Posted by Sasquatch! on 15, 2000 at 4:15 PM:
In Reply to: does every keyboard have flimsy attached to the pcb with brackets. posted by charlie on 14, 2000 at 10:07 PM:
Charlie,
Actually, some of your old keyboards have little microswtiches underneath each key. If you can find one, your job will be alot easier. Most modern keyboards do have little PCB's in them though.
What you'll want to do is solder your wires right to the contact points on the PCB itself. It's kind of hard to describe, but there's a really good article on in here on this website with pictures. The web-format is at:
http://www.arcadecontrols.com/arcade_joyofjoys.htm
and if you want to download it in MS Word format it's at:
http://www.arcadecontrols.speedhost.com/JoyOJoys.zip .
"The matrix" is just the way that the "intersections" of the keys on the keyboard are. On the keyboard PCB, there will be two separate groups of pins, What you'll have to do is trace out the contact points on the clear plastic sheets that are in the keyboard, and see which contacts on the PCB they connect to.
In other words, take the letter "A" on the keyboard. After taking the keyboard apart, you'll see the clear plastic sheets underneath the keys; there will be little contact paths that run all over the sheets, okay? In this example, there will be two contact paths coming from the spot directly underneath the "A" key. You'll have to follow those paths back to the PCB and see which two pins they connect to. So...when those two pins get "crossed", the PCB will send the "A" character to the keyboard. The whole principle behind a "matrix" is that the keys on the keyboard don't have their own solder points; all of the keys share certain solder points on the PCB that's inside the keyboard.
So the big question that you have in front of you is "Which keys connect to which pins on the PCB?" And unfortunately, no one here can tell you, because every keyboard is different. You'll have to find out yourself. Or, in other words, "Unfortunately, no one can be told what the matrix is...you have to see it for yourself."
By the way, since you're going into this keyboard hack thing totally blind, I would say that you might want to just plunk down the money on an IPAC...I believe that they're under $50 these days. Of course, if money is tight, the keyboard hack is the cheapest way to go...it's just also the most difficult.