Butter transformer current from microwave

Microwave transformer. Important chain link generating microwave radiation. This is a power supply voltage converter to the value supplied to the input of Magnetron. The high-voltage converter often becomes caused by a microwave furnace.

Checking the transformer for performance. a mandatory point in the list of activities for technical diagnostics to determine the causes of malfunction. As it is about high voltages, independent intervention is possible only subject to all security measures.

Remove the microwave transformer

If a transformer has a power of 700-800 W in the homemade apparatus for point welding, then with its help you can connect sheets of metal, the thickness of which reaches 1 mm. Such a transformer enters the category of device devices to ensure the power of the magnetron, it is able to produce a voltage equal to 4 kV.

Magnetron, which is equipped with any microwave, requires high voltage to work. In this regard, the transformer connected to it is characterized by a smaller number of turns on its primary winding and large. on the secondary. The latter creates a voltage of the order of 2 kV, the increasing then doubled through the use of a special double. Check the performance of such a device by measuring the voltage connected to its primary winding, there is no point.

Remove the microwave transformer

Remove the transformer from the microwave. Do not take the hammer and other heavy items. From the microwave, its base is unscrewed, all mounts are removed, and the transformer is neatly removed from the place of its installation. In the device extracted from the microwave oven, you will need, firstly, its magnetic pipeline, secondly, the primary winding, which compared to the secondary is made of a thicker wire and has less turns.

Secondary winding because of her insensitiveness you will have to dismantle, for which the hammer and chisel will be. It is very important at the same time not to damage and not to remember the primary winding, so it is necessary to act with maximum accuracy. If when dismantling the secondary winding, you will find in the shunts transformer used to limit the current strength, they also need to remove them.

Secondary winding can be cut off by a chisel

power, microwave, transformer, secondary, winding

If the transformer magnetic circuit breed is not glued, and a welded design, then it is better to remove the secondary winding from it with the help of a chisel or a conventional metal hacksaw. If the winding is very tightly naked into the magnetic pipeline window, then it, cutting the wire, will need to drill or dig. It is necessary to do this very carefully, since the magnetic core can be collapsed due to such manipulations.

After performing dismantling work, you should get a new secondary winding. To do this, you will need a wire with a diameter of at least 1 cm. If you have no such wire in stock, it will have to buy it. At the same time, it is not necessary to purchase a one-piece multi-core wire of such a section, you can use a beam from several individual conductors, which in the amount will ensure the required diameter. After installing the new secondary winding, your upgraded transformer will be able to produce a current, which is up to 1000 A.

BEST Microwave Oven Transformer-MOT Rewinding Tutorial

Old winding can be cut with a metal with a metal

If you want to make a machine for spot welding more powerful, then the technical capabilities of one transformer may not be enough. Here you need to use two such devices (respectively, breaking two microwaves).

Production of electrodes

Spot welding from the old microwave will effectively work only when using high-quality electrodes. You can independently make electrodes from a copper rod. The connection of the electrodes with the contact wire is carried out through the tip, which must be qualitatively soldered to the copper conductor.

The operating side of the electrode should be sharpened in the form of a cone to obtain a better welded joint.

Point Welding Electrode

If there is no desire to independently engage in the manufacture of electrodes, you can buy ready-made, but for 1 pc.

Important Transformer Detail

In the microwave oven there is only one important detail. able to come in handy in the creation of the device. transformer. The transformer in the microwave is the usual two coils from the copper wire. Wrapped on the core. There are two windings. primary and secondary. Coils with winding have a different amount of wire turns: In order to connect to the primary winding, the voltage in the second coil due to the induction there was a current with a smaller voltage, and the strength of the current increased.

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Procedure for secure verification

Getting Started with an independent check, you need to stock multimeter (for the extreme case. a two-pole indicator with a built-in power supply), screwdrivers with different tips, ohmmeter, pliers.

The overall scheme of safe work looks like this:

  • turn off the power supply device;
  • unscrewing the screws, remove the casing;
  • discharge capacitor;
  • From the transformer gently remove the terminals;
  • Checking its windings: if the parameters are normal. installed in place and seek other reasons;
  • When they find a break or closure. perform the replacement of the device;
  • The furnace assemble and check its performance.

If after assembling the microwave does not function, then you should search for more reasons or resort to check with a connected voltage.

If after removing the transformer on its windings, traces of the insulation is visible, there is a strong grown smell from it, then it is no longer suitable for use, but it does not make sense. In this case, only the device replacement will help.

Before you begin to survey the transforming device, you must accurately make sure that it is powered by. To do this, you follow a multimeter to check for availability (pre-turning on the device to the network and running the heating program) at the point of connection of the primary winding of the alternating voltage by the value of 220 V. This work is carried out extremely carefully in order to avoid electric shock.

Since to check the transformer, you will need to disassemble the microwave oven, you can do it only after turning off it from the supply network.

The presence of a high-voltage capacitor capable of maintaining an electric charge leads to the need for its discharge before conducting verification works. This is done by simply closing its contacts among themselves (screwdriver, passatizing) or on the case when the voltage is turned off.


The high-voltage microwave furnace transformer is designed to form the stresses needed to power the magnetron. The choice of transformer in parameters depends on the characteristics of the Magnetron installed in a specific furnace. The more powerful magnetron, the greater power should develop its transformer. Thus, the high-voltage transformer and magneton form a certain inseparable pair. The basis of the transformer is a core, which is a packet typed from electrotechnical steel and fastened by means of welding (in the figure, welds). To the bottom of the package, the flange is welded, in the form of a rectangle from a steel sheet, by means of which the transformer is attached to the bottom of the microwave oven. The transformer contains three windings: primary (network), and two secondary. The secondary windings include: Glow Winding and Enhancing (Anodic) Winding. Network winding is wound (usually) enameled, aluminum wire. End winding, withdrawn under terminals. The slot winding is 2. 3 turns of the mounting wire and is designed to power the filament of the magnetron. Winding conclusions, in the form of conductors are equipped with connectors, for the convenience of accession to Magnetron terminals. Glow winding, issues a voltage of about 3.3V., at current 10a. Accurate values ​​of current and voltage depend on a particular pair, magnetron. transformer. Raising winding forms high voltage required for power Magnetron. About 2000 volts are removed from this winding at a current of 0,3a., Accurate values ​​depend on a particular pair of magnetron. transformer. Winding wounds enamelled wire. One end is derived under the terminal, the second is connected to the core of the transformer (and through the core and with the furnace case) by soldering. The entire design of the transformer, for reliable insulation of the windings and to eliminate the bounce when working, is impregnated with a special impregnated varnish.

power, microwave, transformer, secondary, winding

The main malfunctions of the high-voltage transformer can be attributed to the Mixless closure in the windings. Such a malfunction occurs in the consequence of the insulation disorders between the turns of the winding (the destruction of the enamel of the wire). Accompanied by a reinforced hum when operating a transformer (even without load) and a significant increase in temperature like windings and a core. Visually noticeably darkening enamel winding wire and impregnating material. With long work there is a caustic smell.

Since all transformer windings are made rather thick wire, then the winding break occurs very rarely (if only as a result of external mechanical exposure). often, as a result of not high-quality soldering, the loss of contact arises between one of the ends of the winding and the terminal (in the picture the place of the soldering). The transformer terminals are made of copper alloy, which soldes well, but the winding is wound by aluminum wire, and solder aluminum and copper, without a special flux, is practically no possible. Availability of contact can be checked by an olemic. The slope must be ringing almost short, the network has resistance in the area 4, and approximately 150. 200. The resistance of the windings depends on the parameters of a particular transformer.

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The most common malfunction of the magnetron power supply. is the disappearance of the contact between the transformer winding terminals and the external furnace chain connectors. This happens as a result of bad crimping connectors. The place of bad contact begins to spoke, the contact surface of the connector is very hot and fade, as a result, the contact disappears at all. The consequences of poor plug clamps are shown in the drawing.

Category: Device | Tags: high-voltage transformer, replacement of high-voltage transformer


In this article, consider a specific example of repairing a microwave oven. Daewoo firm came to repair. The owner of the furnace complains that the furnace, in the mode of microwave, does not heat up the products, and the operation of the furnace is accompanied by an elevated level of noise (strong hum and vibration) and not a pleasant smell of Gary.

Making sure the truthfulness of the owner’s words, remove the furnace casing and spend the visual inspection of the internals. In our case, the cause of a malfunction, as they say, is not visible by an armed eye. At the high-voltage transformer, there is a strong darkening of the high-voltage winding and the destruction of the plug-in connection of the high-voltage fuse (Figure 1). On the face of all signs of interstitious closure in the secondary winding of the high-voltage transformer.

Such a malfunction could occur in the result of the failure of the load elements, T.E. Magnetron or one of the components of the high voltage rectifier (condenser or diode). But, judging by the burnt terminal of the fuse, the closure in the winding arose due to the non-quality manufacture of the transformer itself. Most likely, there was not a reliable contact at the place of connecting the output of high voltage winding and terminals. During the work of the furnace, the place of poor contact was very grain, which led to the destruction of the insulation of the winding wire and, as a result, the closure between the winding turns.

In this case, you will have to replace the failed transformer along with the fuse. Next, it will be more convenient to divide the entire replacement process to the steps. So, let’s begin…

Disconnect all conclusions of the transformer, both from the primary and the secondary supply chains of the furnace. Remove the detachable connections with the primary winding terminals, with the Magnetron terminals and disconnect the output of the condenser’s fuse (Figure 2).

We put the oven on the edge, as shown in Figure 3. The flange of fastening the transformer will be pulled to the bottom of the furnace with four screws (in Figure 3, denoted by blue arrows). One hand, with a screwdriver, unscrew the screws, with the other hand we hold the transformer from below. This is to ensure that after extracting the last screw, the heavy transformer did not collapse on the camera wall and did not dent. Then simply remove the faulty transformer from the bowels of the microwave.

Turn over the oven, as they say, from the head to your feet and with an ohmmeter, still check all the elements of the transformer load. How to check magnetron, more described here. But, I repeat, none of the Magnetron power terminals should “be nicknamed” to the body. The device must show “Infinity”. If the Ommeter shows the presence of at least some resistance, then there is a leakage or a breakdown of the passage capacitors of magnetron. The resistance between the terminals of Magnetron, on the contrary, should strive for zero (1. 2 ohms), it says about the health of the filament. When checking a high-voltage capacitor, its terminals should not “be norbled” to any other, nor on the body. the device should show “Infinity”. The high-voltage diode should also not “be nicknamed” by an ohmmeter in one direction.

Further, if we have positive results on paragraph 3, then we take a new or simply obviously good transformer, be sure to set up the parameters to the magnetron installed in this furnace, again put the furnace on the edge, insert, combine the mounting holes and fasten. Return the furnace at home. Attach the power and load connectors. Before checking the performance, once again we carry out a visual inspection. We check whether we are all connected correctly, we look at whether the impeller does not touch the fan’s thick high voltage wires, this often happens after replacing the transformer or high-voltage fuse. If hurts, then we put the conductors properly.

We turn on the microwave to the network, put a glass of water in the chamber in the chamber, set the microwave mode, set the time of operation (for the beginning one minute is enough) and press the start button. We wait until the set time is released. After turning off the furnace, check the water temperature in the glass. With the normal operation of the furnace, in a minute, the water is not heated strongly, but its temperature will differ significantly from the room. If the initial check has passed successfully, will continue and bring water to boil. To do this, we will replace water in the glass on the cold and install a timer for five minutes. In a fully serviceable microwave oven water in standard (200g.) The glass must boil approximately three minutes.

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If the furnace successfully passed all the tests, then you can safely wear a casing and read the repair process finished. Nothing complicated? But there may be nuances. Well, if you managed to find and purchase a transformer completely identical to what was installed in this furnace. But often there are situations when the transformer coming to parameters has a different fastening flange and fastening holes in the flange do not match the holes in the bottom of the furnace. In this case, the replacement process is somewhat more complicated, but not much.

After the execution of paragraph 2, separate the bottom of the furnace from the case. To do this, unscrew the five screws marked in Figure 3 of the Red Arrows. Note five screws! The sixth screw is attached only to the bottom loop of the door and the bottom of the bottom is not related. it is not necessary to unscrew. As a result, it should be done as shown in Figure 4.

Then we take the “donor” transformer and apply it to the place of attachment. Part of the holes may coincide. With the help of a thin marker through the holes in the flange we plan the place of missing holes in the bottom of the oven. We remove the transformer, turn the places marked, charge in a drill of the suitable diameter and drilling holes. After this procedure, you can immediately strengthen the transformer on the bottom, and then fasten the bottom to the housing. Next, you should perform all actions for other points. Successes in repair!

Rubric: Examples of repair | Tags: high-voltage transformer, replacement of a high-voltage transformer, malfunction of magnetron

How to verify how to work

Conventional voltage transformers, pulse converters can be checked in terms of voltage values ​​on windings, producing stress measurements alternately with a multimeter.

Practical rewind of transformer windings after calculations and measurements

  • According to the size of the present magnetic pipeline of the device make it layout for convenience of winding, using the mechanized technique or manual types of work with the wire, to record the possibility of a normal winding of the winding of one or another type, taking into account the technical and electrical parameters of each. At the first moment, make test windings and measure the indicators on them with a measuring device, compare measurement with the value set;
  • Conduct high-quality insulation of conductors of all circuits of windings with each other, as well as relative to the magnetic pipeline for checking the integrity and quality of isolation, possible defects and other points in order to eliminate timely;
  • On the conclusion of installation winding work, perform verification tests for all known measurement classes:
  • Measurements of resistance to assess and understand the implementation of installation work on the isolation of windings, assessing their conformity of nominal values ​​and other factors;
  • Stress measurements under current network values;
  • Tests for the presence of inter-touch closures using the measuring device Multimeter. by specified parameters.

The procedures of the control check will make an audit conclusion about the correctness or error when performing the winding winding process, in the calculation of their values ​​by many properties.

power, microwave, transformer, secondary, winding

Summarizing the rewind of transformer windings should always be the final stage of the release of upgraded or repaired electrical dispense or equipment based on the converter from microwave ovens.

If everything is done correctly without violation of acts of safety and the calculation of basic values ​​is not allowed. all duplicate procedures will be held quickly and without lining and the equipment itself will operate in a nominal with new windings and their manual assembly.

If, with a test connection, the unit behaves suspiciously, publishes the buzzing sound of the buzz, gives small vibrations and strong heating of nodes and mechanisms. checking urgently stop, power to disable and send to a detailed replay with checks of all steps from the very beginning.