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geekhack Community => Keyboards => Topic started by: johnnyric on Sat, 25 October 2014, 14:56:22

Title: IBM Model M2 Pinout?
Post by: johnnyric on Sat, 25 October 2014, 14:56:22

Hello, long time lurker here. After searching this forum for the past few days I fairly certain this has never been asked before. If that is not the case, my apologies in advance. Anyway I recently found an M2 which was missing its PS/2 cable at thrift store for $2.00. Figuring I'd take a chance I picked it up and am now trying to test things out. Keys are all good, springs are in good shape, the board... can't test yet. Here's that the PCB looked like when I took it apart:

(http://i.imgur.com/OHb4Ov9.jpg)

Unicomp sells replacment cables for $15, but I'm hesitant to drop that much if the caps still might be dead. I have another PS/2 cable with known pinouts that I could test this with, but I don't know which pin is which on the M2 board. Is anybody familiar enough with this board to be able to identify the pins? For the sake of clarity, if you do happen to know, let's assume that we're listing left to right looking at it from the angle of the photo I posted (case ground is on the left...)

Title: Re: IBM Model M2 Pinout?
Post by: fohat.digs on Sat, 25 October 2014, 15:38:37

I wish I could help, but I do not have an M2 any more.

Before you buy a cable, make sure that it is for the M2 and is not an ordinary M SDL-to-PS/2 cable.

Title: Re: IBM Model M2 Pinout?
Post by: keyhopper on Sat, 25 October 2014, 20:10:33

Quote from: johnnyric on Sat, 25 October 2014, 14:56:22

[...]  For the sake of clarity, if you do happen to know, let's assume that we're listing left to right looking at it from the angle of the photo I posted (case ground is on the left...)

Here you go:

If these two links are accurate:

       http://sandy55.fc2web.com/keyboard/42h0468.html

       http://geekhack.org/index.php?topic=5065.0

Then the answer would be, from left to right on your photo:

EDIT: this is probably wrong:

       - Clock (black)
       - Data (red)
       - +5V (white)
       - GND (yellow)

But I'm not sure why black and red aren't vcc and gnd. You can make sure by looking at the PCB. GND should be connected to the big gnd plane in the PCB. Also if you find a standard IC on the PCB, you can pull its datasheet from the web and see where vcc and gnd go.


EDIT: Your best bet is to follow the traces in the PCB and deduce Vcc and GND. Clock and data are harder, but I don't think that you'll damage it if you get clock and data mixed up, probably. Don't get VCC and GND wrong or you'll damage something.

Good luck,
Cheers!
.KeyHopper.

Title: Re: IBM Model M2 Pinout?
Post by: keyhopper on Sat, 25 October 2014, 21:25:00

Previous post edited to reflect doubts on the pinout.

Cheers

Title: Re: IBM Model M2 Pinout?
Post by: johnnyric on Sun, 26 October 2014, 09:47:55

Still, thanks for the response and the info, it's a starting point if nothing else!