What should be the fuse for a microwave?

Power surges can cause serious damage to any household appliance. To avoid having to spend money on frequent repairs, or even worse, buy new equipment, manufacturers have come up with simple protection in the form of a fuse. It takes the full impact of the voltage drop and burns out, saving the more significant parts of the device from such a fate. Subsequently, you only need to replace this inexpensive part, and any equipment will work like new. However, not everyone knows where it is. Therefore, replacing the fuse in a microwave will be discussed in detail below.

Microwave oven device

The heart of a microwave oven is a magnetron, the antenna of which supplies high-frequency waves to a special chamber. This radiation passes through a waveguide that transmits radio waves only at the operating frequency (2.4 GHz). It is protected from the ingress of fat and food particles during cooking by a special lid made of mica. The property of this material is such that it easily transmits high-frequency radiation, but does not conduct back electricity, which can arise as a result of improper operation of the furnace . Namely, this phenomenon is fraught with failure of the magnetron.

The operating principle of a microwave oven is as follows. The food, slowly rotating on the plate, is evenly processed by the flow of electrons, which affect the water included in its composition. This process is accompanied by the release of heat, which helps to warm up the food. The design of the chamber is designed in such a way that radiation cannot escape beyond its boundaries, which means it is safe for humans, whose body, as is known, consists of 80% liquid.

Important! In order for the magnetron to generate its waves, a high-voltage transformer is included in the microwave circuit, which provides the lamp with the required voltage. It is this part of the furnace that is most vulnerable to power surges in the household electrical network.

Circuit breakers

A fuse is an element of protection for an electrical circuit. Nowadays, almost all electrical devices are equipped with such elements and microwave ovens are no exception. There are many types of fuses, differing from each other in the operating principle, and one of them is a fuse link. For electrical protection, this type of fuse is used in microwave ovens - a fuse. The operating principle of the fuse is based on the metallurgical effect. Such a fuse in its design contains a thread made of a low-melting material - metal. If the permissible current flowing through this thread is exceeded, the thread heats up to the melting temperature of the metal from which it is made and is destroyed. In this case, the electrical circuit is broken and the device is de-energized. The permissible amount of current that the thread can pass through itself without destruction directly depends on its cross-section and the properties of the material of manufacture. To protect adjacent structural elements of electrical equipment from splashes of molten metal formed when the filament breaks, the filament is placed in a glass or ceramic tube. And, for ease of installation, metal caps are put on this tube at the ends, which are fuse contacts. This is exactly how we are used to seeing a fuse today, in the form of a tube with shiny caps.

Read also: Grounding a three-phase network in a private house

The design of a microwave oven most often contains three fuses. Figure 1 shows one of the options for the location of fuses inside the furnace.

1. Mains fuse. It is located, as a rule, on the network filter board, schematically - at the furnace power input. Through this fuse, all circuits of the device are powered. The protective actions of any fuse are bidirectional. It’s the same with the mains fuse: on the one hand, it protects the furnace itself from power surges, and on the other, it protects the supply network from short circuits that can occur when various types of malfunctions occur in the furnace design. Having a fairly large rating - 8 - 12A, the mains fuse weakly protects the oven electronics from voltage surges, but does a good job of protecting the network from microwave malfunctions.
2. High-voltage fuse – is an element of protection of the high-voltage power supply circuit of the magnetron. It protects, first of all, the high-voltage transformer from overloads that occur in the event of failure of the elements of the multiplier or the magnetron itself. Structurally, the high-voltage fuse is located next to the transformer, and schematically, it is included in the open circuit, between the output of the high-voltage winding and the input of the multiplier. High voltage circuits have special safety requirements. Therefore, the conductors of this circuit have reinforced double insulation, and the fuse is hidden in a special plastic casing. Housings can have different designs and shapes. But, they almost always consist of two halves, connected to each other by a plastic jumper on one side and latches on the other. If you disconnect the latches, the casing opens like a box, providing access to the fuse itself (Figures 2,3,4).

There are furnace models in which there is no high-voltage fuse as such - it is not provided by the manufacturer. In such cases, the function of protecting the high-voltage circuit is performed by the mains fuse. In order for the mains fuse to trip when the elements of the magnetron power circuit fail, the load on the transformer must more than double and for a fairly long period of time, which clearly has a bad effect on its health and can lead to failure of the transformer.

• The presence of a third fuse is typical only for furnaces with an electronic control panel. Each electronic panel is powered by its own separate power source. The basis of such a source is a low-power power transformer, which converts the network voltage into voltages suitable for powering the panel circuits. The primary winding of this transformer is powered from the network through a separate fuse, which is structurally, most often, an element of the design of the transformer itself. In other words, this fuse is located on top of the primary winding and is covered with insulation on top. This arrangement makes it much more difficult to replace the fuse if it fails. But it often happens differently, for example, in Samsung ovens, this fuse is located separately on the control panel board and replacing it, if necessary, is not difficult. This fuse has a very small rating and is very sensitive to voltage instability in the network.

When the high-voltage fuse trips, the oven will “pretend to be working”, everything will function except the magnetron, that is, everything will make noise, burn and spin, but it will not heat. But when the mains fuse or the control panel fuse trips, the effect will be approximately the same - the oven will be completely silent.

Life teaches you not to skimp on safety, so if any of the fuses blows, it is always better to look at its rating on the cap and replace it with the same one. But, if you still decide to install the “beetle”, then I beg you, do not under any circumstances use nails or other conductive objects that are suitable in size for this, and do not do it as shown in Figure 5 on the left - this is not it won't lead to anything good. Don’t be lazy, use the table for calculations, and do it as shown in Figure 5 on the right, believe me, it will be better.

Read also: Density of metals table in ascending order

Filament destruction current, A	Wire diameter, mm
	Copper	Iron	Tin	Lead
0,5	0,03	0,06	0,11	0,13
1,0	0,05	0,12	0,18	0,21
2,0	0,09	0,19	0,29	0,33
3,0	0,11	0,25	0,38	0,43
4,0	0,14	0,3	0,48	0,52
5,0	0,16	0,35	0,53	0,6
6,0	0,18	0,4	0,6	0,68
7,0	0,2	0,45	0,66	0,75
8,0	0,22	0,48	0,73	0,82
9,0	0,24	0,52	0,78	0,89
10	0,25	0,55	0,85	0,95
15	0,32	0,72	1,12	1,25
20	0,41	0,87	1,35	1,52
25	0,46	1,0	1,56	1,75
30	0,52	1,15	1,77	1,98

The table, according to approximate calculations, shows the physical parameters of the threads of homemade fuses made from various materials. This is not an example of how to do it, but a fuse restored using the data in this table is still better and safer than a nail.

Electricity is a good thing, but every double-edged sword, remember this. When repairing electrical devices, be careful, follow safety precautions and do not neglect the safety features. Good luck with the renovation!

This household appliance is an indispensable assistant for the housewife in the kitchen: with the help of a microwave you can quickly heat up food prepared the day before, as well as stew vegetables and meat products, make original hot sandwiches and much more. Like all appliances, a stove can break down; the most common fault is a fuse blowing due to a power surge. We will tell you in detail what kind of fuses there are in a microwave oven, and also provide a replacement algorithm.

The purpose of fuses in a microwave oven

The fuse is a metal thread passing through a glass or ceramic bulb. It is covered with a protective sheath so that when a thin wire burns, molten splashes do not damage other parts.

Kinds

There are three types of fuses installed in a microwave oven:

• network;
• high voltage;
• for electronic control.

Purpose

The mains fuse serves as protection against both voltage surges and short circuits. It is installed directly on the input cord. The part can be considered universal, since it responds to any danger, disconnecting the microwave oven from the network.

The high-voltage fuse provides protection exclusively to the main components of the furnace - the transformer with the magnetron. In case of network congestion, it cuts off power only from these nodes. Therefore, when a part burns, it visually looks like the oven continues to work: there is lighting and sound, the table even rotates, but the product does not heat up. This fuse is located near the transformer. It is enclosed in a separate plastic case with latches. In some cases, when a high-voltage fuse blows, it can trip the circuit breaker on the common panel, which will cut off power to the entire house.

The control module generally requires little voltage. Therefore, to protect the unit, another plug is installed on top of the primary winding of a separate low-power converter that powers the electronic control panel. It is quite difficult to change it, since the part is specially insulated. But in Samsung models, the fuse is located directly on the control module board, which makes access to it much easier.

Before you buy a microwave oven, you need to check which fuses are on the selected model. Some manufacturers do not install high voltage protection on their products . For example, Sharp models do not have it. Therefore, only one fuse will provide protection against all possible threats - the network fuse. And in some cases this is not enough.

Important! The function of the mains fuse is to turn off the magnetron only in the event of a fairly long period of exposure to double load on the transformer. This time is often enough for the two most important components in a microwave oven to fail.

What should be the fuse for a microwave?

The fuse in the Samsung microwave oven and in the Supra microwave oven is located in the magnetron power circuit. Its main purpose is to protect the high-voltage transformer from possible overloads arising from breakdowns of the magnetron or elements of the voltage multiplier circuit.

1 Samsung microwave fuses: features of important microwave elements

If you need to buy a high-voltage microwave fuse, you should know that it has a special device that radically distinguishes it from other types.

It must very quickly break the electrical circuit when an unacceptable current occurs in the magnetron power circuit, and this must be done at a distance of 15 - 20 mm to avoid the formation of an arc discharge, especially on a Panasonic microwave oven.

Considering this feature, replacing a high-voltage fuse with a regular one, which corresponds only to the current and does not have a spring that instantly breaks the circuit, is unacceptable.

2 Where to buy a fuse for a microwave oven, how much to pay for it?

A fuse designed for installation in microwave ovens is a part with metal caps on both ends, and a fuse element and a spring located inside it.

You can choose and buy a fuse for a Samsung microwave from the following options:

• high-voltage fuse 5kV 800 mA for microwave oven with grill;
• high voltage fuse 5kV 500 mA;
• high-voltage fuse 5kV 700 mA for microwave oven Samsung G2739NR;
• high voltage fuse 5kV 600 mA;
• high-voltage fuse 5kV 750 mA for Samsung MS23F302TAS microwave oven.

The following types of fuses are sold in specialized stores or online stores:

• www.service-market.com.ua (Samsung FW77 microwave oven is also sold here)
• remkomplekt.kiev.ua
• zip-service.in.ua (you can also buy a Bork mini oven here)
• kiev.prom.ua
• hometech.biz.ua (Samsung ME712 microwave oven is also sold here)

You can buy a microwave fuse for as little as $5.

2.1 How to replace the fuse yourself

Remember that any repair work related to eliminating a defect in microwave ovens must be carried out in compliance with safety rules.

When starting to replace the high-voltage fuse, you must first turn off the power, and then use a Phillips screwdriver to unscrew the screws and remove the housing cover. Next, you need to find the faulty fuse on the power filter.

Its standard characteristics are a voltage of 250 Volts, like the Samsung ME732 microwave oven, and a current of up to 5 A. These parameters are usually indicated on the case. Having replaced the faulty element with a new one, screw the cover back using the mounting screws.

If a new part is not available, you can give a second life to the old one by winding a copper core around it and soldering it. Then the element is installed in its place.

It’s easy to check the serviceability of the device after self-repair: turn on the microwave oven and pay attention to the digital indicator - it should light up. If this does not happen, it is better to contact a service center.

To avoid damage, do not place metal objects in the chamber, keep the microwave clean and use it for its intended purpose.

Causes of burnout

As mentioned above, fuses burn mainly due to a sudden surge in voltage in the household electrical network, which provokes an overload of the circuit or a short circuit in the turns of the transformer coil. These processes trigger the protection, which occurs by interrupting the contacts in the circuit and disconnecting the microwave from the network. This is necessary not only to preserve the integrity of the more important parts of the stove, but also to prevent a fire hazard in the house.

But there are times when the fuse burns out during a certain action. For example, when opening the microwave door. This situation occurs in ovens of many brands, but most often Samsung and LG models suffer from this. The problem is the door microswitches. Any microwave has three of them, and according to the safety protocol, they are triggered in turn to automatically stop the oven when the chamber is fully opened. This measure is necessary to prevent radiation from penetrating outside. And when particles of fat or carbon deposits get on the springs of the microcontacts, they weaken, which can also happen even simply from prolonged use. Because of this, the switch does not operate and the fuse burns out.

But if the protection is triggered when the microwave oven is turned on, and replacing the fuse does not help, then the problem is most likely a damaged high-voltage diode. This has often been observed with Panasonic models. This can happen when there is a short circuit in the windings of the transformer or inside the magnetron.

Reasons for element failure

There are two most common reasons for a blown fuse:

• Network voltage surge. When more than normal voltage is applied to the microwave, the fuse fails and shuts down the entire system.
• Switches that close the door. Their main purpose is to close the chamber to prevent microwaves from escaping beyond its boundaries. When the microwave is turned off, they operate and open the door. In this type of household appliances, three similar devices are often used. If the springs of these parts become unusable or a layer of fat has accumulated on them, the operation of the function is delayed, and this causes a breakdown.

Replacing the fuse

Replacing a blown fuse is usually not difficult (except in some cases with control module protection). But getting to it and performing some actions related to safety for health and life may seem like a problem for inexperienced craftsmen.

Disassembling the microwave

It's actually simple:

• unplug the oven power cord from the socket;
• find all the bolts on the back cover and unscrew them;

• remove the casing;
• we are working on fuses, but without haste, since if you need to inspect the magnetron, you will have to remove the transformer and air duct.

Advice! To work safely with fuses, it is necessary to perform one more operation - discharge the capacitor.

Capacitor discharge

The electrical circuit of the microwave contains a resistor that automatically discharges the capacitor when the device is disconnected from the network. In fact, it may be absent, or if it is available, it may not function. It is strongly not recommended to ignore these precautions and carry out work inside the oven with bare hands, since even when the power is turned off, the capacitor retains the accumulated voltage (and not a small one). And only if you are completely sure that it is discharged can you safely carry out repairs.

Important! Disconnecting the microwave from the power supply does not guarantee complete safety during repairs. Many parts inside retain residual stress for a long time. Electric shock can be not only painful, but sometimes fatal!

There are enough recommendations on how to discharge a capacitor. It is generally advised to close the contacts using a screwdriver. But this method is not approved by professionals: sparks and even failure of the capacitor are possible, not to mention a melted screwdriver. Experts suggest using a separate resistor with a resistance of 20 ohms. Or you can remove the discharge using a regular light bulb.

Replacing the fuse

Even when the capacitor is guaranteed to be discharged, it is not advisable to change the fuse with bare hands. You need to use current-insulated tweezers or a screwdriver with a well-insulated handle. The replacement algorithm is as follows:

• make sure that the device is disconnected from the network;
• Using a tool, remove the fuse that has burned out from the socket;

• install a new one;
• We assemble the stove and check its functionality.

As you can see, it only takes a few seconds to replace a part. More time is spent on preparation and compliance with safety measures. And to be completely sure, you can watch the training video.

Replacement algorithm

Most stove models have 5kv 0.65 +A elements installed. If it is blown, then you can change the fuse in the microwave using the following technology:

• disconnect the product from the network by removing the plug from the socket;
• carefully remove the top cover;
• open the housing of the high-voltage device and visually check its integrity;
• if the thread burns out, then remove the fuse from the housing;
• we check the contacts for burning, clean them, insert a new element with identical parameters.

For those users who do not know the structure of household appliances well, there are more detailed instructions that will help you cope with the replacement quickly and without problems.

1. To remove the top cover from the device without interference, find all fastening elements and carefully remove them from their location slots.
2. When visually inspecting, use a magnifying glass to accurately determine the presence or absence of thread, and also to examine all the inscriptions on the caps of the product.
3. A new fuse must be installed with identical parameters, otherwise the filament will burn immediately after turning on the product, from the slightest insignificant difference in current or voltage.

If you are not confident in your skills in repairing any complexity, then it is better to call a household appliance service technician.

Advice from the experts

To avoid problems both when replacing the fuse and in the future, experienced technicians recommend following simple tips.

1. You can check a suspicious plug with a multimeter.
2. To see the markings, you need to use a magnifying glass.
3. An element with lower parameters will fail faster, so it should be replaced with identical or higher parameters.

Advice! The most important thing is to realistically assess your strengths and capabilities. Even if you have the slightest uncertainty about your actions, you must stop the repair and contact a specialist.

Microwave oven device

The photo shows the microwave oven disassembled. Using a visual example, you can get acquainted with the internal structure of a microwave oven and the location of the main components. The photo shows where the following elements are located inside the microwave: magnetron, high-voltage fuse, capacitor, diode, thermal relay, grill heating element, lamp, transformer and other components. Microwave oven components in the photo:

This is what a disassembled microwave looks like. The main elements are signed.

This is what the microwave oven control module looks like.

Microwave oven microswitches

Bottom of the microwave and hatch

Open hatch and engine

Safety regulations

The voltage of some microwave oven components can reach 4,000 volts during operation. And even if you disconnect the device from the network, some parts retain residual voltage for a long time (for example, a capacitor and a high-voltage transformer). Therefore, to avoid injury, you need to remember two main rules.

1. It is necessary to use a tested and serviceable tool with good current insulation. All work should be carried out only with its help and under no circumstances should you touch any parts with your bare hands.
2. Even if there is a resistor in the microwave to discharge the capacitor, you should not be lazy and duplicate the discharge. You can use a light bulb for this.

It is strictly forbidden to use homemade “bugs” instead of standard factory products . The price of a conventional fuse is so low that instead of saving, you can get a noticeable loss. This can happen when a homemade device triggers a fire hazard. As a result, you will have to buy not only new equipment, but also spend money on renovations in the room.

Compliance with the safety rules described above in some cases can save not only health, but also life. However, if you adhere to all the requirements and recommendations of specialists, then replacing the fuse will be a simple operation.

DIY replacement

Before replacing a part, unplug the microwave oven. Arm yourself with a Phillips screwdriver and unscrew the screws securing the casing.

Now inspect the constituent elements. What does a blown fuse look like? Upon visual inspection, it will be swollen or black marks of burns will be visible.

If the flask is glass, you may see a broken thread inside. If the circuit is short-circuited, the breakdown is more difficult to detect. To do this, tests are carried out with a multimeter in resistance mode:

• Attach the probes to the contacts of the device.

• Everything is fine if the screen shows zero.
• If it displays a value other than zero or “OL”, the part has burned out and needs to be replaced.

For repairs you will need identical elements. They must have the same dimensions and current range. Usually these indicators are indicated on the case. You can view them through a magnifying glass.

Important! Do not install a new fuse with bare hands. Use pliers or rubber gloves. Some microwave parts retain voltage even when unplugged.

After installation, reassemble the device in reverse order. When you turn it on, make sure all elements are working.

You should not carry out repairs yourself if you have not done this before. Ignorance of the microwave device can lead not only to complete breakdown, but also to electric shock.