Good luck!
Edited by Andryzel (06/29/2016 11:42:12 PM)
And what is the real capacity of the C75 condenser?
The device is half restored, it starts up, but the current is not regulated, only five amperes. Can anyone have a diagram or have encountered such a problem, tell me. Thank you.
the circuit should be in the topics about these devices of the IR series
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and here is the diagram
If a resistor heats up that charges the capacitors of 22-57 Ohm during operation, then look most likely there is a zener diode next to the relay and it is broken. There was something like it works, the current is small, but the problem is not in the control, namely in the relay circuit (the current goes through the poorly pressed relay contacts and through the resistor (it does not burn out at the same time). Or the contacts in the relay burned out, or it happens before laughter - the contacts of the power switch are burnt and does not give out power, although it seems to turn on and there is xx.
Hello everyone. The other day, a welding inverter was brought to the repair, perhaps my note about this repair will be useful to someone.
This is not the first welding machine that had to be done, but if in one case the malfunction manifested itself like this: He switched on the inverter to the network ... and broads, knocked out the circuit breakers in the electrical panel. As the autopsy in the welder showed, the output transistors broke through, after the replacement everything worked.
But in this case, everything was somewhat different, according to the owner, the device at times stopped cooking, although the power-on indicator was on. These guys themselves opened the case - they tried to determine the malfunction and noticed that the inverter reacted to the bending of the board, i.e. when it was bent, it could work. But when the welding inverter came to me, it did not turn on at all, even the on indicator did not light up.
"Titan - BIS - 2300" - it was this model of the inverter that was repaired, the circuitry repeats the welding machine of the same power of "Resant" and, as I suppose, many other inverters. You can view and download the diagram here.
In this welding machine, a pulsed power supply is used to power low-voltage circuits, and it was just it that was faulty. The UPS is based on the UC 3842BN PWM controller. Analogues - domestic 1114EU7, Imported UC3842AN differs from BN only in lower current consumption, and КА3842BN (AN). See UPS diagram below. (Click on it to enlarge) The voltages that were already supplied by the working UPS are marked in red. Please note that you need to measure the 25V voltage not relative to the common minus, namely from the points V1 +, V1- and also V2 +, V2- they are not connected to the common bus. 
The UPS key is made on a transistor, field 4N90C. In my case, the transistor remained intact, but the microcircuit required replacement. There was also an open circuit resistor R 010 - 22 Om / 1Wt. After that, the power supply unit started working.
However, it was too early to rejoice, having measured the voltage at the output of the welder, it turned out that it was not there, and in idle mode it should be about 85 volts. I tried to move the board, remember from the words of the owner it affected, but nothing.
Further searches revealed the absence of one of the voltages of 25 volts at points V2-, V2 +. The reason is an open circuit in the winding transformer 1-2. Had to drink a trance, used a medical needle to release the conclusions.
In the transformer, one of the ends of the winding was cut off from the terminal.
We carefully restore the connection using a suitable wiring, the restored connection will not be superfluous to fix it with a drop of glue or sealant. I had polyurethane glue at my fingertips and used it, we revise other conclusions, if necessary, we solder.
Before installing the transformer, you should prepare the board so that it fits into its place without effort. To do this, you need to clean the holes from the remnants of solder; this can also be done with a needle from a syringe of a suitable diameter.
After installing the transformer, the welding inverter started working.
How to check the microcircuit without unsoldering it from the board and what else to pay attention to.
You can partially check the microcircuit if you have a voltmeter and an adjustable stabilized constant voltage source. A signal generator and oscilloscope are required for a complete test.
Let's talk about what is easier. Be sure to turn off the power to the inverter before checking. Further - from the external regulated power supply to pin 7 of the microcircuit, we apply a voltage of 16 - 17 volts, this is the starting voltage of the MS. In this case, at pin 8 there should be 5 V. this is the reference voltage from the internal stabilizer of the microcircuit.
It should remain stable when the voltage changes at pin 7. If not, the MS is faulty.
When changing the voltage on the microcircuit, keep in mind that below 10 V, the microcircuit turns off, and turns on at 15-17 volts. You should not increase the supply voltage of the MS above 34 V There is a protective zener diode inside the microcircuit and if the voltage is too high, it will simply break through.
Below is a block diagram of the UC3842.
Addendum to this article: After a while, another apparatus was brought. Out of order due to falling on its side. This happened because during the operation the screws holding the case loosened, and some were simply lost, so when the board fell, it played and touched the case with the mounting side.As a result of the short circuit, all 4 output transistors K 30N60HS failed. Analogs G30N60A4D, G40N60UFD. After the replacement, everything worked.
That's all! If you found this article useful, leave your comments, share with your friends by clicking on the social media buttons.
The design of a welding inverter is rather complex, therefore, the least safe to operate. The great advantage is the high quality of the work performed by the device. At the same time, any structure wears out and breaks down over time. Therefore, there are two solutions to this problem.In the first case, the apparatus is repaired by hand, and the second case is associated with contacting specialists for the repair of welding inverters.
Diagram of a welding inverter semiautomatic device.
A complex device requires appropriate knowledge and the correct approach to repair. It is important to understand electronics here, that is, diodes, transistors, resistors and stabilizers.
What devices will be needed for this:
Multimeter connection diagram.
Other special instruments will be required to measure various indicators. It can be too difficult to detect a malfunction, therefore, it will be necessary to check all the elements more than once, their certain sequence, in which they should be contained in the general scheme.
The operation of the inverter is based on a scheme associated with a step-by-step signal conversion. Initially, the current is rectified due to the input rectifier, after which it begins to be converted into variable frequency current due to the inverter module. Then, a power transformer is involved in the conversion process, therefore, the frequency current is converted into a welding one. After the transformer, the variable frequency current is converted into a welding form due to the output rectifier. Before inspecting the inverter, refer to its microcircuit and drawings.
It is necessary to emphasize that the main features of welding inverters is the accuracy of work. If even the highest quality inverter is out of order, then among the main reasons for this are the following:
- Incorrect use of the device.
- Lack of accurate connection of the device.
- Changes in mains voltage.
- Changes in current strength.
Figure 1. List of possible malfunctions of the welding inverter.
The causes of breakdowns can also be bad weather conditions, if they are observed during the operation of the device on the street. These may be too dirty rooms, high levels of humidity, rain, snow, etc. The most vulnerable point of the inverter is the terminal block, the cable is connected to it. The lack of normal contact and at the same time a significant indicator of the current strength will be a prerequisite associated with overheating of all elements and connections.
Melting of the insulation is also a malfunction, which can cause a short circuit. The list of possible malfunctions is presented in the table (Fig. 1). At the same time, do-it-yourself repair of the welding inverter is carried out by stripping the contacts and tightly joining the connection, which heats up during operation.
There are the following main stages associated with the diagnosis of inverter malfunctions:
- The equipment does not turn on.
- The inverter shuts down by itself.
- The appliance makes a lot of noise.
- Strong overheating of the structure occurs.
- An interruption of the electric arc is observed during welding.
- Poor current regulation.
- Electricity consumption is over-limit.
If the device does not turn on, then the main reason for this is:
- Lack of mains voltage.
- Operation of the machine on the dashboard.
- The equipment stops working.
Before starting the repair of the inverter for welding with their own hands, they check the transistors, which often fail in the first place.
Diagram of an electronic oscilloscope device.
A thorough inspection will be required here. The appearance of the faulty part speaks for itself, featuring a warped body. If a burned-out transistor is found, it must be replaced with a new one. If there are no external defects, then with the help of a multimeter it is necessary to ring the transistor, after which you should select a new element and make it a high-quality installation in place of the previous transistor.
Power transistors have driver elements that should be checked second. This type of parts is more resistant to damage, since this can happen to the elements that power the drivers themselves. An ohmmeter allows you to check the performance of the power transistors, after which the part can be evaporated and replaced with an analog.
If there are difficulties in detecting defects, then it is very important to check the rectifiers connected by diode bridges mounted on the basis of a radiator. These elements of the inverter have significant durability, as breakdown inside the mechanism can occur. Diagnostics of the diode bridge requires first to release it from any wires with a soldering iron, removing it from the control board, respectively. The work with the inverter is greatly facilitated by the lack of dependence of the circuit on a short circuit. A soldering iron equipped with a suction helps to evaporate the faulty diode.
Finishing the diagnostics, they inspect the board that allows you to manage the keys. This detail is a complex and important element of the apparatus. Finishing the repair of the inverter, they check the operation of the control signals, which should go to the busbars of the gates of the key module.
Diagram of the front panel of the inverter.
Monitoring this control signal is not difficult as an oscilloscope can be used. If the case is unclear, expert intervention will be required.
Long and trouble-free operation of the inverter can be ensured by observing special rules:
- Carrying out a technical inspection of the welding inverter before starting work with it and preparing the workplace.
- Installation of the device in a horizontal position, which will prepare the workplace.
- Connecting welding cables to the power connectors of the device: to the electrode holder with a "+" sign, and to ground - with a "-" sign.
- Checking the fixation of the cable glands in the soldering sockets by turning them clockwise.
- Connect the appliance to the power supply by plugging it into a power outlet.
- Switch the switch to the "ON" position to turn on the fan.
- Trial arc ignition.
- The current regulator knob sets the required mode for welding.
If you follow the recommendations related to the correct maintenance of the device, then it will serve for a long time:
Block diagram of a digital voltmeter with a time-to-pulse converter.
- It is strictly forbidden to use the device with the cover removed for a long time.
- Inspection of the internal components of the device should be carried out more often, which is determined by the frequency of use of the device and the degree of contamination of the working space.
- The dust accumulated in the device must be removed by using compressed air at low pressure, i.e. less than 10 bar.
- Cleaning of electronic boards is not done with a jet of compressed air, but only with a small brush.
- Before carrying out work, a safety check should be carried out when fixing the power connectors in the corresponding sockets of the device, check the power plug, socket and the insulation of the electronic cable.
- Transport and storage of the device must be suitable for weather conditions.
- When transporting the device by transport, it can also be placed in an upright position.
- Store the device only in a dry room where the relative humidity is 80%.
- The inverter is kept disconnected from the mains.
Welding inverter circuit.
To repair a faulty inverter, you should find out all the principles of its operation. At the first stage of work with the welding inverter, the mains voltage is rectified by the devices, and then it is converted into a variable frequency voltage. After that, it is reduced to a level that allows safe welding. The last stage is associated with the presence of constant welding voltage.
The listed processes are regulated by the control unit, which has a rather complex design.Starting the repair of the welding inverter, it must be visually inspected in order to clean out all the places that do not have normal contact.
These zones are traditionally rectifier diodes. It is possible to mount the diodes using threaded connections, and all special tools are not needed.
Pre-check the diodes, examining their "throughput" or "breakdown", which is associated with the possibility of free passage of current through the diode in the same direction. This is done with a multimeter. With a constant resistance, in the case of measurements from plus to minus, the diode should be replaced.
Even a faulty diode will allow welding with an inverter, and the ability to turn on the device is not associated with ensuring normal operation. If the device cannot be turned on or off normally, an urgent repair will be required. Any inverter model has a fuse on the control board. If you dismantle it, then you can get to this device.
Removing the control board requires marking all connectors, of which there can be more than three, and they themselves are similar to each other. If the fuse is defective, then it is not difficult to assemble and install it, only patience and accuracy are required.
Welding inverter power circuit.
Often the reason for the failure of the transistors of welding inverters is insufficient cooling. The element contact must have thermal grease and a heat sink plate. It is not difficult to unsolder and install the part, but it is imperative to control the possibility of its overheating, since a sufficiently hard-melting solder is used for soldering.
If the power transistor fails, then this leads to breakdown of the drivers adjacent to this part. Diodes and zener diodes can often fail. The transistors are first inspected from the outside and then replaced.
If the transistors have already been inspected and checked, followed by replacement, since the cause of their breakdown has been found, then the presence of a "swinging" driver is considered as a prerequisite. Similarly, using the tester, you can call any elements of the board, replacing them with serviceable ones.
It is imperative to check the printed conductors of the board, which will reveal the presence of burn. Existing burnt-on areas can be removed and the other jumpers can be re-soldered. All soldering points are covered with a special varnish. First, check and clean each pin of the connectors with a white drawing eraser.
Diagram of the internal device of the welding inverter.
Rectifiers are output and input full-wave diode bridges that are equipped with silicon valves. They are considered reliable parts, but they can also wear out. Controlling them is not a difficult task. Soldering bridges from electronic circuits is associated with dismantling the brackets. If the bridge is ringing only in one of the directions, then it is serviceable, and if in both directions at once, then this bridge is broken. The check is carried out when the bridge is already assembled and in place.
Checking the board that allows the control of the device is associated with a continuity tester, which allows you to control the gate control signal using the key module. You can check it using an instrument called an oscilloscope. In a normal test, all signals will be correct, otherwise it will turn out that something has been missed.
Thanks! I rested on them. but how is the plot? strapping? or will the photo help?
