The Thinkpad Keyboard Ribbon Cable Connectors

Today was the day to solder jumpers onto the ribbon cable connectors for the Thinkpad keyboard. I was very fortunate to have friends over who were also working on electronics-related projects: I borrowed a small vice to hold the connectors while I soldered, a "third hand" (alligator clips mounted on a heavy base to hold things) and - probably most importantly - a Hakko soldering station. I have an old Weller SP-23 soldering iron: it works for basic stuff, but for the fine work it turned out I needed something significantly better, and the Hakko was a wonder.

Which isn't to say that this was easy. Soldering jumper wires onto metal pads that are intended to be soldered to a board rather than to a wire is tricky. When the pads are 1mm apart, it requires a LOT of patience and care. The slightest glob of solder and you're getting out the solder wick and redoing the joint because you've created a short. But it got done in the end ... (about six hours work?)

photo: The slow and precise work of soldering jumpers to pins on 1mm centres

soldering jumpers on alternate sides of a connector with very narrow centres

photo: The keyboard with all three modified ribbon cable connectors attached

The Thinkpad keyboard with the three ribbon cable connectors, each with jumper wires sticking off in all directions

The next step is to trace the entire keyboard matrix, which will take several hours of work: essentially you connect a continuity tester to two jumper wires, and then press every single key on the keyboard until you get a short. Then you carefully record the key and the two ribbon numbers, move to the next jumper wire, and repeat. For a grid of roughly 12x18.