This page describes how to upgrade a PS/2 IBM Model-M keyboard to USB. I only tried this on the 84 key space-saver model, so things might not fit on other types of keyboards.
A better solution would be to use a client-side USB connector on the keyboard, so a regular cable can be used. Since I didn't have one of those connectors lying around, I decided to use the host-side plug from the converter.
You might break things while doing this and I might have made errors in this document, so try this at your own risk only!
click on the pictures for a larger view.
|The IBM keyboard has a PS/2 interface, which is not available on most modern computers. to be able to use PS/2 keyboards with USB, clickeykeyboards.com offers nice and small converters. They have put some work in testing a lot of different brands and types of convertes, and these seem to do the job well.|
Open the keyboard by releasing the two screws on the back. You need a
7/32" nut driver for this, or small pliers. Open the PS2/USB converter by
cracking open the casing with a small screwdriver. Disconnect the keyboard from
the controller PCB by gently pulling out the flatcables.
Desolder the PS/2 connector from both the keyboard and the converter. Using litz wire can make things easier.
Now connect the converter to the keyboard as shown on the photograph and
diagram. These four wires replace the original curly PS/2 cable.
If you have the tools (multimeter), confirm if the wiring is actually corresponding to this drawing.
Red: VCC +5v Blue: GND Yellow: PS/2 Clock Green: PS/2 Data
|The PS2/USB converter fits nicely on the location of the IBM PS/2 connector that was removed earlier. With some creative soldering, it can be secured to the ground connector and 2 holes in the PCB to hold it in place.|
Saw, cut or file a small piece of plastic to cover the hole and let the USB
connector peek out of the original hole of the IBM connector on the back.
Put the PCB back in place and close the keyboard.
If the soldering work is not strong enough to hold the converter in place, glueing the plastic cover to the keyboard housing can provide extra support. This will make it hard to remove the PCB in the future, though.
here's another photoshoot of a Model-M being upgraded by Chris Lee