In detail: resanta 160 DIY repair fuse from a real master for the site my.housecope.com.
Once the Resant SAI 250PN welding inverter fell into my hands. The device, without a doubt, inspires respect.
Those who are familiar with the device of welding inverters will appreciate the power of the electronic filling.
As already mentioned, the filling of the welding inverter is designed for high power. This can be seen from the power section of the device.
The input rectifier has two powerful diode bridges on the radiator, and four electrolytic capacitors in the filter. The output rectifier is also complete with: 6 dual diodes, a massive choke at the output of the rectifier.
three ( ! ) soft start relay. Their contacts are connected in parallel to withstand the large current surge when welding starts.
If we compare this Resanta (Resanta SAI-250PN) and TELWIN Force 165, Resanta will give him a dashing head start.
But, even this monster has an Achilles heel.
The cooling cooler does not work;
There is no indication on the control panel.
After a cursory inspection, it turned out that the input rectifier (diode bridges) turned out to be in good order, the output was about 310 volts. Therefore, the problem is not in the power section, but in the control circuits.
External examination revealed three burned out SMD resistors. One in the gate circuit of the 47 Ohm field-effect transistor 4N90C (marking - 470 ), and two at 2.4 ohms (2R4 ) - connected in parallel - in the source circuit of the same transistor.
4N90C bipolar transistor (FQP4N90C ) is controlled by a microcircuit UC3842BN ... This microcircuit is the heart of the switching power supply, which powers the soft-start relay and the integrated stabilizer at + 15V. He, in turn, feeds the entire circuit, which controls the key transistors in the inverter. Here is a piece of the RESant SAI-250PN diagram.
Video (click to play).
It was also found that there is also a resistor in the power circuit of the UC3842BN (U1) ShI controller in the open circuit. In the diagram, it is designated as R010 (22 ohm , 2W ). It has the reference designation R041 on the printed circuit board. I will warn you right away that it is quite difficult to detect a break in this resistor during an external examination. A crack and characteristic burns can be on the side of the resistor that faces the board. This was the case in my case.
Apparently, the cause of the malfunction was the failure of the UC3842BN (U1) ShI controller. This, in turn, led to an increase in the consumed current, and the resistor R010 burned out from a sharp overload. SMD resistors in the FQP4N90C MOSFET circuits played the role of a fuse and, most likely, thanks to them, the transistor remained intact.
As you can see, the whole switching power supply unit on the UC3842BN (U1) has failed. And it feeds all the main units of the welding inverter. Including soft start relay. Therefore, welding did not show any "signs of life."
As a result, we have a bunch of "little things" that need to be replaced in order to revive the unit.
After replacing the indicated elements, the welding inverter turned on, the display showed the value of the set current, the cooling cooler clinked.
For those who want to independently study the device of the welding inverter - the complete schematic diagram of "Resant SAI-250PN".
Tell me the name of the microcircuit with eight legs, otherwise, while one friend of mine was soldering it, all the information on it was burnt. Resanta 160 sais.
Show me on the diagram.
mitka51 , it is pointless.
while one friend of mine was drinking it, all the information on it was burnt.
mitka51, this is pointless.
alek956 , did not get the point.
Show me on the diagram.
Elements with “typical” failure are circled in red. Blue when 3842 fails, etc. In your case, change both. Instead of R013 (SMD 1206), it is necessary to carefully solder in its place a 0.5W output resistor with an insulating tube put on it. The transistor changes to any but at 900V
Not the first person to face this problem.
Sly microcircuit. On sale a rarity, there are no analogues.
Why is that? It's pretty common. And not a deficit. The defect is standard on Resant (and her clones).
And the reason is pretty simple! Before turning off and turning on the device, you need to turn off the current to the end (as the instructions say) and due to a break in the electrical network
Why is that? It's pretty common. And not a deficit. The defect is standard on Resant (and her clones).
In any case, it is almost impossible to find one in the countryside!
No need for welding no matter that.
I have a problem, water is constantly on overload, the output is 2 volts, the diodes are normal at the output, I changed Q2 D3 D4 D7 D8 R5 A3120. On 5 and 8 legs, a3120 has 26 volts on one and 24 volts on the other. on the PWM board on 3 leg 5 volts on 5 leg 15 volts. Overload also burns under load. What else could be the problem?
I need the help of specialists, friends brought SAI160, I opened the device and saw the following picture: Viper22 and R37 exploded, diodes D16, D15 (ER2D) ring shortly, Zener diode DZ8 is also short-circuited. I changed all these parts: U1, Q4, D15, D16, R37, C21-24. U2 (also changed it just in case). When turned on, the vtilators twitch and stand (11.6 v is supplied), the relyushka turns on, a strange sound comes from the board after turning on, as if the pulse generator is closed or very loaded, D20 and D18 begin to warm up strongly, viper22 is also warming up. I did not keep it turned on for more than a minute, it is clear that it does not work correctly. Can you tell me who has met with such a breakdown. There is no oscillograph, I can not see what viper22 produces.
When turned on, the vtilators twitch and stand (11.6 v is supplied)
So temporarily open the fans and measure what is the output of the welder? What is the voltage? Check the fans from a separate power supply. They could well have burned out, tk. there is also a schematic inside them.
gonchiy Did the power transistors themselves ring?
So temporarily open the fans and measure what is the output of the welder? What is the voltage? Check the fans from a separate power supply. They could well have burned out, tk. there is also a schematic inside them.
Logically, I'll try. Do you think they load so much that the diodes and U1 are heating up? What voltage should the output be? no experience in repairing welding inverters
I don’t remember what tension should be. There, the operating voltage is written on the fans. This is something like it should be. A shorted fan will give a considerable load. Almost short. Therefore, the diodes are heated. They are in a serial winding circuit in front of them.
Hands did not reach my resants. But I found a microcircuit worth 50 rubles, I took it to a specialist. He soldered it. And then I soldered for an hour, which I don't know, in short, I took my welding and gave it to the store where I bought it. I was given a guarantee there for 6 months upon purchase. At the moment, she is a little over a year old, but she was assured that they are being renovated in the Regional Center in Kaliningrad quickly and conscientiously. So everyone should mind their own business. Even the body master can repair televisions, but he does not climb into welding. This is me about my friend. So find the address of the warranty workshop in the book from the device and trust the specialists.
So everyone should mind their own business.
It would be nice that everyone would understand this!
Even the body master can repair televisions, but he does not climb into welding. This is me about my friend.
If this master knows how to read diagrams and understands what's what, then he should have figured it out. Another question is if the necessary parts are not at hand.
Do-it-yourself restoration and repair of a welding inverter is possible only if you have sufficiently confident knowledge in the field of electrical engineering and electronics. A rather complex diagram of the Resant apparatus (or another of the same type) requires the use of special equipment to diagnose the causes of the malfunction.
The inverter unit has a rather complex electronic circuit. An apparatus of this class is characterized by the presence of power converting circuits on semiconductor elements, electronic control of operating modes. Without understanding the essence of the work of all these elements, self-repair is impossible.
The main reason for the breakdown of the Resant's apparatus is considered to be overheating of individual structural units. At the same time, such an opportunity exists both for reasons of malfunction of the cooling system, and with the wrong choice of welding modes.
All elements of the cooling system are subject to mandatory checks.
To determine breakdowns, in most cases, you will have to check the main elements of the electronic circuit, special attention should be paid to semiconductor devices.
It is clear that the repair of an inverter device is impossible without a soldering iron and consumables for it (solders, fluxes). But the main devices will be required precisely for diagnosing a malfunction.
Voltmeter, ohmmeter, ammeter. It is best if you have a combined device at hand that can determine all the parameters of the electrical circuit.
An oscilloscope is required to check the operating parameters of the control unit
The presence of such a minimum set of equipment will make it possible to identify all the main malfunctions characteristic of Resant's units.
VIDEO The main malfunctions that can be eliminated on your own include:
No welding current with input voltage present. Most often, the reason for this is the failure of the fuses, but malfunctions in any part of the electrical circuit are quite possible.
Even setting the device to the maximum operating mode in terms of power does not allow obtaining the welding current of the required strength. In most cases, the reason lies in poor contact at the terminals or insufficient voltage in the power supply network. Much less often, a malfunction is caused by breakdowns in the power unit of the device.
The reason for the permanent shutdown of the Resant inverter may be the presence of a short circuit in any parts of the circuit or a malfunction of the elements of the cooling system. Inverter shutdowns indicate the normal operation of the device's overheating protection elements.
The cause of the instability of the welding arc can be a breakdown in the control unit or power circuits of the unit.
Particular attention must be paid to the selection of an acceptable operating mode. With constant overloads, even such a reliable device as the Resanta will last much less than the estimated period. Pay attention to the appearance of any unusual noise or heating of the case or other elements of the device. These signs indicate imminent breakdowns in the near future.
All the main measures for the repair of the device can be divided into the following stages:
An external inspection of the inverter housing, checking the condition of the supply and welding cables should be carried out when any signs of malfunctions appear. In some cases, poor contact on various connections can cause unstable operation of the unit. When inspecting, pay attention to mechanical damage, possible signs of a short circuit that has occurred. Be sure to check the integrity of the fuses and tighten all existing contacts.
The next step is to open the case of the device, and in the same way check the condition of all the main elements. In addition, you should check the parameters of the input and output voltage and current.
If the damage to the electrical circuit could not be identified, then it is necessary to check the condition of the power unit, as well as the control system of the device.
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Let's consider this stage using the example of the Resant inverter.
Check the serviceability of the transistors used in the circuit, they are the ones that fail in the first place. Pay attention to damage to the body of the parts (deformation, burnout). If there are no such visible traces, the transistors must be checked with a tester.
The next part that fails more often than others is drivers based on transistors or microcircuits. All parts of this type are also checked using special testers.
Failure of rectifier diodes occurs somewhat less frequently. When determining a malfunction, it is advisable to check the entire rectifier bridge assembly. If its resistance tends to zero, it is necessary to look for a damaged diode.
When replacing found faulty elements, you should select similar modifications of semiconductor devices. It is necessary to pay attention to the speed of semiconductors, their power.When mounting on radiators, thermal paste should be used to improve heat transfer and reduce the possibility of overheating.
It is best to entrust the search for any defects in the control unit to a specialist. The likelihood of successful self-repair without special equipment and skills tends to zero.
It is much easier to prevent any breakdown than to identify it. Therefore, protect your welding inverter from moisture, regularly clean it from dust, which can also cause a malfunction. And be sure to choose the optimal mode of operation of the device when welding various units and parts.
It is known that a welding machine is necessary for home craftsmen so that they can perform any work on both repair and restoration of something on their land plot. And also very often the welding machine becomes a reliable friend during construction. Therefore, in almost every household, the owners have their own welding machine.
There are many models of inverters, so it is worth learning a little more about everything when you go shopping. After all, the choice of a welding machine is very important, and the price paid for it is never small. For example, the resant welding machine has recently become very popular, which in its appearance cannot but catch the eye.
The resant looks very unattractive outwardly. So, usually it is a small box that has a silvery color. A small handle is attached to the box, which turns out to be inconvenient for carrying, but on the outside of the entire device it seems awkward and, perhaps, even a little ridiculous. But it is small in size and quite light and can be easily carried in a large bag or backpack.
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it is worth picking up several wires at once and purchase them so that they are always at your fingertips.
In order for the resant to work, a lot of tension is not needed, because it spends and absorbs very little of it. It is better to purchase universal electrodes for such an inverter, usually they have a blue marking.
Working with such a device does not cause any trouble. He is obedient, does not require any additional skills or knowledge. Also, the sai inverter is excellent for those who are just starting their work with a welding machine. This Chinese miracle is also loved by professionals, as it easily works even on alternating current.
It does not require additional spare parts, except for electrodes. But on the other hand, you can always have it at hand and transport it wherever you will need it. Of course, in addition to the positive qualities, it has small negative sides, but they are insignificant with the advantages that a homeowner receives by purchasing such a welding machine.
Advantages of purchasing a resant inverter:
Easily transported from one place to another.
Reliable.
Does not require additional equipment.
Has its own electrical circuit.
Protected against overheating.
Equipped with a forced ventilation system.
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the work of its transistor microcircuit that have trendy bipolar zones. The operation of the transistors of the SAI inverter is based on an insulated gate.Such a welding device is designed for welding with current in an environment of various types of shielding gas:
Carbonic acid.
Argon.
Other similar mixtures.
In the design of the inverter, electronic circuits are used, which just help novice welders who do not have the proper experience to work with such equipment. And usually there are no complaints about working with such a device and a person, despite the fact that the job is new for him, very quickly learns to effectively use the welding machine for his own purposes.
The inverter also has its own characteristics, which you should also be aware of, so that no questions arise already during the welding work. So, the output current changes automatically and due to this, the inaccuracy that occurs when the electrode is carried over the surface where the welding takes place is easily compensated. But the electrode is guided manually.
But sometimes there are adhesions. But such short circuits are short and the inverter makes it possible to easily remove the electrode from the surface, reducing the output current. This does not damage the surface of the welding part. The main purpose of the inverter according to the scheme is DC arc welding , which is covered with an electrode.
According to the diagram, it turns out that the main principle of such a welding machine is voltage conversion. It comes in variable, with a frequency of 50 Hz, and is converted to constant. And therefore, the same action according to the scheme occurs the other way around: from the constant voltage of the network to the alternating voltage, which has a high frequency.
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We can safely say that the inverter constantly monitors its work and tries to constantly stabilize the voltage that enters him. Such an inverter is beneficial not only in terms of simplicity of design and control, but also in terms of low cost and highly efficient current transformation circuit.
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They were replaced by inverter-type welding machines, the functioning of which is significantly different.
The scope of application is varied, ranging from households to businesses. The main task is to ensure stable combustion and maintain the welding arc during welding, thanks to the use of high frequency current. The operation of a welding inverter is based on the principles:
Conversion of 220 V AC input voltage to DC (DC is converted to high-frequency non-sinusoidal alternating current).
Subsequent high-frequency current rectification (frequency is maintained).
Thanks to these principles, a significant reduction in the mass and dimensions of the inverter occurs, which makes it possible to additionally integrate cooling.
To troubleshoot inverter welding machines, you need to familiarize yourself with its structural diagram. It consists of the following elements:
Inverter.
Transformer.
High-frequency rectifier.
Control and stabilization circuit (driver and control board).
Welding current regulator.
VIDEO
Thanks to this device, there is a reduction in weight and dimensions. The use of a pulse transformer makes it possible to obtain powerful currents in the secondary winding. Therefore, the welding inverter is an ordinary switching power supply, like in a computer, but with a fairly large power. With increasing frequency, there is a decrease in the mass and dimensions of the transformer (inversely proportional relationship). To obtain a high frequency, powerful key transistors are used.
It switches with a frequency from 30 to 100 kHz (depending on the SAIPA model). Transistors only operate on a constant voltage (U), converting it into high-frequency current. It turns out a constant current from the rectifier (rectifying the mains voltage 50 Hz). In addition, a capacitor filter is included in the rectifier. When current is passed through the diode bridge, negative amplitudes of the alternating U are cut off (the diode passes current in only one direction). Positive amplitudes are not constant and a constant U is obtained with noticeable ripples, which must be smoothed out using a large capacitor.
As a result of the transformations at the output of the filter, DC U appears above 220 V. The diode bridge and the filter form the inverter power supply. The transistors are connected to a step-down pulse high-frequency transformer, the operating frequencies of which are from 30 to 100 kHz (30,000-100,000 Hz), which are 600 or 2000 times higher than the mains frequency. As a result, there is a noticeable reduction in weight and dimensions.
The most common models are the resanta SAI 220 (220a, 220k), as well as the 190 (190a) model. Welding inverters have similar characteristics, differing in the welding current:
Maximum current strength: up to 35 A.
No-load voltage: 75.85 V.
Arc forming voltage: 22.30 V.
Welding current ranges: 5.270 A.
Load duration (maximum current): 4.8 min.
Maximum diameter (d) of the electrode: 5 mm.
Weight: about 5 kg.
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If there is no desire to give the welder for repair and you want to figure it out on your own (after all, the circuit is not so complicated), then you need to find and study the circuit and malfunctions of RESANT SAI 190. If you have experience, then the circuit can not be used at all, which is needed only for convenience and quick search malfunctions. To illustrate an example, a diagram of an inverter-type welder RESANT SAI 220 (190) is shown, and the main radio elements that often fail are marked.
Scheme 1 - Electrical diagram of the SAI 220 resant welding inverter.
To repair the device, you need to disassemble typical malfunctions and ways to eliminate them.
Sometimes the inverter type welding machine fails. The causes and consequences can be varied. If possible, you should take it in for repair. However, many will want to do it themselves. Thanks to this solution of the issue, you can increase your knowledge in the field of electrical engineering, because there are a lot of electrical devices and you can significantly save on their repair. Faults should be classified as simple or complex. Simple ones include:
Broken wires.
Loss of power (due to wet case).
Punching the mass onto the hull.
Bad contacts.
Sticking electrode.
Any electrical device does not like dust, as it makes it difficult to transfer heat, is a conductor of current (possibly short circuit). Even with high-quality cleaning of the room, dust will still be there. Regular maintenance can not only prolong the life of the devices, but also protect you from many financial and repair problems.
Broken wires occur in those places that are subject to constant bends. Bending wires are very difficult to trace and often cause short circuits.In addition, on the pads holding the electrode, the contacts are loosened, making welding less efficient or impossible. All contacts need to be tightened periodically.
Wet work also affects the welder's performance. Power loss may occur. In this case, such working conditions must be avoided.
When punching the mass onto the case (knocks out the fuse and the meter), you need to check the contact points of the live parts with the case and insulate the wire.
Sticking of the electrode occurs in the event that you use a long extension cord with a small cross-section or at a low voltage of the electrical network.
In addition, if the arc is unstable, check the quality of the electrodes and the set current.
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Breakdowns of a complex type include malfunctions of any radio element and require additional knowledge. If there is no experience in repairing radio equipment, then there are 2 ways to solve the problem:
Give it to a qualified technician.
Gain experience in this area and do everything yourself.
You should pay attention to safety rules when repairing equipment and be very careful. In fact, there is nothing difficult in repairing on your own. You just need to open the Internet and find all the parts of the inverter type welder. There is a lot of information on the Internet about checking a particular part. There is even a check of microcircuits at home.
First of all, you need to visually inspect the details. These can be burnt resistors, diodes, swollen electrolytic capacitors, a burnt transformer, and much more. If nothing is found, then you need to check the arrival of the input U to the diode bridge. To do this, its output must be disconnected. If the diodes are broken, the faulty ones must be replaced and try again. If the LEDs do not light up, then you need to check them and, if possible, replace them with serviceable ones.
The next step is to test the fqp4n90c transistor. The key transistor 4n90c in the power supplies of welding inverters serves to increase the frequency of direct current and transmit it to a pulse transformer. An analogue of fqp4n90c (what to replace) is STP3HNK90Z, but it is desirable to find the same one.
In case of faults in the power unit, you need to check the transistors (visual inspection may show nothing). To do this, you need to unsolder them and check with a tester (check methods can be found on the Internet). A driver based on transistors or microcircuits fails in the same way. It is checked by desoldering and checking each element separately.
Replacement of faulty parts is carried out by their analogs or elements, the characteristics of which exceed the parameters of the original parts.
For repair, you need a multimeter and an oscilloscope (measurement of signal parameters on the control board). If the control board is faulty, the yellow LED lights up. This indicates a lack of readiness for welding. In this case, you need to disassemble the inverter and measure the voltages at the connectors of the control board (hereinafter referred to as CP). During measurements, the data should be compared with the tabular values (table 1) of a working CP.
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Table 1 - Comparison of U.
If the measurements differ from the table values, then you need to solder the PU, find the UC3845B (UC3842) microcircuit and measure its operating modes.
Table 2 - Operating modes of the UC3845B (UC3842) microcircuit.
Power is not supplied to the 2nd leg due to a faulty resistor R013. It is necessary to carefully evaporate it and check, the resistance should be about 1.21 ohms. If it is faulty, then it is necessary to replace it with the same one or take more power (initial power 0.25 W).
The third leg of the microcircuit does not receive power due to a faulty R011 (47 by 0.25 W), it must also be checked. Legs 3 and 6 are tied and, therefore, when the resistance is changed, U and 6 will appear. If this does not happen, then you need to check the fqp4n90c transistor.
Next, you need to restore the nutrition of 8 legs (resant scheme sai 190 or 220), it is connected with a chain of elements.Weak points in it, which must be evaporated and checked: diode D011 and R010.
After all this, you need to measure U. In case of coincidence with the tabular ones, you should connect everything and test. When fully restored, the inverter will turn on and the yellow LED will not be on. After a positive test run, you can reassemble it completely.
Failure of the transformer is possible, and this phenomenon is quite rare. It is necessary to ring the windings for short-circuit and current leakage to the case.
This makes troubleshooting common welding inverters easy. The principle of operation of each of the models is the same, and they differ only in details and design. When repairing, it is very important to follow the safety rules when repairing radio equipment. The initial stage in the repair of a welding inverter (this rule applies to any equipment) is to conduct a visual inspection of all elements for breakage of contacts, burning and swelling of elements, as well as poor contact (before starting the repair, all contacts must be well cleaned).
Video (click to play).
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