The microwave touch panel does not work, the buttons cannot be pressed: step-by-step repair instructions

Of all the possible reasons, the most unpleasant one can be considered the one due to which the microwave panel does not work. It's not that it can't be repaired, it's just that a board with buttons or a touchpad is always a black box. It is not easy to determine the cause of a malfunction only by inspection - you have to check and test the device.

The main reasons for panel failure

Any control unit, no matter whether it is a microwave oven, a gas boiler or a water heater, will function stably only if the button is pressed correctly. As a rule, the touch panel on a microwave oven does not work in the following cases:

1. The sensor is stuck, the contact on the button is dirty. The panel can function, but it is unstable; clicks are triggered every once in a while.
2. Some of the buttons do not work due to a broken conductive path.
3. Damage to the cable that connects the keyboard to the control controller board.
4. The board does not work due to damage to the controller.

The latter case is more often the result of a break on the board, a blown fuse or a breakdown of the capacitor. Sometimes the reason why the panel stops working is a sharp surge in voltage in the network. Then a backlight or a high-voltage fuse on the TVN can be added to the control panel.

But most often, the reason why touch buttons do not respond is due to excessive pressure.

The touch panels of budget microwave ovens in the mid-price category are not full-fledged sensors, like those found in smartphones. Essentially, this is a membrane keyboard in the form of a board with applied current-carrying tracks and a soft plastic membrane cover with buttons. A metallized layer is applied on the reverse side (sometimes foil is glued on). If you press the button with great force, the microwave panel will not work after a couple of months.

More expensive microwaves may have a full touch screen. It also needs to be pressed with a little force, much like on a smartphone. If such a panel does not work, the cause may be dirt on the glass or too cold (or even dry) fingers. The sensor is programmed to a certain temperature of the skin of the hands.

How to fix a microwave sensor

The amount of work directly depends on the type of microwave panel. For many brands Daewoo or LG, the touch screen has to be replaced as one unit with the entire panel. Therefore, the microwave is often sent to a workshop. But even if you manage to remove the unit with the screen, it is impossible to work with it without a special tester, and if you dismantle it carelessly, you can easily break the cable.

Therefore, you can attempt repairs at home only in the case of a microwave with a membrane panel. Another thing is Samsung brand microwave ovens. It is easier to work with them, since they mainly have sensors on membranes.

Step one - disassemble the oven

First of all, turn off the power to the device and remove the outer cladding. Almost all microwaves are disassembled in the same or similar way.We unscrew the screws on the back side with a screwdriver and remove the lining from the body - the lid and side walls, all of this is one element in the shape of the letter “P”. All that remains is the front with the door and the back wall.

Find the panel. The part itself is plastic and is attached to the microwave frame with a pair of self-tapping screws. You will need to use a screwdriver to unscrew the fasteners and remove the chips and wires. Carefully disconnect the cable from the display that connects the panel to the unit. After which you can remove the keyboard as one block, along with the plastic box and circuit board.

The keyboard itself is a flexible plastic strip glued to the front of the box. The control part is made in the form of a board. It may also be damaged, preventing the microwave from operating stably under load.

Step two - diagnosis

The most difficult thing is to determine the reason (there may be several) why the panel does not work. First of all, you need to do a visual inspection. Sometimes the reason why the panel does not work lies on the surface.

We immediately pay attention to the peeling of conductive paths, broken contacts, and oxidized surfaces. Perhaps some parts on the control board look burnt out. If the unit is constantly overheating due to increased voltage, then the capacitors will be damaged (swollen) first.

Initially you need:

1. Inspect the cable and metallized sublayer, especially under the start or stop buttons. The microwave may not work if there are breaks in the tracks, conductors, or if there is dirt or grease deposits on the contact surface.
2. We inspect the board, check the break in the fuse. Usually the microwave does not work due to a burnt fuse.
3. We examine the details on the board.If there are swollen capacitors, then this is definitely one of the reasons why the panel will not work.
4. We check the fixation of the cable in the connector on the board. Often, water-fat vapors formed during the heating of the microwave get inside the connector, which is why some panel buttons may not work.

A common damage is a break in the current-carrying path on the cable. The damaged area can be seen with your eyes, even without checking with a multimeter. But you need to be careful, the cable may be damaged during the process of disassembling the microwave and removing the panel. Therefore, the stove may not work for another reason.

Step three - how to fix it

Repair work must begin with the board. Before attempting to repair, you must clean all contacts on the cable with alcohol.

The next step is to check the cable itself. If there is a break, then it needs to be sealed with conductive glue, on top of which stick adhesive tape.

There are a pair of relays on the microwave control board. If visually it works, but no heating, then most likely the cause is the switching relay. If the stove works every day, then the service life of these parts lasts for a maximum of 5-6 years.

If possible, the relays should be replaced, even if they are in working order. The microwave will be able to work for at least another 5 years.

The last operation is to clear the tracks on the membrane keyboard itself. Initially, wipe and clean the surface with a swab moistened with alcohol. If gray spots are visually visible on the contacts, additionally erase the dirt with a rubber eraser for drawing.

The membrane keyboard can be glued together with a few drops of glue and immediately installed on the microwave; you need to check how the oven works after repairing the panel.

What to do if the opening button does not work

The problem is usually associated with severe wear on the pusher that lifts the door latch. You press the key and the lock does not respond. If the microwave is used every day, then problems with the door may begin already in the second year of operation.

It is difficult to get to the pusher even with the housing removed. In some models, you can dismantle the door blocking module or remove the hinges.

But in most cases, the door is unlocked using a steel locksmith's ruler (thickness 0.2-0.3 mm). First, turn off the microwave so that the heating does not start working if the sensor is triggered. Next, you need to insert the ruler into the gap between the door and the body and press firmly up. This allows you to lift the latch and open the door.

How to open the oven if the button is broken

If the mechanism breaks down, you will have to disassemble the microwave. Remove all parts until the locking mechanism is accessible. Repair is carried out by replacing it with a new unit. In order for the button to work stably, you will need to adjust its position using shims.

In old microwaves produced 10-15 years ago, the lever lifting mechanism does not work due to the poor quality of the plastic. In this case, the button is not pressed at all. You can open it if you remove the casing and try to pass a small weight attached to a cord under the locking flag. Then you will have to work like fishing. The cord is passed through the bottom of the block and pulled up. With the resulting loop, you can pry the latch flag and lift it up. The door will open.

Often the microwave panel does not work due to rough handling of the sensor, pressing the buttons too hard, or poor quality of the keyboard itself.It is possible to repair the unit yourself, but you need to know exactly the procedure and remember that there may be several breakdowns.

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