Cooking in a slow cooker different dishes is a pleasure. I fell asleep the necessary ingredients, turned on the program and go about your business, and the crock-pot will do everything on its own. The food prepared in it, in its appearance and usefulness, sometimes surpasses that cooked on a gas stove.
To all this, the multicooker does not consume a lot of electricity, since during operation it is periodically turned off, using the heat of an already heated heater.
In their appearance and design, multicookers practically do not differ from each other. Brand models may have a higher price and workmanship. But, despite the brand, they all have a heating element (TEN), a control unit that sets programs and power circuits.
In addition, its device includes various temperature sensors and protection devices from overheating or overcurrent in the circuit.
Over time, some of these elements may fail, but this is not a reason to throw the crock-pot into a landfill. Despite the apparent complexity of the design, even a person who does not have experience in repairing such devices is capable of repairing a failed device. Enough basic knowledge of electricity and the ability to hold a screwdriver and a soldering iron in hand. Well, of course, the most important thing to do when repairing such equipment is to comply with electrical safety rules. That is, disconnect the device from the network during various manipulations in the device circuits.
In this article, we prepared a step-by-step master class for repairing the Delfa multicooker, but the principle and methods of determining malfunctions are similar when repairing other models of similar devices, for example, Redmond, Polaris, Moulinex, Tefal, Philips and others.
To be more precise, this is most likely not a repair, but the modernization of the multicooker of this model, which as a whole will improve its work and extend its service life.
For disassembly, you will need a Phillips screwdriver and pliers.
For further work, you will still need a soldering iron, a multimeter and a voltage indicator.
Below, a photo of a multicooker with a problem in operation.
Damage is not visible at first sight. The device turns on, shows the cooking modes and time, but over time it becomes clear that the bowl inside does not heat up.
That is, the cooking cycle seems to have passed, but the products in the bowl remained raw.
Moreover, in some modes, she still tries to get a little warm.
We can immediately conclude that the heater is intact, since heating does occur sometimes, and this is already good.
On the other hand, with such floating breakdowns, the reason is determined quite difficult, since it requires the study of the details of the electronic board.
But do not immediately get upset and think that nothing will work. Everything may not be as scary as it seems at first glance.
So, where to start the disassembly. First you need to open the multicooker lid and pull out the bowl.
Under the bowl you can see the disc heater and the central spring. The spring presses on the bowl from below and its top fits snugly on the lid of the device, ensuring the tightness of the container.
We turn the multicooker upside down, and we find the screw that secures the lower part to the body.
Unscrew it and carefully remove the bottom.
In addition to the screw, the bottom rests on the side latches. If you can’t take it off with your hands, you can use a screwdriver by prying off the cover.
Now you can see the main components and components of the multicooker.
In the center is a temperature sensor, which is a special resistor with outputs coming out of it.
The control board is located on the side of the device and serves to select programs.
The two heater leads are slightly away from the center and have plates for connecting screw wires to them. The overheating sensor is located on the side of the heater body and is pressed by a metal plate clamped by a screw. The sensor itself is located inside a heat-resistant tube and is connected to red wires, one end of which goes to the network power connector, the other to the control board.
The power and switching circuit board is located under the plastic cover and is located on the bottom of the device. Wires from all nodes and sensors are suitable for it.
The first thing to check is the heater. In order for the instrument readings to be correct, one wire must be disconnected from the output of the heater. If this is not done, the device can show the circuit through an electronic circuit, although the heater can be blown.
It is better to disconnect the blue wire, which is one and the phase is usually fed to it.
If the screw is loosened tight so as not to break the tip, it should be held with pliers and a screwdriver to unscrew the screw.
We remove the wire and take it to the side, and connect the ends of the "proverbs" to the heater leads. A serviceable heater should show the circuit, that is, the LED on the indicator should be lit, which is what happens. This shows that the heater is intact and the cause of the breakdown is not in it, but in something else.
It will not be superfluous to check the resistance of the heater to the housing to make sure that potential voltage is being applied to the metal part of the multicooker, which can be dangerous.
To do this, we connect one end of the pointer to any terminal of the heater, and the other end to its metal casing. In this case, the circuit should not show the device, if it shows even a weak one, then such a device is life-threatening to use. In this case, replace the heater.
Now that everything is clear with the heater, we turn to the power and switching board.
In order to inspect it, you need to remove the plastic casing that protects the parts on it, and then the board itself.
We unscrew the two screws securing the cover and two screws holding the board. Now you can see the components of the electronic board and take a closer look at them.
Of the main elements, a large orange capacitor can be noted, which is necessary to quench the mains voltage to 12 volts, and with it in conjunction there is a resistor with a resistance of 20 ohms.
In the photo below, a fragment of the concept of the main board.
A diode bridge, consisting of four diodes for rectifying an alternating voltage into a constant, blue relay, which serves as a switching device that supplies the mains voltage to the heater.
Control transistors acting as a key for powering the relay coil, a speaker that emits system sounds, connectors for connecting the sensor and the control panel, as well as a harness consisting of resistors and capacitors.
To find possible damage, it is necessary to carefully examine all electronic components for the presence of blackouts, soot or damage. The same thing must be done on the back of the board, where the conductive tracks are located. You can do this with a magnifier so as not to miss microcracks, poor soldering and other defects.
If no visible defects are found, go to the temperature sensor check - this is one of the parts that often fails.
To make a check, disconnect the sensor connector from the board. It has two wires.
We disconnect the connector, connect the multimeter probes to the contacts and measure the resistance of the sensor. A working sensor in cold condition should have a resistance of about 50 kOhm.
If the resistance is significantly different or the device shows an open circuit, then replacement cannot be avoided. From the readings of the device it is clear that the sensor is working. So the problem is not in it.
Next, we return to the switching board, namely to the power relay. This element also falls into the risk zone, as it is often the reason for the lack of heating of the heating element.
Judging by the marking 973-12VDC-SL-A, the relay control winding is rated for 12 volts, and switching contacts for 220 volts or more.
In the photo below, a finger shows the place of soldering the terminals of the coil windings.
The following photo shows the outputs of the relay power contacts that supply mains voltage to the heating element.
A possible breakdown could be that the relay contacts were burned out and did not pass current to the load.
The next reason may be a failed relay coil or insufficient voltage supplied to it, which would not allow it to work in normal mode.
First, check whether the voltage passes through the relay contacts. To do this, we connect one end of the voltage indicator to the output on the board to which the red wire is connected, and the second to one of the ends of the heater, since the second power wire remains on it.
Next, turn on the multicooker in the network and look at the readings of the device. The indicator shows that the mains voltage is being supplied to the input of the relay power contacts.
Next, we rearrange the voltage indicator to the output of the power contacts, a blue wire is soldered to them on the board.
The pointer does not react in any way, which means that the voltage does not pass through the relay contacts.
While the multicooker is on, we take a multimeter, put a switch on it in the mode of measuring constant voltage and throw its conclusions in place of soldering the relay winding.
The photo below shows that the device shows a voltage of about 6 volts, and this is not quite enough for normal operation of the relay with a coil voltage of 12 volts.
To trace initially, what is the reason for such a low voltage, you need to find the device power circuit on the circuit board. They include: a diode bridge, a large-capacity electrolytic capacitor, a limiting resistor, and a capacitor. Start with low voltage circuits.
To do this, with the multicooker turned on, we wrap the ends of the multimeter in the DC voltage measurement mode directly to the places of soldering the electrolytic capacitor 470 μF / 25 volts.
At this point, the voltage was also about 6 volts, which was not enough for the normal operation of the electronics. And if you also take into account that the voltage further through the circuit passes through the stabilizer, necessary for power supply of the control unit and after which the power is reduced by 2 volts, then the conclusion suggests itself by myself.
When measuring the voltage on the control board, it turned out that it is only 3.2 volts, which may not be sufficient for the normal operation of digital circuits.
It becomes clear that the cause of unstable operation of the multicooker is insufficient supply voltage.
The incoming quenching capacitor and resistance are responsible for it. Such a circuit for lowering the voltage of the network is not reliable enough and there is no point in restoring it, therefore it was decided to apply a more stable power supply circuit, namely using transformer.
Transformer power supplies, in addition to reliability, provide isolation from the network, that is, reduce the likelihood of electric shock.
It is necessary to select a small-sized transformer so that it can fit in the bottom body with parameters ~ 220 and an output voltage of about 9 volts of alternating current.
The voltage passing through the diode bridge and the smoothing capacitor increases to about 12 volts, which will be optimal for the operation of the electronic circuit.
One of the ways it is easy to find a suitable transformer is to find an old power supply or charger for a mobile phone.
Such chargers are small and have sufficient load current. Also, at a voltage of 5 volts indicated on his case, he actually gives out all 9.
But in any case, before using the found unit, you need to measure its output voltage. Here, in the photo, one of the representatives of such power supplies.
The voltage declared on the case is 5 volts, but when connecting a voltmeter to its output, it showed almost all 11.
That is, such a transformer power supply would be ideal for repairing our multicooker. In addition to the transformer, a diode bridge with a capacitor can also be used from this block.
It is not difficult to get the transformer, you only need to separate the two parts of the charger housing. It happens that the covers are connected with screws, but most often they are simply glued and do not have the ability to disassemble. Therefore, armed with a knife or a sharp screwdriver, we divide these parts exactly in the middle, where the connecting seam is located.
This must be done carefully so as not to damage the transformer winding itself and the diode bridge with a capacitor.
Here is a transformer with a diode bridge and capacitor board soldered to it that came out of this block.
It is very compact and fits easily on the bottom of the multicooker.
In order to install it, you need to find a suitable place. It should be as far away from the center and from the heating element. It’s best to do this on the bottom side.
Immediately you need to think about the fact that the transformer, when installing the bottom, does not fall on the place where the heater leads come out.
You can fix the transformer with plastic clamps.
To do this, put it on the bottom and outline a place under the slot. Next, make a slot with a screwdriver for the clamp.
We dress the clamp so that it, with its lock, is on the side of the transformer.
Tighten the clamp as much as possible so that the transformer does not move.
Extra bite off with wire cutters.
Next, we prepare two wires for connecting the transformer to the circuit. It is desirable that they be heat resistant. Their cross section must be at least 1.5 mm.
We clean and tin their ends.
Next, we lay the wire around the perimeter of the bottom and solder one side to the terminals of the transformer.
The wires at the output of the transformer can be left the same that were originally soldered. Only need to bite off the required length.
Also, you should trace which one is positive and which is negative. You can do this by looking at the board and tracing the wire going from the plus mark.
In order not to mix up afterwards, it can be bent.
We lay it next to the first. We remove the plastic casing and remove the main board from it.
Since the diode bridge on the main board will not be used, it must be disconnected from the circuit. To do this, with a knife or something else sharp, make the track break on the board. To do so, it is enough in one place, at the exit of the diode bridge.
Next, we solder the twelve-volt leads (figures 52 and 53) parallel to the electrolytic capacitor, observing the polarity. The minus is indicated on the side of the capacitor.
Solder carefully so as not to short circuit the adjacent tracks with tin or wire.
Next, solder the transformer power wires.
Solder should be to those places on the board to which the wires from the power connector on the side of the bottom fit. They have red and black colors, parallel to them and solder our wires.
So, how is alternating current here, what, where to solder the wire does not matter.
The main thing is that the soldering is of high quality and the hairs of the wire do not puff in different directions. Here's what the connection diagram of the unit to the multicooker circuit looks like. New components are highlighted in red.
Next, insert the board into the cover and screw it to the bottom of the multicooker.
When the cover is screwed, we lay the wires as close to the bottom edge and, if possible, fix them with bundles.
We solder the transformer inlet, where 220 volts will flow, we isolate with heat-resistant electrical tape. If it is not, cotton is also suitable.
So that the wires do not touch the heating element, we tighten them with a plait.
Next, we combine the bottom mounting holes with the hole on the heater body.
We snap the cover all the way around and tighten the fixing screw.
We insert the power cord into the multicooker connector and plug it into the network.
After pouring two glasses of water into the bowl, close the lid.
We select a cooking mode that previously did not work, for example, a double boiler, and press the "start" button.
After a while, you can open the lid and see if the water heats up? It can be seen that the water is boiling, which means that the repair can be considered successful.
It is important not to forget to drain the water from the condensate collection container, otherwise it may end up in the bottom where all the electronics are located. You need to do this after each use.
Such modernization will significantly extend the life of this wonderful device, delighting you with delicious dishes for a long time.
- How to make a refrigerator repair with your own hands?
- How to make a do-it-yourself infrared heater repair?
- How to make a hair dryer repair with your own hands?
- How to make an iron repair with your own hands?
