Author Topic: Installing PS/2 cable next to a SDL port on a Model M...  (Read 3716 times)

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Offline Ethaniel

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Installing PS/2 cable next to a SDL port on a Model M...
« on: Sat, 01 March 2014, 03:56:14 »
Greetings everyone,

I'm having problems finding SDL cables for my Model M's. Recycling centers are dry, and buying them online is not an option down here at the moment (customs must rot in hell, etc. etc.). So, I've been studying one of the controller boards, and saw this "J2" port/connector/thingie. Looking at the back of the controller, it seems that J2 is connected to J1. Now, the question: Can I solder a pin header or something similar on J2 to bypass the SDL port and connect a standard PS/2 cable from another keyboard? I have a few vintage PS/2 cables that would look great on a Model M. I assume I'll have to drill a hole next to the SDL port, but I can live with that. I have the SDL pinout from KbdBabel, so tracing each dot shouldn't be an issue... I hope...

P.S.: I've tried half a dozen searches and nothing came up on the forum. If this has been asked before, I apologize.

Offline fohat.digs

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Re: Installing PS/2 cable next to a SDL port on a Model M...
« Reply #1 on: Sat, 01 March 2014, 09:09:52 »
That seems reasonable.

I have never tried it, but please let us know if it works.
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Offline dorkvader

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Re: Installing PS/2 cable next to a SDL port on a Model M...
« Reply #2 on: Sat, 01 March 2014, 11:31:53 »
It should work. One thing to be cautions of (other than getting the proper pinout) is to ensure that the second pin from the left in your second image actually goes to the farmost right pins of the SDL. They both appear to be ground, but I dont see any direct continuity between them in the image.

edit: no, nevermind it's there. JP1 connects them. You should be good. Be careful not to reverse power and ground.
Also, I don't know about SDL cables, but you can get SDL connectors online. TE connectivity still makes them (and it appears that IBM POS keyboards still use them). The part number is 1-520424-2 and I think onlinecomponents still has stock. You don't need the rest of the metal housing or the ferrule as long as you glue the cable properly.

I have a straight IBM cable that appears to have been made by orihalcon that was done this way. Category 6 cable was used and just the SDL plug was on the end. It was superglued in place and works very well.
« Last Edit: Sat, 01 March 2014, 11:35:57 by dorkvader »

Offline Ethaniel

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Re: Installing PS/2 cable next to a SDL port on a Model M...
« Reply #3 on: Sat, 01 March 2014, 17:44:10 »
So, if I use the SDL pinout from KbdBabel, and combine that info with some multimeter tests, I get the projected pinout on the last image (please check it, all corrections are welcome). One thing: "1" should be floating just like "6", but there's two bridges connecting it to GND. If the pin on the SDL cable is floating, that shouldn't be a problem... but I'm tempted to cut those bridges with an X-Acto knife or similar, just in case. Now I need to find a pin header small enough to fit there. I guess I'll butcher an old sound card or something, standard pin headers are too big.

I would love to buy those connectors, and SDL cables as well, but we have a bit of a nuclear war with customs down here. I'm still waiting for two Teensy clones I bought in november, and I'm receiving packages with a delay of 100 days or more. It's a nightmare.