Microwave keypad buttons not partially working
Issue description:
The control unit, equipped with a touch keyboard, requires careful handling during operation and does not tolerate voltage surges in the mains. Unfortunately, in modern conditions, it is almost impossible to provide gentle working conditions for microwave ovens, therefore, sensor control units (CU) often fail. In this case, the cause of the malfunction may be caused by the fact that the buttons on the microwave do not work.
The touch (sometimes called membrane) keyboard is a compact three-layer film structure that does not have separate moving mechanical parts. On two films, in the places where the keys (buttons) are located, there are contact pads that are connected to each other by conductive tracks. Between them is an adhesive mask with slots (holes) that allow the contact pads to touch when pressed lightly. The operation of the membrane keyboard is provided due to the high flexibility of the constituent elements.
All malfunctions due to which the touch keyboard stopped working can be divided into three groups:
membrane contacts sticking, due to which the touch panel buttons are not pressed
break conductors
violation of contacts at the points of connection between the loop and the connector on the control unit.
Solution:
The work on disassembling the keyboard must be carried out very carefully and carefully.
First of all, you need to stratify the three-layer "sandwich". To do this, use a clerical knife to pry the corner of one of the films, intercept it with your fingers and smoothly separate the layer from the base.
Restoring the integrity of the conductive tracks
Before starting repair operations, you must visually inspect the films for signs of oxidation of the contact pads and damage to the conductive tracks,. Particular attention is paid to checking their status in the area where the buttons are not working. If it was not possible to visually detect damage, it is necessary to check (ring out) the integrity of the tracks with a multimeter.
Having found a break in the conductive track, they begin to restore it. To do this, it must be thoroughly degreased, and then a layer of special glue is applied to the damaged area. After the adhesive mixture is dry, a tester is used to check the tracks for conductivity.
Repair of "sticky" buttons
Sticky buttons can be caused by a number of reasons, among which the most common are excessive finger pressure on the button and contamination of the contact pads. Eliminate the causes of "sticking" by slightly increasing the distance between the upper and lower films. To do this, first, both films are thoroughly degreased, and then the inner surface of one of them is carefully sealed with tape or electrical tape. In this case, it is necessary to ensure that the contact pads remain open. After finishing work, you need to make sure that the buttons do not stick and provide reliable contact with a light touch. If you need help with home microwave repair, call us right now!
