Kensington Expert Mouse (trackball)


My desk setup at home

I’ve been using a Kesington Expert Mouse for about 6 years now and would like to share my experience with both the device and repair.  It is my favourite “mousing” device since it occupies a fixed area on my desk.  Too often I’ll have piles of paperwork or hardware on my desk with no room for a regular mouse to move around.  It has the right amount of controls, and a nice no frills design that fits right alongside  my new favourite keyboard.

When I’m away from work people will generally bring a regular mouse and plug it in.  The trackball tends to scare people for some reason, even though it is easy to translate trackpad movements to it (larger ones like the Apple Magic Trackpad).

Recently the unit I inherited from another person at work started giving me issues with the left-click.  I would drag things around but it would let go and pick up something else.  It was infuriating but I adjusted my “grip” and the issue went away with a bit more force.  I eventually decided enough was enough, and grabbed a donor mouse to replace the failing microswitch.

You can see from the photo below that the left one is fairly worn.  I bought a second one to keep the same type of setup at home.  It’s developing a bit of wear on the mouse button, but it still hasn’t quite broken in yet — the ball is a bit stiff to roll around, and the clicks are 10x louder than the one I keep at work.  Some people grease the little mini-ball rollers on the inside, but I haven’t gone that far yet.

There are four mouse buttons, a scroll ring, and an optional wrist rest.  You can map the buttons as you please, but default is:

Top left- middle click
Top right- back
Bottom left- left click
Bottom right- right click

I haven’t seen a need to change this as it suits web browsing/tab management quite perfectly.

Some people have issues with the click being a bit too stiff and have come up with a modification where you shave some of the plastic away, but I haven’t found that to be a problem with both the old  and the brand new units. The clicks are very loud on the new one, and are quite sharp – reminiscent of a Cherry MX Blue keyboard switch.

This Kensington Expert Mouse uses Omron switches for the four buttons.


Opted to leave the ball at work so I wouldn’t risk losing it during transport.

The wrist-rest keeps your fore-arm and wrist in a bit more of a natural straight line so you have less risk of causing carpal stress when activating the mouse buttons.  The feeling of the vinyl rest is a bit smooth with just enough friction that you won’t slip off if you put a bit of weight on it.  The rest attaches with two little plastic buttons which unfortunately are a very tight fit and are very easy to break off.  You may have better luck attaching it to the bottom with some clear packing tape.

The scroll wheel is smooth to operate with a little bit of ‘gritty’ friction and accompanying noise.  It feels much more comfortable to use than a regular mouse wheel and is much easier to continually scroll (think iPod classic).  I feel I get more scroll out of one movement on this ring than I do on a regular mouse wheel.  I also use it as a fake fly-wheel sometimes where I flick it with extra force to scroll through long documents.  It uses an optical sensor for the scroll.

The trackball optical sensor is easy to skip if you flick the ball very fast.  You’ll want a medium sensitivity on the trackball so it doesn’t skip when moving the ball fast.  The skipping doesn’t jump around much – it instead mostly stays in the same place with a little bit of back/forth motion (in the direction you spin) until the ball slows down enough that the sensor can track it.  I feel much more precise with a trackball since I’m using my fine finger motor skills, rather than arm & wrist movements with a mouse.  It’s easier to overcome the slight force “bump” of friction.

I prefer to mouse with ‘enhance pointer precision’ disabled.  It makes movement more easily predictable with less thought involved.  A throwback to my old days playing competitive FPS.


Side profile

Now, on to the real reason I decided to write this post.  As I mentioned earlier, I had issues with the left-click.  I finally decided to get off my lazy bum and swap the mouse switch, thanks to a donor mouse that had some issues keeping a USB connection.  Most mouses use compatible switches, so I was hoping for the best.

It was fairly easy to disassemble the Expert Mouse, and you probably will want to do it at least once every few years, if not for repair then at least to clean out the dirt that gets trapped inside.

Once you get inside, there are three PCBs that make up the mouse.

Left main board – controller chip, two left-side buttons, optical scroll sensor
Top board – optical ball sensor
Right board – two right-side buttons

The left PCB is held with three screws.  The right PCB held by one.  The optical board sits in a diagonal retention clip.


Inside the Expert Mouse


Here is the left-click button that was giving me issues.  It is an Omron D2F-01.  They cost approximately $2 per switch in low quantities.


Left-click button that was having issues

I harvested a Kailh switch from another mouse.  It feels different, sounds different, and figured it doesn’t deserve to be my left-click.  What I ended up doing was transplanting the switch on the “back” button to the left-click position, and installing the Kailh for the “back” button since it sees so little use.  Desoldering the switch was arguable the most difficult part.  I added some solder to the points, and heated up two pins at a time, “rocking” the switch out.  You will have an easier time with a solder sucker, but I have not yet invested in one.

The repair was a success, but I can’t fight the feeling I should have opted for a legit Omron replacement switch.  Total cost of parts for this repair was $0, so hard to argue with that.  I have a few classic Razer Deathadder mouses (my favourite mouse) that need this same treatment, so perhaps I will spring for a bulk order and make my Expert Mouse ‘whole’ and untainted once again.



Filed under computers

2 Responses to Kensington Expert Mouse (trackball)

  1. Ionut

    I know this is a very old post but I was wondering if you are still using this trackball.
    I have one that I used for many years with no problem what so ever. Then it sit on its box for another few years and recently found it and I wanted to put it to use again but the optical thing its not working anymore. Buttons are all working fine but when I remove the ball there is no red light. Tried to clean it thoroughly and even opened the case for this.
    Do you have any idea what might be the cause?
    When I plug it in the USB port the red led is flashing rapidly for a 1-2 seconds but then it goes off.
    I would try to replace the broken part if I knew which one is broken.
    I like this gadget very much and I kind of feel it deserves more days.

    Thank you

  2. Jim Maneri

    they don’t work great without take-apart cleaning and maintenance about every 5 years. the laser gets jolted and doesn’t aim right, and dirt in the works are the main baddies. I’ve been using them all day every day since they came out.

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