Do-it-yourself rusich welding machine repair

In detail: do-it-yourself repair of a Rusich welding machine from a real master for the site my.housecope.com.

Inverter welding machines are gaining more and more popularity among master welders due to their compact size, low weight and reasonable prices. Like any other equipment, these devices can fail due to improper operation or due to design flaws. In some cases, the repair of inverter welding machines can be carried out independently by examining the inverter device, but there are breakdowns that are eliminated only at the service center.

Welding inverters, depending on the models, operate both from a household electrical network (220 V) and from a 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 capabilities of the wiring, then the unit will not work with a sagging network.

So, the following main modules are included in the device of an inverter welding machine.

Just like diodes, transistors are installed on radiators for better heat dissipation from them. To protect the transistor unit from voltage surges, an RC filter is installed in front of it.

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 is supplied with voltage from the household electrical network or from generators, gasoline or diesel. The incoming current is alternating, but passing through the diode block, becomes permanent... The rectified current is fed to the inverter, where it is converted back 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 the current strength. At the next stage, the current again enters the rectifier, where it is converted to DC, after which it is supplied to the output terminals of the unit. All current conversions controlled by a microprocessor control unit.

Video (click to play).

Modern inverters, especially those based on the IGBT module, are quite demanding on the rules of operation. This is explained by the fact that when the unit is operating, its internal modules give off a lot of heat... Although both radiators 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, you need to strictly follow the rules that are indicated in the instructions for the device, implying periodic shutdown of the installation for cooling.

This rule is usually referred to as the “Duty Cycle” (Duty Cycle), which is measured as a percentage. Not observing the PV, overheating of the main units of the apparatus occurs and their failure occurs. If this happens with a new unit, then this breakdown is not subject to warranty repair.

Also, if the inverter welding machine is working 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 dirt.

But most often inverters fail when they work at low temperatures. Breakdowns occur due to the appearance of condensation on the heated control board, as a result of which a short circuit occurs between the parts of this electronic module.

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

From the above, 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 repairing the welding inverter will cost half the cost of a new unit.

As already mentioned, inverters fail due to external factors affecting the “vital” units of the apparatus. Also, malfunctions of the welding inverter can occur due to improper operation of the equipment or errors in its settings. The most common malfunctions or interruptions in inverter operation are as follows.

Very often, this breakdown is caused by faulty network cable apparatus. Therefore, first you need to remove the cover from the unit and ring each wire of the cable 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 source of the device. The repair technique for the “duty room” using the example of a Resant brand inverter is shown in this video.

This malfunction can be caused by an incorrect setting of the amperage for a certain diameter of the electrode.

You should also consider and welding speed... The smaller it is, the lower the current value must be set on the control panel of the unit. In addition, to match the current strength to the diameter of the additive, you can use the table below.

If the welding current is not regulated, the cause may be breakdown of the regulator or violation of the contacts of the wires connected to it. It is necessary to remove the cover 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 him, 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 to a specialist.

Excessive power consumption, even when the device is not loaded, most often causes turn-to-turn closure 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.

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

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

If the indicator is on, this indicates overheating of the main modules of the unit. Also, the device can turn off spontaneously, which indicates tripping of thermal protection... So that these interruptions in the operation of the unit do not occur in the future, again, it is necessary to adhere to the correct mode of the duration of the on (DC). For example, if duty cycle = 70%, then the device should work in the following mode: after 7 minutes of operation, the unit will have 3 minutes to cool down.

In fact, there can be a lot of various breakdowns and the reasons 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 watching the following training video.

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

Even an electrical engineer can be confused by just trying to turn off the protection of an inverter. So in this case, it is best to seek help from a specialized workshop.

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

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

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 not picky to maintain. In inverter devices, it is more difficult to determine the breakdown, and repair at home is often impossible.

However, if handled correctly, inverters will last a long time and will not break down. Protect from dust, high humidity, frost, store in a dry place. There are the most typical malfunctions of welding machines, which can be eliminated by hand.

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 working properly, 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 failure 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.

If all the elements of the circuit are working properly, 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 and arc interruption can be caused by a voltage drop due to a short circuit in the transformer windings, diode failure, or loose connection contacts. A breakdown of the capacitor filter or short circuiting of individual parts to the body of the welding machine is also possible.

For reasons of an organizational nature, due to which the device does not cook as it should, it is possible to attribute the excessive length of the 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 with the elimination of these effects can be the restoration of the insulation of the connecting cables, as well as the tightening of loose contacts and terminal blocks.

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

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

If the protective unit re-operates, it is necessary to proceed to troubleshooting according to one of the methods described above, associated with short circuits or malfunction of individual parts.

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

It also happens that the cooling unit does not cope with its functions due to the fact that the welding machine has been under a load exceeding the permissible norm for a long time. The only correct decision in this case is to give it a "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 the electrical panel. To maintain the normal functioning of the welding unit, its settings must correspond to the selected modes.

So, some models of such machines (welding inverter, in particular), in accordance with the instructions, should work according to a schedule that assumes a break for 3-4 minutes after 7-8 minutes of continuous welding.

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.

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 impulse device that has the ability to effectively adjust the value of the output current.

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

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

The method for detecting inverter malfunctions associated with malfunctions of the circuit involves the sequential execution of operations performed according to the principle "from simple damage to more complex breakdown." The nature and cause of breakdowns, as well as repair methods, can be found in more detail in the summary table.

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

Maintenance and repair of inverter-type welding machines is distinguished by a number of features associated with the complexity of the circuitry of these electronic units. To repair them, you will need certain knowledge, as well as the ability to handle measuring instruments such as a digital multimeter, an 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 in the composition 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 the voltage levels and the presence of a signal at its control points). Image - DIY welding machine repair

To do this, you will need an oscilloscope and a multimeter, which you should start working with only if you have full confidence in your abilities. If you have any doubts about your qualifications, the only correct solution would be to take (carry) the device to a specialized workshop.

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

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

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 in, which will eliminate the option 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 inspection of the electronic signal conversion circuits.

To do this, it is necessary to find sources in which the diagrams of voltages and currents are given, intended for a more complete understanding of the operation of this unit.

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

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

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

In case 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 when there is a suspicion that all other modules or blocks of the welding machine are in good working order.

In conclusion, we recall that the repair of any welding units (and inverters, in particular) is considered a rather complex procedure that requires certain skills and 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.The availability of equipment for manual arc welding has led to the fact that this type of work has become very common among DIYers and professional craftsmen. Early industrial welding equipment could be found on the farm very rarely, mostly home-made machines.By type of equipment, welding inverters and welding transformers are now produced.Since every model that is produced by companies producing this equipment, designers are trying to improve, now it is impossible to say unequivocally which is better, a transformer or an inverter. Each type has its own advantages and disadvantages. To understand the choice of equipment, you need to consider the principles of their operation and the device.A typical apparatus consists of the following elements:

magnetic circuit;

primary winding, made of a core and an insulated wire;

the secondary winding, in which the number of turns can be adjusted, is made without insulation;

an adjusting screw with a tape thread and fixed vertically together with its running nut attached to the winding;

a handle is attached to the screw, with which the indicators are adjusted;

leads for attaching wires;

housing, which must have special horizontal or vertical louvers so that the unit can be cooled.

Complete set of a simple welding transformer

The core, which works to create a magnetic field, is made of special plates that are very tightly assembled into one package. The plate pack is then covered with special insulation or varnish. By the way, the hum, which is so familiar from the operation of the transformer, mainly creates this package of plates.

The welding transformer works as follows:

Transformer windings

When connected to the power supply to the device, the voltage goes to the primary winding. A so-called magnetic flux is formed in it, which is concentrated on the core. The magnetic flux voltage is transmitted to the secondary winding. The core, which is made of ferromagnets, creates its own magnetic field.In this case, the magnetic flux that is created on both windings forms variable electromotive forces. To change, whether to increase or decrease the voltage that are necessary for a certain type of work, on the secondary winding the possibility of switching to a different number of turns is created, and it is also regulated by increasing - decreasing the distance between the induction coils.

Since such a device is considered to be a step-down one, it is clear that its total number of turns on the primary coil is always greater than on the secondary one.

The welding inverter has a more complex device circuit. The chipset makes it a little like a processor in a computer. The received current from the network, which is alternating current of low frequency, it rectifies, then converts direct current into alternating current, but already of high frequency. In this case, the current strength becomes greater than the received one and is suitable for conducting the welding process, and the voltage, on the contrary, decreases.

Scheme of a conventional inverter device

Of course, inverter equipment has a number of advantages over transformer equipment, here the welding seam is also cleaner, without metal droplets due to a more stable arc, a greater return on the consumed current, it is easy to transfer. But there are downsides:

if one of the electrical circuits is out of order, the repair will cost half the cost of the equipment, which is already much higher than that of a transformer analogue;
store in a warm, dry place;
cover from dust;
in case of overheating, it fails, you need to stop work and let it cool if the fan is turned off or does not cope.

From a large number of welding transformers and inverters, which are produced by various manufacturers and are offered by various stores, it is possible to single out a combined welding transformer Rusich, which combines a single-phase transformer and an oscillator, from NPO Svarka, which is located in Domodedovo, Moscow region. Firstly, it is a young company that is trying to gain popularity with product quality and price.

His electrical circuit is standard: but with amendments to the model, for example Rusich 165 and Rusich 200 have such a circuit, and Rusich 400 is slightly different:

Schematic diagram for apparatus Rusich 165

The specialist, of course, will see the difference in the circuit.

The models of Rusich welding machines have different characteristics, but the instructions for use are almost the same for all.

The manufacturer suggests that you familiarize yourself with it before starting work on this device.

Before starting work, connect the cable "Earth" to the surface of the metal, directly on which the cooking work will take place or with the part to be cooked. In order for the contact to be good, the surface to which the grounding will be carried out must be free from dirt, paint, and also from rust.
The electrode clamp, which is located at the end of the second cable, must be periodically descaled for better contact with the electrode.
To protect your eyes from burns, be sure to use a protective mask.
To clean the welding seam from scale, use a special striker and a metal brush.
Terminals and holder may not be included with the device.

Before performing work, the following actions are performed:

We check the condition of the wires, especially if the device has not been used for a long time.
We check for contact between the plug and the socket.
We clamp the ground with a terminal on the surface of the part or metal base.
We insert the electrode into the clamp with the part of the electrode that is not covered with flux.
We clean the device with an air stream from dust.
We ground the device itself.
Preparing the mask for use.

If you use the ASP model - RUSICH and ASP RUSICH M and V, the upper connecting lead is used for the electrode holder, and the lower one for grounding!

When working in one hand, hold the grip, turn on the device with the other hand. Then, putting on the mask or holding it in hand, we bring the holder with the electrode to the surface to be cooked. Light the arc and start the process. When welding, you need to make small vibrational movements with the electrode along the seam.

If you need to adjust the amount of current during welding, it is done by turning the handle. To the right - to decrease the amperage, to the left to increase.

During operation, there must be good air access to the body of the device. Liquid and foreign objects must not enter the device.

If you need to move the device to another place during operation, unplug it from the outlet.

Technical characteristics for the most used models of the Rusich device

All models can withstand voltage drops of up to 180 V and can be plugged into a regular outlet. The welding arc is ignited at a distance of the electrode from the welding surface by 1.5 mm

Rusich 165 apparatus has the smallest power and can give a maximum current of 165 A, the voltage that is measured during no-load operation is 26 V. It is the smallest and most convenient argon welding machine. If you work for home, the operating time of the device is not limited. It can weld both stainless and alloy steel, as well as cast iron, aluminum, copper, brass and similar metals. If you cook with the maximum current, its duration is 50% min. Electrodes are used from 2 to 3 mm.

Reviews for this Rusich welding machine are generally good, the price is also, in Moscow you can buy for 11,620 rubles without delivery. Disadvantage, the case is warming up, the current regulator handle and the current exciter need to be revised.

Welding machine Rusich M 180, you can choose different models

Apparatus Rusich M -180 welds the same materials as the 160 model and can be used for argon welding. Numerical indicators - current 170 A maximum, 20 - minimum, voltage 32 V, duration 70%. It can weld steel with a minimum thickness of 8 mm and cut metal with a non-consumable electrode up to 3 mm, has a fan for cooling. There are modifications of Rusich Lux M 180, M 180 m, M 180 s.

Welding machine Rusich Lux 200 can cook with electrodes from 2.5 to 4 mm, load duration 45% min, current strength is adjustable from 140 to 200 A. Other characteristics are the same. Reviews left by buyers for this device give reason to put the device solid 4.

Such good reviews on welding machine Rusich Lux 215, which can support a current up to 215 A maximum, the lower value is 20 A, electrodes can be used from 1.5 to 5 mm, welds up to 10 mm thick and cuts metal up to 3 mm. Its price is from 17,200 rubles. There are modifications M 215 m, M 215 s.

Welding machine Rusich 250 in a metal case

The new generation of the Rusich M 250 apparatus is equipped with a special control for an argon burner, an electromagnetic valve, and European devices for connecting cables.

The welding current can be adjusted from 20 to 250 A, the maximum electrode number is 5, it is quite heavy, 25 kg. Can cut metal up to 6 mm thick, load duration 70% min.

The most powerful apparatus this company is Rusich S 300 with a maximum current strength up to АС - 300 А, DC - 20-230А, ММА / TIG. It has thermal protection, it can weld steel from 0.8 mm to 15 mm and cut thickness with a non-consumable electrode up to 16 mm. For ease of movement, it has wheels on the bottom of the body.

The Rusich C 300 welding machine is the most powerful and productive one.

There is a gas valve in the kit, but there is no burner control, although there is a place for connection. Its price from the manufacturer is from 32,000 rubles.

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

Replacement of radio components in the process of repairing a welding inverter

The main purpose of any inverter is to generate a constant welding current, which is obtained by rectifying a high-frequency alternating current.The use of a high-frequency alternating current, converted by means of a special inverter module from a rectified mains supply, is due to the fact that the strength of such a current can be effectively increased to the required value using a compact transformer. It is this principle underlying the operation of the inverter that allows such equipment to have compact dimensions with high efficiency.

Functional diagram of the welding inverter

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

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

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

Repair of an inverter-type welding machine has a number of features, which is explained by the complexity of the design of such a device. Any inverter, unlike other types of welding machines, is electronic, which requires specialists involved in its maintenance and repair to have at least basic radio engineering knowledge, as well as skills in handling various measuring instruments - a voltmeter, digital multimeter, oscilloscope, etc. ...In the process of maintenance and repair, the elements that make up the welding inverter circuit are checked. This includes transistors, diodes, resistors, zener diodes, transformer and choke devices. The peculiarity of the design of the inverter is that very often during its repair it is impossible or very difficult to determine the failure of which particular element was the cause of the malfunction.A sign of a burnt out resistor may be a small carbon deposit on the board, which is difficult to distinguish with an inexperienced eye.In such situations, all the details are checked sequentially. To successfully solve such a problem, it is necessary not only to be able to use measuring instruments, but also to be quite familiar with electronic circuits. If you do not have such skills and knowledge at least at the initial level, then repairing a welding inverter with your own hands can lead to even more serious damage.Realistically assessing their strengths, knowledge and experience and deciding to undertake independent repair of inverter-type equipment, it is important not only to watch a training video on this topic, but also to carefully study the instructions, in which manufacturers list the most typical malfunctions of welding inverters, as well as ways to eliminate them.