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New Project: Restoring a CH Products DT225 Trackball

In late 2011, I was struck by a fantastic idea: using a second CH Products DT225 trackball for scrolling. I already owned a DT225 with a USB connector and had configured it such that it could perform scrolling on Linux. But having to press the top right button with my right ring finger every time I scrolled was taking its toll on my wrist.

What if I could use a similarly large trackball to scroll with my left wrist instead? With this setup, I would move the cursor with my right hand and scroll with my left.

Coincidentally, a used DT225 with a PS/2 connector became available on eBay, and I purchased it for a good (i.e., low) price. The advantage of having two different connectors was that my Linux box recognize them as two different devices. This made configuration extremely easy—essentially following the steps here.

In /usr/share/X11/xorg.conf.d/10-evdev.conf, I added the following lines:

#       - - - CH Products DT225 Trackball Settings - - -
#       - - - - - by bootstrap (geekhack.org) - - - - - - 
#       To help readers understand the configuration better, a CH Products DT225 
#       trackball has buttons labeled as follows:
#       A (left-large), B (left-small), C (right-large), D (right-small). 
#       Usage: A=normal-click  B=Back C=right-click D=Forward 
#       Press button D (hold button while rolling trackball) to emulate 
#       wheel-scrolling. 
#       The trackball can scroll in two-axes, unlike a typical wheel mouse. 
#       Adjust the settings to constrain the scroll action to vertical-axis-only 
#       if you prefer. 
Section "InputClass"
Identifier  "Mouse1"
MatchProduct "Composite USB PS2 Converter USB to PS2 Adaptor"
MatchIsPointer "on"
MatchDevicePath "/dev/input/event*"
Driver "evdev"
#       Physical button labels:     A B C - - - - D (- = no button)
Option "ButtonMapping"     "1 8 3 4 5 6 7 2"
#       EmulateWheel refers to emulating a mouse wheel using trackball.
Option "EmulateWheel" "true"
Option "EmulateWheelButton" "0"
Option "ZAxisMapping" "4 5"
Option "XAxisMapping" "6 7" # Disable this for vertical-only scrolling.

At the time I purchased the second DT225, I wasn’t sure if my plan would work or if using a second trackball for scrolling only would be a longstanding solution.

Well, it’s been more than 8 months and I’m still using two trackballs on both sides of my keyboard—left and right. Occasionally, I scroll with my right trackball by pressing the top right button out of habit but overall using the left trackball for scrolling has done wonders for my right wrist pain.

However, there is one problem with the left trackball. It’s more a cosmetic issue, rather than a functional one. You see, the “used” DT225 I acquired was really “used” with some fairly deep scratches at some spots.

New Project: Restoring a CH Products DT225 Trackball

New Project: Restoring a CH Products DT225 Trackball

New Project: Restoring a CH Products DT225 Trackball

The left side of the device remains in very good condition:

New Project: Restoring a CH Products DT225 Trackball

The back of the device had residue of some sticky tape. Removing this should not be a problem.

New Project: Restoring a CH Products DT225 Trackball

New Project: Restoring a CH Products DT225 Trackball

In addition, the cable was probably rolled over on a rough surface (possibly gravel).

New Project: Restoring a CH Products DT225 Trackball

I had the option of replacing the trackball but the issues were:

  • Finding a DT225 trackball with a PS/2 connector;
  • Spending an additional $120 or so to replace a perfectly functional trackball; and
  • Fixing the cosmetics of the current trackball.

As it was a cosmetic issue, I’ve been dragging my feet over the matter. However, on my most recent trip to Singapore, I found a few extra hours for myself (as opposed to business) and was fortunate to come across a hobby shop that specialises in plastic models. I purchased two items that would probably fix the cosmetics of the trackball:

1. Tamiya Epoxy Putty

New Project: Restoring a CH Products DT225 Trackball

This will be used to fill up the defects.

2. Humbrol Maskol

PhotoNew Project: Restoring a CH Products DT225 Trackballucket

This will be used to cover the DT225 sticker on the top of the device when I paint it.

I also purchased a can of Krylon Fusion for Plastic spray paint in Satin Almond, which is close enough to the original colour of the trackball.

New Project: Restoring a CH Products DT225 Trackball

I already had a full can of Krylon Fusion for Plastic in Flat Black—I’ll use this on the cable.

Here’s the plan:

  1. Fill up all the scratches on the DT225 with the epoxy putty.
  2. Fill up all the scratches and other defects on the cable with the epoxy putty.
  3. Sand the surfaces of the DT225 and its cable.
  4. Cover the sticker on the DT225 with Humbrol Maskol.
  5. Paint the case in Satin Almond.
  6. Paint the cable in Flat Black.

After what I went through with the Model F, this job should be a walk in the park.

{ 12 comments… add one }
  • DT225User December 7, 2012, 1:00 PM


    I, too, am restoring a DT-225. Mine is serial and came off of a lathe. Unfortunately the serial connector was removed when I bought it and I haven’t been able to figure out which wire goes to which pin in the connector. I’ve managed to get the buttons working, but the ball does nothing.

    By any chance, would you have any tips as to which color wire goes to which pin on the serial connector?


    • Andy Teh December 7, 2012, 1:14 PM

      @DT225User—I could open one of my DT225s that has a serial connector (I have three DT225 trackballs in total—USB, PS/2, and serial) and take a photo of the cables and pins. I should be able to do this on the weekend.

  • DT225User December 7, 2012, 1:15 PM

    Thank you. That would be very helpful.

    • Andy Teh December 8, 2012, 3:28 PM

      @DT225User—I have taken some photos of my DT225 trackball with a serial connector. It’s quite dirty but it works as expected. In particular, the internal parts look good. The coloured cables and pins are probably what you are most interested in. I also took a close-up shot of the cables for good measure. Hope these photos help you to get your DT225 trackball working. If you are still running into issues, feel free to drop a note here.

      • DT225User December 13, 2012, 12:56 AM

        Thank you for taking the time to snap the photos, Andy. I still haven’t had any luck getting the dt225 working, but I’ll keep trying. The connector inside the unit is correct; the colors match yours. The problem is that the serial connector at the other end of the cord was missing when I’d purchased the unit. I wired the cord into a standard serial connector, and after trial and error, got the buttons working, however, ball movement is not being tracked.

        I’d assumed that the trackball was serial up to this point, but it may wind up being a Sun compatible.

        • Andy Teh December 13, 2012, 1:50 AM

          @DT225User—I’m sorry I don’t know which pin of the serial connector the coloured wires lead to. I’ve just had a look at the serial connector again and I can’t see any way to open it without doing permanent damage.

          • DT225User December 13, 2012, 6:05 AM

            Hi, Andy.

            Perhaps you could disconnect the internal plug and use a circuit tester to individually test and match each wire its corresponding pin on the serial connector? Here’s a picture of the circuit tester I have in mind: “http://www.allproducts.com/tool/three-in-one/24-ground_circuit_tester-l.jpg”.

  • Andy Teh December 13, 2012, 2:16 PM

    @DT225User—I don’t have access to a circuit tester, so I would have to buy one. A decent circuit tester costs the equivalent of about US$17 if I purchase one locally. For that amount, and probably less (I’ve got to check), I could sell and ship you this DT225, which has the serial connector, minus the ball (to reduce the weight of the package, and your trackball is probably in much better condition). I have no need for this DT225 because I already have two, and I certainly don’t see myself using a circuit tester for any other purpose in the future.

    • DT225User December 14, 2012, 12:48 AM

      Thanks, Andy. I’d be interested in buying the DT225 from you. Can you see the e-mail I’ve entered for these posts? If so, drop me a line and I’ll give/get more information for the sale.

      Thanks again for the help.

      • Andy Teh December 14, 2012, 2:11 PM

        @DT225User—I’ve sent you an e-mail. I’ll get a shipping quote within the next day or two and let you know the total amount—without the ball, it should be quite nominal.

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