How to repair the welding inverter yourself

Technical progress does not stand still, therefore modern people more often prefer inverters, as they have a lot of advantages over many long-obsolete versions of welding devices, including rectifiers and transformers.

Scheme of the welding inverter device

Scheme of the device welding inverter.

Modern welding inverters allow high quality work even for those people who do not have significant experience in welding. Repair of welding inverters is a difficult task, as it is necessary to pay for the comfort during operation and the quality of welding by the multi-level technical organization of the device.

Components of welding inverters

Elements of the welding inverter

Elements of the welding inverter.

Failures of welding inverters are an unpleasant surprise for their owners, because in workshops that specialize in repairs, diagnosing problems and eliminating them can be very expensive. Despite the fact that welding inverters have a complex structure, if you wish, you can repair many types of damage yourself, thus saving money.

In order to effectively carry out diagnostics and repair of the welding inverter, it is necessary first of all to understand the structure of this unit. The main difference between the welding inverter and other representatives of this class of equipment is the fact that this unit is not an ordinary electrical device, since its work is provided by a complex electronic assembly. Considering all the features and characteristics of the inverters, in order to identify the problem, you need to check the individual parts of the circuits, including the following components:

Welding inverter functionality

The functionality of the welding inverter.

  • capacitors;
  • diodes;
  • resistors;
  • stabilitrons;
  • transistors;
  • resistance.

This is not the whole list of components contained in welding inverters, but these elements should be paid attention to first of all. To effectively carry out the repair of the inverter, it is necessary to have at least a little experience with microcircuits. Since it is impossible to get ahead of the eye exactly where the failure is located, it is necessary to immediately prepare the following equipment:

  • oscilloscope;
  • tester;
  • digital multitester;
  • voltomer.
The scheme of the welding inverter

The scheme of the welding inverter.

The principle of operation of the inverter is based on the phased conversion of the electric signal. At the first stage, rectification of the mains voltage is carried out in a special rectifying unit of the apparatus. The rectified current passes into the inverter module, where it is again converted to alternating current. In the future, the power transformer converts the current to the welding performance. Lastly, the conversion of welding alternating current to direct current is carried out.

In various models of welding inverters can be a variety of elements that ensure this process. In addition, it is impossible to accurately determine the location of certain important details, since the design of the units can also be very diverse, but the technical schemes, which are often attached in the instructions for using the device, will help in this matter.

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Classification of causes of failure of welding inverters

Classification of welding inverters

Classification of welding inverters.

Failures occurring in household, industrial and professional welding inverters can be divided into several different groups.

  1. Failures of the device due to the wrong choice of place of work or violation of the technology of welding.
  2. Violations of the apparatus due to improper operation or failure of individual electronic components.

In some cases, violations in the operation of the unit can be caused by several reasons at once, therefore, in order to identify them, it is necessary to begin diagnostics from simple to complex. First, check the conditions of use of the inverter, disconnect it from the mains and let it cool, and then reconnect. If the problem persists, you need to check the operation of individual circuits.

Current conversion in welding inverter

Current conversion in welding inverter.

There are many reasons that can contribute to the failure of individual circuits. They should be considered in more detail, since if they exist, it is possible to say with certainty whether the failure is in electronics.

  1. Water entering the inside of the case. The insignificant amount of moisture that gets on the board when the machine is working outside during snowy or rainy weather can lead to electronic circuit board failure.
  2. Non-observance of the work continuity mode specified by the manufacturer of the unit. In this case, the inverter often overheats, which can cause the chips to burn out.
  3. Large amounts of dust. Dust coating of microcircuits leads to disruption of the normal cooling process of individual elements of the microcircuits. Ordinary household dust can not cause damage, but construction, in large quantities available on construction sites, leads to a significant amount of plaque.
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The most common failure of welding inverters

Many failures of welding inverters have specific features, manifestations and signs that allow you to quickly identify the cause of the malfunction and, accordingly, eliminate it. There are a number of the most common malfunctions that are often encountered by the owners of these units.

Electric circuit welding inverter

Electric circuit welding inverter.

  1. The welding electrode constantly sticks to the metal. This problem can be caused by several reasons at once. First, the causes of the problem may lie in the low voltage of the network, which is not enough to cover even the necessary minimum. Secondly, the problem may lie in the poor contact of the modules located in the panel sockets. This problem can be eliminated by tightly fixing the inserts or tightening the fasteners. In addition, adhesion of the electrode to the metal may be due to oxidation or burning of the contacts in the power circuit. Poor quality surface preparation also often leads to adhesion of the electrode to the metal.
  2. Unstable arc or splashing electrode material. This problem is often observed in the event of an incorrect instrument setup and current selection. When choosing a current, it is necessary to take into account that it must correspond to the strength and diameter of the electrode, and in addition, the welding speed. In order to correct the situation, it is necessary to set the current strength indicated on the package in which the electrodes were sold. If such information is not provided, it is necessary to calculate the current strength independently using the formula 20-40 A per 1 mm diameter of the electrode.
  3. Spontaneous shutdown of the inverter after a long period of operation. As a rule, the problem in this case lies in the protection against overheating. It is recommended to continue work after about 20-30 minutes, when the device has cooled down a bit.
  4. The inverter is on, as indicated by the indicators, but no welding. The main cause of such a malfunction, as a rule, is overheating. The second reason for such a breakdown may be a break or spontaneous disconnection of welding cables.
  5. The inverter is turned on, but the lights are off, there is no welding. A similar phenomenon can be caused by a wide variety of breakdowns, both in the wiring and in the chips. Such failures require serious diagnostic work to identify the damaged element.

Most of the serious faults in welding inverters are accompanied by a burning smell. In order to repair welding inverters with such failures, it is very important to have the skill of using many specific devices intended for evaluating the state of microcircuits and wiring.

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Diagnostics of different elements of inverters for the presence of breakdowns

Ways to connect a welding inverter

Ways to connect a welding inverter.

So, when it was found out that no external factors interfere with the operation of individual elements and the repair of welding inverters with damaged microcircuits is required, we should start diagnostics. In order to begin diagnostics to identify a malfunction, first of all you need to remove the case and carry out an external inspection of all the details. If there are no visible areas of burning and oxidation, it is necessary to test all the elements that ensure the operation of the device.

After removing the case, it is necessary to check all areas of the soldering of wires, contacts and other elements in the diagrams. It is not uncommon for spikes of individual elements to be produced with insufficient quality, which leads to the fact that if the device is shaken while carrying or abruptly dropping the device onto a table or floor, there may be a violation of the fixture integrity. In this case, it is enough to rewrite the elements again.

Damaged parts of the board in case of overheating and other direct adverse factors are immediately visible, as small cracks snake at them, there are darkening, burnt areas of the electrodes, swollen electrolytic capacitors in the upper region of these elements.

Repair of damage identified involves their watering and the complete replacement of individual parts.

It is easy to pick up elements for replacement, as the instrument case is marked or the instructions contain a table of installed elements. Repair schemes should be carried out very carefully. A soldering iron with a suction is an ideal tool for watering out components. If the inspection did not give results, and the damaged elements were not identified, the diagnosis becomes much more complicated, since the welding inverter can be repaired only with the use of special tools.

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Diagnosis and repair of implicit breakdowns of the welding inverter electronics

Welding inverter control

Control of the welding inverter.

It is important to find out which particular circuit element is damaged, otherwise repair is not possible. This is difficult to do when there are no characteristic external signs of circuit damage. The most vulnerable parts are transistors located in the inverter module. Their verification should be carried out using multitester and ohmmeter. When checking the power transistors, it is required to examine all the component parts of the driver. Lastly, other elements located on the board are checked with a tester.

Next, you need to carefully test all printed conductors that are on the board, making sure that they do not have tears or podgaras. In the presence of such, it is necessary to carefully clean the damaged area, and then make a new jumper by soldering individual sections. In the event of such a breakdown, you should carefully clean with an eraser all other contacts in the connectors that are available in the board.

The next stage of testing the functionality and electronics is the diagnosis of the state of the output and input rectifiers. These elements are special diode bridges that are mounted on the radiator. These components are rarely subject to breakdowns, but it is still impossible to completely eliminate their failure. It is best for a high-quality diagnostics diode bridge to solder it from the board. If the entire group of the diode bridge is short, then further testing of each diode is carried out separately. Repair involves replacing a punched diode.

The final stage of the electronics check is the examination of the key management board located in the inverter module. This element has a very complex organization, so if it malfunctions, the function of the entire device may be impaired. It is necessary to check the presence of control signals that are received through the block gate buses. Verification can only be carried out using an oscilloscope. Only after checking and eliminating all the above problems, if any, can the device be tested. If you did not manage to repair the welding inverter yourself, you should contact the specialized center for consultation and diagnostics.

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