fixing a broken graphics tablet pen - graphics tablet

Last Christmas I bought a Ugee graphic tablet for my little brother.
The tablet works fine but the pen is broken.
After checking the pen, I found that the wire of the pressure sensor was broken.
I think it will be a great opportunity to improve my welding skills and choose to fix it.
You need: can skip this, it's just a FYI section.
In the load sensor, the wire revolves around the material (
Called substrate).
The wire is stretched when the force is applied to the substrate.
With the extension of the wire, CrossSection area (A)
Reduction and length (L)is increased.
This increases resistance (R)
, As we can see with equation R = p * L/(
Where p is the resistivity of the wire material.
For example, the resistivity of copper is quite low).
With the increase of wire resistance, the current decreases (
We can see with equation V = IR).
ADC can process this information (
Analog-to-digital converter)
So we can figure out how much pressure is applied.
If the wire is broken, the resistance is infinite and there is no current.
Therefore, the sensor is useless unless it is repaired.
These sensors are used by the pressure sensing pen of the graphic tablet.
The Wii Fit board also uses these types of sensors.
Before you get a soldering iron near your project, you'll want to put a piece of paper between the broken wire and the rest of the pressure sensor wire.
Don't skip this step, you may get welded in the rest of the pressure sensor, which is the beginning of a very bad day.
In preparation, I cut a small piece of paper and folded it in half.
I then wrapped it in the rest of the pressure sensor and fixed it with clear tape.
Later, I tied the broken wire to the paper so that the end of the wire would come into contact or be very close to each other.
Leave enough space so you don't get welded on the tape.
The transparent tape is perfect for this as it doesn't stick very well.
Do not use strong tape as this will make it difficult to remove the paper later.
Do this well, otherwise the welding will be terrible.
In the picture above, you can see that there is already some solder on the wire.
This was my first attempt, when I was not very careful about the recording.
I also taped the whole pen to a piece of paper.
This makes it easier to weld.
This is not a description of how to weld.
If you are not good at welding, I suggest you practice in advance.
The welding speed is very fast, but it needs to be gently.
You don't want to burn out on paper or get a lot of welding on the sensor.
The wire for the pressure sensor of the pen is really thin, so I found it better to put the solder on the soldering iron instead of adding it when you fix the soldering iron in the project.
In any case, you should always weld on the iron, so you will add a small amount more in this case.
These are very small wires and do not require a lot of welding.
This photo shows the wire I welded.
I am not the best in welding but the result seems to be good.
As you can see, the paper was burned a little but not.
After the pen cools, gently remove the tape and paper.
After that, you can see the finished pen.
It should be like this.
However, it may look better if you are better at welding than I am.
After fixing the pen, I put it back together and tested it on the computer.
I am very happy to find that not only did it write, but the pressure sensing ability also worked as expected.