A geek and his keyboard

Simply accepting the death of one keyboard and the failure of its backup was simply not an option, so I started off this morning with my trusty screwdriver.

I opened up the bottom of the dead keyboard and studied its innards. From top to bottom the keyboard consists of:

1. keys
2. translucent rubber layer
3. flexible transparent layer with printed circuit
4. flexible transparent buffer layer with no circuit
5. flexible transparent layer with printed circuit
6. 3 large white plastic structural pieces
7. 1 PCB

Given the simple structure it is apparent that the PCB is the failing component of the backup keyboard. The PCB design and rev number differ between the two keyboards, but I thought swapping them out would be worth a shot. Fortunately the physical structure of both keyboards is identical. Unfortunately swapping them didn’t work and examining the circuit layers (#3) it’s obvious why: they changed the circuit layout to the PCB.

I went with Plan B which was determining why those specific keys on the dead keyboard were dead. One look at layer #3 confirmed that all the dead keys are on the same circuit. Bringing out my trusty multimeter I discovered a break in the circuit to the PCB. But how to fix that? The transparent circuit layers are on a plastic layer so even if I had my soldering iron here in Denver, there was no way that was going to work. The dead gap wasn’t all that large, just a couple of millimeters, I just needed something to bridge it. A small piece of wire wasn’t optimal as it wouldn’t be flat and it would be hard to secure. Then the light bulb went off: aluminum foil. Conductive, easily trimmed down to the right size, and flat. Throw in a small piece of scotch tape and a few minutes later I have my first hardhack:

And thus far it works beautifully. As a bonus I moved layers #3-5 and #7 to the shell of the backup keyboard so I get the pearly white keys of the backup with the tried-and-true workings of the original.

I’m a bit concerned that the failure of that one circuit is simply a foreshadowing of things to come with different circuits. By the looks of the backup keyboard’s circuits it’s clear that the degradation isn’t from use but with age (which makes perfect sense anyway). We’ll see how long my hardhack works and if there are future failures elsewhere. Who knows, by the time I’m through maybe I’ll have a completely rebuilt keyboard full of aluminum foil.