Fix a Broken Optical Mouse

Is your mouse button broken? Or does it just not click right anymore? Is the scroll-wheel not working? Have I got the fix for you! In this quick-fix project we're going to save a broken mouse from the landfill, and breed new life into it!

We're going to need a couple of basic tools to achieve our goal. Here's a list of essential items:

• Soldering iron
• Phillips (Torx) head screwdriver
• Rubbing alcohol
• A piece of cloth or a paper towel

A tool you can use for extra convenience (but is not necessary to complete the project):

• Third-hand tool for soldering

The body of an optical mouse is made up of two major plastic parts, which we are going to call lower and upper halves. The upper half has additional smaller parts, aka the buttons and scroll-wheel. The lower half is where you will find the holes of the screws holding the mouse together. We need to remove these screws so we can work on the PCB. You will find that most mouse use Phillips head screws, but you might encounter ones using Torx head screws. It's good to have the right screwdrivers ready. Usually the screws are hidden under labels or plastic feet. There should be around 2 or 3 that you need to remove. After removing the screws, separate the plastic parts. Now the PCB should be visible. If it is held in place by screws, remove those as well, and take the PCB out.

Based on the symptoms of your mouse, you need to locate the faulty parts. Usually if a button is not working or is less tactile, it means its microswitch is dead or dying. If the scroll-wheel is acting up, the rotary encoder could be at fault. Locate the broken switch based on the layout of the mouse buttons. In my case it was the part circled with red. The rotary encoder is the little 5 legged part, circled with blue.

You can order the necessary parts online, or you can do as I did and harvest some from a dead mouse. (a mouse is dead if the main IC is fried) The process of disassembly is the same for the donor mouse. Prepare your soldering iron and start removing the necessary components. Removing the switches is fairly straightforward as they only have 3 legs, the rotary encoder might be a little bit more difficult. Older mouse's use solder that's easier to melt, with some newer mouse's you might need to heat the board with a heat gun to be able to melt the solder.

Remove the broken components from the PCB and install the new ones. As we have already seen when desoldering them, microswitches are pretty easy to work with, however rotary encoders might be a little bit trickier, as they have 5 legs, and the 3 in the middle bend easily, so inserting them into the proper holes in the pcb is fiddly work. Once inserted however, soldering them is a breeze.

It's time to test the mouse. First visually inspect the mouse, check for solder bridges you may have accidentally made if it's your first time soldering. This is a good time to clean the inside of your mouse, from dust and grime accumulated inside of it over the years. Use rubbing alcohol and a paper towel.

Insert the PCB back into the plastic case and close it. You don't have to screw it in yet. Plug the mouse into your pc and test it out! The button/scroll-wheel works again? Yes? Great, you can add the screws and you have a working mouse again! No? You might just be out of luck, could be that the main IC of the mouse is fried. In that case there's nothing else we can do, the time has come to recycle the mouse.

If everything went as planned and the mouse is working again, you can assemble it, but don't forget to screw the PCB in ,as you don't want it rattling around inside the case. And we're done!

A working mouse is a happy mouse!