Do-it-yourself microwave oven panasonic

The algorithm for starting the inverter is as follows:
1. The control unit (CU) issues a control signal (“meander”, the duty cycle is determined by the selected power value) through the IC701 optocoupler to the inverter driver;
2. The driver turns on the inverter - voltages are formed: filament and anode. If there are no start-up attempts (there is no voltage on the inverter or it is significantly damaged) - after 3 seconds, the control unit turns off the furnace;
3. If the filament current is for a long time more than twice the nominal 10A, the driver turns off the inverter. Four attempts are made to start this way, it takes about 10 seconds. If you disconnect the anode voltage from the magnetron, then the current consumption of the 220V furnace is about 1A (that is, only when the heating is running);
4. As soon as the driver considers that the inverter is working normally, a feedback signal is issued through the second optocoupler IC702. If there is no signal, the control unit stops working after 23 seconds.
5. During normal operation, the current consumption over the 220V network is about 5A.

For those who wish - inverter circuit:

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Microwave (microwave) oven Panasonic NN-G335 is a very successful model, both in design and in functionality. Until now, this model has not been discontinued, but only underwent a slight restyling. The oven has an exceptionally convenient handle for opening the door, equipped with a grill and electronic (touch) control. Despite the relatively high price in its class, the Panasonic NN-G335 microwave is in great demand among buyers. What is the furnace in operation in terms of the reliability of the electronic and mechanical components?

Corroded bottom of the chamber.

After about three years of operation, through corrosion of the bottom of the chamber formed. The high humidity and friction of the turntable wheels are likely to be the cause of the corrosion. Immediately after the discovery of such a defect in the chamber, the furnace was checked for radiation leakage using a microwave detector. Everything turned out to be normal. The outer casing shields well despite the major destruction of the camera.
In the second year of operation, the camera illumination lamp burned out. The breakdown is not at all terrible and easily removable. You need to: open the oven (remove the cover), disconnect the wires on the lamp, remove the lamp and install a new one. However, the lamp there is used not ordinary, but a special one for microwave ovens (the base is not threaded, but in the form of two contacts). Buying a lamp is not particularly problematic. As a last resort, you can put an ordinary lamp, having come up with a way to fix it and connect the power wires.

Backlight lamp.
Shines through small through holes directly into the camera.

In the third year of operation, at one "fine" moment the furnace refused to work at all (the display did not light up, there were no signs of life). After opening the case, first of all, the thermostats were checked, and a malfunction was immediately found - one of the thermostats was in a permanently open state. There are two such thermostats in the Panasonic NN-G335 oven, both operate to open when their body is heated above the nominal response temperature (indicated on the thermostat body). In order to replace a failed thermostat in any microwave oven, you need to know the response temperature of the failed thermostat, its operating current, the type of switching (on or off) and the type of case (appearance). We could not find the same thermostat (by fixings).This is not scary, the main thing is to ensure reliable thermal contact of the thermostat body with the body of the investigated object (details of the furnace structure on which it is installed).

"Live" thermostat in the standard setting (photo on the left).
Replaced thermostat. Installed with an additional pressure plate and self-tapping screws (photo on the right).

It is difficult to say what was the reason for the failure of the thermostat. Most likely, the reason is simply in time, because everything has its own service life. If overheating took place, for example, due to the closing of the external ventilation slots by something, then after turning off the oven and cooling it down, a working thermostat should turn on again, which did not happen.
And the last thing I had to face was the blown of the power supply fuse as a result of the operation of the protective diode.

Power board with blown fuse F1 removed (photo on the left).
Power board, speaker view (buzzer). The hole marked with a red circle can be sealed, for example, with electrical tape, and the microwave will not beep loudly (photo on the right).

Protective diode 2X062H mounted on a high-voltage capacitor 1 μF x 2100 V (photo on the left).
The inscription on the high-voltage capacitor (photo on the right).

In order to find the reason for the operation of the protective diode 2X062H and, as a consequence, the blown out of the fuse, the resistance of the magnetron heating circuit was checked, it turned out to be extremely small (about 0.1 Ohm), it was not possible to accurately measure it with an ordinary multimeter. According to the found reference data for this magnetron, such a low resistance was normal for a working magnetron, or rather, should be 0.07 Ohm. The resistance between the magnetron body and its terminals was also checked, the resistance turned out to be "infinite", as it should be. From these measurements, it was concluded that the magnetron was in good condition (for lack of the possibility of a deeper test). However, when dismantling the magnetron and removing the protective metal cover, traces of excessive local heating of the coils were revealed (the enamel of the insulation had darkening), but the wire itself was not damaged. To ensure the conditional serviceability of the high-voltage transformer, the DC resistances of all its windings were checked. The resistances roughly coincided with the reference data. The measurement results were written with a pen on the transformer itself for the possibility, if necessary, to re-check the measurements in the future.

Magnetron Panasonic 2M211 (photo on the left).
View of the furnace with the magnetron removed (photo on the right).

Magnetron.A slightly burnt insulation of the coil is visible (photo on the left).

Magnetron. The cover is removed (photo on the right).

As a result, it was decided to replace the fuse with a higher current (10A), assemble and check the furnace in operation. As it turned out, this decision was correct. After the last repair, the microwave oven works perfectly, no extraneous noise or abnormal operation was observed. Of course, if repaired according to all the rules, then it was also necessary to replace the burnt out protective diode with a new one, but its far from the lowest price, the absence of radio supplies in the vicinity of the store and the extreme need for a kitchen in the oven outweighed the rest of the arguments. At the end of the article, you can see a few more photos of the repair process.

High voltage transformer. View of the nameplate (photo on the left).
The resistance of the high-voltage transformer windings was measured with a Mastech M-838 digital multimeter (photo on the right).

Contact to body one of the terminals of the transformer winding (during testing, it is necessary to check the presence of this contact with a multimeter).

Everything is connected.

Rectifier diode. Body contact (in red circle).

By the will of fate and the Almighty, it so happened that an employee in our service center who repaired stoves quit and they put me in the load about 2 years ago, as it seemed then an unbearable burden - you will repair stoves, they say, blah blah blah. At that time, I knew a lot about the stove from the position of a cook - something radiates there and everything is heated there. Moreover, it can make a good jerk when Steven Seagal mixes semolina with chilean pepper in the galley ... And in 2 years what I have drawn conclusions - nothing is easier than repairing a microwave - no! Well this is how grit IMHO. To do this, you need a screwdriver and a tester (it is desirable to ring on the dial - convenient) and self-confidence.

So. a terrible thing happened - the sandwich and porridge remained cold.

Warning - NEVER AND IN NO EVENT TOUCH THE OVEN WITH THE COVER REMOVED - ALWAYS UNPLUG THE PLUG FROM THE SOCKET (but it is possible to check the stove with the cover removed as if it were correct, but at the same time it is advisable to open the door and short-circuit the high-voltage output of the capacitor with a screwdriver to the housing with a screwdriver , about which below.)

There are 2 types of stoves - inverter (only Panasonic) (inverter is an electronic unit that feeds a magnetron - and a magnetron is a piece of iron with magnets that emits microwave) and transformer - all other brands. The transformer, as you understand, replaces the inverter, or vice versa ..

I'll start with the most difficult ones - Panasonic inverter ones (they always have an inverter nameplate on their face - they say it's cool).

One of the advantages (IMHO, the only one) of inverter ovens is that they can work normally at reduced mains voltage. The soup in the village will heat up 15 seconds faster. But at the same time, the power circuits of the inverter are overloaded like a rocket at Baikanur.

There are two cases inherent in these devices (in addition to the general malfunctions of which below) -

Now about the usual (Transformer) stoves

Again, there are 2 options - with mechanical control (power and time are set by knobs) and electronic (with a bunch of buttons and a clock)

I will describe the malfunctions of individual elements and what this leads to, and you can decide for yourself what went wrong in a particular case.

So remove the Cover (well, the cover)

1 A light bulb - they are all at 220 volts, low power and after 5 years they are terribly dirty

Well, everything is clear - you can do without it - Lights up when cooking and when the door is opened. It is not cheap - about $ 5 (I will quote Panasonic prices, maybe I work in a Panasonic service center)

2 MAGNETRON

Everything flows from it. If everything works, but the chicken is still cold, we check the magnetron. There should be almost 0 Ohm between its terminals, and infinity between the terminal and the case. If not infinity, then the through-line capacitor in the case is punctured - the device is for scrap. Although I read that some kulibins drilled out the plug and removed this condender. But I don't think the oven is worth it. Just out of pure curiosity.

The second point - one of the 2 magnets cracked due to overheating (due to the fact that a lot of dirt has accumulated on the fan blade - right?) If there is a crack in the magnet - a magnetron for a waste (about 40-70 bucks)

The third point (the most disgusting) is that the magnetron is in order in terms of parameters, but the chicken is still cold. Probably the emitter of the magnetron has broken through (the topmost pimple). Verification - only by replacement with a known good one. Although, do not rush to replace it yet. More on that later.

In general, you can install ABSOLUTELY any magnetrons in transformer furnaces - they really differ in power (but who counts the seconds for the sandwich to reach its standard), if only they fit constructively (here the main fastening and blowing of the radiator). In especially urgent cases, I rearrange the mounting plate. It rests on a curled antennae (even a mustache that is not so easy to unbend).And most importantly, if anyone is going to do this, you cannot knock on the magnetron - this is essentially a lamp but in a metal (I wanted to write - all-metal - I like this film) shell.

3 Thermal fuse

There are several of them in the furnace - on the case and on the magnetron. Should ring to zero. If not, we unscrew it and throw it on the stone floor with all that is urine - it should go into working condition (this is from the practice of repairing copier and printer stoves - there is the same thing)

4 End switches

First of all, after opening the stove, I check them.

If the mains fuse has blown (10 amperes), then you need to ring this particular limit switch (it closes the high-voltage part to ground). (The upper contact - the lower one in the figure - should clearly switch to the other 2 when opening and closing the stove door. You can't do without a tester. You also need to check the operation of the remaining 2-contact limit switches (there are from 2 to 4). You can of course tinker

4 bis Child Lock (protection against unintentional)

Also applies to "limit switches" - look if something like a child lock does not light up on the display or if there is a switch near the door (sorry for the people who are dragging a huge stove instead of reading the instructions)

5 Capacitor

In general, a trivial thing. In my memory, only a couple of dead Conders (the stove hums terribly). It is checked - if the tester is put on megaohms - it should be charged (according to indications)

Although if the power of the stove drops, everything depends on it (not counting the magnetron).

5 High voltage diode

It does not ring in any way (you need a tester with a 12 volt power supply). Leave him alone. The main thing is that it is well screwed to the body. (There was a case when I went to the stove under the guarantee 4 times changing everything in a row - but it was just because of my laziness and stupidity that one terminal of this diode was badly screwed onto the case. Forget it)

6 Protective diode (or whatever it is)

It stands in some stoves between the terminals of the capacitor. When it breaks down, the mains fuse immediately flies out. We bite it mercilessly and enjoy the hot soup (replacing the mains fuse)

7 High voltage fuse

There are different designs. Stands between the transformer and the capacitor. It should ring (The first thing I do when the stove is open and the mains fuse is live) In my humble opinion, it is not needed nafig (it simply is not in some stoves). It just signals that maybe the magnetron will become a kirdyk. We short it with a thick wire. If the magnetron dies, then let it suffer for a few more months.

8 Transformer

Constructions - an incredible amount. The symptom of a malfunction is that it heats up terribly and buzzes. Replacement with any one anyhow fits constructively and is necessarily well screwed to the body.

Here is a small remark. Perhaps some will say that manufacturers calculate a transformer for a magnetron or vice versa, and here I put any magnetrons under any transformers and vice versa. They may be right. But firstly, I do it in our realities, secondly, after repair, these stoves work, and thirdly, I am self-taught in this matter, so bribes are smooth from me. Something like this.

9 Management board

There is no limit to variety. Its main function is to turn on and off the voltage on the transformer. Check - we stick the terminals of the tester at the limit of 220V change to the terminals of the input winding of the transformer (those that are at the bottom left). We remove our hands. We turn on the oven. There are 220 volts - forget about the timer. No - the contacts in the clockwork are burnt. You can, of course, disassemble the watch and clean it (which I did with success 1 to 5) which will take you 2 hours and after assembly nothing will work (I mean the watch - there are a bunch of gears and springs that strive to get out on the floor) I came to the conclusion - either stove for scrap (by this time she is clearly 10 years old) or, if she is dear as a memory, to a Swiss watch repair shop.

10 Cymbal motor

Well, everything is clear. Not - spinning - replacement.But in some furnaces, when the engine is short-circuited, the fan starts to spin spontaneously (this is if the motor is 21 volts, and usually they are 220)

It happens (often) with a working motor, the fan and the plate do not spin - the relay on the control board is to blame. There are 3-4 large ones and one small dark one. Here you need to carefully cut off the hat (it is surprisingly easy) and clean the contacts with zero sandpaper and then close it with electrical tape. Helps for at least a year

11 Magnetron protection

Plain mica plate (plastic in some stoves) To be located on the right inside the stove.

If fat gets on it, the light starts and the housewives in horror pull the stove out of the socket.

For the first time, just throw it out, removing the fat around, then replace it

The article was written spontaneously, inaccuracies and archaeological (also a mistake) errors are possible. But I think the essence is clear. Over time, it will be supplemented.

There is no copyright, it is desirable that the readers express an opinion about my site (which is a week without a year) I will be pleased

Well, we are completely generous here is my Yandex wallet 410013929195468

And what questions - call. The world is not without good people

Guide to action if your printer starts to wrinkle paper

Protection operation in the Yamaha RX-V357 receiver One of the special cases

Many of us have forgotten about various stoves, hobs and completely trust the process of cooking microwave ovens. And this is not surprising at all: microwave ovens take up little space, have a rich set of different functions and significantly save time. Naturally, we are very upset when our microwave breaks down. The reasons for the breakdown and malfunction can be different. Consider what breaks down most often in a microwave oven. Often, if a microwave oven breaks down, it is necessary to contact a specialized master. After all, this is not the simplest device, so the repair is rather complicated. But in fact, the design of a microwave oven is elementary and includes only a few basic elements. If you first familiarize yourself with frequent breakdowns, then repairing the microwave on your own will not be difficult.

Although the design of a microwave oven contains a lot of elements, most of them do not play a special functional role. To repair this device, you only need to know the basic elements of the circuit that ensure its operation. Among them:

1. Magnetron.
2. Transformer.
3. High voltage fuse.
4. Rectifier diode.
5. Capacitor.
6. Control block.

Arrangement of elements in the microwave

It is easy to distinguish them, because outwardly the design is not very complex. The magnetron is always installed in the middle, directed towards the food warming unit. The transformer is located under it, representing a massive box with a protruding coil. The capacitor, diode and fuse are located to the right of it, and the control unit is often located near the input panel.

When the device is turned on, a voltage of 220 V is supplied to the transformer. Passing through the primary and secondary windings, a current of 2 kV is already flowing out of the element. Further, the negative half-wave goes to the diode, and the positive one charges the capacitor, which again leads to a twofold increase in voltage. After that, the generation of microwaves by means of a magnetron begins. The power of the magnetron is regulated by the control unit.

Therefore, in the event of a breakdown, it is worth paying attention to these elements. They carry the greatest load, so they are often the problem.

When disassembling the microwave, be sure to disconnect it from the mains.

Search for breakage in a microwave oven is based on "symptoms". This allows you to gradually eliminate possible causes and find the real one. So, if the oven does not turn on at all, then it is worth checking the following points:

• The integrity of the power cord.
• Door position and closing system.
• Mains fuse and thermal relay status.

In the first case, the situation is elementary - there is no power supply due to damage to the power cord. A similar situation occurs when the outlet is damaged or overloaded. In this case, it is enough to replace this element, everything is in order with the microwave itself.

Next, it is worth checking the operation and position of the door. The fact is that the operation of a microwave oven when the door is open is dangerous for others. Therefore, the design provides for the possibility of operation only when it is completely closed. If a latch, a locking system or a checking element is broken on the door, the protection system will not allow the device to start.

The last points also concern the protective systems of the oven. The fuse prevents damage to the device due to power surges, and the thermal relay provides a complete shutdown of the system when the door is open. Both can fail, it is quite easy to replace them.

It is also worth checking the voltage in the network and the number of devices connected to the outlet. The microwave oven is very demanding on power supply, therefore its slight deviations can interfere with the operation of the appliance.

Procedure if there is no heating Fuse faults

Most models suffer from common problems and have similar, typical faults. For example, if the microwave works, but does not heat, then this indicates a malfunction of the capacitor, diode or magnetron. To repair a microwave oven yourself, you will need a simple set of tools: pliers, wire cutters, a screwdriver, an adjustable wrench and a five-spanner wrench, as well as a soldering iron with the necessary equipment.

When repairing a microwave microwave yourself, you should remember about safety measures. The two most important hazards in microwave oven repairs are high voltage in oven components and microwave radiation. Do not turn it on if the door is defectively locked or the mesh on the viewing window is damaged. Do not make independent holes in the case and introduce any conductive objects into the units and elements of the furnace. Never touch internal parts and assemblies while the microwave is in operation. Be sure to use a tester or other electrical meter to measure AC and DC current.

If the above reasons are not confirmed, then you need to disassemble the device for troubleshooting. Before that, be sure to turn off the oven from the network and wait a couple of minutes.

Fuse

What should you look for when searching for breakdowns? There are several basic elements that often fail:

1. Circuit breakers.
2. Capacitor.
3. Diode.
4. Transformer.
5. Magnetron.

Photo of a microwave condenser

These elements are directly involved in the operation of the device and were mentioned earlier. First you need to check the health of the fuses. Their breakage can be seen immediately, because during combustion, the conductor inside is destroyed. If this did not happen, then it is worth looking further.

For further verification, you need to take a multimeter, because outwardly it is extremely difficult to find a breakdown on the remaining parts. To check the capacitor, you need to switch the device to ohmmeter mode, and then connect it to the part. If there is no resistance, then the part must be replaced.

High voltage diode

It is impossible to check the high-voltage diode with a tester. It is recommended to replace it in case of breakage of other parts, because often the blow falls on it. It can be checked in a slightly different way - by connecting it to the network on the way to the light bulb. If the light is weak or blinking, then the part is working properly. If it burns brightly or does not turn on at all, then the diode must be replaced.

Next, the transformer is checked.

Photo of a microwave transformer

It is important to observe safety precautions, because

Photo of microwave magnetron

this element is able to hold a charge for a long time. It will take several minutes to discharge a serviceable transformer, and if the discharge resistor breaks down, it will take much longer.It is worth discharging it on the case or not touching it at all if there is no experience with such a technique.

Next, the transformer windings are checked. It is necessary to remove the terminals and check the terminals of the device one by one with an ohmmeter. First, the primary winding is checked, for which the rate varies from 2 to 4.5 ohms. For the secondary winding, the limits are 140 and 350 ohms. It is also worth checking the filament winding by connecting the terminals leading to the magnetron to the multimeter. The norm here varies from 3.5 to 8 ohms.

All previous tests have failed, then the problem may lie in the magnetron.

To test the magnetron, just connect the tester to its power terminals. The tester switches to ohmmeter mode. If the resistance is 2-3 ohms, then this means a breakdown of the device. The situation is the same if the tester reads infinity. In both cases, the device must be replaced.

These items are the most common culprits in microwave oven breakdowns. However, the failure of the device is often associated with other malfunctions, such as problems with the electronic control unit, timer and other electronic parts. Here, simple checks with a multimeter will not help; the help of a qualified technician is needed. Although it is much easier to simply replace a part if you are sure that it is broken.

There are frequent cases of breakage associated with the destruction of the cap on the magnetron. The thin aluminum body simply cannot withstand stress and is destroyed by microwave waves. This problem often occurs in older devices that are more than a few years old. The obvious symptoms in this case are noise and sparks during the operation of the device.

To check, it is enough to remove the transformer, because the cap is located towards the food chamber. If the cap is destroyed, then there are 2 options:

• Cap replacement.
• Flip the cap.

The first option is a priority, it is enough to order a replacement or return the magnetron for repair. The second option is considered a temporary alternative that allows you to extend the life of the device indefinitely. It is enough just to rotate the cap 180 degrees around the axis, because the load falls on only one half.

Repairing a microwave oven is a feasible task for a novice electrician. If the problem lies in the breakdown of one of the constituent elements of the furnace, then the simplest and correct solution is to replace it. The bottom line is that most of the parts of this device cannot be repaired, but only completely replaced with a new one. This especially applies to fuses, diodes and capacitors - the main reasons for the failure of the device.

Parts replacement is carried out in several steps:

1. The microwave is disconnected from the network.
2. The transformer is discharged (5 minutes).
3. The terminals are disconnected from the defective part, it is removed.
4. A workable part is connected to the same place.

There are two important factors to consider when replacing a part. The first is schema compliance. It is important to remember that each part has its own characteristics, selected for the performance of the entire electrical circuit. If, after replacement, this nuance is not taken into account, then this leads to new breakdowns. This is especially true for the transformer and capacitor.

The second important factor is the connection of the part. It is necessary to connect the replacement correctly, keeping the previous arrangement of the terminals. Reconnecting the device in reverse order can damage it, as well as several other parts in the system.

This will restore your microwave in most cases. If the breakdown is related to the electronic part of the device, then you should contact the professionals. This will ensure quality repairs and prolong the operation of the device for a long time.

The most common malfunction is the failure of the waveguide cover in the microwave oven chamber. This is caused by splashes from cooking. This starts sparking between the magnetron antenna and the protective cover.Untimely removal of burnt products leads to local burnout of the lid and to complete destruction.

Local burnout of the lid mica plate can be removed with alcohol or solvent 646. It is enough to gently wipe the burnout area.

Burning out mica

If the mica plate of the lid is clearly in poor condition, is greasy or begins to paint, then it should be replaced. Removing the diffuser plate is a snap. This can be done using an ordinary sharpened knife. Usually, the mica plate is attached with a self-tapping screw or rivets. Carefully place the old plate on the new template and cut out a new one. The best way to do this is with a knife - you can break the mica with scissors. We make holes in the new plate with a sharp screwdriver and process the edges of the fields of the plate with sandpaper. We install the new plate in place of the old one.

The question often arises, how to replace mica for microwave ovens? For these purposes, any dielectric with a similar dielectric constant is suitable. For example, PTFE or Teflon.

Common breakdowns in a microwave oven are also malfunctions associated with other elements of the oven. For example, such as the keyboard of the oven control unit, the microwave oven electronic control unit and the dissector. Less often, the high-voltage capacitor and transformer, the microwave waveguide plug and the rotating pan fail. The power supply and magnetron of the microwave oven are subject to wear and tear.

Knowing how to troubleshoot microwave ovens can save you significant repair costs. However, if you do not know how to repair the microwave yourself, then it is best to contact a specialist. Specialized service centers will help you to repair a microwave microwave oven. In addition, watch the video on microwave repair, perhaps there is exactly that breakdown that will help you fix your beloved household assistant.