Model M Troubleshooting

[sülyek]

Never used a forum before but I have no idea where else to go, the story goes i bought a 1994 Model M off ebay for pretty cheap as it had an obvious but repairable problem: the attached cord was worn out and eventually cut off.
So to try to save a bit I took apart some cheap dell keyboard from the mid-late 2000s and took the cord out, checked for continuity on all of the pins because i knew not to trust the colours, and soldered it to what was left of the Model M.

Well the results were that it would flash the caps/num/scroll lights on boot but went dead immediately after, it also wouldn't do it again unless it was left unplugged for a while so i'd guess it was something to do with the capacitors.

Since it didn't work so I ordered an active PS/2 to USB adapter which had a review about it working with a Model M. Didn't fix anything so I've ordered a new cable from Unicomp and while that might fix the issue I don't have high hopes, I've tried it in both my desktop and laptop, my desktop doesn't detect it in the PS/2 port but they both detect the adapter as a barcode reader.

Is it a problem with the logic board or should I just relax until the cable arrives?

[fohat.digs]

checked for continuity on all of the pins

Depending on what you mean by this, are you certain that you used the right pin out? Sorry, I don't have one on hand to post here.

Also, did you verify that it is a desktop model and not a terminal? If it is a terminal, you will need something like Soarer's Converter.

[sülyek]

Depending on what you mean by this, are you certain that you used the right pin out? Sorry, I don't have one on hand to post here.

It's entirely possible I made a mistake, to avoid making one I went checked each pin with each wire and noted the only one which got a reading for which pin number, and then wired it according to this:
https://geekhack.org/index.php?action=dlattach;topic=84750.0;attach=148690

Also, did you verify that it is a desktop model and not a terminal? If it is a terminal, you will need something like Soarer's Converter.

Don't really know how to check, but this says "either retail products or were distributed with IBM computers"
https://deskthority.net/wiki/IBM_Enhanced_Keyboard#82G2383

[fohat.digs]

wired it according to this

Remember that those diagrams are for the socket, not the plug.

I have never had an 82G but I think that is a conventional desktop unit.

[sülyek]

I think they just sent me a generic off the shelf cable with the same amount of pins:

The cable itself is the wrong colour and shape
The wires inside the cable are different colours from the original
It doesn't have the bend protector on it so i have to somehow cut open the one i have and seal it onto the new one
There's an extra screw ring wire coming off that wasn't on the original
They don't accept returns on cables

I sent the part number for the keyboard and they did not notify me that they were out of stock for that specific type

On the bright side it actually works, even without the USB adapter so I'm using it right now

[Snowdog993]

I think they just sent me a generic off the shelf cable with the same amount of pins:

The cable itself is the wrong colour and shape
The wires inside the cable are different colours from the original
It doesn't have the bend protector on it so i have to somehow cut open the one i have and seal it onto the new one
There's an extra screw ring wire coming off that wasn't on the original
They don't accept returns on cables

I sent the part number for the keyboard and they did not notify me that they were out of stock for that specific type

On the bright side it actually works, even without the USB adapter so I'm using it right now

Relax and wait. You should be fine.

[sülyek]

Relax and wait. You should be fine.

Wait for what?

[Snowdog993]

Relax and wait. You should be fine.

Wait for what?

I tried to follow this thread, and it seems you did get a replacement cable from Unicomp? I was assuming you didn't get the replacement cable yet, but you are using your keyboard. I was confused. I thought you just took a regular PS/2 cable and spliced it into the existing cable and are using that. As long as it works, all is good.

[sülyek]

I was assuming you didn't get the replacement cable yet

I did get it and was describing the issues in the last post

[yui]

most modern M do not have any strain relief on the keyboard side, so pretty normal that your unicomp cable did not come with it.
the extra screw is because some M do have the cable shield tied to the metal backplate of the M, all mine have this, although only one of them is not unicomp.
really who cares about the color of the internal wires, as far as i know IBM did change them a few times, so not that the unicomp would match would be a fit of luck
as for the shape i think unicomp only make straight cables, but there are guides on how to coil a cable though, although for the color i thought there was 2 options, beige and black, maybe check you ordered the right one before complaining.

i think that Unicomp is more of a making it work company rather than making it pretty, so they sent you what would make your keyboard actually work, and they did not do too bad of a job at it given that it does work. if you want it pretty as well i think you need to give them precise instructions.

[sülyek]

maybe check you ordered the right one before complaining.
 if you want it pretty as well i think you need to give them precise instructions.

There was no option to enter instructions other than the part number, which i used

most modern M do not have any strain relief on the keyboard side, so pretty normal that your unicomp cable did not come with it.

As far as I know, all keyboards with attached cables need a way to separate the internal from the external, otherwise this happens, which is the main problem

[Snowdog993]

As far as I know, all keyboards with attached cables need a way to separate the internal from the external, otherwise this happens, which is the main problem
(Attachment Link)

This reminds me of the M13 I got a new cable for. It's a flat cable, not round.
Maybe you needed to specify a flat cable.

[sülyek]

Maybe you needed to specify a flat cable.

That looks like the exact one i needed but like I said, there was no option to add additional information aside from the part no.

this piece was all that was left of the original cable when i got the keyboard, can tell that it has a flat cable

[Snowdog993]

Maybe you needed to specify a flat cable.

That looks like the exact one i needed but like I said, there was no option to add additional information aside from the part no.
(Attachment Link)
this piece was all that was left of the original cable when i got the keyboard, can tell that it has a flat cable

You CAN slice it down the middle and superglue it to your new cable.

[yui]

maybe check you ordered the right one before complaining.
 if you want it pretty as well i think you need to give them precise instructions.

There was no option to enter instructions other than the part number, which i used

most modern M do not have any strain relief on the keyboard side, so pretty normal that your unicomp cable did not come with it.

As far as I know, all keyboards with attached cables need a way to separate the internal from the external, otherwise this happens, which is the main problem
[ Attachment Invalid Or Does Not Exist ]

ok yeah you are missing a part. i did not understand what you meant. and Unicomp sells this part as well, on all of my M it is separate from the cable, and just a piece of plastic that sits there... actually lost it on 2 of the 4...

[Maledicted]

This all seems like a missed opportunity to drill out a big hole on the back of the case and screw a 5-pin DIN socket onto it and use nice beefy HOSA MIDI cables of various lengths with an adapter. I'm going to do that to every single ps/2 board I modify that's not particularly rare/collectable.

[Snowdog993]

This all seems like a missed opportunity to drill out a big hole on the back of the case and screw a 5-pin DIN socket onto it and use nice beefy HOSA MIDI cables of various lengths with an adapter. I'm going to do that to every single ps/2 board I modify that's not particularly rare/collectable.

Uh, not a very good idea. I suppose you can have a little fun tinkering. Just be sure you aren't messing up something of value.

[Maledicted]

This all seems like a missed opportunity to drill out a big hole on the back of the case and screw a 5-pin DIN socket onto it and use nice beefy HOSA MIDI cables of various lengths with an adapter. I'm going to do that to every single ps/2 board I modify that's not particularly rare/collectable.

Uh, not a very good idea. I suppose you can have a little fun tinkering. Just be sure you aren't messing up something of value.

I addressed that in my post. We're talking about a run-of-the-mill 1994 Model M with no removable cable here. I didn't even put a din socket on my F XT when I bought it with no cable, since the case was in good shape. The DC-2014 I converted and my F107 have no permanent modifications to their cases for removable cables. I don't plan on ever separating good Alps switches from perfectly good boards, etc.

[fohat.digs]

a way to separate the internal from the external

The quick and cheap way to do it without permanent modifications, if temporary aesthetics aren't your primary driver, is with a combination of rubber washers, cable ties, and hot glue.

Just make one or more lumps, like the snake that ate 2 rabbits a few minutes apart. Or can just use a simple overhand knot in the cable.