Mouse repair

Copyright Ian Stedman, 4th May 2004.


 This document details common methods of repairing Amiga computer mice, with particular emphasis on the Wizard Developments, Wizard Mouse.


Common faults & their solution

Mouse will not in one axis!?
Probable cause: A broken wire in the mouse lead. The easiest solution is to cut the lead 5 cm from the mouse (thus removing the bad cable) and then strip and solder the wires into the mouse. Observe the colour code.

Mouse movement is jerky?
Probably as simple a task as cleaning the pinch rollers of the mouse. You can use your finger nail to do this. The other, less likely option is that dust has gotten into the optical encoder wheel. To clean this you will need to disassemble the mouse and clean the wheel, simply by blowing it.

A mouse button does not work?

There are two possible causes, a failed micro switch or a mechanical issue.
Sometimes, there is a piece of plastic that connects from the mouse button to the miroswitch, this can break. You will soon find out if this is the case when you open the mouse, a bit of plastic will fall out!

To test if the micro switch has gone, remove the top of your mouse (as shown later) and plug it in to your Amiga. Try depressing the micro switch directly and does it now work?
If it does not work, you need a new micro switch!
Replacements are available from good electronic component suppliers, RS, Farnell, Digikey, Rapid and many more.


A case study, disassembly of a Wizard developments mouse

 A picture says a thousand words, so let me add a few pictures and type less!
Whilst this section concentrates on a particular mouse, the information is relevant to any make, especially the drawings/schematic shown later.

I disassembled one of my Wizard mice a while ago just so that I could write this article, it was and still is, working fine.

The mouse I took apart.
Turn it over and remove the PTFE covers on the screws to undo the case.

Carefully unclip the case at the rear and the front.

The PCB is held in place by the two plastic lugs near the bottom of the photo.
The ball assembly/optical wheels are still in place, in this mouse they simply slide out.
The three black micro switches from left to right are amazingly, LMB, MMB and RMB!

One useful check I did like this was to connect the mouse to the Amiga and check the infra-red LEDs work fine. How did I see the infra-red LEDs?

I used my digital camera!

The four glowing white things are the infra-red LEDs, as seen by my digital camera’s CCD array.

For completeness, here is the underside of the PCB, not much to see!

The final part, a schematic of the mouse!
I reverse engineered this schematic and the colour coding of the cable, useful if you have to repair a cable.
There may be errors or omissions so use at your own risk!

Well that’s it for now.

By Ian Stedman.