Samsung‘s Control Centre.
Electric circuits of microwave ovens
Microwaves with electromechanical controls usually have a standard electrical circuit. The differences between different models are insignificant and are not a fundamental nature.
The power part of the furnaces with electronic control units practically does not differ from furnaces with electromechanical control. On a scheme, these differences are manifested only in the fact that instead of the Tiemer’s contacts there are relay contacts. Sometimes instead of a repay is a simistor, but the mode of its work is actually the same as the timer.
Such interchangeability of control units allows, in particular, to inhale a new life in the furnace with a completely burned electronics by replacing the electronic control unit with electromechanical or electronic, but from another model. The restrictions on such a replacement are mainly associated with overall dimensions, fasteners and design of the door opening mechanism.
As an example, consider the Samsung RE290D microwave diagram, depicted in rice. One.
Rice. One. Samsung RE290D circuit circuit of the microwave oven “
To turn on the microwave of heating, it is required to submit a voltage of 220 V to the primary winding of the high.Voltage transformer. This will happen if the Monitor Switch microswitching contacts (MS) are open, and the contacts of all other elements of the chain are closed. Consider the conditions under which the required state of contacts is established.
Thermorele “Cavity Tco” and “Magnetron Tco” is closed if the temperature of the chamber and magnetron does not exceed the permissible temperature.
Primary Switch (PS) and Secondary Switch (SS) microswaters block the power of the magnetron when the door open is opened and closed when it is closed when closing it. In the figure, the condition of the micro.Transcripts corresponds to the open door.
The inclusion of the microwave oven occurs when the timer handle is installed for a given time. In this case, the contacts “Timer Switch” (TS) located inside the timer are closed. The voltage begins to arrive on the winding of the insured relay “Safety Relay”, and its contacts are closed. As a result, the electric motors of the timer and fan are included, and voltage is supplied to the transformer through the Resistor resistance.
Monitor Switch microwter monitors the working operation elements of the door blocking elements. If for any reason the PS and SS microswitchchers cease to open, then an attempt to turn on the stove with an open door will lead to a fuse of the Monitor Fuse fuse.
As a result, the inclusion of the SR relay will become impossible, and the generation of the microwave of power will not happen. It should be noted that for the coordinated operation, the PS microwter should closed later, and open up earlier than, respectively, MS contacts will be opened and closed. Violation of this synchronism will lead to the fact that the PS contacts will be closed before MS will open, or vice versa, the MS contacts will be closed earlier than PS. In both cases, this will lead to a short.Term short circuit at the entrance with the subsequent burnout of the fuse. Unfortunately, such an asynchronism in the work of micro.Transcripts is not uncommon, therefore, if fuses burn in the microwave for without any visible reasons when closing or opening the door, the problem is most likely in the inconsistent work of micro.Transcripts.
The resistor R1 serves to reduce the starting current and works only a few millisecond processes of each inclusion, until the Inrush Relay relay works, the voltage is supplied simultaneously with the start of the current through the resistor.
The need for resistance is caused by the fact that at the initial moment, the high.Voltage capacitor is discharged and in a positive half.Period, when a direct displacement is filed on the diode, the secondary winding of the transformer is closed “accurately”. As a result, when the furnace is turned on, there is a sharp throw of the current and it shudders like from fright, passing its spiritual state to others. The resistance allows you to limit the starting current for a while, during which the capacitor is gradually loaded to the nominal value and the furnace is smoothly included in the operating mode.
Currently, most developed countries have standards that limit the amount of starting current, so the elements under consideration become an obligatory attribute of microwave ovens with electromechanical control.
The VPS Switch microwter installed on the timer serves to adjust the power. When setting a power level, less maximum, it carries out a periodic shutdown of the furnace in accordance with pattern
The “Noise Filter” filter serves to reduce radio interference penetrating on the power chains into the external network. The scheme also contains an incandescent lamp “LAMP” and the Timer Motor timer and Fan Motor fan, the purpose of which does not require Комментарии и мнения владельцев.
Depending on the model of the microwave oven, it may not have any components considered or, conversely, have additional (for example, when using combined heating methods), but this does not make significant changes to the operation of the electrical circuit.
Unlike the power part of the microwave ovens, the circuit of electronic control units have a much greater variety. Stoves that do not have a specialized microcontroller are especially different, built on the basis of discrete elements. This is characteristic of the first models that are currently not produced, but are still in everyday life. In this regard, it makes no sense to consider any of the schemes as an example.
Instead, we consider the work of some of the most common nodes and related malfunctions.
The initial installation circuit. Designed for the preliminary discharge in the “0” cells of the RAM and the installation of all the triggers, meters, etc.P. To the original state when the voltage is supplied to the control unit.
Rice. 2. The initial installation circuit
At the time of inclusion of the microwave on the network, the capacitor is discharged, so the voltage on it is “0” and the reset signal is received at the input “Reset” of the controller. After a short period of time, the capacitor will be charged through resistance R until the power voltage, the reset signal at the input will disappear and the circuit will be ready for further operation.
Sometimes the discharge signal is formed not only when the power is turned on, but also when it is removed. The diagram of the device performing this function is shown in the rice. 3.
The vast majority of microwave furnaces have a pseudo.Sensory film keyboard. The principle of its action is shown in rice. 4.
Rice. 4 The cross section of the film keyboard in the area of closed contact
The keyboard is made in the form of a three.Layer polymer film glued to a hard surface. Metallized or coal contact platforms are applied to the upper and lower layers from the inside, combined using a system of conductors into several tires.
At the location of the contact sites, the middle layer has cutouts, and buttons are images on the front side of the keyboard. When clicking on the image of the button, the contact sites are closed, applying the corresponding signal to the microcontroller. When releasing the button, the keyboard due to the elasticity of the material restores the original form, and the contact opens. As an example on rice. 5 shows the internal structure and connections of the conductors of one of the most common keyboards, from the Buvi-2 control unit.
Rice. 5 The internal structure of the film keyboard from the control unit “Buvi-2”
Doubts about the serviceability of the keyboard arise if the effect when clicking on the image of buttons is either absent at all or does not correspond to the expected. Of course, if your expectations do not go beyond the operating instructions.
Make sure that the malfunctions of the control unit are caused by the keyboard operation, you can, having removed the keyboard from the connector and closing for a short time with a segment of the wire, those conclusions of the control unit that should be close the button of the suspect in the sabotage. If the effect corresponds to the prescribed, then your doubts are justified and the keyboard must be repaired.
The difficulty is that you must first know which conclusions with which button are closed. If the required information is absent, you can choose two ways of further actions. The first path is radical. It is necessary to peel off the keyboard from the control unit and on topology, which is visible from the reverse, transparent, side, draw up a switching scheme.
The second path is the so.Called method of “scientific poke”. It can be used when the entrance and output tires are divided by each other, such as, for example, in rice. 5. In this case, the switching scheme can be made alternating all the entrance tires with all the weekend, each time analyzing the result. Difficulties here are due to the fact that some buttons, such as the “start”, can only be turned on if preliminary information is typed.
Therefore, the preparation of the scheme will occur in several stages. At first, those compounds that can be installed immediately, and then, using the established contacts for the preliminary set, are also determined by the missing links of the switching scheme. Lovers of puzzles and reboses will receive true pleasure.
Typical keyboard malfunctions
The first case is the simplest, and it is often enough to correct contact in the connector to eliminate the problems that have arisen. Therefore, it always makes sense to start with the check of this link, especially if the keyboard conclusions in the connector have some backlash and are not rigidly fixed.
The breakdown of the conductive paths most often occurs in the keyboard conclusions. This is due to the fact that this place is most susceptible to deformation and, in addition, the conductors here are open, unlike other parts of the keyboard, where the conducting coating is closed by film on both sides. Defective paths can be detected by looking at the lumen.
Restore damaged areas is easiest with conducting glue. The technology of such repairs is so obvious that no explanation is required. In the absence of such glue, you can cut a thin strip of copper or aluminum foil and glue it into the damaged area with tape.
You should not try to solve the problem using a soldering iron, because when heated, the metal from which the conductive paths consist, will slide into balls and thus only aggravate troubles. Even if you manage to solder the jumper using a low.Temperature solder, the reliability of such a connection will be small. After some time, the solder falls off, simultaneously taking with it part of the conductive paths.
In some cases, the breaks of the paths occur inside the keyboard. In addition to production marriage, this can be caused by excessive zeal when the keys are pressed and moisture on the conductive surface. As a rule, the tracks are made by spraying a thin layer of silver on a polymer film. The presence of moisture causes silver oxidation, which can cause the path of destruction. It is characteristic that at the same time the closure of neighboring paths can occur, since the water, oversaturated with silver ions, is a good electrolyte that conducts current.
Therefore, when caring for a microwave oven, the keyboard can be wiped with a damp rag, but you can not wash it.
Repair of the electronic module (control unit) of Samsung.
A few words about how to find a break in the conductive paths. To do this, the input and output tires must be interconnected and connected to the tester, as shown in rice. 6.
Rice. 6. Detection of a break in the conductive tracks in the film keyboard
With this connection diagram, when pressing any button, the resistance of the corresponding connection will be measured. If the conductive tracks are cut off somewhere, then pressing on certain keys will not lead to a change in the readings of the device. Over, depending on which keys do not work, you can approximately determine the location of the defective area. For example, if in the previous figure a section marked with a thickened line has a cliff, then the “5” and “B” buttons will not work.
If none of the buttons work, then a possible reason for this may be an unsnowned contact in any button or tire closure. If the button is guilty, then you can check it using the scheme for rice. 6. Tester testimonies will record the presence of a closure, while no buttons are pressed. Removing the jumpers connecting the conductive tracks and measuring the resistance between each pair of entrance and output paths, the sticky button can be localized.
The cause of such floods may be deformation of the film and detachment of the conducting coating in the area of contact sites. The latter option is typical for keyboards, which in which a coating is used to use coal. The substance from which the contact sites consist, crumbling, fills the gap between them and, with some accumulation, leads to close.
Typical malfunctions and ways to eliminate them
Before the elimination of the malfunctions below in detail, we consider it necessary to warn that before diagnosis and repair, it is necessary to physically turn off the device from the power supply, that is, pull the plug out of the outlet.
No reaction to the power button.
In this case, diagnostics and repair must obey the next algorithm of actions:
- Check the presence of voltage in the power supply network. If it is not, we solve the problem with the power source, otherwise we proceed to the next action.
- Check the control power control system control. Start with the fuse. If it is burnt, we replace. After that, turn on the device and try to heat, for example, a glass of water. If everything works, the repair is completed. If the fuse burns out, the problem is in the control module, it should be repaired or replaced.
In order to independently repair the control module, it is necessary to have certain skills in radio electronics, without them to start independently repair of the control module is not recommended.
An example of the location of the fuse on the control module
Microwave do not turn off after working out the mode.
In most cases, this problem indicates a malfunction of the door position of the door position. To eliminate the problem, we find, check and, if necessary, we replace the switch.
If microswaters are normal, then the problem may be associated with the relay that provides voltage supply to the power transformer in the power supply circuit of the magnetron. “Call” the relay contacts with a multimeter, if they are “flooded”, we change the electric compensation to a new.
When there are no problems with the relay, it means that the malfunction is associated with the control unit, change or repair it.
Most often, this malfunction is associated with the voltage drop in the household power supply. If it falls below 205.0-210.0 V, there is a sharp decrease in the intensity of the microwave. Such a problem is characteristic of private houses in rural areas, where the energy network is regularly overstrain, and as a result, a drop in voltage.
If the multimeter shows the permissible voltage of the household network, then you should check the power circuit of the magnetron, how to do this, we will describe in the next section.
When the diagnosis of the magnetron chain did not give results, everything indicates problems with the control module.
Such a malfunction unambiguously indicates a malfunction in the power supply chain of magnetron. Diagnosis is as follows:
- We check using the multimeter the presence of voltage on the primary winding T1 (cm. Rice. One). If it is not, the problem should be sought in the control module.
- The presence of voltage indicates that it is necessary to check the fuse of the high.Voltage circuit, transformer T1, fuse, capacity C1, diode VD1 and magnetron itself. Checking the listed elements is performed with disabled power!
- The fuse “nickname” by a multimeter by switching it to the diodes check or resistance measurement mode. If the device shows a break, we replace the fuse.
- Check T1, cliff and KZ primary and secondary windings.
- We test C1 capacity how to check the capacitor using a multimeter, was described on our website.
- “Call” VD if anyone is unfamiliar technology for testing diodes, then it can be found in the previously published article.
- Check the magnetron. There are certain features with its testing, so we consider this process in more detail:
- First of all, it is necessary to “call” the thread of the intensity if the multimeter shows the resistance close to zero (see. And in Fig. 6), then everything is fine with her, we continue testing. If the device shows a break, check the contact of the filter coils (marked with yellow arrows on b rice. 6). In case of problems with the contact of the coil fastening, the device can be restored, otherwise, everything indicates the need to replace it.
- After testing the thread, check the passage containers on the breakdown. To do this, we convert the multimeter into the “call” mode, touch the case with one probe, the second one is in turn touch the contacts of the magnetron (B in rice. 6). An endless resistance will be a normal indicator, otherwise everything indicates that the capacity is penetrated, which means that the replacement of the magnetron is necessary.
- If the verification of the magnetron did not give a result, it is necessary to measure the input voltages on the device. If they are below the permissible parameters, then this can be caused by an interval circuit in a high.Voltage transformer or a reduced power supply in a household power supply.
Important! Magnetron must be changed to the same type. This is due to the fact that the parameters of the high-voltage transformer and the control circuit are calculated based on the specific model of the microwave generator.
Such a malfunction can be caused by the following reasons:
- Burning of a mica plate isolating a waveguide from spray and pieces of food. The plate is located inside the camera from the side of the magnetron. The condition is determined visually. If the problem is related to the plate, it is enough to replace it.
- During operation, Black’s cover burned out. This is such a plastic cap that rotates the pallet. In this case, only replacement will help. Naturally, it is necessary to install a purchase from the same type of models, since the design of such a cover can be different even in one manufacturer.
- The chamber is installed “wrong” dishes. We remind you that metal devices, as well as those on which metallized dyes are applied, cannot be used in microwaves.
First of all, it is necessary to check, the pallet is not blocked by some extraneous item, it is correctly installed or the separator. If everything is fine, then the reason lies in the drive. This may be due to the following reasons:
An example of repairing a microwave
Before throwing the SARP R-2371K hC-smell into a landfill, my acquaintances turned to me with the question whether it was possible to repair it? They refused to repair the service due to the lack of spare parts, as the stove has long been discontinued from production.
In the stove, at the next opening of the door, the handle broke off and the door frame cracked, in addition, the fasteners of the plate with hooks broke off. The handle and spring of the plate were lost, as the stove lay in the pantry for many years.
The problem was not only in the repair of the door, it was also necessary to ensure its reliable fixation in the closed position and blocking the electrical circuit when opening. It was not possible to restore the stove in its original form. After a few days of thoughtfulness, a simple design solution was found to restore the restoration repair of the microwave stuff.
Before starting the repair of the door, the serviceability of its electric part was checked. The door was closed, the bar with hooks was inserted into the slot and held. A cup of water was placed in the chamber of the stove. After turning on, after a couple of minutes the water boiled.
Fix the door of the stove in the closed position, it was decided using a magnetic latch. To do this, a neodymium magnet was taken, which is shown in the photo extracted from a computer hard drive. A distinctive feature of neodymium magnets is high magnetic induction (power of attraction).
To verify the idea from the end switches, the uniform terminals and the bar were removed on which they were installed, after the two screws were unscrewed, extracted from the stove. With an open door, the average circuit breaker is in a closed state, and the extreme ones are open.
Further, the magnet was installed between the slots for the hooks. In the doorway, to protect against microwave radiation, an iron frame is installed. Therefore, when checking, the door with sufficient effort was held by the installed magnet. The decision was successful. I didn’t even have to make a hole under the magnet in the stove case.
To restore the door frame and the creation of the handle, the aluminum profile of a rectangular cross section was to take. In it, samples for dense landing and two holes with M4 thread were made at the edges.
There were already holes in the door for attaching a broken handle, so a home.Made handle was fixed without finalizing the door and fit well into the design. It remains only to solve the issue with automatic shutdown of the stove when opening the door.
In any microwave oven, when opening the door, the operation of the work is carried out using three terminal switches that are physically connected with the hooks of the door planet. With the door open, the extreme switches are open, and the middle ones are closed.
Blocking the furnace is carried out in two stages. When closing the door, the lower hook first presses the medium switch pusher.
Next, the hook, holding the pusher of the average switch in the pressure, lowers down and the lower switch pusher is lifted.
Next, the hook, holding the pusher of the average switch in the pressure, lowers down and the lower switch pusher is lifted. Thus, the SWC switch (indicated on the diagram at the beginning of the article) opening the supply wires is first triggered, and then the switches of SWA and SWB are closed, which supply the supply voltage to the magnetron and other nodes of the circuit.
I could not simulate the situation in which I could not protect the SWC switch, except that the contacts of the Enterprise, SWB and the relay of the stove in the control unit will be chopped at the same time. But with modern reliability of radio electronics, the probability of such a case is zero. And even if this happens during the operation of the stove, then no one will open the door. Therefore, it was decided when repairing SWC not to use.
To simplify the design, it was decided to use only one of the end switches of SWA or SWB, since in order to de.Energize the closed circuit, it is enough to break off one wire. The proposed decision, in case of desire, allows you to use both end switch.
It was technically convenient to implement the lock using the end switch installed in the middle of the bar. Therefore, one of the extreme ones was installed in his place. To remove the switch, you need to drown the lock, turn the switch and remove from the axis.
Further, from a strip of steel 0.5 mm thick, it was curved and installed on the axis in the form of a screw m2.5 detail shown in the photo. The form turned out to be intricate in connection with the adjustment of geometry in the place. Between the detail and the plane of the bar, for better sliding, the puck was worn on the screw.
Designation of the microwave furnaces of Samsung
. Type of furnace: m. The furnace works only in micro mode; C. A coating furnace from a biocramic enamel (models work with a grill or grill and convection); SK. Stove with grill and convection. . Type of furnace: 1. The furnace works only in the “micro” mode; 2. Grilm oven. . Camera volume: 6. 17 l; 8-23 l; 9-28 l. . Type of control: 1. Mechanical; 2. Mechanical with a rotary switch “Easy Dial”; 3. Sensory; 7. Clock. . Design style . N new model . The color of the case: s. Silver; BL-blue-white; RD-red-white; GN-green-white; BS-blue-silver; TV-blue-white mother-of-pearl.
The connection diagram of the magnetron block, common to all Samsung furnaces, is shown in the connection diagram.
A warning! To ensure constant, reliable protection against microwave radiation, replace parts of the locking mechanism in accordance with the fundamental electrical circuit of the furnace.
Use only the types of switches specified by the manufacturer. First of all, this applies to the primary, door (or secondary in different types of furnaces) and protective switches.
If there is a need to replace at least one of these switches, you should replace all three at the same time. After which it is necessary to configure the position of the switches in accordance with the procedure described below.
The circuit of the electrical principled control unit of type F209 is shown in the rice.7. (There is no grill heater in the M1974NR oven and all chains related to it in the scheme).
|Primary winding||1.45 Ohm|
|Secondary winding||114 Ohm 10%|
|Nepal winding||Less than 0.1 ohms|
Checking specific components of the furnace high.Voltage transformer. Disconnect all wires and measure the following resistances (table.One).
|Low.Voltage power transformer of the control unit|
Low.Voltage power transformer of the control unit. The resistance of its windings must correspond to the table given in the table.2.
Rice.6 Scheme of the compounds of the furnaces CE2974R and M1974NR (there is no grill heater and all chains related to it in the scheme in the furnace)
Rice.7 Diagram Electric principled control unit type F209. (There is no grill heater in the M1974NR oven and all chains related to it in the scheme)
Samsung DE34-00438E microwave touch panel
Samsung (samsung) microwave touch panel: length: 200 mm width: 89. Length (mm): 200 width (mm): 89 Material: metal, plastic color: silver
Features of the repair
One of the most common malfunctions is due to the fact that the microwave does not respond to the opening of the door and the action with the equation panel. It happens at least so that the stove does not warm, although it demonstrates signs of performance: light bulbs are burning, the glass table rotates.
If there is no reaction to launch
First you need to check whether the current is on the network filter. For this, the casing is removed, and the high.Voltage capacitor is forcibly discharge. CHECTION CHECTION CHECTION CHECTION. All wires coming from sockets to terminals should be nicknamed. The grounding terminal should be nicknamed the case.
If the wire is safe, then you need to check the condition of the network fuse. It can be found on the filter board. In the event of a malfunction, you will have to put the same. It is important to consider that a more serious malfunction has led to the fuse to combat it. It will not be superfluous to examine the microwave.
During visual examination, it is better to use a flashlight and a magnifying glass. The following factors signal the problem:
The smell will help to diagnose a malfunction. The smells of burning insulation, failed printed circuit boards or transformer oil, are quite bright, therefore, they are easily determined. If you understand where the smell comes from, then you can localize the problem.
Light without heating
Often, malfunctions with a high.Voltage chain or magnetron lead to such a situation. But before checking these components, you need to inspect the camera. You need to make sure that there are no scorched holes, pollution and ejected enamel anywhere. A rectangular plate of a radio transparent dielectric, located on the left, must be removed and especially carefully examined. To do this, you have to rinse it with alcohol.
If there are through holes or darkening on the plate, then it will have to be replaced. Most likely, this happened due to the fact that metal dishes were placed inside the furnace or forgot about timely cleaning.
In the magnetron circuit, you need to check the safety diode. If it burned out, then just put a new. The part should have original parameters.
A burnt cap of antenna indicates the need to replace the magnetron. The same applies to breaks in the housing. If the microwave oven has served more than five years, then the repair can be inappropriate. It is more economically profitable to buy new equipment.