Converting a PS/2 Keyboard to USB

Oops. I seem to have lost the photos. I'll put them back if I find them.

A while ago I found this IBM mini keyboard (P/N 84G2524, FRU 84G2529) with a built-in trackpoint. It is not the best to type on since it is laptop style, but I wanted to give it a try. The problem is that I didn't have the cable that turned the SDL connector to PS/2 connectors and didn't want to spend $15 for a new one.

Top view of keyboard

The PS/2 connector is on the far right. It is an SDL connector which are not easy to find. The mini-DIN is an input for another mouse (since the trackpoint will plug into the computer's PS/2 port). I have no idea what the RJ45 in the middle is for.

Back of keyboard

What I decided to do was internally mount a PS/2 to USB converter. So I went out and bought the cheapest one I could find ($5 at a place that mostly sells satallite TV accessories). Taking the adapter apart was easier then I thought; the rubber cover just peeled right off after a few cuts. I was expecting the have to get out the multimeter to figure out the pinouts, but the board was very well labelled.

Starting to disassemble the adapter More Disassembly Top of adapter board Board Board Bottom of adapter board

Taking the keyboard apart made it obvious the converter would fit on top of the keyboard controller and small wires would eaily run over to the pins on the SDL connector.

Keyboard Insides Adapter board sitting on top of keyboard board

Hooking up the wires was easy with the pinout from [2], but couldn't find the mouse pins. Since there were only 2 pins left I just tried it both ways.

Adapter board with wires added Wiring to the keyboard board

Everything fit together well after adding a notch for the USB cable and adding some glue to hold everything in place.

Finished keybaord insides Installed Back of keyboard with USB cable leaving

After reassembling it it worked great.

Keyboard connected to computer


[1] Great PS/2 keyboard Reference -
[2] After writing this I noticed I am not the first person to have this idea -

Created by Shawn D'Alimonte
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