Repair courses for welding inverters

Learn to understand in detail the device and diagnostics of welding inverters. Practice testing and soldering IGBT transistors.

Start: 12 December
There are: 5 places
enroll in the course
up to 5 people
In employment

Who is this course for?

For beginners
For those who want to improve their skills
For those who are looking for work
For students
For those who want to open their own SC

What will you learn?

  • Understand in detail the device of welding inverters
  • Diagnostic sequence rules
  • Checking powerful power transistors by various methods
  • Replacing faulty PWM controllers
  • Take voltage measurements at different nodes using a multimeter and an oscilloscope
  • Reading circuits of welding inverters: Resanta, Corundum, Tig, Svarog, Aurora, Volta, Solaris, Start, Fubag

What will you get after the training

Выдача сертификатов
Certificate — an official document of education
After completing the training, you receive a Certificate. Your advantage when applying for a service center or company
Help with employment
Owners and managers of service centers apply to Bgacenter if there are vacancies - phone repairman or service center receiver. Therefore, there is almost always a possibility of employment in the service centers of St. Petersburg, upon completion of training and successful certification.
Компенсация обучения
Tuition compensation, 13%
By completing any training program at bgacenter, you can receive a tax deduction for training

Training program

The welding inverter repair training program is built on a ratio of 80% (practice) to 20% (theoretical classes). Definitely, when repairing inverters, there is a certain approach to circuitry. Since structurally the welding machine is a powerful power supply, consisting of an auxiliary and a main one.

The power supply is a complex electronic-technical device, so its repair requires a certain qualification of a specialist.

During the training, circuits of various switching power supplies that are used in welding inverters will be considered. You will learn how to diagnose, understand the principle of AIS operation, and eliminate common malfunctions.


Block diagrams of welding machines

In the course of training, you will study the circuitry and design of welding machines. Structurally, most inverters have a similar design. Having mastered the repair of welding machines from one manufacturer, you can easily repair inverters from other manufacturers. On the course, consider the design and principle of operation of such types of SA, such as:

  • MMA – manual arc welding
  • MAG – semi-automatic welding
  • Combined (MMA+MAG)


The welding machine consists of:

  • metal case with controls
  • main board with heatsinks and power transformer
  • submodules with an installed master oscillator and protection against overheating and sticking
  • standby power supply
  • power module
  • cooling fans
  • power welding leads and electrode holder lock

Блок-схема СИ
Block diagram of the welding inverter



When using AIS, frequent breakdowns occur. On the welding machine repair course, you will acquire the skill of diagnosing and subsequent repair.

Typical malfunctions of welding inverters:

  • Welding inverter does not turn on
  • The inverter turns on, the indicators light up, the fans work, but the machine does not cook
  • Inverter turns on but fans do not work
  • The device turns on, after a short time overheats and turns off
  • The device works at the output voltage is normal, but when trying to ignite the arc, the welding current is not enough
  • Unstable welding arc, metal spatter during welding
  • It is not possible to adjust the set current or max or min values ​​with the current regulator
  • IGBT transistors constantly fail under load
  • IGBT output transistors are OK, voltage is present on the filter capacitors, but the device does not work
  • When turned on, the green (working) and orange (emergency) LEDs on the control panel light up simultaneously
  • With serviceable IGBT transistors and a serviceable standby unit, there is no output welding voltage
  • Mechanical damage to the welding machine when falling from a height

Первичная проверка работоспособности выходного сварочного диодного выпрямителя

Primary performance check of the output welding diode rectifier


Repair of welding machines

When restoring the AIS, we check the supply of mains voltage to the main board. Using a multimeter, we determine the performance of the diode bridge, the supply of the rectified voltage to the standby mode module and to the power unit. During training, you yourself identify a faulty node, with its subsequent repair.

Ремонт сварочного инвертора

Welding inverter repair


Soldering power IGBT transistors

Learning how to repair welding inverters, you will be able to practice the following in practice:

  • Soldering IGBT transistors
  • Soldering power transistors
  • Dismantling SMD and DIP elements on the AIS board
  • Soldering microcircuits
  • Replacing burned out connectors

Пайка транзисторов

Soldering transistors


Repair of the primary power supply of the welding inverter

The standby unit diagnostics consists in checking the incoming voltage from the diode bridge to the power transistor through the transformer winding. The pulses are checked using an oscilloscope for the PWM controller and the supply voltage of this microcircuit.

The health of the strapping of the microcircuit is checked, if it is in good condition, we install a new PWM controller and check the output pulses.

Начало диагностики ШИМ контроллера со встроенным транзистором

Start diagnosing a PWM controller with a built-in transistor


Repair of the power unit of the welding machine

Diagnostics of the main unit is carried out in the following sequence:

  • the serviceability of the IGBT transistor is checked after it is soldered
  • we check the supply of the rectified voltage from the filter to the collector of the upper key of the IGBT transistor
  • we check the trigger pulses on the oscilloscope on the gates of the upper and lower arms
  • we pay special attention to the shape of the impulses (front decay)
  • we check the health of SMD resistors and zener diodes in the gate circuit
  • we perform a visual inspection of non-electrolytic capacitors in the collector circuit

Проверка IGBT транзистора

Checking the IGBT transistor


The best device for evaluating IGBT transistors for originality is the SMD-tester or LCR-T4 with additional power. The IGBT transistor differs in its internal structure from the MOSFET, therefore it requires a different approach for diagnosis.

Импульсы поступления сигнала на затвор IGBT транзисторов

Pulses of signal arrival at the gate of IGBT transistors


Checking the functionality of the welding machine

After completion of the repair work, it is necessary to connect the welding inverter to the 220V network and make sure that the output voltage is on the welding cable connectors. The open circuit voltage of a serviceable AIS should be in the range of 60 to 90 Volts, depending on the manufacturer’s company. As a rule, it is indicated in the table on the body of the device.

Then you need to take the electrodes and ignite the volt arc. During welding, it is necessary to measure the voltage at the cable outlets using a voltmeter. It should be 23 – 30 volts.

With the current regulator on the front panel of the SI, set various current values ​​​​and make sure the operation is stable.

Выходное напряжение на отремонтированном СИ

Output voltage on a repaired inverter


Repair Safety

When performing repair work, special attention should be paid to safety. The main hazard is the voltage across the smoothing capacitors of the rectifier. It can reach the maximum value of the amplitude of the AC network 310V. During the repair it is necessary to discharge the capacitors, alternatively with a 60 watt incandescent lamp or a load resistor.

Special care must be taken when repairing the auxiliary unit. Since many elements are under mains voltage 220V. The output voltage of the welding inverter at idle reaches 65 – 85V. When connecting welding cables, precautions must be taken to protect against electric shock.

Sign up for a course or get a free consultation

Start: 12 December
There are: 5 places
Training instructor —
practicing expert
Maxim Isaev

The head of the service center. Training in modular and software repair of phones and tablets.

Your result after training

After completing training at Bgacenter, you will be able to:
  • Perform full diagnostics of the welding inverter
  • Perform component-level repairs in the converter circuitry
  • Understand electrical circuit diagrams and understand the meaning of their work
  • Check IGBT transistors
  • Understand the relationship between the primary and main units of the welding inverter
  • Check the galvanic isolation transformer (TGR) and repair it

Sign up for a training or get a free consultation

Start: 12 December
There are: 5 places
The cost of training
33900 rubles
51900 rubles
Study now, pay later!
Take the training in installments or on credit. The installment plan is available in equal installments for 4 and 6 months, without a down


What can break in a welding machine?

Most often in a welding inverter it fails:

  • IGBT transistors
  • output diodes
  • network switch
How much does a welder repair cost?

Repair of a welding machine can cost from two to four thousand rubles.

What voltage should be at the output of the welding inverter?

The output voltage of the AIS varies from 60 to 90 Volts.

Why does the inverter welding machine not work?

There could be many reasons. Starting from a faulty diode bridge and ending with an output rectifier. In the courses, you will learn how to fix the most common breakdowns of the welding inverter.

Why does the welding machine not weld?

The welding inverter may not cook for the following reasons:

  • no output voltage
  • thermal protection trip
  • lack of voltage in the network
  • failure of power switches
  • auxiliary power supply failure
  • control circuit not working
What is the open circuit voltage of the welding transformer?

The open circuit voltage of the welding transformer is 48 to 72 volts AC

What most often breaks in a welding machine?

In the welding machine, the following most often breaks:

  • IGBT transistors
  • interruption of the limiting resistance for powering the auxiliary unit
  • cooling fans
  • PWM controller and auxiliary unit power transistor
  • relay control
How does a welding machine work?

The welding inverter works according to the following principle:

  • from an alternating voltage with a frequency of 50 Hz is converted into a high-frequency voltage of 40 – 60 kHz
  • this voltage is supplied to the output of the rectifier welding bridge
  • voltage supply through the terminals to the welding electrode
  • arc ignition
I have a Resanta SAI250A. What is inside the welding machine?

SI consists of:

  • corps
  • control panels
  • auxiliary unit
  • main unit
  • output terminals
  • welding wires
What does a welding machine do?

The welding machine welds with current using electrodes

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