Keyboard on the Apple Lisa

[compu_85]

Here's a design you don't see anymore. Let's look at the insides of the keyboard of the Apple Lisa



The keyboard is made by KeyTronic. They used this same design for the original Compaq Portable keyboard (The Compaq Portable was the first Compaq ever)

The keys are mounted on sliders on a metal frame. Springs push the keys back up.



The PCB is attached to the backs of the slider assemblies with very small screws. Take care not to strip them!



Like the original XT keyboard, this uses capacitive resistance. You can actually trigger the switches by touching them.



The switches have a plastic disk clicked into the catches on the bottom of the slider. Glued to the disk is some foam, then a circle of foily plastic.



Problem is, the foam degrades Here's a comparison between a new good foam contact, and one that has degraded:



And after pushing it down:



You can guess how well those worked

Here's the KeyTronic PN:



The connector to the machine is a stereo 1/4" audio jack! (IE, has 3 terminals on it)

-Jason

[AlphaKilo470]

I once owned a circa 1987 (or sometime around then) Compaq Portable III luggable computer and after it dies I disscected everything (including keyboard) and it used those same exact foam pads with the metal sheet on the bottom.