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geekhack Community => Keyboards => Topic started by: Chevy_Monsenhor on Thu, 29 March 2018, 11:29:25

Title: Alternative attached cable for the IBM Model M?
Post by: Chevy_Monsenhor on Thu, 29 March 2018, 11:29:25
About two months bought this pair of Model Ms for dirt cheap, an ABNT PS2 model (P/N: 61G3974) and an ANSI Terminal RJ45 model (P/N: 64F7681).
Both are pretty clean on the outside (besides a few minor dings on the cases), both have very well kept keycaps, but both have their fair share of problems.
I'll start with the terminal model, despite looking the best overall, it has a dry rotted barrel frame (the plastic part where the spring assemblies poke out of) and it has to be converted from RJ45>PS2 which is already a pain in the neck. I set this one asside, drilled the plate and scavenged the springs and assemblies from it.
The other one is the ABNT PS2 model, i can't even begin to say how much i love this one! Its my favorite layout (i'm brazilian), the case is in ok shape, bottom plate is great shape, barrel frame is great shape and it works 100%, problem is, the attached cable from it is knackered and while it works, it has lost its entire shielding as well as the ground cable. I'm planning on bolt modding it to prevent further deterioration, as well as changing some of the springs while i'm at it (pause, F1, l-alt and num-pad enter have stretched springs).
Continuing on the cable, while i'm well aware Unicomp still sell attached cables for it, thing is, it costs US$30 just to ship the cable over to Brazil, which is frankly unreasonable and inconvenient since i'd have to wait at least 3 months for it to arrive.
So i was thinking, can i scavenge the cable from another keyboard, like a rubber dome IBM/Lenovo/Dell/HP PS2 keyboard? It would be much easier and cheaper to do it this way, since a keyboard like that costs US$5 shipped over here.
I attached a picture of the connector from my M so you guys can take a closer look and tell me if such thing is possible.
Title: Re: Alternative attached cable for the IBM Model M?
Post by: E TwentyNine on Thu, 29 March 2018, 11:48:37
Any standard ps/2 cable will work.  You may need to splice the wires if you can't fit them into that connector, but it'll work.
Title: Re: Alternative attached cable for the IBM Model M?
Post by: fohat.digs on Thu, 29 March 2018, 11:52:41
Yes, you can use almost any cable if you figure out which wires are connected (never trust colors!).

Unicomp will sell you a new barrel plate (they refer to barrels as "chimneys") if that is all you need to make the other one work.

If you are comfortable with wiring, you might get Teensys and install them internally and then have USB cables.

With Soarer's firmware, that would also do the terminal conversion and allow you to program them any way that you wish.
Title: Re: Alternative attached cable for the IBM Model M?
Post by: Chevy_Monsenhor on Thu, 29 March 2018, 14:56:50
Any standard ps/2 cable will work.  You may need to splice the wires if you can't fit them into that connector, but it'll work.

Looked around to see if i could find anything in my stash of unused things here at the job, found a PS2 mouse that has that same conector but the pinout at the end of the cable doesn't match, if i find the cable that has the right pinouts with the wrong connector, i can steal the connector from this mouse.
Title: Re: Alternative attached cable for the IBM Model M?
Post by: Chevy_Monsenhor on Thu, 29 March 2018, 15:03:34
Yes, you can use almost any cable if you figure out which wires are connected (never trust colors!).

Unicomp will sell you a new barrel plate (they refer to barrels as "chimneys") if that is all you need to make the other one work.

If you are comfortable with wiring, you might get Teensys and install them internally and then have USB cables.

With Soarer's firmware, that would also do the terminal conversion and allow you to program them any way that you wish.

That is a great idea! I was thinking about that the other day, the only thing that keeps me from doing the conversion is the lack of hardware, i'll have to buy the soldering iron and the rest (that i need anyway, i have a lot of pendent projects due to the lack of a soldering iron) but i already got a bit of experience with soldering things, so it should be smooth sailing when i get around doing it.
I also spoke with Unicomp about the barrel plates a few weeks ago, US$10 a piece which is not a bad price, its just the price of the shipping that kills it. Eventually i'll get around fixing that one as well, it also needs a few more springs (two are missing and some are stretched, not a big deal) which shouldn't be a big issue.
Title: Re: Alternative attached cable for the IBM Model M?
Post by: fohat.digs on Thu, 29 March 2018, 17:55:56

found a PS2 mouse that has that same conector but the pinout at the end of the cable doesn't match,


I think that a mouse has only 3 hot wires, and a keyboard needs 4: Data, Clock, Power, and Ground.

Unicomp is good about combining shipping, and you might buy some replacement caps and miscellaneous gear (RGB sets are nice and tasteful).
Title: Re: Alternative attached cable for the IBM Model M?
Post by: Chevy_Monsenhor on Fri, 30 March 2018, 12:55:47

found a PS2 mouse that has that same conector but the pinout at the end of the cable doesn't match,


I think that a mouse has only 3 hot wires, and a keyboard needs 4: Data, Clock, Power, and Ground.

Unicomp is good about combining shipping, and you might buy some replacement caps and miscellaneous gear (RGB sets are nice and tasteful).

The one i found does have 4 wires and the same internal connector, but they are wired different at the connector end. I stole the connector from it, should the donnor keyboard have a different connector.
Title: Re: Alternative attached cable for the IBM Model M?
Post by: Chevy_Monsenhor on Tue, 03 April 2018, 14:15:47
Got a donor IBM Preferred keyboard with a pretty thick and decent cable for my M, but yet i had no luck finding out which wire communicated with which pin because i have no multimeter around to test continuity. I guess i'll try it again when my multimeter arrives...
Title: Re: Alternative attached cable for the IBM Model M?
Post by: fohat.digs on Tue, 03 April 2018, 16:25:37

i have no multimeter around to test continuity.


You can make a continuity checker with a battery, a light bulb, and 3 pieces of wire. Attach 2 wire to the battery terminals with tape, and 2 to the bulb (1 common and 1 separate). Use the 2 loose ends between battery and bulb to connect to the points you are testing.

When you have a complete circuit, the bulb will light.
Title: Re: Alternative attached cable for the IBM Model M?
Post by: Chevy_Monsenhor on Tue, 03 April 2018, 18:41:56
Thanks a lot for the tip! I would never think about doing that lol, gonna try it out latter...
Title: Re: Alternative attached cable for the IBM Model M?
Post by: Chevy_Monsenhor on Mon, 16 April 2018, 08:44:58
Would it be too much of a heresy to solder the wires directly to the controller?
I can't find a damn soul that will crimp me those dupont pins that go inside the JST connector...