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A Multi Trouble Computer Mouse Repaired

By on July 24, 2015
mouse repair








mouse repair

Some time ago my veteran Leadership optical mouse started to work badly. Two basic symptoms: the scroll wheel seemed to be gliding freely, without really driving the expected movement in the screen, and when the left-button was pressed, the screen jumped up and down in an unpredictable manner, making it difficult to position the insertion point in the desired location. Selecting a part of a text became almost impracticable. Over time, its performance got to be worse and worse, until became extremely difficult to use.

It would be simpler and (perhaps) time-saving to throw away the mouse and buy another new one. Ok, it’s a cheap hardware, no problem about. The real problem (at least from my point of view) is that this contributes to increase the technological waste…bad! Just opposite to my ecological thinking. So I decide to fix it, considering that I could learn something with, avoid spending money (even a bit) and give a (even small, but better than nothing) contribution to the health of our planet. No doubt three good reasons!

I had to stop the (important) work being done and disassemble the mouse. Just one screw and it was open.

computer mouse repair

The first job was to do a general cleaning inside, especially on the optical path (the way between the LED and the optical sensor chip). This can be one of the reasons why the screen jumps.

mouse repair3

Then I inspected the scroll wheel. Around the big rigid wheel there was another soft wheel remembering a tire. This “tire” is the soft part that comes in touch with the fingers when turning the wheel.

mouse repair4

mouse repair5

It was completely oiled, which was the cause of the gliding action over the rigid wheel. Some products are produced with embedded oil, which is “distilled” on its surface over the time. That was the case of this soft wheel oiled, I don’t understand why. It’s nonsense, not applicable to this case and utterly unnecessary. The soft wheel was carefully washed using a detergent and then dried. When installed, it drove the rigid wheel firmly and stable, with no more slipping. The problem is that I know the “tire” still has embedded oil, and in the future it will require another cleaning…

Therefore, the problem still remained, with the screen continuing to jump up and down as the scroll wheel was turned. I observed that the big rigid wheel, by its shaft, drives a second smaller component with the appearance of a potentiometer near the left-click microswitch.

mouse repair switch

In fact, it is not a potentiometer: it’s a contact set assembly that produce pulses that are sent to the software in order to obtain the scroll effect. I’ve seen on the internet a report saying that this could be an imperfect match between the male axis and the female small wheel. In fact this could happen, but it was not the case here. The component was unsoldered from the PCB and disassembled with the aid of small pliers.

mouse repair7

It was all dirty inside. A simple cleaning with ethanol (could be isopropyl alcohol) with the aid of a cotton swab corrected the problem (it’s important to be sure that no lint from the cotton swab remains inside). The moving contacts sliders pressure were slightly reinforced, taking care to not applying too much pressure, which could prematurely wear out the contact set.

mouse repair8

The component was assembled again and soldered on the PCB. The screen does not show the uncontrollable jumps anymore when commanded by the scroll wheel.

More problems: when left-clicking, the screen continued to show jumps. There are three microswitches on PCB (of identical type): for left clicking, for right-clicking and for continuous scrolling, that is in this case actuated by pressing down the scroll wheel (instead of turning it).


Pressing gently with a small screwdriver, the left-click microswitch gave a sound different from the other two. And more: required less pressure to be actuated as compared to the other two. So I’ve suspected that it was a problem of mechanical wear, possibly with contact bouncing. According to the literature, this kind of switch is expected to have a useful life of about 1 million mechanical operations. Of course this was not the case – it’s highly unlikely that I have used it this great amount, even over all these years. Obviously the quality of this microswitch is not that great either! As this kind of microswitch is normally difficult to disassemble (or, still worse, to reassemble), I decide to turn the soldering iron on and swap the left-click microswitch with the one used for continuous scrolling (a function that I hardly use). The action corrected this another problem, confirming that the left-click microswitch was not OK (and confirming also the contact bounce problem).

Each plastic pivoting parts in the mouse cover have a kind of tooth, in the point they touch the actuating button of the respective microswitch. The right-click protuberance was OK, as can be seen in the picture below:

mouse repair 11

On the other hand, the tooth that mechanically drives the left-click microswitch was deformed, causing doubts related to the correct matching to the microswitch actuating button.

mouse repairing

Nevertheless, I affixed a plastic foil between the tooth and the microswitch, trying to minimize the problem. I am not shure if this effectively was decisive to correct the problem. As it was said, at this point, with so many problems in a single hardware (i.e. the mouse itself) the things become confusing…

Amazing: what initially seemed to be only two problems just demanded five corrective actions! This sometimes occurs to maintenance people, rendering the things completely confused. And it was occurring with me at that moment! The important thing is that now it is all working fine. And at zero-cost (no component replaced).

One could say: OK, you say no component cost, but have spent time; this is also a cost. I nearly agree, but take into consideration the following: the maintenance work took around only 2 hours of service, I’ve avoided a small trip (consuming gasoline and anyhow time) in order to go downtown to buy another mouse, (i.e. a few dollars saved in my bank account), more experience gotten, all working fine in my computer, a contribution to the environment, much satisfaction to give something useful … and the opportunity to take part of this community. Much more than the initial three good reasons given above. In fact, it’s a remarkable gain. Nothing bad!









This article was prepared for you by Henrique Jorge Guimarães Ulbrich from Curitiba, Brazil. Retired electronics technician. Loves electronics, telecommunications and cars.

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  1. Anwar Shiekh

    July 24, 2015 at 8:42 pm

    The oil on the wheel is from human sweat.

    • Henrique Jorge Guimarães Ulbrich - Brazil

      July 24, 2015 at 10:33 pm

      You are right, Anwar, this might also happen. But this was not true in this case. The oil was between the inner part of the tire and the big wheel, too difficult to be reached by fingers natural oil. This is a practice from some manufacturers. For example: remote control sets (TV, sound equipment) I've already serviced had the same problem. The oil impregnated in the rubber mantle of the keyboard is slowly released over time and deposits on the PCB. It requires cleaning due to the large amount of spread oil. Over time, the oil release continues, demanding another cleaning service. Thanks for your repply.

      • Albert

        July 25, 2015 at 4:13 am

        About this I like to add the fact that they sell little mouses and parts that are on the outside rubberised to give them a better touch and feel. Those parts become very sticky after some years and are not usable anymore because of this. Today you can even buy spray cans and to rubberise things yourself but I think it is a good thing not to rubberise anything for the reason just mentioned. Don't know about the oil they use but normally Rubber is best used as little 'feet' that keep things from falling from tables. To prevent them from moving and breaking. Or like little Bumpers one uses on Doorstops etc.

    • Sabu

      July 27, 2015 at 3:18 pm

      Thought provoking article, because generally people do not think what damage we cause to our nature by just throwing away an equipment because it is cheap instead of repairing and using it.

  2. AccordionTom

    July 24, 2015 at 9:09 pm

    Very nice, Henrique! Excellent write-up! I enjoyed your story and the really good pictures. I agree with your thinking. I am the same way. I also must compliment you on your excellent English. I recently tried to refurbish a Microsoft 4000 wireless mouse, but the "tire" around the scroll wheel did not cooperate. It was full of debris, which I think maybe was from deterioration of the "tire" itself. It became too stretched-out when I put it back together, and I was forced to buy a new mouse...but I felt good anyway because I had tried to fix it! Again, enjoyed your post. Tom in Indiana.

    • Henrique Jorge Guimarães Ulbrich - Brazil

      July 24, 2015 at 10:44 pm

      Tom, the problem with your tire full of debris is a consequence of the planned obsolescence practice employed by the majority of the industry. It's the irresponsible consumer society, that does not take into account the health of our planet... Thanks for your repply. I congratulate you for the try to recover your mouse to life.

  3. Yogesh Panchal

    July 24, 2015 at 9:20 pm

    Thanks for saving the equipment by earth filling.

  4. Albert

    July 24, 2015 at 10:34 pm

    Good job, in my early days mouses would cost (my old Logitech XT mouse) about 100 Dutch Gulden or about 45 Euro to todays standard. I have repaired one or two mouses that used IR leds for their scroll wheels. And because they do not give visible light it is more difficult to find the bad IR Leds. But I did manage by using my old oscilloscope and checking the photocell that recieved the IR light.
    Those could be bad too of course and then again an oscilloscope is very usefull.
    But when nothing works and the mouse cable is the bad part it means buying a new usb cabled mouse. (I hate those mouses or little Wifi keyboards with those leaking batteries or the fact that you first have to type a letter or two before the keyboard is activated.)

  5. Anwar Shiekh

    July 24, 2015 at 11:09 pm

    I also find that when the micro switches start failing it is easier to use a little silicone oil in them than replace them.

  6. Merlin Marquardt

    July 24, 2015 at 11:23 pm

    Interesting, informative, and impressive. Good work.

    • Henrique Jorge Guimarães Ulbrich - Brazil

      August 6, 2015 at 10:37 pm

      Thanks, Merlin

  7. vikrant

    July 25, 2015 at 1:28 am

    Dear Henrique!Hope you doing wel....hummmm....You have spend precious "Two hours " for Mouse? and please note...Technician never get retirement from his job. sometimes it's all about passion.BEST luck...

  8. Gary

    July 25, 2015 at 4:29 am

    I have had a similar problem with my mouse double clicking and it was microswitch - clean with alcohol fixed problem - I am same as yourself i never throw electrical items out i try to fix them all and have saved £1000's from my cars using obdii to diagnose , plasma tv , washing machine , cooker , oven and more...I am glad my father taught me electronics , plumbing , woodwork etc

    Good work I have learned a litle about the rotating contact device I didnt know it could be opened and fixed - thank you Henrique it is a good day when you learn something new as nobody knows everything - NOT EVEN JUSTINE YONG...Lol

  9. Anthony

    July 25, 2015 at 5:04 am

    Great job Henrique ! You may have spent some time repairing a device that could be easily thrown away...but there is no greater reward than the satisfaction of learning from a repair and as you pointed out saving the planet from this kind of waste ! Thank you for sharing because these are the stories that inspire others to try to repair devices which they may also be tempted to just throw away and if that saves more of these from landfill....then you have certainly done your bit for the planet ! Great photos by the way !

    Kind Regards

    • Henrique Jorge Guimarães Ulbrich - Brazil

      August 6, 2015 at 10:34 pm

      Thanks, Anthony. I sincerely hope my effort can encourage more people to try fixing products that have conditions to be maintained. In relation to the quality of the photos, I've used a Sony DSC-H2 camera, that has the useful function Macro, which allows photos to be taken from very small distances (such as 3 to 8 cm), even so keeping good focus. I strongly recommend all to use this resource. Despite the practicality of the cameras embedded in smarphones, they are inefficient at very small distances, as in the case of maintenance reports.

  10. Ehsan murad

    July 25, 2015 at 6:45 pm

    Very nice presentation.

  11. Biruk Aweke

    July 25, 2015 at 8:39 pm

    very nice explanation thanks for sharing this article.

  12. Humberto

    July 25, 2015 at 11:25 pm

    Good job Henrique. Congratulations and keep up.


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