How to check a welding inverter - Metals and their processing

Repair of welding inverters: main breakdowns and do-it-yourself methods for fixing them

Since the beginning of the 2000s, inverter welding has been used more and more often, which is understandable. Now you can easily buy a budget device that meets all the requirements.

Such mechanisms boast good technical characteristics. This may be quite enough for simple repairs - for example, in a country house or in a garage.

If the welding transformer and rectifier have a narrow purpose, then the inverter for welding is used very often.

Through microcircuits, which are rightly called the soul of the mechanism, the developers managed to provide the welding machine with a number of advantages while simultaneously reducing its weight.

No matter how much we would like not to think about repairs for a longer time, complex devices sometimes become faulty. We will share our experience on the most common breakdowns.

After reading the article, you will be able to repair the inverter. You will find a lot of useful tips in the material. We hope you find them useful.

Sparks in the inverter

In inexpensive inverters, such a breakdown is common. It looks like this: the device produces a spark, but refuses to work. There are logical explanations for this, which we will tell you about.

The first thing you should do is take a close look at the welding cables: very often they need “reanimation”. At first glance, there may not be any obvious defects, but just in case, take new cables and insert them into the ground with a holder.

This will start the arc and give you the opportunity to check the connectors for proper operation.

Sometimes sparks will not stop coming from the inverter. Then you need to check the electrolytic capacitors located in the converter. No matter how sad it may sound, these broken parts need to be replaced with new ones.

Do you have extensive experience in this matter? Try to carry out the repair yourself. In all other cases, the wires located on the package switch have failed. What if the last ones got burned?

Don’t be discouraged: repairs aren’t for everyone. In order not to waste time, you need to contact a specialist. It will return your inverter to working condition.

The device refuses to cook

It may also happen that the light indicators will be on, but the welding process will not start. As a rule, this is due to overheating of the inverter. We'll talk about this in a minute.

In the meantime, check the welding cables for integrity or connect new ones and try to start the mechanism again. Perhaps such a simple repair will help immediately.

Inverter overheating

This is one of the most common problems. If the device operates for 10-15 minutes without stopping, it may overheat and turn off for a while. This happens despite the fact that many inverters have an overheating lock.

Solving the issue and performing repairs is quite logical: just turn off the device for 30 minutes and let it cool. Only after half an hour do you start working again: the inverter should turn on. This will be the repair.

The mechanism does not turn on

This is also a common problem that leads to repairs. It is usually discovered when they try to connect the inverter to the outlet, but it refuses to work.

A common reason for repairs is very low electrical voltage at the output. To eliminate the malfunction, you need to purchase a special stabilizer that will control the voltage supply.

The problem may be with the network cable. It may be damaged. To check, remove the case from the device and look inside.

If you don’t notice anything suspicious (the cable turns out to be intact, the stabilizer does not help) - then ask for help from specialists.

The current is not adjusted

The process goes like this: you turn on the current regulator, but the mechanism does not work. The reason for this is usually the regulator. There are two options: either it needs to be completely replaced, or some connection has simply moved away from the wire.

After removing the mechanism housing, arm yourself with a multimeter and check the regulator. If it is not broken, then you need to pay attention to how the choke is closed and whether the secondary transformer is broken.

Don't know what to do or how to repair the device? Give your inverter to someone who knows about it.

Electrode and metal “stick”

The anti-stick settings that modern inverters are equipped with often do not work. And then you have to decide what the reason is and what repairs are needed.

Firstly, you could have selected the wrong welding mode. This often happens to an inexperienced master.

Secondly, the electrical network may not be powerful enough for the device. As we have already said, it is worth purchasing a stabilizer. It will help control the mains voltage and avoid surges.

Thirdly, you forgot to buy an extension cord for the device, and the cord is not long enough to work. As a result, due to its small size, the voltage may decrease. Be sure to take this point into account.

And finally, point number 4 - you could have poorly prepared for welding work. One of the options could be: welding the metal with an oxide film and carelessly cleaning the mechanism before welding.

The film is likely to reoccur and will likely impair the metal-to-mesh bond.

Determining the breakdown

Be careful: if you smell something burning or notice smoke coming out of the mechanism, this malfunction is more than serious and requires the hands of an experienced technician who should be contacted.

In other cases, home repairs are possible. To do this, release the inverter from the housing, checking the device for serviceability. Pay attention to the quality of the soldering of the wires. Often the problem is solved by grinding out individual parts of the inverter.

If parts are broken, cracked or uneven in color, then they need urgent replacement. Do not forget to take into account the branding.

To find out about internal faults, it is important to use a multimeter. It is necessary to diagnose the operation of the board and individual transistors. There should be nothing burnt or partially torn off.

If burns are found, it is worth eliminating them and soldering them using PEL type winding wires. Make sure that the board conductor and cross-section match each other.

A white eraser will help clean the connector contacts in the inverter, which is also extremely important.

Diode converters mounted on a radiator can operate as rectifiers. Such a breakdown occurs rarely, but it is still worth not forgetting about it.

To determine the location of the breakdown, it is necessary to unsolder the wires from the bridges and separate them from the board. Using a multimeter, you can determine the serviceability of all parts of the mechanism.

Have you tried all the methods from our article, but the inverter still does not work? Have it diagnosed by a good specialist. This must be done immediately - the device may be under warranty.

Let's sum it up

We talked about the option of self-repairing welding mechanisms. You can start working without outside help. But only if you have such experience.

More serious faults should be repaired by competent technicians. Don't take risks if you're not confident in your skills. Tune in to the fact that you need a working inverter, not new problems.

Contact a repair center. Read reviews in advance about the specialists who work there. Don't be afraid to trust someone else if your skills aren't great enough.

Do not forget about the safety of performing all work: control the mains voltage, wear gloves and a special mask, and do not bring the devices too close to parts of the body.

Remember: an inverter is a complex electrical mechanism with its own operating algorithm.

They can be dangerous when handled by an incompetent craftsman. Always assess the situation wisely. Throw the device in a landfill if repairs cost more than buying a new inverter.

If possible, try to buy a high-quality welding machine right away so as not to think about problems in the future. Good luck and safe work, colleagues!

Source: https://prosvarku.info/apparaty/remont-invertorov-dlya-svarki

How to check a welding inverter when purchasing

Welding inverters are increasingly becoming widespread among a wide range of users, displacing old-style devices. This is due to the large number of advantages of this type of welding devices. It works on the principle of phase shift voltage.

Types of welding inverters

There are four main types of inverters:

The MMA marking indicates that this machine is intended for manual welding using coated electrodes . Mainly used by amateurs at home. Using this type of inverter, small and simple work is performed.

The MIG/MAG marking denotes semi-automatic welding devices . They are more powerful and functional, unlike the previous type. Well suited for small productions.

Welding inverters marked TIG are based on the principle of operating in a protective gas environment . They are more complex in their design than the previous ones. Intended for use in production. At home, having such a device is unprofitable because of its high cost, and the need to purchase additional equipment; you also need to buy special consumables.

Devices marked CUT are capable of cutting metal using air plasma . Designed for cutting metal up to 15 mm thick.

Device weight

This characteristic directly depends on the model and manufacturer. Usually it is in the range of 5-10 kilograms. Often, the more powerful and functional the device, the more it weighs.

Nutrition

One of the important characteristics is the power supply of the welding inverter . Some inverters can only be powered from 380V, others only from a regular 220V outlet . The corresponding mark is always indicated on the body of the device.

Current strength

Most welding inverters have a number after the name, usually this is an indicator of the maximum current power declared by the manufacturer. Sometimes careless manufacturers overestimate this figure. In fact, you can find out by looking under the cover of the diode bridge. The current strength of modern devices can be adjusted in the range of 5–500 A.

Welding cycle time

All inverter machines have such an indicator as the duration of the welding cycle. It is measured as a percentage. The generally accepted length is 5 minutes. Therefore, if the manual indicates 40%, then you can work continuously for 2 minutes, and the device should rest for 3 minutes.

Surge protection

Allows you to withstand a decrease or increase in voltage in the outlet. The better the protection, the greater the fluctuations it can withstand.

Ambient temperature

Any device has a range of temperatures at which work is carried out; each type is different, depending on the purpose and manufacturer, and the price category also greatly influences.

Welding inverter cooling system

This characteristic determines how well the welding inverter will be cooled.

Maximum electrode diameter

This parameter shows what the largest thickness of the electrode is when working on a specific device.

Available functionality

Additional functions greatly facilitate the work of the master. One of these is “Hot Start”. With its help, the arc is ignited more easily.

The Arc Force feature helps prevent electrode sticking by automatically increasing the current. "Antistick" automatically reduces the current when there is a threat of electrode sticking to the surface being welded .

How to choose the right welding inverter

In order to choose the right welding inverter, you need to decide for what purpose the device is being purchased. When working at home, infrequently used, with small volumes, you can limit yourself to a small budget option with a power of 160-180 A. If large volumes of welding work are required, then it is better to use semi-professional or professional ones, it all depends on the specific tasks.

Source: https://respect-kovka.com/kak-proverit-svarochnyy-invertor-pri-pokupke/

Repair of welding inverters and do-it-yourself troubleshooting: types of faults, their occurrence, repairs - SibNovStroy

Date: 07/28/2015
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: 42

The welding inverter ensures good quality of welding work, creating the most comfortable working conditions for the welder. However, these advantages lead to increased complexity of its design. This can cause various malfunctions of the welding inverter and reduce its reliability.

Diagram of an inverter for welding.

Features of inverter repair

Unlike conventional welding machines, which are electrical products, a welding inverter is an electronic device.

Consequently, diagnostics and repair of inverter welding machines are carried out by checking the operating condition of diode bridges, transistor connections, zener diodes and other parts that are part of electronic circuits.

In this case, you need to have skills in handling oscilloscopes, voltmeters, multimeters and other measuring instruments.

Diagram of an inverter for welding.

The main distinguishing feature in repairing a welding inverter is the difficulty in determining the nature of the breakdown and detecting the failed part. Therefore, it is very often necessary to diagnose all components of the electrical circuit.

Based on the above, we can conclude that to repair inverter-type welding machines, you must have minimal knowledge in the field of electronics and be able to understand the design of electrical circuits. If such skills and abilities are absent, then it is not recommended to undertake independent repair of such a device, so as not to waste extra effort and time.

Operating principle of the inverter

The operating principle of inverter devices is the sequential (step-by-step) transformation of the incoming electric current signal:

Functional diagram of the device.

the process of rectifying incoming network currents using a special rectifier;
the process of converting rectified currents into alternating high-frequency signals;
the process of reducing high voltage currents to welding voltage, occurring on a power transformer;
Conversion of high frequency alternating current into direct current using an output rectifier.

To perform such operations, the design of the welding inverter has several modules with electronic filling. The main module is the input current rectifier. Then there is a control board on which transistors (switches) are located, and it ends with a rectifier for the output signals.

At the same time, in devices from different manufacturers with different models, the layout of the unit components can be very diverse, but the installation of the main components will always be unchanged.

Therefore, knowing the basic operating principle of such units and the location of the main modules of their design, it is possible to diagnose possible faults and carry out the necessary repairs.

Types of main faults

Simplified diagram of the power part of a welding inverter.

If a welding inverter fails, the first thing you should do is check its transistors, since they are one of the weakest points of such units.

Initially, a visual inspection of the transistors should be carried out. Such a broken part is very easy to identify: it has a broken or cracked case with burnt-out leads at the solder points on the board.

This part needs to be replaced immediately.

New transistors should be installed on a special thermal paste. It will ensure heat removal from the transistor to a radiator made of aluminum. But very often a visual inspection does not reveal faulty elements, then you should make a “diagnosis” using a multimeter.

Replacement of faulty elements is carried out according to precisely specified parameters. In some cases, it is possible to supply analogue parts, and the required parameters can be determined from the datashift. If replacing the burnt-out transistors does not help, you need to move on to further diagnostics.

Scheme of a welding inverter with a soft ignition system.

In normal operation, transistors cannot simply fail; most likely, this is due to the incorrect operation of other elements. Most often this is the driver. It is checked with an ohmmeter. If faulty parts are found, they must be removed and replaced with similar parts.

Then the input and output current rectifiers, which consist of diode bridges, are checked. They are installed on the radiator and are reliable components for welding inverters. But they can also fail. Their functionality is checked using a voltmeter.

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Control board fault

It is best to check diode bridges by unsoldering the wires from them and then detaching them from the board. This can make all further work easier and will not raise doubts when a short circuit occurs in the entire inverter circuit.

The check follows a fairly simple algorithm. It is necessary to “ring” the entire group of parts. If a “short” is detected, then you should search for a broken diode. Once it is detected, the diode should be carefully removed and replaced.

If, after carrying out all the above steps, the welding machine still does not work, you should test the control board. It monitors the operation (control) of the keys. The reliability of all equipment will depend on the reliability of such a board.

To carry out competent and qualified repair of the inverter, it is necessary to check for the presence of the necessary signals that produce its operation. These signals must be sent to the gate buses of the key module. You can perform a similar check using oscilloscopes.

Periodically, high heating of the inverter housing may occur. This may be due to violations of the rules for using the unit and incorrect selection of the value of the current used for welding.

This can also occur when the electrodes are incorrectly selected or the unit is operated for too long.

To avoid such difficulties when using the inverter, it is necessary to observe the optimal operating modes, which are specified in the technical data sheet.

Source: https://sibnovostroy.ru/bez-rubriki/remont-svarochnyh-invertorov-i-poisk-nepoladok-svoimi-rukami-vidy-neispravnostej-ih-vozniknoveniya-remont.html

The main breakdowns of welding machines and how to fix them

It is well known that the repair of welding machines in the vast majority of cases can be organized and carried out independently. The only exception is the restoration of the electronic inverter, the complexity of the circuitry of which does not allow for a full repair at home.

Just trying to disable the inverter protection can baffle even an electrical specialist. So in this case, it is best to seek help from a specialized workshop.

Frequent malfunctions

The main manifestations of problems with electric arc welding machines are:

the device does not turn on when connected to the mains and started;
sticking of the electrode with a simultaneous hum in the area of the converter;
spontaneous shutdown of the welding machine in case of overheating.

Repairs always begin with an inspection of the welding machine and checking the supply voltage. Repairing transformer welding machines is not difficult, and they are not picky about maintenance. With inverter devices, it is more difficult to determine a breakdown, and repairs at home are often impossible.

However, if handled properly, inverters last a long time and do not break down. It is necessary to protect from dust, high humidity, frost, and store in a dry place. There are the most typical malfunctions of welding machines that you can fix yourself.

The device does not start

In this case, first of all, you need to make sure that there is voltage in the network and the integrity of the fuses installed in the transformer windings. If they are in good condition, you should use a tester to ring the current windings and each of the rectifier diodes, thereby checking their performance.

If one of the current windings breaks, it will need to be rewinded, and if both are faulty, it is easier to replace the entire transformer. The damaged or “suspicious” diode is replaced with a new one. After repair, the welding machine is turned on again and checked for serviceability.

Sometimes the filter capacitor fails. In this case, the repair will consist of checking it and replacing it with a new part.

If all elements of the circuit are in working order, it is necessary to deal with the mains voltage, which can be greatly underestimated and is simply not enough for the normal functioning of the welding machine.

Electrode sticking (arc interruption)

The cause of electrode sticking and arc interruption may be a decrease in voltage due to a short circuit in the transformer windings, faulty diodes or loose connecting contacts. A breakdown of the capacitor filter or short circuit of individual parts to the body of the welding machine is also possible.

Organizational reasons due to which the machine does not weld as it should include the excessive length of welding wires (more than 30 meters).

If sticking is accompanied by a strong hum from the transformer, this also indicates an overload in the load circuits of the device or a short circuit in the welding wires.

One of the repair options to eliminate these effects could be restoring the insulation of connecting cables, as well as tightening loose contacts and terminal blocks.

Spontaneous shutdown

In some cases, repairs can be carried out independently if the device begins to turn off spontaneously. Most models of welding machines are equipped with a protective circuit (automatic) that is triggered in a critical situation, accompanied by a deviation from normal operation. One of the options for such protection involves blocking the operation of the device when the ventilation module is turned off.

After spontaneous shutdown of the welding machine, first of all, you should check the state of the protection and try to return this element to working condition.

If the protective unit is triggered again, it is necessary to proceed to troubleshooting using one of the methods described above related to short circuits or malfunctions of individual parts.

In this situation, first of all, you should make sure that the cooling unit of the unit is working normally and that overheating of the internal spaces is excluded.

It also happens that the cooling unit does not cope with its functions due to the fact that the welding machine was under a load for a long time that exceeded the permissible norm. The only correct solution in this case is to let it “rest” for about 30-40 minutes, and then try to turn it on again.

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In the absence of internal protection, a circuit breaker can be installed in the electrical panel. To maintain normal functioning of the welding unit, its settings must correspond to the selected modes.

Thus, some models of such devices (welding inverter, in particular), in accordance with the instructions, must work according to a schedule that requires a break of 3-4 minutes after 7-8 minutes of continuous welding.

Malfunctions of inverter devices

Before repairing an inverter welding machine with your own hands, it is advisable to familiarize yourself with the principle of operation, as well as its electronic circuit. Knowing them will allow you to quickly identify the causes of breakdowns and try to eliminate them in a timely manner.

Electrical diagram

The operation of this device is based on the principle of double conversion of the input voltage and obtaining a direct welding current at the output by rectifying the high-frequency signal.

The use of an intermediate high-frequency signal makes it possible to obtain a compact pulse device that has the ability to effectively regulate the output current.

Failures of all welding inverters can be divided into the following types:

malfunctions associated with errors in choosing the welding mode;
operational failures caused by failure of the electronic (converter) module or other parts of the device.

The method for identifying inverter malfunctions associated with disturbances in the operation of the circuit involves sequential execution of operations carried out according to the principle “from simple damage to more complex damage.” The nature and cause of breakdowns, as well as repair methods, can be found in more detail in the summary table.

It also provides data on the main welding parameters, ensuring trouble-free (without turning off the inverter) operation of the device.

Features of operation

Maintenance and repair of inverter-type welding machines differs in a number of features related to the complexity of the circuitry of these electronic units. Repairing them will require certain knowledge, as well as the ability to handle measuring instruments such as a digital multimeter, oscilloscope and the like.

In the process of repairing an electronic circuit, a visual inspection of the circuit boards is first carried out in order to identify burnt or “suspicious” elements within individual functional modules.

If during the inspection no violations can be detected, the troubleshooting continues by identifying violations in the operation of the electronic circuit (checking voltage levels and the presence of a signal at its control points).

To do this, you will need an oscilloscope and a multimeter, which you should start working with only if you have complete confidence in your abilities. If you have any doubts about your qualifications, the only right decision is to take (take) the device to a specialized workshop.

Specialists in the repair of complex pulse devices will quickly find and eliminate the malfunction, and at the same time carry out maintenance of this unit.

Self-repair procedure

If you decide to repair the board yourself, we recommend using the following advice from experienced specialists.

If burnt wires and parts are discovered during a visual inspection, you should replace them with new ones, and at the same time reconnect all connectors, which will eliminate the possibility of loss of contact in them.

If such repairs do not lead to the desired result, you will have to begin a block-by-block examination of the electronic signal conversion circuits.

To do this, it is necessary to find sources that provide voltage and current diagrams intended for a more complete understanding of the operation of this unit.

Focusing on these diagrams using an oscilloscope, you can sequentially check all electronic chains and identify a node in which the normal signal conversion pattern is disrupted.

One of the most complex components of an inverter welding machine is the electronic key control board, the serviceability of which can be checked using the same oscilloscope.

If you have doubts about the functionality of this board, you can try replacing it with a working one (from another, working inverter) and try to start the welding machine again.

If the outcome is favorable, all that remains is to send your board for repair or replace it with a purchased new one. The same should be done if there are suspicions about the serviceability of all other modules or blocks of the welding machine.

In conclusion, let us recall that the repair of any welding units (and inverters, in particular) is considered a rather complex procedure that requires certain skills and the ability to handle complex measuring equipment.

If you have the slightest doubt about your professionalism, you should use the help of specialists and give them the opportunity to return the faulty device to work.

Source: https://svaring.com/welding/apparaty/remont-svarochnyh-apparatov

Repair of welding inverters: device malfunctions and how to check a semi-automatic machine

Many home workshops are equipped with welding equipment based on an inverter power supply. Such products have many advantages. However, from time to time any equipment breaks down and repair of welding inverters may be required.

Such an operation can be easily performed at home, since the internal layout of the inverter installation for igniting the arc is easy to diagnose and maintain. The success of correcting inverter welding faults depends, first of all, on the skills and knowledge of the repairman.

Features of welding inverters and their repair

The inverter-type semi-automatic welding machine has a number of features and advantages.

Most users of such welding devices note:

high installation power;
mobility of the device;
ease of maintenance;
reliability of the inverter design;
minimum consumption of electrical energy when performing work on welding metal products.

A characteristic feature of inverter welding devices is a more complex electrical circuit compared to transformer or rectifier welding.

Inverter for welding work.

Repair of inverter welding machines should begin by checking the following elements:

transistors;
diode bridge;
cooling system.

Before you repair welding machines yourself, you need to diagnose the main components. Typically, faulty parts, such as transistors or diodes, can be easily identified by a significant change in geometry.

If such parts can be identified visually, then restoring a welding machine with your own hands will come down to a banal replacement of faulty electrical elements using a soldering iron and solder.

Most models of inverter welding machines come with instructions. It is easier to carry out maintenance of these devices using the diagrams available in the corresponding section of the documentation.

Diagnosis of inverter faults

Immediately before restoring the functionality of inverter welding equipment, you should familiarize yourself with typical faults and the most effective diagnostic methods.

In most cases, repair of semi-automatic welding machines should be carried out according to the following algorithm:

Visual inspection of all inverter components.
Cleaning oxidized contacts using a solvent and a brush.
Studying the design of the inverter using the documentation included in the kit.
Fault diagnosis.
Replacement of non-working electronic components.
Test run.

Functional diagram of a welding inverter.

All malfunctions that may require DIY repair of welding machines are divided into three types:

arising due to incorrect choice of welding mode;
arising due to a malfunction of one of the elements of the electronic circuit of the device;
caused by dust or foreign objects entering the housing of the inverter power supply.

Before checking the welding machine for faulty radio components, you should completely clean it of dust and dirt. Clogging of the cooling elements of the arc support system can adversely affect the performance of many electronic components.

If a preliminary visual check does not reveal any malfunctions, then you should proceed to a more in-depth diagnosis.

Typical reasons for inverter failure are presented:

liquid entering the inverter housing, resulting in oxidation of the conductive paths and corrosion of the main radio elements;
an abundance of dust and dirt inside the case, as a result of which the cooling significantly deteriorated and the power microcircuits overheated;
overheating of the inverter due to the selection of an incorrect operating mode, which may require repair of welding rectifiers.

Repairing a welding transformer, unlike an inverter, can be performed without significant skills and abilities. Transformer assemblies use radioelements that have an incredibly long life cycle.

The repair technique for the converter and other key components of the inverter current source will be shown in the next section.

Main types of breakdowns and their elimination

Before considering the main types of malfunctions of inverter devices, you should familiarize yourself with the inverter device.

Electrical circuit of a welding inverter.

Recommendations for DIY repairs

Electrical circuit of the welding machine.

When repairing inverter-type welding machines, you should adhere to a certain algorithm:

If a malfunction occurs, you must immediately disconnect the electrical device from the network, allow it to cool, and only then open the metal casing.
Diagnostics must begin with a visual inspection of the electrical components of the inverter.
There are often cases when repairing an inverter welding machine involves simply replacing damaged parts or soldering conductive contacts. Visually enlarged capacitors or cracked transistors should be replaced first.
If, during a visual inspection, it was not possible to determine the cause of the malfunction of the welding machine, you need to proceed to checking the parameters of the parts using a multimeter, voltmeter and oscilloscope.
The most common breakdowns of power units are associated with malfunction of transistors.
After replacing the electrical elements, it is worth moving on to checking the printed conductors located on the inverter board.
If you find torn or damaged tracks on the printed circuit board of a welding tool, you must immediately eliminate the defect by soldering jumpers or restoring the tracks using copper wire of the required cross-section.
After completing work with the tracks, it makes sense to move on to servicing the connectors.
If the inverter device stopped working gradually, then there may be poor contact in the connecting connectors. In this case, it is enough to measure all contacts with a multimeter and clean the connectors with an ordinary household eraser.
Despite the fact that malfunctions of a welding inverter are rarely associated with diode bridges, it would be a good idea to check their performance.
It is better to diagnose this electrical element in a soldered state. If all the legs of the bridge are short-circuited, then you should search for the faulty diode and replace it.
The last step in inverter repair is checking the board and control panels.
Diagnostics of all components of the board should be carried out using a high-resolution oscilloscope.

When performing independent repair work, you should not forget about the safety rules:

Do not use electrical appliances without a protective top casing;
all diagnostic and repair work should be carried out on completely de-energized equipment;
It is safest to remove accumulated dust and dirt using an air flow generated by a compressor or a compressed gas cylinder;
Cleaning of printed circuit boards must be done using neutral solvents applied to a special brush;
Long-term storage of electrical appliances should be done in dry rooms and completely switched off.

Most inverter electrical appliances are supplied complete with accompanying documentation. In these papers you can find a description of the most common faults and repair methods. Therefore, if malfunctions occur, you should carefully study the documentation and only then begin repair work.

Conclusion

Self-repair can be done at home. The main malfunctions of inverters are associated with the choice of the wrong operating mode or failure of radio elements.

Some malfunctions of semi-automatic welding machines can be determined visually. There are only a few reasons why the welding inverter does not turn on. Most causes of failure of a working inverter are associated with burnt capacitors or broken welding transistors.

Source: https://tutsvarka.ru/oborudovanie/remont-svarochnyh-invertorov

Do-it-yourself repair of inverter welding machines

The difference between an old welding transformer and a new inverter welder is about the same as between the first Daimler Benz cars and a modern Mercedes.

The inverter is much lighter than its heavy-duty predecessor and has built-in functions that previously could only be dreamed of, for example, the ability to control the welding current value or a function to prevent electrode sticking.

But the brilliantly conceived idea has a significant drawback - the electronic filling fails much more often than the “oldies”, and repairing inverter welding machines requires considerable knowledge and skills. Any attempt to repair equipment blindly, without preparation, is fraught with fire or even injury.

Of course, situations where an electronic welding machine burns out like a candle and cannot be repaired further are extremely rare. In practice, repairing a welding machine can be much simpler than it seemed at first. In 90% of cases, power circuits fail, and in 50%, sensitive control elements of the circuit fail. But in order to repair inverter welding machines with your own hands, desire is not enough; at a minimum, you will need the following equipment:

In addition to the above, the work may require a syringe for pumping out solder, a brush, alcohol, a magnifying glass, a strong flashlight, an incandescent lamp with wires, and, of course, reference books for ordering spare parts.

It’s not a fact that you will need an oscilloscope to repair a welding machine yourself, but in particularly difficult cases you simply cannot do without it.

Before opening the device and delving into the details of the breakdown, you need to find out two main details from the welder. Firstly, it is necessary to find out how and under what conditions the welding inverter broke down, and secondly, whether there were attempts to carry out repairs by other specialists.

The problem is that “hobbyists” often replace factory parts with the first components that come to hand. Without a diagram, it is very difficult to restore the value and brand of a part, which is extremely important for high-quality repair of a welding machine.

The welding machine restoration process is carried out in three stages:

Disassembling the device and inspecting internal damage;

Consistent diagnosis and elimination of identified problems;

Testing and checking the performance of the welding machine not by spark, as most amateurs do, but by a high-power ballast rheostat.

Often, amateur repairs of welding machines end with checking whether the arc lights or not. Using a rheostat allows you to check one of the main performance parameters of a welding inverter - the ability to regulate and adjust the welding current under load.

Before you begin repairs, you need to understand and find out for yourself how the device works and what are the features of its operation. For example, look at a typical diagram or block diagram, then it will become clear what and where is on the board.

Stage one, we determine the problems by external inspection of the board

To gain access to the internal filling of the welding unit, it is necessary to free the electronic board from the housing and the power cord.

To disassemble, you need to remove two or four screw or self-tapping fastenings of the housing and pull out the wires from the connecting chips. For repairs, a bare circuit board is left, studded with electronic parts. First of all, we inspect it, trying to identify burnt or damaged elements critical for repair, burnt board tracks, black resistors and swollen capacitors.

In the vast majority of cases, the following elements of the welding machine board fail and must be repaired:

A powerful ballast resistance that discharges capacitors in the power block of the circuit. If the power supply is working properly, then when you try to turn on the welding machine, the capacitors will instantly gain a rather large capacity and a voltage of 300V. If during repairs, in the absence of a resistor, you turn on the welding machine and accidentally touch the terminals with your hands, you will receive an extremely painful electric shock, almost like an electric shock;
Field effect transistors. They are easy to find and are always mounted on massive aluminum radiators. If the resistance burns out, repair and replacement of at least one of the transistors is almost always required;
If the welding current is not regulated, then most likely the driver, one of its channels, or the operational amplifier included in the control circuit will need to be repaired.

Of course, the above list for repairs is the most common, but not exhaustive. For example, a temperature sensor that monitors overheating of the welding machine, a current transformer working in tandem with an op-amp, elements of an input diode bridge, and much more may burn out. Therefore, repairing a welding machine must begin with testing the elements along the circuit.

The second stage of repair, we check the circuits by testing

During repairs, you need to check the most loaded elements of the board. We turn it over with the back side up and use the sharp probes of the tester, piercing through the layer of protective varnish, to check for a short circuit. First, let's check whether the rectifier diode bridge at the output is broken. Repairing diodes is a rather rare thing, unless water gets inside the welding machine or a short circuit occurs on the cord. We measure the bridge at the entrance in the same way.

After the power supply, we move on to the most critical places in the power part of the circuit. This is a pair of powerful capacitors and field-effect transistor switches. To repair, it is necessary to establish the presence of resistance between the collector and the emitter, or more correctly, the drain-drain, drain-gate transitions. In 99% of cases, field-effect transistors fail first, resulting in a short circuit between the collector and drain.

Besides them, the second candidate for repair and replacement is the welding machine board driver. But repairing it will require very serious skills and knowledge. Therefore, if, after replacing the transistors, faults are identified in the driver channels, it is better to entrust its repair to a more qualified specialist.

How to check driver integrity

Looking ahead, we can say that after dismantling the keys or field-effect transistors, the need for driver repair is initially determined by the state of the reference resistors connecting the driver channel to the gate of the field-effect transistor - the switch.

To do this, simply trace the path with your finger along the board from the gate location to the first resistor.

We check it for an open circuit; if the resistances of the resistors in each channel are approximately the same, then we can assume that the control device is 99% in working condition.

Otherwise, you will have to contact a specialist to repair the welding machine.

The simplest repair of a welding machine

To repair the unit, you will need to remove the old transistors and replace them with new parts. Each key is attached to a massive aluminum radiator with a bolt. After removing the bolts, unscrew the screws securing the radiators.

For repairs, you will need to carefully desolder the field-effect transistor using a soldering station hair dryer; this is done with the utmost care so as not to damage the tracks and mounted mounting.

When soldering, the transistor must come out without force, otherwise the tracks will rise, and the cost of repairing the welding machine may jump several times. The desoldering area must be freed from solder using a blower or syringe and cleaned of burnt varnish.

Before installing new field-effect transistors - switches, you need to repair the ballast resistance. Instead of the old resistor, we solder a new part at 47 Ohm, 10 W. In addition, we call the capacitors and suppressors installed according to the scheme on the field paths.

To continue the repair, it is necessary to check the shape and size of the signal coming through each driver channel to the gates of its switch - a field-effect transistor.

Before connecting the oscilloscope, it is recommended to connect a capacitor of several hundred picofarads between the drain and the gate, thereby simulating the gate capacitance of the transistor.

This method allows, during the restoration of the welding machine board, to optimally load each driver channel, so the signal arrives in the form in which it exists in real conditions during welding work.

After soldering the capacitors, the oscilloscope probes are connected, and the power to the welding machine board is turned on.

The shape of the signal confirms that the repair was performed correctly; the gates of the transistors receive a signal from the driver of the required shape and size.

All that remains is to attach the new field-effect transistors with heat-removing paste applied to the aluminum radiators. Radiators are installed on the board, and the legs of the transistors are soldered one by one. The restoration of the welding machine is almost complete, all that remains is to test the device.

DIY welding inverter repair

Inverter-type welding machines are common models due to their mobility and the ability to operate from almost any supply voltage in the range from 175 V to 240 V. However, cases of welder failure are possible. There are many causes of breakdowns, and to repair welding inverters you need to know the main faults, structure and operating principle. It is not difficult to repair inverter welding machines with your own hands.

General information about inverters

Transformer welding machines have a low cost compared to inverter welding devices and are simple in design, allowing for simple repair operations. The main disadvantages include their dimensions, weight and sensitivity to the parameters of the power supply network. At low voltage values (U), it is almost impossible to cook, since the power consumed by the device increases significantly, and electricity meters have a power limit of up to 6 kW.

As a result of this, the protection is triggered: the machine is triggered after a certain time due to heating or the fuses on the plugs burn out. If you install a circuit breaker with a higher value or use a “bug” (bypassing the fuse with a copper wire of a larger diameter), then the likelihood of a wiring fire increases.

In addition, when working with ordinary transformer welding, short-term changes in the U value occur, due to which other equipment and household appliances may fail. Transformer welding machines are relatively inexpensive and very easy to repair due to their simple design.

However, they have significant weight and are very sensitive to supply voltage (U). At low U, it is simply impossible to carry out welding work, since significant changes in U occur, as a result of which household appliances can fail. To avoid all these inconveniences during work, inverter devices are used.

Design and operating features

Inverter welding is used at home and in various enterprises. It ensures stable burning of the welding arc at high-frequency current. The device is designed as a powerful switching power supply (UPS), the operation of which is based on the principles of:

Converting alternating supply (mains) U into constant.
Conversion of direct to alternating high-frequency current.
Current rectification while maintaining frequency.

If you follow these design principles, then there is a significant reduction in the welder by several hundred or thousand times. In addition, such a device allows you to equip the device with additional cooling.

To carry out high-quality repairs of a welding inverter, you need to know the structure and principle of operation. Thanks to understanding the work, it is possible to correctly diagnose, find out the cause of the malfunction and eliminate it yourself. An inverter-type welding machine consists of main components (Figure 1):

Rectifier.
Inverter.
Transformer.
High frequency rectifier.
Control circuit (electronic regulator).

Figure 1 - Block diagram of a welding inverter.

The rectifier consists of a semiconductor rectifier bridge and a filter made on a capacitor. The diode bridge rectifies the alternating current of the industrial supply network. When alternating current passes through a diode, current flows in one direction.

As a result, the current becomes constant, but it is dominated by significant ripples. Current with such parameters is not suitable for powering the inverter, since it only operates on direct current. To smooth out ripples, a large capacitor (2200.

5000 µF).

Source: https://pochini.guru/remont/svarochnyih-invertorov

How to check a welding inverter when purchasing - Metalworker's Guide

Inverter welding machines are designed for manual arc welding. Such devices will be especially interesting to novice welders. There are several reasons for this: ease of operation, decent quality of the weld and not the largest dimensions of the device.

THIS IS INTERESTING: What can be done with a soldering iron

However, now you can easily fall for the bait of sales consultants trying to sell stale goods. Typically, such units do not cope with their task as well as we would like. Therefore, do not listen to such people! Instead, check out this article for the best welding inverters.

Believe me, none of the models reviewed will disappoint you!

Aurora

The Aurora brand produces a wide variety of equipment intended for construction and repair work. Among other things, the range also includes welding machines. Any equipment has a warranty period of one to two years. Manufacturer service centers can be found in approximately 60 regions of Russia.

Blueweld

Blueweld was founded in 1963. Quite quickly, its products penetrated the markets of Germany, France, Austria and many other European countries. And now Blueweld welding inverters are in great demand even in Asia, South America and Africa. It is assumed that this company produces the most similar devices.

Daewoo

The South Korean company Daewoo has been reporting its history since 1967. In 1999 it was abolished. However, individual divisions of this chaebol still continue to operate, producing products under the famous brand. In particular, now you can easily buy Daewoo welding machines and other devices that help in construction.

Elitech

The Elitech brand produces a huge number of tools and other devices needed in the construction and repair business. Although the trademark belongs to a Russian company, the products are of quite European quality. All products have a long service life, and any builder or mechanic will be satisfied with the functionality.

FUBAG

The German company FUBAG has been producing equipment for repair and construction work for more than 40 years. Its products are used by specialized services around the world. For example, in Russia, the Ministry of Emergency Situations made its choice in favor of FUBAG. Isn't this what best shows the level of quality?

Patriot

The American company Patriot was founded in 1973. The company specializes in the production of gas and electric tools, not forgetting other devices needed in construction and repair. The range of Patriot welding inverters is not very wide, but the models included in it do not cost the most money. Almost all of them have a signature orange color.

Interskol

Interskol power tools are very popular among Russians. People like low prices and decent features. And builders and mechanics often use Interskol welding machines. They can often be purchased at a big discount, and such devices are in no way inferior to their foreign counterparts. This is confirmed by our selection, which includes one of the products of the Russian company.

Resanta

The Resanta brand produces a large number of products needed by electricians, mechanics, builders and other professionals in their field. The company's assembly line produces both portable devices (for example, multimeters) and stationary ones (heat curtains). Large appliances that are still portable can be brought into the intermediate section. In particular, such devices are welding machines.

best welding inverters

This rating, based on user reviews, took into account:

Welding current and its adjustment range;
Maximum electrode diameter;
Power;
Complaints about breakdowns;
Input voltage;
Weight and dimensions.

Resanta SAI-220

The insides of the Resant SAI-220 are located under a silver aluminum body. This specimen weighs 5 kg, which allows you to move it with your own hands over a fairly large distance. The main feature of the device is IP21 protection - it is not afraid of dust or light splashes. However, it is still not recommended to work with this inverter in the rain.

Advantages:

Welding current varies from 10 to 220 A;
The input voltage can range from 140 to 260 V;
The device operates using single-phase power;
The electrode diameter (5 mm) is sufficient in most cases;
The device has a protection class of IP21;
Light weight (5 kg);
Presence of hot start and anti-stick.

Flaws:

There is no storage case included;
Weak current regulator - it can be turned by accidental touch;
The fan is made of fragile plastic.

Reviews of the Resanta SAI-220 show that this welding machine is well worth the money invested in its purchase. It has certain disadvantages, but they all pale in comparison to the opportunities it provides.

Source: https://ssk2121.com/kak-proverit-svarochnyy-invertor-pri-pokupke/

DIY inverter welding machine repair

Repair of welding inverters, despite its complexity, in most cases can be done independently. And if you have a good understanding of the design of such devices and have an idea of what is most likely to fail in them, you can successfully optimize the costs of professional service.

Replacing radio components during repair of a welding inverter

Purpose of the equipment and features of its design

The main purpose of any inverter is to generate direct welding current, which is obtained by rectifying high-frequency alternating current.

The use of high-frequency alternating current, converted by means of a special inverter module from rectified mains power, is due to the fact that the strength of such current can be effectively increased to the required value using a compact transformer.

It is this principle underlying the operation of the inverter that allows such equipment to have compact dimensions with high efficiency.

Functional diagram of the welding inverter

The welding inverter circuit, which determines its technical characteristics, includes the following main elements:

a primary rectifier unit, the basis of which is a diode bridge (the task of such a unit is to rectify alternating current coming from a standard electrical network);
an inverter unit, the main element of which is a transistor assembly (it is with the help of this unit that the direct current supplied to its input is converted into alternating current, the frequency of which is 50–100 kHz);
a high-frequency step-down transformer, on which, by lowering the input voltage, the output current significantly increases (thanks to the principle of high-frequency transformation, a current of up to 200–250 A can be generated at the output of such a device);
output rectifier assembled on the basis of power diodes (the task of this inverter block is to rectify alternating high-frequency current, which is necessary for welding work).

The welding inverter circuit also contains a number of other elements that improve its operation and functionality, but the main ones are those listed above.

Features of maintenance and repair of inverter devices

Repairing an inverter-type welding machine has a number of features, which is explained by the complexity of the design of such a device. Any inverter, unlike other types of welding machines, is electronic, which requires specialists involved in its maintenance and repair to have at least basic radio engineering knowledge, as well as skills in handling various measuring instruments - a voltmeter, digital multimeter, oscilloscope, etc. .

During the process of maintenance and repair, the elements that make up the welding inverter circuit are checked. This includes transistors, diodes, resistors, zener diodes, transformer and choke devices. The peculiarity of the inverter design is that very often during its repair it is impossible or very difficult to determine which element failure caused the malfunction.

A sign of a burnt resistor may be a small deposit on the board, difficult to discern by the inexperienced eye.

In such situations, all details are checked sequentially. To successfully solve such a problem, you must not only be able to use measuring instruments, but also have a fairly good understanding of electronic circuits. If you do not have such skills and knowledge, at least at an initial level, then repairing a welding inverter with your own hands can lead to even more serious damage.

Having really assessed your strengths, knowledge and experience and decided to undertake independent repair of inverter-type equipment, it is important not only to watch a training video on this topic, but also to carefully study the instructions in which manufacturers list the most typical malfunctions of welding inverters, as well as ways to eliminate them.

Factors leading to failure of the welding inverter

Situations that can cause the inverter to fail or lead to disruptions in its operation can be divided into two main types:

associated with incorrect choice of welding mode;
caused by failure of device parts or their incorrect operation.

The method for identifying an inverter malfunction for subsequent repair comes down to sequential execution of technological operations, from the simplest to the most complex. The modes in which such checks are performed and what their essence is are usually specified in the equipment instructions.

Common inverter malfunctions, their causes and solutions

If the recommended actions do not lead to the desired results and the operation of the device is not restored, most often this means that the cause of the malfunction should be sought in the electronic circuit. The reasons for the failure of its blocks and individual elements may be different. Let's list the most common ones.

Moisture has penetrated into the inside of the device, which can happen if the body of the device is exposed to precipitation.
Dust has accumulated on the elements of the electronic circuit, which leads to a disruption in their proper cooling. The maximum amount of dust gets into inverters when they are operated in very dusty rooms or on construction sites. To avoid this condition, the inside of the equipment must be cleaned regularly.
Failure to comply with the on-time (ON) can lead to overheating of the electronic circuit elements of the inverter and, as a consequence, to their failure. This parameter, which must be strictly observed, is indicated in the technical data sheet of the equipment.

Traces of liquid entering the inverter housing

Common faults

The most common faults encountered when operating inverters are the following.

Unstable burning of the welding arc or active spattering of metal

This situation may indicate that the current strength for welding is incorrectly selected. As is known, this parameter is selected depending on the type and diameter of the electrode, as well as on the speed of welding work.

If the packaging of the electrodes you are using does not contain recommendations on the optimal current value, you can calculate it using a simple formula: per 1 mm of electrode diameter there should be 20–40 A of welding current.

It should also be taken into account that the lower the welding speed, the lower the current should be.

Dependence of electrode diameter on welding current strength

Electrode sticking to the surface of the parts being connected

This problem can be due to a number of reasons, most of which are due to low supply voltage. Modern models of inverter devices operate at reduced voltage, but when its value drops below the minimum value for which the equipment is designed, the electrode begins to stick. A drop in voltage at the equipment output can occur if the device blocks are in poor contact with the panel sockets.

This reason can be eliminated very simply: by cleaning the contact sockets and more tightly fixing the electronic boards in them. If the wire with which the inverter is connected to the electrical network has a cross-section of less than 2.5 mm2, this can also lead to a voltage drop at the input of the device. This is guaranteed to happen even if such a wire is too long.

If the length of the supply wire exceeds 40 meters, it is almost impossible to use an inverter for welding, which will be connected with its help. The voltage in the supply circuit may also drop if its contacts are burnt or oxidized. A common cause of electrode sticking is insufficient preparation of the surfaces of the parts being welded, which must be thoroughly cleaned not only of existing contaminants, but also of oxide film.

Selection of welding cable cross-section

Inability to start the welding process when the machine is turned on

This situation often occurs when the inverter apparatus overheats. The control indicator on the device panel should light up. If the glow of the latter is barely noticeable, and the inverter does not have a sound warning function, then the welder may simply not be aware of overheating. This state of the welding inverter is also typical when the welding wires break or spontaneously disconnect.

Spontaneous shutdown of the inverter when welding

Most often, this situation occurs when the supply voltage is turned off by circuit breakers whose operating parameters are incorrectly selected. When working with an inverter device, circuit breakers rated for a current of at least 25 A must be installed in the electrical panel.

Inability to turn on the inverter when turning the toggle switch

Most likely, this situation indicates that the voltage in the supply network is too low.

Automatic inverter shutdown during prolonged welding

Most modern inverter devices are equipped with temperature sensors that automatically turn off the equipment when the temperature in its internal part rises to a critical level. There is only one way out of this situation: give the welding machine a rest for 20–30 minutes, during which it cools down.

How to repair an inverter device yourself

If after testing it becomes clear that the cause of malfunctions in the operation of the inverter device lies in its internal part, you should disassemble the case and begin to inspect the electronic filling. It is quite possible that the reason lies in poor-quality soldering of the device parts or poorly connected wires.

A careful inspection of electronic circuits will reveal faulty parts that may be darkened, cracked, with a swollen case or have burnt contacts.

Burnt parts on the Fubac IN-160 inverter board (AC-DC regulator, 2NK90 transistor, 47 Ohm resistor)

During repairs, such parts must be desoldered from the boards (it is advisable to use a soldering iron with suction for this), and then replaced with similar ones. If the markings on faulty elements are not readable, then special tables can be used to select them. After replacing faulty parts, it is advisable to test the electronic boards using a tester. This is especially necessary if the inspection did not reveal elements that need to be repaired.

Visual inspection of the electronic circuits of the inverter and their analysis using a tester should begin with the power unit with transistors, since it is this that is the most vulnerable. If the transistors are faulty, then most likely the circuit that drives them (driver) has also failed. The elements that make up such a circuit also need to be checked first.

After checking the transistor block, all other blocks are checked, for which a tester is also used. The surface of printed circuit boards must be carefully inspected to determine the presence of burnt areas and breaks. If any are found, then you should thoroughly clean such places and solder jumpers on them.

If burnt or torn wires are found in the inverter filling, then during repairs they must be replaced with similar cross-sections. Although the diode bridges of the inverter rectifiers are quite reliable elements, they should also be tested using a tester.

The most complex element of the inverter is the key control board, the serviceability of which determines the performance of the entire device. Such a board is checked using an oscilloscope for the presence of control signals that are supplied to the gate buses of the key block. The final stage of testing and repairing the electronic circuits of the inverter device should be checking the contacts of all available connectors and cleaning them using a regular eraser.

Self-repair of an electronic device such as an inverter is quite complicated. It is almost impossible to learn how to repair this equipment simply by watching a training video; for this you need to have certain knowledge and skills. If you have such knowledge and skills, then watching such a video will give you the opportunity to make up for your lack of experience.

Source: http://met-all.org/oborudovanie/svarochnye/remont-svarochnyh-invertorov-svoimi-rukami.html