[Keyboard Matrix] Electronics noob needs help

[sixty]

Okay,

I now need the help of someone who actually knows what they are doing/talking about, since I have no clue. I am a total electronics noob, and I assume this question will make me seem really stupid.

Anyway. I have this Amiga 2000 keyboard, that I want to convert to USB with the help of the Aikon controller. So what I did was follow a Korean guide on how to figure out rows and cols with a multimeter. The Amiga keyboard has one main IC chip with 40 pins, so I was able to follow the guide straight along:


*Picture is not the actual Amiga keyboard, taken from OTD.kr guide.

That worked awesome and I had the full board mapped out for rows in like 20 mins, by holding one end of the multimeter to the left (solder side) pin of a switch and then just sliding the other side over the IC until I get a beep from the multimeter. So far so good, full matrix done:


* This is my excel chart of the Amiga 2000 keyboard, numbers are the actual IC pins as shown.

Looking at the picture and what I wrote above you may already see where this is going. I have all the rows, but I'm lacking the cols. Holding the multimeter to the right pin of the switch does absolutely nothing with any of the IC pins. I am assuming this has to do with the diodes that are in the COL circuits, but my electronical knowledge is too low to solve this problem.

So in short: How am I supposed to figure out the cols?

I could do this by bruteforce with a hotwire while the Aikon is connected, but I would rather learn how to do this properly and maybe actually understand it.

[msiegel]

cool progress

i too am a n00b... but if the problem is diodes, wouldn't reversing the multimeter probes work?

i.e., if you were using the red probe on the ic pins, then try using the black one instead.

/star trek physics

[sixty]

i too am a n00b... but if the problem is diodes, wouldn't reversing the multimeter probes work?

i.e., if you were using the red probe on the ic pins, then try using the black one instead.

Tried that already, since all I knew about Diodes was that they block a circuit coming in from one side. However the result was the same, no beep ever.

[msiegel]

hmm, next i'd try visually tracing one of the lines from a switch's right pin to the ic...

does the Matrix Table in here shed any light?

[lowpoly]

The diodes were no problem with decoding my Toshiba keyboard. IIRC I pressed each switch and looked which column connected to which row. More to test but after a short while you recognize the patterns.

[Soarer]

On Cherry switches with the diodes built-in, you'd ignore the two connected pins:



I dunno how close that is to what you're testing...?

[PRISONER 24601]

Good luck Sixty.
The only advice I can give is that melted solder, when applied to bare skin, burns really really bad.

Lord, I wish there was an Aikon controller equivalent that was easy to get ahold of.