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This article will focus on repairing touch-sensitive hobs. Unfortunately, in most cases, it is not always possible to repair them with your own hands. However, first things first.
In case you have mechanical control, which is usually the case for dependent panels or for stationary electric stoves, then you can read about faults here. Everything else I will divide into two parts: what happens and what cannot be repaired with my own hands.
If the touch control works, you can change the power, turn on and off the hotplate, but at the same time the hotplate either constantly works, and it starts working immediately as soon as you turn on the hob, or it does not work, regardless of the mode that you set through the sensor, then malfunctions of two types can be distinguished:
If the hotplate heats up immediately when the hob is turned on and does not respond to changes in modes, then it is most likely that you have a sticking of the relay contacts, which is responsible for this hotplate. Here you need to check the relay contacts. Relays usually have two pairs of contacts. One pair comes with food. When power is applied, the coil draws in the core, which closes the contacts. The second pair is just the contacts that the relay controls. The most likely reason is the welding of the contacts. In principle, if you know how to hold a soldering iron in your hands, then you can try to replace the relay with your own hands. You need to check two things: whether the power supply to the relay coil is turned off and whether the relay contacts open. If the coil power appears immediately when the panel is turned on, then you will have to go to a repair shop. If the coil power appears when you turn on the hotplate with the touch panel, then you need to check the control contacts. But in this case, as a rule, they are always closed. If the problem is in the relay, then in any case, a replacement will be required.
If the relay is working properly, but the burner does not work, while the power is supplied to the relay, and the power contacts are closed, then we read here how to determine the malfunction of the burner.
If this is a new panel that you installed yourself, or, suddenly, half of the panel stops working, or the sensor works, but the burners do not turn on, then look at the terminal block. In touch panels, the terminals in the block can be distributed in this way: one terminal is responsible for powering the electronics, the other two power the burners. That is, the situation when the electronics is working, the touch panel shows that the power of the burners is regulated, but the burners themselves do not work at the same time.
There may be two repairable problems and one conditionally repairable problem.
The sensor is triggered with some delay. Some manufacturers have deliberately made this delay to prevent accidental pressing. That is, in order for the sensor to trigger, you need to put your finger in the required area and wait a little (usually up to two seconds), after which the sensors will react quickly for some time (sometimes any sensor triggering occurs with a delay - the triggering algorithm is determined by the manufacturer).
Child lock might be worth it. Read the instructions for your panel about the lock or child protection mode.
It is possible that the glass above the touch panel or on the back side is somehow dirty.If wiping the glass does not help, then you will have to contact the service center.
Some hobs have a heating function. Usually, in this case, the display does not show 0, but the crockery icon | _ | (like half zero). In this case, the hotplate does not turn off completely, but goes into heating mode. Water, for example, will not boil in this mode, but will remain very hot until you turn off the hotplate or an automatic shutdown occurs, if provided by the manufacturer.
This is most likely not a malfunction. The cooking temperature in touch-sensitive hobs is adjusted by turning it on and off. The more the power is set, the less frequent shutdowns occur and the longer the turn-on period. At maximum setting, the hotplate works without switching off, except in case of overheating of the hotplate. In this case, the temperature sensor will be triggered. As soon as the hotplate cools down, the temperature sensor is triggered and the hotplate turns on again.
The malfunction can be conditionally removable and not. I wrote about this malfunction here. In this case, replacing the temperature sensor will help.
There may be a malfunction of another kind. The problem may lie in the electronics, then you will have to go to the workshop.
This is where the conditionally repaired malfunctions end, so we turn to the malfunctions that you are unlikely to cope with on your own. Therefore, to eliminate them, you will have to contact a specialized workshop. I do not particularly recommend contacting service centers. High-class specialists rarely sit in them, and often you overpay for some services. Therefore, it is better to contact private companies. Repair can be much cheaper, but you need to carefully approach the choice of the company.
This usually happens with panels that are many years old. This is largely due to electrolytic capacitors, which lose their capacity over time. In theory, you can try to replace them. In practice, such a replacement helps only 50%. In this case, especially if the panels are more than 10 years old, it makes sense to think about buying a new one.
This includes all other faults that have not been considered.
Summarize. The malfunctions of analog elements, that is, non-electronic ones, can be considered conditionally removable. In this case, if you have the necessary skills, you can try to fix the problem yourself. When it comes to electronics, it is unlikely that someone will advise you on the Internet, because when it comes to electronics, it is not always possible to immediately determine the cause, even when the master directly examines the panel. And explaining what a diode, transistor and other electronic components look like is even more difficult.
The high manufacturability of hobs raises doubts about the possibility of repairing them with their own hands from users and home craftsmen. But, like all sophisticated electronic equipment, kitchen surfaces are made up of separate functional units that interact with each other.
Having understood the functionality and interaction of components, having studied the methods for determining common malfunctions, understanding what and thanks to what turns on, you can, without resorting to the services of masters, carry out a simple repair of the hob with your own hands.
All modern hobs work according to the same principle - the user acts on the control sensors, thereby turning on the power relays that switch large currents in the heating elements.
Therefore, first you need to localize the breakdown, that is, determine the defective node. It is assumed that the cable, connection terminals, fuse, voltage presence is checked, and command set errors are excluded.
Cooking surfaces (panels) are electric heating kitchen appliances (electric stoves) that have glass-ceramic outer cover.Glass-ceramic has great strength, allowing it to withstand a significant weight of dishes, and has good thermal conductivity.
The attractive appearance, which some manufacturers (for example, Hansa) complement with artistic decorations, allows the stylish hob to fit well into the modern kitchen design.
Artistic hob design
Heating elements hidden under the glass-ceramic surface are of several types:
Spiral, working like conventional heating elements;
Corrugated tapes (modified filaments);
Halogen infrared lamps (HaloLight technology);
Induction coils that only heat the cookware material.
Various designs of thermoelectric burners
Burners of the first three types convert electric current into heat according to the Joule-Lenz law in the same way as an incandescent filament in a conventional light bulb or a spiral in a conventional electric heating element is heated. The principle of heating using induction is described in detail in the article on induction boilers. Do-it-yourself repair of induction hobs will be discussed below.
Thermoelectric heaters have a heat-releasing corrugation or spiral laid in a heat-resistant material, connection terminals, as well as heating sensors presented in the form of a bimetallic plate located on the line of the radius or diameter of the burner. Expanding, the bimetallic plate acts on the contacts, closing or opening them.
Hob burner device
Depending on the design of the hob, the contacts of the temperature sensor can be power contacts (acting like a thermostat), or signal contacts included in the electronic control circuit. Malfunctioning sensors (thermostats) are a common reason that the hob does not turn on.
In general, repairing hobs differs little from repairing electric stoves, which is described in detail in one of the articles of this resource. The main visual difference is the presence of a glass-ceramic surface and the type of heaters, the spirals of which are visible through the transparent surface. Also a characteristic distinguishing feature is sensory electronic unit and the complete absence of the usual control levers.
Hob touch control unit
Therefore, the greatest difficulty in the repair of electric hobs is the electronic touch control unit, which is also a display. To repair it with your own hands, you will need knowledge in radio engineering and special equipment.
But otherwise, the hob is not much different from an electric stove - the heating elements are switched on by power relays, controlled by an electronic control board, which receives signals from the sensor.
But at first, even without disassembling the hob case, you can determine the malfunction of the touch display and the electronic control unit. As a rule, the receipt of a command from the user is accompanied by a sound signal and is displayed on the display. If there is no reaction to touch, then it becomes clear that there is a breakdown in the sensor.
Indication of a properly working hob
The sensitivity of the sensor may deteriorate due to severe surface contamination. It should be remembered that the entire glass-ceramic surface of the hob requires careful maintenance and cleaning, otherwise cracks may form from the accumulation of scale and burning.
Operation of a stove with cracked glass ceramics will lead to its further destruction and breakdown, therefore, timely care and cleaning of the hobs is needed, as shown in the video:
VIDEO If cleaning the surface above the sensor does not bring any results, you should disconnect the hob from the mains, first disconnect the line, disassemble the case and remove the electronic board with sensors.
Electronic board with display elements and control sensors
As you can see from the figure, the electronic board of the control unit has many small parts, including microcircuits, so repairing such a module with your own hands requires deep knowledge of radio engineering. If the malfunction of the sensor control unit is reliably established, then it is better to take this board to a specialized repair shop.
If surface diagnostics have not yielded results (the command turns on, but heating does not occur), you should look for a malfunction in the power switching unit. Some models of hobs can independently diagnose some malfunctions, signaling them using the error codes that appear on the display. You should carefully study the user manual and these codes - this will save time when troubleshooting.
Error codes for some hobs
The power control unit (switching) of the hob consists of relay groups controlled by an electronic sensor unit. When the operating mode is selected, one or more relays are energized, supplying power to the respective heating elements.
Arrows indicate power relays
Even for a novice master, it will be easy to disassemble the panel case with his own hands in order to independently determine the malfunction of a heating element or power relay. For this purpose, you will need a multimeter and skills to work with it. You will also need to determine the type of heating element itself in order to check it correctly (for example, the resistance of the induction coil is close to zero).
More experienced craftsmen often use a different method - they check the voltage supply to the main nodes, moving from the power terminals through the power relays to the heating elements. The power relay contacts may burn due to frequent switching on, and checking the presence of voltage at the input terminals of the burner will determine if the relay has been activated.
Measuring the supply voltage of a cooking zone
It should be remembered that many elements inside the enclosure carry life-threatening voltages. Working under stress requires focus, mindfulness and sober thinking.
If the terminals of the hotplate are normal supply voltage, you can check the performance of the heating element visually - the filament should be warmed up. But, if the burner turns on, but does not heat up to the required temperature, you need to measure the flowing current. The easiest way to do this without breaking the circuit is with a multimeter equipped with a clamp meter.
The use of a clamp meter to check the current in the power circuits of the hob
Knowing the maximum power of the burner and the supply voltage, you can calculate the rated current according to Ohm's law. In the case of heating elements that work like a heating element, a decrease in the current and heating temperature may be associated with malfunctions in the electronic control unit, thermostatic elements or in the power relays.
If the halogen burner does not heat well, then an internal chemical change in the composition of the gas in the heating element or degeneration of the spiral is possible. In this case, if all other possible malfunctions have been ruled out, the HaloLight Heater should be removed and replaced.
The appearance of the hob burners without glass-ceramic coating
It happens that the burner turns on, but after working for some time, it turns off ahead of time. Improper operation of the heating element may be due to a malfunction temperature sensor installed on the hotplate. In order not to change the entire expensive burner, you need to disassemble the sensor with your own hands, clean or bend its contacts, as shown in the video:
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To diagnose and repair the hobs, you will have to dismantle the equipment from the countertop, disconnect the power terminals and disassemble the case. It must be remembered that the glass-ceramic coating is vulnerable to point impacts and loads.Therefore, when turning the hob over, avoid small objects falling under the surface so that the weight of the cabinet is not applied to one point.
Mandatory care in the workplace when repairing a hob
It goes without saying that bumps, scratches and carelessness should be avoided. You should carefully examine the hardware fastening mechanisms - these can be bolted connections, screws, or latches. Some elements, for example, an electronic board, can be additionally fixed with glue or adhesive tape. When disassembling a particular model of the hob, you should first study the articles, images, videos available on the Internet.
Experienced craftsmen always check the physical strength of the terminal connections (with the voltage removed) - very often it is poor contact that is the reason that some burner does not turn on. If a faulty burner is detected with a multimeter, or a breakdown in the electronic board is detected, then it can be turned off with one hand alone, without the aid of a soldering iron, and taken to a workshop, where, to replace radioelements or relays, you will need skills in working with a soldering iron and the ability to work with radio components.
VIDEO In another video below, the wizard describes troubleshooting, shows the process of dismantling and disassembling equipment and identifying a faulty relay, implying that desoldering and soldering the relay is a well-known action.
VIDEO You should check the circuits very carefully so as not to confuse anything. In the video above, the author confused the relay, but nothing terrible happened. But, far from always, an error during radio installation can do without consequences, such as a short circuit, burnout of power circuits and failure of radio components.
The peculiarities of the operation of induction heaters can very often be interpreted as a breakdown - the command is given, but the burner does not turn on, there is no characteristic glow, and heating does not occur. The fact is that the metal of the cookware and the coil of the burner form a single oscillatory circuit, due to which high-frequency oscillations arise that induce currents in the metal kitchen utensils.
VIDEO Eddy and surface currents in the metal of the cookware heat it up, due to which the cooking process takes place. The hob itself does not emit heat at the same time, but it can heat up from the dishes standing on it. The induction hob's protection system will prevent it from turning on if there is nothing metal on it.
As mentioned above, the physical processes and the principle of heating using induction are described in detail in the previous article on induction boilers - you should familiarize yourself with this material in order to have an understanding of the operation of such equipment. In the case of hobs, induction heating is used to heat cookware, but the principle remains the same.
The working surface of the induction heater does not burn immediately after switching off
Repairing induction hobs requires an understanding of the high frequency generator and the self-oscillating processes that occur in the electronic circuit. The most susceptible to breakdowns are power switches (transistors), diodes and high-voltage capacitors that are part of the circuit. Transistors like these are often MOSFETs, and are not called bipolar semiconductors, but they can be detected if they are out of order.
VIDEO You should find a diagram of an induction heater with designations of the nominal values of the elements. For masters who own an oscilloscope, it will be very helpful to have the oscillograms shown in the diagram, measured at the control points. Without circuitry and laboratory equipment, you can find a malfunction in the electronic board by visual inspection and nickname of individual components.
As shown in the video, technicians in service centers can determine malfunctions in electronic circuits, relying on experience, having available equipment and a large stock of various element base in order to carry out repairs by replacing defective elements. Surface diagnostics of the main components is carried out by the breakdown test method.
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