Search Results for: kensington scroll

Kensington Expert Mouse Trackball: Scroll Ring Aperture Alignment

That comment suggested scroll ring failures on a Kensington Expert Mouse (it’s a trackball) might occur when the apertures become misaligned from the IR emitter-detector pair, although later results were equivocal. I tore apart a failed unit to see what the alignment looked like for a known-bad scroll ring.

The right side view shows the receiver roughly centered in an aperture:

Kensington Expert Mouse - Scroll Ring aperture - right

Kensington Expert Mouse – Scroll Ring aperture – right

The left side view shows that the ring is almost flush against the circuit board, with the isolating cutout just in front, and it’s not obvious how to lower it any further:

Kensington Expert Mouse - Scroll Ring aperture - left

Kensington Expert Mouse – Scroll Ring aperture – left

So I think there’s no way to realign this one, other than to raise the aperture ring a bit, but that doesn’t seem like it would make any difference: the detector already has a good view of the emitter.

If your trackball has a failed scroll ring, tweaking the aperture ring’s alignment certainly can’t hurt: try it and report back.

If you don’t expect a miracle, you probably won’t be disappointed, alas.

The pix come from the Canon pocket camera mounted on the macro lens / illuminator, handheld with manual focus. The dust speck on the detector is just slightly out of focus, but you get the general idea.

[Update: 2015-07-29 – A success story from Tom:

Hi, I wanted to leave a comment for your page here: [this url]

I’ve got an expert mouse trackball that was having intermittent scroll ring problems, then finally quit working altogether. Dismantled it easily using the instructions on this site.

Cleaned it and it still wasn’t working. Tried changing the alignment of the IR emitter/detectors and it still wasn’t working. Then we kept on fiddling with the alignment and voilà.

Like others have said, the alignment seems to be SUPER sensitive. So if any others are reading this with the same problem, keep persevering.

Thanks to everyone who has posted to help find solutions!




Kensington Trackball: Scroll Ring Tweakage

Of late, something in the pile of input devices attached to my main PC has been feeding occasional bursts of upward scroll commands, to the extent that editing long documents (something I do quite a bit of, oddly enough) was becoming difficult. By process of elimination, the culprit turned out to be the Kensington trackball to the left of the keyboard: unplugging it eliminated the problem.

Having had problems with that thing before and having gotten considerable feedback from other folks, I had a general idea of how to proceed: putz with the IR emitter-detector pair, but not very much. A side view of the pair with the trackball cup and scroll ring removed:

Scroll ring IR emitter-detector quadrature pair

Scroll ring IR emitter-detector quadrature pair

Now, what’s weird about that setup is that the detector lens seems to be pointing in the wrong direction: away from the emitter’s lens. You know it’s the detector because it’s tinted: there’s no point in filtering the emitter’s output (although I have seen gray-tinted IR LEDs, which I think is just to mark them as different from visible LEDs). Here’s proof: a pure IR picture from my Sony DSC-F717 in Nightshot (a.k.a. IR) mode through a Hoya R72 visible-block filter:

Quadrature pair in pure IR

Quadrature pair in pure IR

Some possibilities for why the detector is backwards:

  • It’s an assembly screwup (unlikely, but possible)
  • That’s not a lens, it’s a locating tab (different on emitter & detector?)
  • The backside uses the metal conductors as slits to enhance the signal (my favorite)

Here’s a grossly image-enhanced blowup of the detector from that picture:

Quadrature IR detector in pure IR - detail

Quadrature IR detector in pure IR – detail

The case becomes transparent in pure IR, so you can see the metal lead frame inside. I think they’re using the gaps between the leads to enhance the contrast of the scroll ring edges passing through the beam: absolutely no IR except when a gap aligns with a scroll ring opening.

[Update: read the comments for a different interpretation; I’m probably wrong.]

That would also explain why the pair seems so sensitive to alignment: there’s very little IR hitting the detector, because the IR illumination passes through the transparent-to-IR case and vanishes out the far side, with only a tiny bit reflected to the sensor!

Anyhow, I pushed the pair minutely toward each other, just enough to feel the leads bend, and put everything back together. So far it seems to be working perfectly, but it’s done that before …

[Comment: Jack found a different solution that might produce better results:

Just got the Problem with my Scroll ring and thanks to your blog i digged a bit deeper.

here is the Solution for my Problem:

I checked this while connected and i found that bending worked only for a short time, so i gave a closer look to the contacts.

all are soldered from below BUT two contacts are on the upper side.
normaly solder should flow into but here it was as simple as just resolder the receiver with enough solder an its now working again. (btw a realigned the magnet to get a better response)


ps. the size of the cuts in the metall from the scroll ring differ, a shame for that price..

It’s certainly worth trying, particularly when your Expert Mouse trackball isn’t working…


Kensington Expert Mouse Trackball: Scroll Ring Troubles

Trackball Scroll Ring

Trackball Scroll Ring

The oddly named Kensington “Expert Mouse” (it’s a trackball) sits to the left of my keyboard, where it serves as my main pointer controller; I’m right-handed, but have used a left-hand mouse / trackball for years.

[Edit: a comment from the future compares it with a different trackball that may work on the right.

Also, search for Kensington scroll to find other posts. There may be no good fix for scroll ring problems.]

Recently the scroll ring has become balky, stuttering upward & downward rather than actually scrolling. It’s an optical device, so I suspected it had ingested a wad of fuzz that blocked the beam path.

The top photo shows the infra-red emitter adjacent to the scroll ring’s slotted rim. The silver bar to the right of the emitter is the magnet that provides those soft detents. There’s no obvious fuzz.

Disassembly is straightforward.

  • Tip the ball out into your hand and put it where it can’t possibly roll off the desk.
  • Peel the four rubber feet off the bottom, remove four screws, and the top half of the body pops off.
  • Remove three screws from each of the two button cap assemblies and pry the button caps off the case bottom.
  • Remove two screws from the ball socket, pull it off, and clean any fuzz from the openings.

Surprisingly, I didn’t find much crud at all.

Scroll Ring Emitter and Detector

Scroll Ring Emitter and Detector

This photo shows the IR emitter and detector, peering at each other across the electrical isolation gap in the circuit board. Nothing obviously wrong here, either…

They both seem to be dual elements, which makes sense for a quadrature position encoder. Unfortunately, replacing them seems to be really difficult; they don’t look like stock items.

So I put it back together, plugged the USB cable in, restarted the X server (this being Xubuntu 8.10), and it pretty much works again.

Kensington replaced a previous Expert Mouse under warranty when one of the three minuscule red bearing balls that support the trackball went walkaround, but that gadget had been getting erratic, too.

I’m not sure what’s going on, but I have a bad feeling about this.

[Update: More troubles lead to some interesting pix and an insight. Maybe even a fix!]


Kensington Expert Mouse Cable Replacement

My posts about troubles with the Kensington Expert Mouse scroll ring remain disturbingly popular. My most recent warranty replacement has been running fine for several years, so I suspect they had a bad lot of IR detectors go their production line and into the field.

In any event, a recent email asked about where to get the little connector inside the mouse to replace a worn-out USB cable:

Kensington Expert Mouse - internal USB connector

Kensington Expert Mouse – internal USB connector

Maybe you’d be lucky enough to find an identical connector inside an old mouse in a junk box, but that’s not the way to bet.

Given that you need not only the proper plastic shell, but also the pins and the crimper for a proper repair, I suggested just chopping the wires an inch from the connector and splicing the new cable onto the wires.

Not an elegant solution, but it works for me …


Kensington Expert Mouse: Unit 3

A week or so ago, the scroll ring on the Kensington Expert Mouse trackball at my left hand failed completely. Unlike the previous repair attempts, tweaking the IR emitter-detector pair positions did nothing. Tried it on three different PCs and five different operating systems with the same result: the ring stayed dead.

Fortunately, this one was a warranty replacement for the dead Unit 1 I bought some years back and was still within its 5 year warranty, so when I contacted Kensington tech support with the story they immediately shipped a replacement. It just arrived and works fine.

The scroll ring detents seem much smoother on this one, so I haven’t taken it apart to remove the magnetic latch and don’t know if they’re using a different quadrature sensor. One can but hope.

Kensington Expert Mouse - ball bearing

Kensington Expert Mouse - ball bearing

For what it’s worth, an absolutely brand new ball barely moves on those three jeweled bearings (one marked with the yellow oval in the picture). Just rub the ball on one side of your nose to add some skin oil: shazam it spins like glass on ice.

They don’t mention that trick anywhere in the meager instructions…


Arch Linux: Kensington Expert Mouse FDI File

The FDI file is similar to the one I used for Xubuntu, with the exact match changed to a partial match. For some reason, the exact match seemed to not work.

Because the XFCE4 Mouse configuration utility sets handedness on a per-mouse basis, you need not swap buttons 1+3 here. I did, anyway, and the mouse automagically came up left-handed.

I swapped 2+8, the top two buttons, putting the browser “back one page” button at the upper left and the “open in new tab” button at the upper right.

The contents of /etc/hal/fdi/policy/10-expertmouse.fdi:

<?xml version="1.0" encoding="ISO-8859-1"?>
<deviceinfo version="0.2">
 <match key="input.product" contains="Kensington Expert Mouse">
 <append key="input.x11_options.ButtonMapping" type="string">3 8 1 4 5 6 7 2</append>

And, for whatever reason, the scroll ring now works perfectly without the least hint of stuttering or jamming.


Xubuntu 9.10: Quasi-functional Kensington Trackball Configuration

As mentioned there, Ubuntu prohibits having two mice with different handedness. Xubuntu enumerates the various mice and allows you to set their handedness separately.

This file swaps the upper two buttons.

The scroll ring operates intermittently. I no longer believe it’s a hardware problem, as I have two Kensington trackballs and both behave the same way. I’m guessing the evdev driver has trouble with button pushes from two devices, but that’s just a guess. Sometimes it works perfectly for hours on end, other times it jams up first thing in the morning. Restarting X helps, which indicates the hole isn’t in the trackball’s end of the boat.

Here’s my /usr/share/hal/fdi/policy/20thirdparty/10-expertmouse.fdi file:

<?xml version="1.0" encoding="ISO-8859-1"?>
<deviceinfo version="0.2">
 <match key="input.product" string="Kensington      Kensington Expert Mouse">
 <append key="input.x11_options.ButtonMapping" type="string">3 8 1 4 5 6 7 2</merge>

[Update: made the code block cut-and-paste-able. Sorry ’bout that…]