The welding inverter turns off and the heat sensor lights up. How to repair a welding inverter with your own hands. Features of welding inverters and their repair

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.

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 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. Must be protected from dust high humidity, frost, 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 working order, 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 short circuit in the transformer windings, faulty diodes or loose connecting contacts. A breakdown of the capacitor filter or a short circuit is also possible. individual parts on the body of the welding machine.

Organizational reasons due to which the device does not cook as it should include excessive length 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 protective circuit(automatic), triggered in a critical situation, accompanied by 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 internal spaces 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 exceeding 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.

In the absence of internal protection, the safety circuit breaker can be installed in 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 constant 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.

Breakdowns of all welding inverters can be roughly 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 faults 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 welding machines inverter type 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 such measuring instruments, How digital multimeter, oscilloscope and the like.

Under renovation electronic circuit produced first visual inspection boards 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.

Complex repair specialists pulse devices They will quickly find and eliminate the malfunction that has arisen, and at the same time carry out maintenance of this unit.

Self-repair procedure

If a decision is made to self-repair fees - we recommend using the following tips 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.

Welding inverter is modern equipment, the use of which in the welding process makes it possible to achieve very High Quality work and provides the welder with the opportunity to work in comfortable conditions. But at the same time, the welding inverter also has a more complex design, compared to previous models of welding equipment, which increases the chance of a malfunction occurring during its operation.

As a rule, all malfunctions of the welding inverter can be divided into two groups:

• malfunctions associated with improper operation of the electronic “stuffing” of the device

• malfunctions associated with incorrect choice of operating mode.

The second type of malfunction occurs most often, therefore, before contacting a specialized workshop or starting to disassemble the device yourself in order to identify a breakdown, you need to check whether all operating mode settings are set correctly, and in addition, you should read the operating instructions for this device again, to determine if you are making any mistakes while working. Most manufacturers, when drawing up instructions, indicate the causes of welding inverter malfunctions that may occur during operation, and also describe how these malfunctions can be eliminated independently.

Causes of breakdowns of welding inverters and options for eliminating them.

There are a number typical faults, which arise when we're talking about about welding inverters:

• combustion instability welding arc and strong metal splashing;
• sticking welding electrode;
• lack of welding process when the machine is turned on;
• lack of response from the device when it is turned on.

Let us consider in more detail why this or that situation may arise, and what can be done in the event of any malfunction of welding inverters.

• Instability of the welding arc and strong spattering of metal.

This malfunction can occur if you select the wrong current when welding. Usually, welding current is selected in accordance with the type and size of the electrode used for welding. But here it is necessary to remember one more thing important rule: the selected current must correspond to the speed at which welding is carried out. If the welding speed decreases during operation, then the welding current must be reduced.

• Welding electrode sticking.

In fact, there may be several reasons for this type of malfunction. It is quite possible that during welding the voltage in the network suddenly decreased, which led to severe sticking of the welding electrode. It can also “stick” if the inverter is connected to the network with a cable with a cross-section that is too small. Another reason for this “behavior” of the electrode may be poor contact of the electrode with the surface to be welded due to the fact that the surface has undergone oxidation due to exposure to atmospheric oxygen. In this case, welding must be stopped and the surface of the part must be cleaned of film.

• Lack of welding process when the machine is turned on.

In the vast majority of cases, this behavior of the welding inverter can be explained by the lack of mass on the surface of the part being welded. In addition, it would be useful to check the condition of the welding cable - it may be damaged. This situation occurs quite often if the part being welded is heavy, as a result of which the part falling onto the wire can damage its integrity.

• The device does not respond when turned on.

If nothing happens when you turn on the welding inverter, then the cause of such a malfunction should be sought, in many cases, not in the inverter itself, but in electrical network to which it is connected. The mains voltage may be too low and therefore the device cannot operate. Another reason that the device does not turn on may be an incorrectly selected circuit breaker, installed in the shield. A weak switch can turn off when the inverter is turned on. In addition, turning off the device can lead to a loss of electricity throughout the house.

In addition to the indicated malfunctions, there are also interruptions in the operation of the welding inverter, which are not related to the breakdown of the device, but are a consequence of the fairly high-quality and timely operation of the protection systems with which the inverter is equipped. So, for example, with long-term continuous operation The inverter may turn off spontaneously. This happens if the device overheats and the temperature protection trips. In this case, you should stop the welding process for about 20-30 minutes, allow the device to cool, after which work can be continued.

An inverter welder differs from a conventional welding machine in an easier and better welding process. However, malfunctions of the welding inverter, due to its more complex design, can be more serious and complex.

To determine the cause of a device failure, you need to diagnose it: check transistors, resistors, diodes, stabilizers, contacts, etc. Each device is supplied with detailed instructions with a description of the most common faults that you can fix yourself. However, very often repairs may require special equipment: ohmmeter, voltmeter, multimeter, oscilloscope. And you need to know how to use them. And in special cases, knowledge of electronics and the ability to work with electrical circuits are required. Therefore, if self-checking and eliminating simple faults described below did not lead to success, it is better to entrust the repair of the inverter apparatus to the specialists at the service center.

What are the types of inverter malfunctions?

There are several groups of breakdowns of welding inverters:

• malfunctions arising due to non-compliance with the welding workflow standards specified in the instructions;
• malfunctions arising as a result of proper operation or failure of device elements;
• breakdowns resulting from moisture, dust and foreign objects entering the device.

Return to contents

Common faults that you can fix yourself

Let's look at some of the most common malfunctions of welding inverters:

To identify and eliminate the cause of the malfunction, the body of the device is opened and a visual inspection of its contents is carried out.

1. The welding arc burns unsteadily or the electrode spatters material heavily. The reason for this may lie in wrong choice current The current strength must correspond to the type and diameter of the electrode and the speed of the welding process. If the current strength is not indicated on the electrode packaging, then you can start supplying current from 20-40 A for each millimeter of electrode diameter. When the welding speed is reduced, the current must also be reduced.
2. The electrode sticks to the material. This often happens due to low voltage in the network, the value of which is less than the minimum permissible when working with an inverter. The cause of electrode sticking can also be poor contact in the panel sockets, which can be eliminated by fixing the boards more tightly. Using an extension cord with a wire size smaller than 2.5 mm2 or with a wire that is too long (more than 40 m) may reduce the voltage. Burnt or oxidized contacts in an electrical circuit can also reduce the voltage.
3. There is no welding process, while the device is connected to the network. In this case, you need to check the presence of mass on the part being welded. Also check the inverter cable for damage.
4. The device turns off spontaneously. The device is switched off when the transformer is connected to the network, after which its protection is triggered. The reason for this may be a short circuit in the voltage circuit. The protection can be activated not only when the wires are shorted to each other or to the housing, but also when there is a short circuit between the turns of the coils or a breakdown of the capacitors. To repair a hollow part, you first need to disconnect the transformer and find the fault, and then insulate or replace the damaged element.

If there is no welding when the machine is turned on, check the connection of the electrode holder cable.

During prolonged operation, the device turned off. Most likely, this is not a breakdown, but an overheating of the inverter. You need to wait 20-30 minutes and then resume work. You should adhere to the rules for operating the device: do not overheat it, that is, take breaks in operation, connect the appropriate current values ​​to it, do not use electrodes of too large diameters.

The transformer makes a loud noise and overheats. Perhaps the reason for this was an overload of the transformer, loosening of the bolts that tighten the sheets of the magnetic core, or a breakdown of the core fastening. Due to a short circuit between the magnetic core sheets or cables, the device can also make a loud noise. Tighten all fastening elements and restore cable insulation.

Welding current is poorly regulated. The reason for this may be a breakdown in the current regulation mechanism: a fault in the current regulation screw, a short circuit between the regulator mounts, a short circuit in the inductor, poor mobility of the secondary coils as a result of clogging, etc. Remove the casing from the inverter and examine the current regulation mechanism to identify the breakdown.

The welding arc breaks off abruptly, and it is impossible to ignite it; only sparks appear. Perhaps the problem lies in the breakdown of the winding high voltage, short circuit between the wires or poor connection with the inverter terminals.

High current consumption at no load. The reason may be short circuit of the turns on the coil. It can be eliminated either by restoring the insulation or by completely rewinding the coil.

Return to contents

If excessive spattering of the electrode metal occurs during welding, the cause may be an incorrectly selected value of the welding current.

If a burning smell and smoke appear from the device body, this may indicate a serious breakdown. IN in this case You may need qualified repairs at a service center.

To identify the malfunction, first disassemble the housing. Carry out a visual inspection of parts for damage, cracks, burnt contacts and swelling of capacitors. They also check the soldering points of parts and contacts on the inverter boards. Often the causes of malfunctions lie precisely in poor-quality soldering; they can be easily eliminated by re-soldering the parts.

All faulty parts should be removed and replaced with new ones corresponding to the given model of the device.

You can select parts in accordance with the markings indicated on the device body or in a special reference book.

You need to solder the parts using a soldering iron that has a suction, which will make the work convenient and fast.

Equipment such as a welding machine has always been in demand. Especially if he small sizes, compact, operating at a voltage of 220 volts, which is very convenient when carrying out welding work in places where it is difficult to use bulky and powerful devices. For example, on construction sites, in car repair services, household appliances etc.

But, most importantly, the welding machine, the weight of which seems ridiculous for such equipment, sometimes it does not exceed 5 kg, due to its compactness and mobility it is easy to use when repairing personal equipment, construction individual houses, construction of some metal structures on summer cottages etc. In a word, such a welding baby will come in handy everywhere.

Now modern technologies allow to manufacture in wide range and a large number of compact and mobile welding machines that are used not only in industry, but also at home. You can practically buy them in any store for the sale of equipment. Big choice and the reasonable price of welding machines allow everyone to buy them without any problems.

Currently, welding machines are very popular. different models Latvian company Resanta. This is high quality equipment. In Russia, the demand for Resanta welding machines is very high. They are convenient to transport, because their size and weight allow you to transport equipment even in the trunk passenger car. And carry it over short distances by one person.

The advantages of Resanta were appreciated not only by professional welders, but also by amateurs who do not have sufficient experience in welding work.

The company produces two types of welding equipment: Resanta welding machine and Resanta welding inverter. The difference between them is that the first type is a transformer unit, and the second is an inverter unit. Both differ from each other in various respects.

However, no matter how reliable the device is, and no matter how much safety margin it has, sooner or later some part may fail and it will need repair. Just as there is no perpetual motion machine in nature, there are no perpetual mechanisms. Breakdowns are inevitable with both the Resanta welding machine and the Resanta inverter. Let's consider general signs and the reasons for both types of welding equipment from a Latvian company, leading to repairs.

Signs and causes of welding inverter breakdowns

Signs by which you can determine that the Resanta welding inverter repair required:

• electrode sticking
• instability electric arc
• lack of arc
• device overheating
• inverter does not turn on

Causes of malfunction

Electrode sticking occurs in the following cases:

• low voltage
• using an extension cord with a cross-section of less than 2.5 mm
• burnt contacts
• poor cable contact

Arc instability is caused by:

• incorrect adjustment of welding current
• mismatch between the type and diameter of electrodes

Lack of arc in caused by the following reasons:

• cable break
• inverter overheating
• lack of "mass"
• refusal printed circuit board where one or even several parts have failed

Device overheating can happen when:

• he works long time at full load without interruption
• cooling fan failed
• there is a large layer of dust on the printed circuit board parts

Reasons when the inverter does not start after pressing the “Start” button. those. does not start working, may be as follows:

• absent completely or low voltage nutrition
• something is faulty: cable, socket or switch
• Some element has broken down on the printed circuit board
• extension cord needs to be replaced

Welding machine breakdowns

Causes of breakdowns, because of which often welding units are being repaired:

Any manufacturer values ​​his reputation and will not produce low-quality products. However, no matter how good the assembly of the same welding machine, during operation from vibration, constant transportation, etc., the contacts on terminal blocks, to which the welding cables are connected, weaken. And as a result, strong heating of the parts occurs at the junction points, which leads to their destruction and short circuit in the network, and therefore to repair. To prevent this, you need to regularly monitor the contacts on the terminals, and, if necessary, sort out and clean the connecting contacts, thereby ensuring tight contact of all parts.

It often happens that the welding machine suddenly he can switch off on his own. And this happens because a short circuit has occurred in the high voltage circuit. In this case, it is necessary to identify the defective location and eliminate the malfunction.

Loosening of the bolts tightening the transformer plates, overloads in the operation of the transformer unit of the welding machine, as well as loosening of the core or the mechanism for moving the coils lead to overheating of the unit’s transformer.

If the welding machine overheats, then it needs to take a “break”. Equipment overheating is possible during his intense work. In such cases, to prevent the unit from malfunctioning, it is recommended to reduce the operating current or use electrodes of a smaller diameter, otherwise the matter may end in repair.

If the machine does not “pull”, the reason should be sought in the mains voltage or the welding current regulator.

Main types of repair work

Some minor breakdowns of Resanta can be repaired yourself, without the help of specialists. But it also happens that serious repairs are required. In this case it is best contact service center . There, for example, they can make a replacement:

• fan
• inverter boards
• transformer
• diode rectifier
• capacitors
• and other details

And carry out repairs:

• control boards
• power supply
• control module
• IMS module
• main board

To reduce repairs to your welding machine, try to operate it correctly. And then you won’t need to spend money on repairs often.

When buying an inverter welding machine for work in a garage or in a country house, the first thought is - wow, now I can cook everything! You do not need a welding diploma; the device is designed for users without special education. Handling welding has become easier and more comfortable. The main thing is to understand the principle of operation and first aid in case of difficulties and breakdowns.

Inverter machines - a new generation of manual welding

Since the beginning of 2000, inverter welding machines have become cheaper and more accessible. To spend at home welding work, all you need is this small and easy-to-use device and good electrodes.

Advantages of inverters

Inverter machines are lightweight, compact in size, and their scope of use and welding quality are higher than those of heavy and bulky welding transformers. They carry out their task in full: they weld cars, gates, pipe structures (for example, greenhouses or gazebos). Working with them is mobile - throwing an extendable belt over your shoulder, welding is carried out in any hard-to-reach places.

When vertical, horizontal or overhead welding, the current is reduced by 10–20%, and when welding at an angle, it is increased by the same amount compared to the normal position.

There are also no problems with the connection; the welding machine operates from a regular electrical network. It's great that it won't stop when going down mains voltage. If the deviation is within +/- 15%, the device will continue to operate normally. The current value can be adjusted by selecting the power depending on the type and thickness of the metal. All this makes inverters ideal for both beginners and professionals.

Video: testing a homemade inverter device

How welding inverters work

The inverter apparatus connects the parts DC using electric arc welding with a coated electrode. The big plus is that at the very beginning of the process there are no power surges in the network to which the device is connected. The storage capacitor ensures uninterrupted electrical circuit and soft ignition of the arc with its further automatic maintenance. When connected to electrical outlet AC mains voltage with a frequency of 50 Hz is converted first into direct voltage and then into high-frequency modulated voltage. Then, using a high-frequency transformer, the current increases, the voltage decreases, and the output current is rectified. The device provides adjustment of the welding current value and protection against overheating.

The inverter device first rectifies and modulates the input current, and then increases its strength by reducing the voltage until the arc appears

The basic operating mode of inverter welding machines is MMA. This is manual arc welding with piece coating electrodes. For welding steel and cast iron products permanently or alternating current use a diameter of 1.6–5.0 mm.

The devices differ in power and cycle time. The second indicator is the period during which it is allowed to cook at the maximum permissible power in order to prevent the device from overheating. It is designated by the letters PV (on period) and is determined as a percentage relative to a time unit of 10 minutes. For example, if the device indicates a PV of 60%, this means that it can be cooked for 6 minutes and then turned off for 4 minutes. Sometimes the welding cycle is set to 5 minutes. Then a PT value of 60% means a work period of 3 and a rest period of 2 minutes. PV and duty cycle indicators are indicated in the instructions for each device.

Welding machine design

In order not to look for a repair specialist at the first difficulties in the operation of the device, it is advisable to have at least a basic understanding of its design.

DIY inverter assembly diagram

Craftsmen with knowledge of electrical engineering assemble the welding machine themselves. Not only for the sake of economy, but also at the behest creative soul. Posted on the Internet circuit diagrams inverters, drawings and instructions from those who made the inverter themselves. The main thing is to get stability of the welding arc. Most often, an “oblique bridge” circuit (“Barmaley circuit”) is used using two key transistors: bipolar or field-effect. They are placed on a radiator to remove heat; they open and close synchronously.

In the “Barmaley circuit” the main control elements are two transistors, which open and close synchronously

The electrical solution of the circuit eliminates high-voltage emissions and allows the use of relatively low-level switches. The scheme is used because of its simplicity, reliability and not very expensive consumables.

Video: review of the Barmaley scheme

DIY inverter assembly

The apparatus is assembled from the following blocks:

• power supply for stabilizing input signals. A metal partition is placed between it and other elements and blocks. The multi-winding inductor is controlled by transistors and a capacitor with stored energy. The throttle control system uses diodes;
• power unit, with the participation of which a full cycle of current conversion takes place. Assembled from a primary rectifier, an inverter transistor converter, a step-down high-frequency transformer and an output rectifier;
• Control block. It is based on a master oscillator with a special microcircuit or a pulse-width modulator. They install a resonant choke and 6–10 resonant capacitors;
• protective block. More often collected on power block, installing thermal switches for thermal protection of its elements. To avoid overloads, install a board based on the 561LA7 chip. Snubbers with resistors and capacitors K78–2 protect the converter and rectifiers.

Video: assembling a welding inverter

Reasons for failure of inverters

The design of inverter welding machines is more complex than transformer welding machines and, unfortunately, less reliable. This often leads to failure of various components for the following reasons:

• low protection from dust. When it accumulates inside, a thermal protection signal is triggered and the device turns off. Requires disassembly at least twice a year to clean the internal parts with a jet compressed air or with a soft brush;
• moisture getting inside, causing a short circuit that is dangerous for the unit;
• low quality cooling system in cheap devices. Because of this, the plastic parts of the structure melt and the emergency shutdown does not work. In models with tunnel ventilation, the radiator is located along the body, and the main components are located inside it. Such devices are much more expensive;
• voltage surges, especially drops to 190 V or more;
• overload when cutting thick metal and work for which a particular device is not designed. Then the IGBT power module fails;
• poor-quality fastening in the contacts of the pads, which provokes overheating of these places and sparking;
• sensitivity to shocks and falls due to the presence of plastic parts;
• low quality of spare parts used for repairs;
• violation of the permissible temperature regime. Electronic microprocessors melt and destroy when overheated. It is recommended to adhere to the range from -10 to +40 o C.

Frequent breakdowns of welding inverters

Malfunctions can be either mechanical or related to electronic failure. Welding machine - complex device, problems can arise anywhere:

Short circuit or breakdown in any important node electrical circuit makes it impossible to operate the welding machine:

• a malfunction of the control board does not provide a stable welding current and does not allow a normal arc to be obtained;
• damage to the transistor on the upper printed circuit board leads to the device shutting down;
• Failure of the overheating protection system is determined by the smell of burnt insulation and smoke coming from inside the housing.

Methods for repairing inverter welding machines

When starting to repair a faulty unit, it is worth considering some points.

What can be fixed without opening it?

Poor performance of the device does not always mean internal failure. Wet or poor-quality electrodes are often the culprit. If drying or replacement does not produce a beautiful seam, consider other possible reasons:

• poor ignition, sticking of electrodes to the metal often occurs due to loss of power in the work cables or low welding current. Correct selection cable cross-sections and increasing the current may solve the problem. Do not use power extension cords with a wire cross-section of less than 2.5 mm 2 or more long length. Optimal length up to 15 m, maximum - 40 m, otherwise the device will not work due to loss of current. Welding cable is recommended up to 5 m long;

  To connect the welding machine, you must use an extension cord with a wire with a cross-section of at least 2.5 square meters. mm and length no more than 40 m

• interruption, pulsation of the arc causes instability or low welding current. Check the reliability of the connections or increase the current. If there are significant voltage surges in the network, use a stabilizer;
• Strong spattering of metal is caused by high welding current or incorrect polarity. The issue is solved by reducing the current strength and maintaining polarity;
• humped, with undercuts, the seam is corrected by increasing the current and correct installation polarity;
• porous seam with big amount defects are caused by unprepared metal or long-arc welding. The number of weld defects can be reduced by cleaning the rusty and dirty surface and bringing the electrode closer to the metal.

  Defects weld occur due to insufficient cleaning of the treated surfaces, incorrect polarity or too far distance of the electrode from the welding site

It is important to choose the correct electrode size for proper operation of the welding machine.

Table: correspondence between the diameter of the electrodes and the thickness of the metal

Internal organization

To be able to repair a welding machine yourself, you first need to understand its internal structure. The front panel contains sockets for working cables, a current control knob and a power indicator. If the design provides additional functions, operating indicators are located here.

On the front panel of the welding machine there are sockets for connecting cables, a current control knob and an operating mode indicator

The check begins with an external inspection of the device. First of all, check the availability mechanical damage. If there are black spots on the case, most likely there is a short circuit. The tester checks fuses, replaces them if necessary, and examines the insulation of welding cables and connections in sockets. If necessary, tighten the bolts and clean the contacts.

After unscrewing the screws and removing the casing, it opens inner part device containing the following components:

• board with power transistors;
• control board;
• rectifier diode board;
• mains voltage rectification board;
• fan;
• controls - knob and switches.

Tools for work

The following tools will be required for repairs: .

DIY welding machine repair

The filling of the welding machine is clear to those who work with radio electronics. If the necessary skills in this area are not available, intervention will only do harm. Without knowing the rules for handling the board and the technology of such delicate work, you can cause damage much greater than the initial one. It is cheaper and safer to entrust the repair to a professional.

If it is difficult to find a specialized workshop, you have to restore the welding inverter yourself. Important consistently check what stopped the device from working.

If difficulties arise, first read the operating instructions for the welding machine. It must have a section about possible problems when welding, the causes of malfunctions and recommendations for their elimination.

After removing the cover of the device, a violation of the soldering of parts, swelling of the capacitors, and broken contacts are often noticeable. In such cases, damaged spare parts are replaced with similar ones. Torn and burnt areas are removed and re-soldered. If it is not possible to quickly determine the cause of the breakdown, each element of the electrical circuit is checked. Diodes, transistors, zener diodes, resistors and other parts are tested.

A detailed check is carried out sequentially: from the parts that most often fail to the most resistant.

1. Power diodes. To check their continuity, the tester is switched to diode mode, and the probes are touched to the output terminals. If there is ringing in one direction, but not in the other, the power diodes are in order, the lower module of the device is working.

   If the input terminals only ring in one direction, then the power diodes are working properly

2. Power transistors. Power transistors are the most vulnerable parts in the inverter. Keep in mind that when transistors are arranged in blocks, due to one faulty one, the entire arm does not work. They are checked in the following sequence:
   
3. Contact in the button. It is checked in ringing mode by placing the button in the “on” position. If the contacts ring, the button works.

   The button is checked in the “on” mode by ringing its contacts

4. Network bridges. These are reliable elements, but they also sometimes fail. Before checking, it is better to unsolder the wires from them and remove the board. In the ringing mode, the black probe is placed on the positive terminal of the diode, and each terminal of the network bridge is touched in turn with the red one. Then vice versa - red is placed on the negative terminal of the diode, black on each terminal of the network bridge. If the tester shows numbers everywhere, there is no short circuit, the diode bridges are fine.

   The diode bridge is tested by touching each of its terminals in turn.

5. Field effect transistor in the primary power supply. It is checked according to the scheme described in the second paragraph. If there is a charge, the power supply is working.

   The field-effect transistor in the primary power supply rings in the same sequence as the power transistors

6. Power nodes. If you don’t have an oscilloscope, use a tester that is set to voltage testing mode. The device is connected to the network via a light bulb. If there is voltage at the output, the light will light up, i.e. the components are working.

   If the light bulb connected in series with the device lights up, the power units are working properly

7. Charging resistor. Break charger possible if the light does not light up when the device is turned on. Check the serial circuit of the PTC and NTC, which ensures the charge of the capacitor. The resistance breaks off when the diode bridges or power transistors are short-circuited.

   To check the charging resistor, check the serial chain of PTC and NTC

8. Key management board. This is a complex element of the inverter, on the functioning of which the operation of the entire device depends. Check the switched on device in voltage mode up to 20 V. Set the regulator to the minimum position, the black probe is installed on the terminal, the red probe on the sixth pin. When the regulator is turned to the maximum position, the tester shows a change in voltage. If on devices 160–200 A the change is in the range of 2.4–3.2 V, the regulator circuit is in order.

   Testing of the key control board is carried out with a tester when the device is turned on in voltage mode up to 20 V

9. Break feedback. Turn on the device, set the voltage on the tester to 20 V. The black probe is placed on the terminal, the red one on the second terminal. A 200 A device will display a voltage of 14–50 mV. If there is a break in the shunt feedback, the tester will show about 500 mV. This means there is no feedback somewhere.
   

   When searching for a break in the reverse connection, the red probe is installed on the second pin of the microcircuit

10. Power unit. In the “on” mode, check for the presence of a voltage of 300 V from the capacitor to the inverter board. Check the integrity of the circuit and transistor. At the output of the power supply, two diodes provide 25 V. If the ringing shows that there is no short circuit, the secondary circuits do not load the power supply, it will start. If there is no startup, the optocoupler or transistor may be broken. If the power supply starts for a short time and then is disconnected from the network, check the transistor. If it gets hot, it means that the diode nearby is broken and needs to be replaced.
    

    Before checking the power supply, unplug the device from the outlet!

    At the first stage of repairing the power supply, check for the presence of a voltage of 300 V on the inverter board

When doing self-repairs, craftsmen use phosphoric acid. If something needs to be soldered to the diode cases (for example, broken stands), they are first tinned. When repairing a broken post, perpendicularity is taken into account. It is important to install it, clearly aligning the holes. If you solder even with minimal distortion, the post will break again when you subsequently tighten the fastener.

If not technical hair dryer, for soldering use a 100–150 W soldering iron. This will prevent damage to the connectors and tracks. Experts recommend for best result Before soldering, heat the block to 160–170 0 C, while the plastic parts of the fan must not be heated. When working with a soldering iron or other heating elements Care is required to avoid touching fusible parts of the device.

Video: repair of a welding machine and analysis of its main faults

An inverter welding machine is confidently prescribed in home workshops. Before purchasing, it is worth spending time learning the basics of welding and electrical engineering. This will help you navigate the characteristics of the device and, if necessary, repair it yourself. Complex cases It's better to leave it to specialists.