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Today we will look at an example of touchscreen recovery after liquid contact in Samsung Galaxy A31 smartphone. Our solution can also be used when repairing Samsung A20, A30, A30s, A40, A50, A70 models, etc.
Before proceeding to repair it is necessary to make sure that the problem is in the display module! Then carefully, using a special lcd screen separator (heats evenly) or other heating device to glue the display out of the frame.
We are looking at this part of the module, which is located on the back side from the bottom. In this place is located touchscreen cable with the controller and the place of connection (solder) of this cable with the display cable.
The cable itself is glued to the display with conductive glue and to separate it, we need to heat the surface of the cable slightly with a soldering heat gun. In order to avoid overheating and damage to the display by high temperatures, it is important to put some metal plates under the flat cable.
In the photo we can see that the touchscreen cable and the display cable have several damaged tracks that transmit the signals.
Clean the tracks with a scalpel and repair the contacts with a thin copper wire and a soldering iron with a thin tip. And of course, for such delicate work, it is best to have a microscope!
Do the same with the display cable.
Solder everything back in place, insulate with thermal adhesive tape, then connect the display module to the phone for testing.
In the picture we can see that the touchscreen works. Repair was successful and we need to glue the display module into the frame and assemble the phone back.
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