The overheating lamp is on during welding. Breakdowns and repair of various types of welding machines. Inverter devices - a new generation of manual welding

Inverter welding machines are gaining more and more popularity among master welders due to their compact size, light weight and reasonable prices. Like any other equipment, these devices can fail due to improper operation or due to design flaws. In some cases, repair of inverter welding machines you can do it yourself by examining the device of the inverter, but there are breakdowns that are fixed only in a service center.

Welding inverters, depending on the models, work like from a household electrical network(220 V), and from three-phase (380 V). The only thing to consider when connecting the device to a household network is its power consumption. If it exceeds the possibilities of electrical wiring, then the unit will not work with a sagging network.

So, the device of the inverter welding machine includes the following main modules.

How an inverter works

Below is a diagram that clearly shows the principle of operation of the welding inverter.

So, the principle of operation of this module of the welding machine is as follows. The primary rectifier of the inverter receives voltage from the household electrical network or from generators, gasoline or diesel. The incoming current is variable, but passing through the diode block, becomes permanent. The rectified current is fed to the inverter, where it is inversely converted to alternating current, but with changed frequency characteristics, that is, it becomes high-frequency. Further, the high-frequency voltage is reduced by a transformer to 60-70 V with a simultaneous increase in current strength. At the next stage, the current again enters the rectifier, where it is converted to direct current, after which it is fed to the output terminals of the unit. All current conversion controlled microprocessor unit management.

Causes of breakdowns of inverters

Modern inverters, especially those made on the basis of an IGBT module, are quite demanding on the operating rules. This is explained by the fact that during the operation of the unit, its internal modules give off a lot of heat. Although both heatsinks and a fan are used to remove heat from power units and electronic boards, these measures are sometimes not enough, especially in inexpensive units. Therefore, it is necessary to strictly follow the rules that are indicated in the instructions for the device, which imply periodic shutdown of the unit for cooling.

This rule is usually referred to as “Duration On” (DU), which is measured as a percentage. Not observing the PV, the main components of the apparatus overheat and fail. If this happens with a new unit, then this failure is not subject to warranty repair.

Also, if the inverter welding machine is running in dusty rooms, dust settles on its radiators and interferes with normal heat transfer, which inevitably leads to overheating and breakdown of electrical components. If it is impossible to get rid of the presence of dust in the air, it is necessary to open the inverter case more often and clean all the components of the device from accumulated contaminants.

But more often than not, inverters fail when they work at low temperatures. Breakdowns occur due to the appearance of condensate on a heated control board, resulting in a short circuit between the parts of this electronic module.

Repair features

A distinctive feature of the inverters is the presence of an electronic control board, so only a qualified specialist can diagnose and fix a malfunction in this unit. In addition, diode bridges, transistor blocks, transformers and other parts of the electrical circuit of the device may fail. To carry out diagnostics with your own hands, you need to have certain knowledge and skills in working with such measuring instruments like an oscilloscope and a multimeter.

From the foregoing, it becomes clear that, without the necessary skills and knowledge, it is not recommended to start repairing the device, especially electronics. Otherwise, it can be completely disabled, and the repair of the welding inverter will cost half the cost of a new unit.

The main malfunctions of the unit and their diagnostics

As already mentioned, inverters fail due to the impact on the “vital” blocks of the apparatus external factors. Also, malfunctions of the welding inverter can occur due to improper operation of the equipment or errors in its settings. The following malfunctions or interruptions in the operation of inverters are most often encountered.

The device does not turn on

Very often this failure is caused malfunction network cable apparatus. Therefore, you first need to remove the casing from the unit and ring each cable wire with a tester. But if everything is in order with the cable, then more serious diagnostics of the inverter will be required. Perhaps the problem lies in the standby power supply of the device. The technique for repairing the "duty room" using the example of a Resant brand inverter is shown in this video.

Welding arc instability or metal spatter

This error may be caused incorrect setting current strength for a certain electrode diameter.

Advice! If there are no recommended current values ​​on the package for the electrodes, then it can be calculated using the following formula: for each millimeter of equipment there should be welding current within 20-40 A.

It should also be taken into account welding speed. The smaller it is, the lower the current value must be set on the control panel of the unit. In addition, in order for the current strength to correspond to the diameter of the additive, you can use the table below.

Welding current not adjustable

If the welding current is not adjusted, the cause may be regulator failure or violation of the contacts of the wires connected to it. It is necessary to remove the casing of the unit and check the reliability of the connection of the conductors, and, if necessary, ring the regulator with a multimeter. If everything is in order with it, then this breakdown can be caused by a short circuit in the inductor or a malfunction of the secondary transformer, which will need to be checked with a multimeter. If a malfunction is found in these modules, they must be replaced or rewound by a specialist.

Large power consumption

Excessive power consumption, even when the machine is unloaded, causes, most often, interturn short circuit in one of the transformers. In this case, you will not be able to repair them yourself. It is necessary to take the transformer to the master for rewinding.

The electrode sticks to the metal

This happens if network voltage drops. To get rid of the electrode sticking to the parts to be welded, you will need to correctly select and adjust the welding mode (according to the instructions for the machine). Also, the voltage in the network may sag if the device is connected to an extension cord with a small wire section (less than 2.5 mm 2).

It is not uncommon for a voltage drop to cause electrode sticking to occur when using a power extension that is too long. In this case, the problem is solved by connecting the inverter to the generator.

Burning overheat

If the indicator is on, this indicates overheating of the main modules of the unit. Also, the device may spontaneously turn off, which indicates thermal protection trip. So that these interruptions in the operation of the unit do not happen in the future, again, you need to adhere to correct mode duration of inclusion (PV). For example, if PV = 70%, then the device must operate in the following mode: after 7 minutes of operation, the unit will be given 3 minutes to cool down.

In fact, various breakdowns and there can be quite a lot of causes that cause them, and it is difficult to list them all. Therefore, it is better to immediately understand what algorithm is used to diagnose the welding inverter in search of faults. You can find out how the device is diagnosed by looking at the following tutorial.

The welding inverter differs from the conventional welding machine in an easier and better welding process. However, malfunctions of the welding inverter, due to its more complex device may be more serious and complex.

To determine the cause of the breakdown of the device, you need to diagnose it: check transistors, resistors, diodes, stabilizers, contacts, etc. Each device comes 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 in electronics, the ability to work with electrical circuits is necessary. Therefore, if self-checking and elimination simple faults described below did not lead to success, it is better to entrust the repair of the inverter apparatus to the masters in the service center.

What are inverter faults?

Several groups of failures can be distinguished welding inverters:

• malfunctions arising from non-compliance with the norms of the welding workflow specified in the instructions;
• malfunctions arising as a result of improper operation or failure of the elements of the device;
• damage caused by moisture, dust and foreign objects entering the device.

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Common malfunctions that you can fix yourself

Consider 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 visual inspection its contents.

1. The welding arc is unstable or the electrode spatters the material. The reason for this may lie in the wrong choice of 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 packaging of the electrodes, then you can start supplying current from 20-40 A per millimeter of electrode diameter. When reducing the welding speed, the amperage must also be reduced.
2. The electrode sticks to the material. Often this is due to low voltage in the network, the value of which is less than the minimum allowable when working with the inverter. The reason for sticking of the electrode can also be poor contact in the sockets of the panel, which can be eliminated by fixing the boards more tightly. Using an extension cable 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 electrical circuit can also lower the voltage.
3. There is no welding process, while the machine is connected to the network. In this case, you need to check the presence of mass on the part to be welded. Also check the inverter cable for damage.
4. The device turns off by itself. The device is switched off at the moment the transformer is connected to the network, after which its protection is activated. The reason for this may be a short circuit in the voltage circuit. Protection can be activated not only when the wires are shorted to each other or with the case, but also when the short circuit between the turns of the coils or the breakdown of capacitors. To repair a floor, you first need to turn off the transformer and find the fault, and then insulate or replace the damaged element.

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

During a long period of operation, the device turned off. Most likely, this is not a breakdown, but an overheating of the inverter. It is necessary to wait 20-30 minutes, and then resume work. You should follow the rules for operating the device: do not overheat it, that is, take breaks in operation, connect appropriate current values ​​\u200b\u200bto it, do not use electrodes of too large diameters.

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

Welding current is poorly regulated. The reason for this may be breakdowns in the current regulation mechanism: a malfunction 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 blockage, etc. Remove the casing from the inverter and examine the current regulation mechanism in order to identify a breakdown.

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

High current consumption at no load. The reason may be the closure of the turns on the coil. You can eliminate it either by restoring the insulation, or by completely rewinding the coil.

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

If a smell of burning and smoke appeared from the body of the device, this may indicate a serious breakdown. AT this case You may need a qualified repair at a service center.

To identify a malfunction, the case is first disassembled. Perform 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 a malfunction lie precisely in poor-quality soldering, they can be easily eliminated by re-soldering the parts.

All defective parts should be unsoldered and replaced with new ones corresponding to this model of the device.

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

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

Malfunctions of welding inverters are most often caused by either illiterate or careless operation, since these are quite reliable devices and there is simply nothing to break. However, there is also the fault of the manufacturer, who installed a low-quality part, or carried out poor installation.
Let's try to summarize typical faults welding inverters and ways to eliminate them.

1. Unstable arc burning or strong metal spatter during the welding process.
This may be the result of an incorrectly chosen . Recommendations for the selection of the manufacturer indicates on the pack of electrodes. If this information is not available, use the simplest formula: 20 to 40 amps of current must be applied to 1 mm of stick electrode thickness.

2. Sticking of the electrode even with the existing "anti-stick" function.
Most often it is caused by too low voltage in the supply network, and if a welding machine with reduced voltage is possible, the latter will fall below the minimum when the load is connected.
Another reason for sticking is poor contact in panel jacks. To eliminate it, it is enough to tighten the fasteners or fix the inserts.
The voltage drop may be due to the use of a power extension cable with a wire cross section of less than 2.5 mm, which again leads to a decrease in the effective supply voltage of the welding machine. In addition, the reason may lie in an extension wire that is too long. It should be noted that with a cable length of more than 40 meters effective work impossible - too big losses.
The cause of sticking can also be the burning of contacts in the connections of the supply circuit, which again leads to a significant “drawdown” of the voltage.

3. No welding, although all indicators work.
The first cause of the malfunction is overheating of the welding inverter. In the presence of control lamp or indicator, their glow may not be noticeable if the welding inverter does not have an overheating sound signal.

Transistor damaged due to overheating in a welding inverter

Working transistor in a welding inverter

The second reason is a break in the welding cables, or spontaneous disconnection.
The third is the failure of control parts. To eliminate the cause, you will have to open the case and first visually inspect the filling for damaged parts. Sometimes the reason lies in poor-quality soldering - it is enough to re-solder the parts.

4. Power off when welding.
It is most often caused by a malfunction of the switch itself or by a mismatch of its rated current. The switch must be capable of withstanding up to 25 A.

5. Lighting up of the indicator of an overheat.
Excessive load, especially when either thick layer dust inside the case. If the cooling fan fails, the welding inverter will usually not turn on, although this may depend on the specific model.
Of course, in a small article it is impossible to detail all the causes and possible malfunctions of welding machines. However, careful attention to the welding inverter used can prolong its “life” for a long time, and bring joy to the owner from work.

Welder on a run-in after repair. Thermal control:

Radical repair of malfunctions of the GYS 3200 welding inverter:

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 circuit of which does not allow for a full repair at home.

Just one attempt to disable the inverter protection can confuse even an electrical engineer. So in this case, it is best to seek help from a specialized workshop.

The main manifestations of malfunctions of electric arc welding machines are:

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

Repair always begins with an inspection of the welding machine, checking the supply voltage. It is not difficult to repair transformer welding machines, moreover, they are picky in maintenance. For inverter devices, it is more difficult to determine a breakdown, and repairs at home are often impossible.

However, with proper handling, inverters last a long time and do not break. Must be protected from dust high humidity, frost, store in a dry place. There are the most typical malfunctions of welding machines, which you can fix with your own hands.

Device won't 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, use the 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 rewound, and in the event of a malfunction of both, it is easier to replace the entire transformer. A 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 in checking it and replacing it with a new part.

In case of serviceability of all elements of the circuit, it is necessary to deal with mains voltage, which can be greatly underestimated and is simply not enough for the normal functioning of the welding machine.

Sticky electrode (arc interruption)

The cause of sticking of the electrode and interruption of the arc may be a decrease in voltage due to a short circuit in the transformer windings, faulty diodes or loose connecting contacts. Breakdown of the capacitor filter or 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 of 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 can be the restoration of the insulation of the connecting cables, as well as the tightening of loose contacts and terminal blocks.

Spontaneous shutdown

In some cases, repairs can be carried out independently if the device starts to turn off spontaneously. Most models of welding machines are equipped with protective circuit(automatic), 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 a spontaneous shutdown of the welding machine, first of all, you should check the state of protection and try to return this element to working condition.

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

In this situation, the first thing to do is to make sure that the cooling unit of the unit is working properly and that the overheating interior spaces excluded.

It also happens that the cooling unit does not cope with its functions due to the fact that the welding machine has been under a load exceeding allowable rate. The only right decision 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 circuit breaker can be installed in electrical panel. To maintain the normal functioning of the welding unit, its settings must correspond to the selected modes.

So, some models of such devices (a welding inverter, in particular), in accordance with the instructions, must work according to a schedule that involves 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 with its electronic circuit. Their knowledge will allow you to quickly identify the causes of breakdowns and try to eliminate them in a timely manner.

Wiring 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 a high-frequency signal.

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

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

• malfunctions associated with errors in the choice of welding mode;
• failures in operation due to failure of the electronic (converting) module or other parts of the device.

The method for identifying inverter malfunctions associated with malfunctions in the operation of the circuit involves the sequential execution of operations performed according to the principle “from simple damage to more complex failure”. 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 parameters of welding, providing a trouble-free (without turning off the inverter) operation of the device.

Operation features

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

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

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

This will require an oscilloscope and a multimeter, which should be started only if you have full confidence in your abilities. If you have any doubts about your qualifications, the only right decision would be to take (take) the device to a specialized workshop.

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

Self-repair procedure

If you decide to repair the board yourself, we recommend using the following tips experienced professionals.

If burnt wires and parts are found during a visual inspection, they should be replaced with new ones, and at the same time, all connectors should be plugged, which will eliminate the possibility of losing contact in them.

If such a repair did not lead to the desired result, you will have to start a block-by-block examination of the electronic signal conversion circuits.

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

Based on these diagrams, using an oscilloscope, you can sequentially check all electronic circuits and identify a node in which the normal signal conversion picture is disturbed.

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 doubt the performance of this board, you can try to replace it with a working one (from another working inverter) and try to start the welding machine again.

In the event of a favorable outcome, it remains only to give 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, we recall that the repair of any welding units(and inverters, in particular) is considered a rather complicated 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 provides good quality holding welding work, creating the welder maximum comfortable conditions for work. However, these advantages lead to an increase in the complexity of its design. This can cause various malfunctions of the welding inverter and reduce its reliability.

Inverter repair features

Unlike conventional welding machines, which are electrical products, the welding inverter is electronic device. Therefore, diagnostics and repair of inverter welding machines are carried out by checking the working condition of diode bridges, transistor connections, zener diodes and other parts that are part of electronic circuits. In this case, you need to have the skills to handle oscilloscopes, voltmeters, multimeters and other measuring instruments.

Home hallmark in repairing a welding inverter, it is difficult to determine the nature of the breakdown and detect a failed part. Therefore, very often it is required to diagnose all the nodes of the electrical circuit.

Based on the foregoing, we can conclude that it is necessary to have minimal knowledge in the field of electronics and be able to understand the design electrical circuits. If such skills and abilities are absent, then take on self repair such a device is not recommended, so as not to waste extra time and effort.

The principle of operation of the inverter

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

• the process of rectifying incoming mains currents using a special rectifier;
• the process of converting rectified currents into alternating high-frequency signals;
• the process of lowering currents with high voltage to the welding voltage occurring on the power transformer;
• transformation alternating current with high frequency in D.C. that occurs with the help of the output rectifier.

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

However, in devices different manufacturers having different models, the layout of the units of the unit can be very diverse, but the installation of the main components will always be unchanged.

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

Types of basic faults

When a welding inverter fails, the first thing to do is to check its transistors, since they are one of the most weaknesses such units. Initially, a visual inspection of the transistors should be carried out. It is very easy to identify such a broken part: 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 provide heat dissipation from the transistor to a radiator made of aluminum. But very often a visual inspection does not allow you to identify faulty elements, then you should perform a “ring” with a multimeter.

Replacement defective items performed according to precisely specified parameters. In some cases, analogues of parts can be supplied, while the required parameters can be determined from the datashift. If replacing the burnt transistors did not help, you need to proceed to further diagnostics.

AT normal mode work, transistors cannot fail just like that, most likely, this is due to the incorrect operation of other elements. Most often it is the driver. It is checked with an ohmmeter. If defective parts are found, they must be soldered and replaced with similar parts.

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

Control board failure

It is best to check diode bridges by soldering wires from them and then detaching them from the board. This can alleviate further work and will not cause doubts when it happened short circuit the entire inverter circuit.

Verification occurs according to a fairly simple algorithm. It is necessary to "ring" the entire group of parts. If at the same time a “shorty” is revealed, then you should search for a broken diode. After its detection, the diode should be carefully soldered and replaced.

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

To perform a competent and qualified repair of the inverter, it is necessary to check for the presence of the necessary signals that make it work. These signals must be fed to the gate busbars 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 wrong choice values ​​of current used for welding. It can also occur if the electrodes are incorrectly selected or the unit is running for too long. To avoid such difficulties when using the inverter, it is necessary to observe optimal modes works that are registered in the technical passport.

Inverter malfunctions that occur can be eliminated on your own, but this can only be done if you have the necessary diagnostic tool and experience in using it. Otherwise, it is better to seek help from specialists.