to throw them away right away.

An uninterruptible power supply serves the purpose of ensuring a uniform supply of power to the electrical consumer. For various reasons, network power may fluctuate. It could be:

• drop in solar panel generation (due to changes in illumination);
• change in output from wind power plants (due to calm weather, for example);
• power fluctuations in a network with a limited number of generators and a large number of consumers (so-called unstable networks).

The UPS is not designed to maintain the level of energy consumption for a long time. Its main task is to cover dips and surges in power so that “thin” electronics do not suffer from fluctuations. If there is no voltage for a long time (and if, for example, we are talking about computer equipment), then it is necessary that there is a possibility of correct shutdown of programs. UPS malfunctions can render entire expensive electrical equipment useless, despite the structural integrity of all its other components. It turns out that if the uninterruptible power supply fails, it is simply not possible to use such a device. Therefore, it is so important to pay attention to its correct operation.

We propose to consider in more detail the possible malfunctions of this electrical appliance, and also list ways to eliminate them. However, it is worth remembering that at the moment the UPS is a high-tech device, unprofessional intervention in the operation of which is fraught with more serious damage. Repair of an uninterruptible power supply should be trusted exclusively to specialists.

Diagnostics

Repair of an uninterruptible power supply is logically divided into diagnostics and subsequent correction of defects. Sometimes it is possible to diagnose visually (for example, a cable break), but often fault detection is carried out using specialized equipment.

Diagnostics includes the following activities:

1. Examination of key elements for dustiness and the presence of oxidations that can lead to short circuits and breaks in the power electrical circuit.
2. Regular inspection of rotating parts is required. In particular, cooling fans (coolers).
3. Rechargeable batteries, first of all, need to be inspected for reliability of contacts on the terminals, absence of signs of oxidation, or presence of damage to the case.
4. It is required to measure the parameters of various operating modes of the rectifier and inverter.
5. Using monitoring equipment, you need to check the capacity of each battery and its wear.

Standard repair measures

An uninterruptible power supply, as a rule, is always repairable. It is extremely difficult to imagine a situation where it would be hopeless (unless it was a fire emergency). And the entire set of repair actions after diagnosing a faulty UPS usually comes down to the following:

• Maintenance within the framework of warranty service repairs (this is carried out by certified centers).
• Carrying out qualified repairs of UPS control unit boards.
• Restoring the parameters of working uninterruptible power supply batteries using specialized charging and discharging equipment.
• The most extensive repair (in terms of cost) is the complete or partial replacement of UPS batteries.

Typical, common UPS problems and how to fix them

It is worth listing them with separate comments:

Uninterruptible power supply cannot be turned on

This is a fairly frequently reported fault. The cause is usually a lack of contact with the UPS storage batteries.

The device runs only on its own batteries

We are talking about a lack of power from the network. Most likely the fuses have failed. They just need to be replaced.

The battery change indicator light is on

If testing reveals that the battery is working properly, it means that the device is not able to complete the program cycle. To solve this problem, you should calibrate the incoming as well as the outgoing voltage of the batteries.

Being connected to the network, the UPS is not traced there - no energy is consumed from the circuit

A typical case of lack of contact. The device's network cable is damaged or broken.

After turning on the device and using its battery reserves, the power drops

Most likely the voltage sensor is broken. It needs to be replaced, and then calibrated to the parameters of the elements that depend on it.

Display indication suffers from flickering

Here the capacitors “flow” (i.e., an emergency intense loss of charge occurs). It is necessary to find out the defective capacitor (“ring” them) and replace them.

The indicator shows the activity of the charging procedure, but in reality the batteries do not accept a new charge

The range of reasons can be very diverse:

• violation of the program code of the uninterruptible power supply control unit;
• defective battery charging circuit;
• malfunction of the electrical circuit: internal loops, cables;
• failure of the battery(s).

It is necessary to find out in more detail the source of the malfunction. It is possible that you will have to change the battery.

The appearance of external signs of a fire emergency, such as smell and smoke

An urgent replacement of the entire device is required. Most likely, at this stage, partial repair of the UPS is no longer possible.

UPS failures are of a wide variety of nature, but this technology is characterized by a certain set of problems that most owners of uninterruptible power supply systems face. Compliance with the basic recommendations for operating UPS will allow you to avoid common problems that arise when using them. The best recommendations for proper operation of the UPS are provided by the manufacturer.

It should also be noted that for UPSs of different brands, the same problem can be caused by different faults. Most often, the causes of malfunctions in uninterruptible power supply systems are long-term operation and difficult working conditions. Failure of the device can be caused by ordinary dust, and construction dust has a particularly negative impact. This is why it is so important to maintain the cleanliness of the room in which the IPS is located. If you do not follow the simple rules of proper operation, you may soon find that the device cannot withstand the load. In any case, you can contact the Bestcom service center, where they will give you a free diagnosis, and then agree on it.

UPS does not turn on

The control board of small UPSs is usually powered by a built-in battery. That is why, if the battery is completely discharged or its capacity is lost, it may be difficult to turn on the UPS. You can try to turn on the uninterruptible power supply by using the same battery and inserting it into the UPS (if available). If a spare battery is not available, the existing battery must be charged. To do this, you can plug the UPS into the network and leave it for a day - some uninterruptible power supply systems allow you to charge your batteries in this way.

If this method does not help, you will still have to find a working and charged battery. When it is connected, the device may not work - this may have various reasons:

• The connection cable is broken connecting the display and other boards;
• Fuse burned out;
• The start buttons are faulty after a long service life of the UPS (from 2 to 5 years);
• Onboardthere are any defects. To find out if there are defects on the board, you need to diagnose it by taking the program from a working device.
• Available software malfunctions UPS. The software is checked using special diagnostic software.
• The voltage sensor has failed. It is necessary to check the serviceability of this element.

UPS beeps

• In most cases, a beeping sound from the UPS indicates that the battery is insufficiently charged.

To solve this problem, just charge the battery. For this action, if there is power from the network, you do not need to do anything. After a few hours, the battery will charge automatically and you will be able to continue working from the UPS. If there is a constant lack of power from the network, then you need to disconnect the battery (battery) and recharge it with a third-party device in places where there is electric power. If such manipulations do not help solve the problem, then you need to replace the battery.

• It beeps due to insufficient power of the equipment.

When equipment is connected to the UPS that exceeds the power permissible for the load of the corresponding UPS. In this case, you need to reduce the load on the UPS or purchase equipment with higher performance. It is possible to reduce the load by disconnecting devices one by one from the UPS, or by comparing the permissible loads displayed on the back of the uninterruptible power supply with the power of the connected equipment.

• Sometimes you can see an error code on the UPS screen.

In this case, after studying the instructions for the equipment in detail, we will find out the cause of the defect and a method for eliminating it.

The UPS does not want to hold the load

• When the UPS turns off after a fairly short period of battery operation, the battery is clearly to blame.

It is quite easy to verify that the battery is working. On a fully charged battery, connect a 100 W incandescent lamp to the UPS output. A battery with a performance of at least 7 Ah should last about 20 minutes. When the values ​​are significantly below 20 minutes, the battery has outlived its usefulness.

• The UPS turns off immediately after the mains is disconnected.

In this case, the cause of the problem may be a faulty battery or a broken UPS. You will need to check the battery separately from the UPS. It is best to do this using a tester, which can be purchased at any household store for pennies. In another scenario, the UPS itself needs repair.

The UPS does not shut down randomly

• In most cases, the cause of the shutdown is a UPS reboot.

This can be found out by manipulating the disconnection of equipment from the UPS. If, when minimizing the UPS load, the operation stabilizes (no shutdowns occur), you will need to study the equipment that causes the overload. In some household equipment, the starting load significantly exceeds the operating load, so when choosing a UPS, you need to focus on the startup load.

If even without load the equipment turns off or reboots, you need to entrust the repair to professionals.

• Sometimes the cause of a shutdown may be a faulty UPS plug.

In this case, the equipment will not turn on at all, or it will turn on when the cord of the plug plugged into the socket is moved. You can also replace the UPS plug at home by first disconnecting the UPS from the power supply.

This story is about how I almost threw a working (as it turned out) UPS into a landfill. Of course, no one was going to throw it away, but I was almost ready to make it a donor of radio components :) This is how it all happened...

In 2009, while still a student, I purchased my first uninterruptable power source from Ippon. The reason for purchasing the UPS was the recent hard drive death which occurred after another power outage in the village. The hard drive contained an almost completed thesis project, which was completely destroyed. I had to restore everything from the scraps available on the flash drive and email. This fact added motivation for purchasing an uninterruptible power supply :)

The device turned out to be very reliable, and worked honestly and efficiently for almost 7 years.

But a couple of years ago problems began. Or rather, the most common problem is The UPS stopped holding a charge. At least that's what I thought when the uninterruptible power supply, instead of continuing to supply power to the computer after a power outage, started beep continuously, reporting on low battery.

Well, “it served its purpose, 7 years and so well,” I thought, and decided to leave the UPS as a tee (6 sockets and an electronic on/off button - very convenient). I didn't intend to change the battery. But just a couple of weeks ago, UPS shutdown button stopped working. The output sockets were constantly supplied with power, both on and off. I wondered what happened to him?

Having started to find out the reasons for this behavior of the UPS, I disassembled the device, and the first thing I decided make sure the battery is faulty, which, in my opinion, failed 2 years ago.

I was extremely surprised when I connected the multimeter to the battery terminals and saw the readings of the device - 13 volts!!! This meant only one thing - The battery is fully charged and operational!

And then it dawned on me. Having compared 2 facts - a working battery, as well as a constant supply of power from line 220 when the UPS is turned off - I immediately realized that The problem is most likely in the relay, which switches power from the 220V input line to backup power from the battery at the time of a power outage.

I unsoldered the relay, started ringing its contacts - and indeed: those contacts that should be closed in the off state of the relay are not closed at all (normally closed relay contacts), and the contacts that supply power from line 220 (normally open contacts) are constantly closed , even when the relay is on! Most likely over a long period of work the contacts just got stuck, and began to constantly supply electricity only from external power - from the outlet. It is for this reason that the function of switching to backup power stopped working. 2 years ago (at first one of the contacts stuck, and the second was still switching, this was enough to turn off the external power when the device was turned off, but not enough to switch to backup power)! It turns out cause There was no UPS malfunction at all not in the battery.

Purchase new relay cost me exactly 200 rubles (and buying a new battery would have cost 2000 rubles, not to mention the cost of a new UPS)

UPS - main board with new relay

Replacing the relay, I got completely working uninterruptible power supply, which again successfully fulfills its direct responsibility - maintaining the supply of electricity to the computer during a power outage.

A few words about the battery. The sticker shows that battery manufactured in July 2008. At the time of writing, she is almost 10 years, and it still holds a charge. CSB battery, made in Vietnam.

By the way, the UPS itself is made in Taiwan.

So if your uninterruptible power supply suddenly stops “holding a charge,” don’t rush to blame the battery - you should first check the switching relay :)

Uninterruptible power supply faults

An uninterruptible power supply (Fig. 1.14) is a device that is highly desirable for creating normal operating conditions for a computer. Not only the stability of the computer depends on it, but also the frequency of occurrence of hardware faults.

Unfortunately, uninterruptible power supplies can also fail. Although, as practice shows, the only thing you need to do to prevent damage to this device is to change the batteries on time.

As for repairing an uninterruptible power supply at home, having a little understanding of the basics of electrical engineering and having a multimeter, you can independently determine and eliminate the causes of many malfunctions.

Rice. 1.14. Uninterruptable power source

Load connection sockets

If the indication of the uninterruptible power supply does not show any deviations in its operation, and there is no voltage at the outputs, then first of all you need to check the output sockets on the rear wall of the device.

Disassemble the uninterruptible power supply and remove the back panel from it. Pay attention to the wires coming from the AC input connector and stabilizers. To one output (usually marked white) the wires should go directly from the input, and to the outputs connected in parallel using plates, two wires from the stabilizers should go - red and yellow (Fig. 1.15).

Rice. 1.15. Outputs on the rear wall of the unit

If you see some kind of problem, such as a soldered wire or plate, arm yourself with a soldering iron and solder and fix the problem. If all the wires are in their places, then the cause of the malfunction should be looked for elsewhere.

Circuit breakers

Like any other AC-powered device, an uninterruptible power supply is equipped with fuses. Fuses allow you to quickly shut down the entire electronic control circuit if a short circuit or other serious fault occurs.

Typically, an uninterruptible power supply is equipped with a pair of fuses enclosed in a plastic shell, that is, made in the form of a key that closes the circuit. They have different powers, and, as a rule, the fuse with weaker characteristics blows.

After pulling out each of them, make sure that the connecting thread between the fuse contacts is not destroyed. Otherwise, they need to be replaced. To easily locate a blown fuse, you can use a multimeter to check for resistance. If the fuse is good, the multimeter will show a resistance of a few ohms, otherwise there will be no reading.

Transformer

The uninterruptible power supply contains a power transformer, which is designed to step down or step up the voltage by using the magnetic properties of the transformer. The use of a power transformer allows you to achieve higher output power than switching power supplies. On the other hand, this makes the device heavier.

Be that as it may, quite often a short circuit occurs in the transformer winding and the winding partially burns out. This can be facilitated by rather difficult conditions for using an uninterruptible power supply (instability of the input voltage, constant voltage surges and powerful impulse noise, for example from a laser printer or copier, high humidity in the room, etc.). In this case, the transformer becomes very hot, and its further use is possible only after the short circuit has been eliminated.

If the transformer gets very hot, check all windings in pairs with a multimeter. If damage is detected, the transformer must be replaced, since at home it is quite difficult to make a new winding with the required characteristics.

High voltage transistors

As with any other electronic device, the circuit of an uninterruptible power supply unit necessarily contains components that are subjected to severe loads, passing through a large current. At the same time, heat generation increases, and if the cooling system does not cope with its functions, then these components simply burn out.

It’s quite simple to verify this: look carefully at their appearance. As a rule, such components have cracks, and sometimes are so destroyed that only their leads remain instead.

As a rule, such elements are powerful transistors or microcircuits installed on aluminum radiators (Fig. 1.16). The minimum number of transistors is two. High-quality uninterruptible power supplies usually contain more than four transistors.

Rice. 1.16. Powerful field effect transistors

To check transistors, use a multimeter, having previously specified the location of the semiconductor junctions of the transistors in a special reference book or on the Internet, using the markings on the transistor body. As a rule, transistors fail in pairs, so if you find one faulty element, continue further testing.

Accumulator battery

The battery (Fig. 1.17) is one of the main components of an uninterruptible power supply. Depending on the power, the uninterruptible power supply may contain several batteries. The power of the unit and the battery life of the devices connected to it depend on the condition of the battery and their power.

Rice. 1.17. Accumulator battery

The battery life is three to four years. However, in conditions of frequent power outages or when the power supply is operating in an overloaded mode, the battery life is halved and is usually no more than two years.

Checking the battery condition is quite simple. If the computer's battery life lasts less than five minutes, the battery should be replaced. If the uninterruptible power supply turns off immediately after a power outage, the battery must be replaced as quickly as possible, otherwise it will fail you at the most inopportune moment.

The battery should also be replaced if you notice external swelling or severe oxidation of the terminals. In addition, the battery case may develop cracks or leak electrolyte.

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