Author Topic: IBM Model M "Stuck" Keys  (Read 1223 times)

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Offline mt583

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IBM Model M "Stuck" Keys
« on: Sun, 28 June 2020, 16:39:38 »
Recently I've noticed that, when pressing multiple keys on my Model M at once, one of the keys will sometimes continue to register as being pressed even after being released.

You can see what this looks like below:

Any ideas on what causes this or how to fix it?

Offline powwu

  • Posts: 36
  • Location: Massachusetts, USA
Re: IBM Model M "Stuck" Keys
« Reply #1 on: Sun, 28 June 2020, 16:42:08 »
The membrane is likely physically stuck together. You could try cleaning it, that'd probably fix the issue.

Online yui

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Re: IBM Model M "Stuck" Keys
« Reply #2 on: Mon, 29 June 2020, 02:27:59 »
are you using a usb adapter? out of the 3 i have one does that sometimes, when i send to many keys at once it crashes and never sends the key up event to the pc which then get stuck in typematic (keys repeating themselves while held). my experience though was with an Unicomp M122 so maybe a normal M does not have those issues. I mainly got this issue in games but also sometimes when typing and a lot with ctrl being to the stuck key. Changing the adapter resolved my issues.
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Offline Maledicted

  • Posts: 1261
  • Location: Wisconsin, United States
Re: IBM Model M "Stuck" Keys
« Reply #3 on: Mon, 29 June 2020, 12:01:07 »
are you using a usb adapter? out of the 3 i have one does that sometimes, when i send to many keys at once it crashes and never sends the key up event to the pc which then get stuck in typematic (keys repeating themselves while held). my experience though was with an Unicomp M122 so maybe a normal M does not have those issues. I mainly got this issue in games but also sometimes when typing and a lot with ctrl being to the stuck key. Changing the adapter resolved my issues.

Your recent posts on this make me curious about whether or not the M and adapter just need a little more amperage than the port can supply. Have you tried the same adapters with a powered USB hub? I have piles of cheap adapters, since I bought as many variations as I could find to try to test with my beige label Zenith Z-150, and plenty enough old Ms to play with ... but I don't like typing on Model Ms.

Offline funkmon

  • Posts: 250
Re: IBM Model M "Stuck" Keys
« Reply #4 on: Mon, 29 June 2020, 17:08:55 »
are you using a usb adapter? out of the 3 i have one does that sometimes, when i send to many keys at once it crashes and never sends the key up event to the pc which then get stuck in typematic (keys repeating themselves while held). my experience though was with an Unicomp M122 so maybe a normal M does not have those issues. I mainly got this issue in games but also sometimes when typing and a lot with ctrl being to the stuck key. Changing the adapter resolved my issues.

I second this. Though I haven't had this issue with a Model M, I did a long time ago with an older keyboard and a bad PS/2 adapter I used at the office. I switched over to a monoprice one and it worked fine.
« Last Edit: Mon, 29 June 2020, 17:57:50 by funkmon »

Offline Maledicted

  • Posts: 1261
  • Location: Wisconsin, United States
Re: IBM Model M "Stuck" Keys
« Reply #5 on: Mon, 29 June 2020, 17:13:51 »
are you using a usb adapter? out of the 3 i have one does that sometimes, when i send to many keys at once it crashes and never sends the key up event to the pc which then get stuck in typematic (keys repeating themselves while held). my experience though was with an Unicomp M122 so maybe a normal M does not have those issues. I mainly got this issue in games but also sometimes when typing and a lot with ctrl being to the stuck key. Changing the adapter resolved my issues.

I second this. Though I haven't had this issue with a Model M, I did a long time ago with an older keyboard and a bad PS/2 adapter I used at the office. I switched over to a monprice one and it worked fine.

Those Monoprice adapters are literally the only (commercial) ones I have tried that work with the beige label Zeith Z-150 as well. I literally went through every single listing on Amazon (and some on Ebay) that was reasonably priced and bought one of each where the product images looked different. Many ended up being duplicates, but I still ended up with 3 or 4 distinct adapters. Nothing worked until Hasu suggested the Monoprice one, which I had never ordered since all of the old links I had seen to a working adapter were long dead.

TMK sort of works with that board now, but the lock lights still don't.

Offline mt583

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Re: IBM Model M "Stuck" Keys
« Reply #6 on: Tue, 30 June 2020, 02:25:35 »
Thanks for the responses, everyone.

It does seem like this could be a USB adapter issue. Here's the one I've been using, for anyone curious: https://www.amazon.com/UCEC-Mouse-Keyboard-Converter-Cable/dp/B00X9QX9MS/ref=sr_1_2_sspa. Many reviews for that converter say that it worked for Model Ms, so I may want to purchase another (or try a different converter, like the Monoprice one mentioned) and see if that works.

Regarding under-powered USB ports: That shouldn't be an issue if the USB converter is plugged in directly to my computer (not through a USB hub), right?

The membrane is likely physically stuck together. You could try cleaning it, that'd probably fix the issue.

I plan on giving the keyboard a deeper cleaning sometime soon, and I can see if that changes anything. Based on how the board's behaving, though, it seems like this is more likely a USB converter issue.
« Last Edit: Tue, 30 June 2020, 02:29:30 by mt583 »

Offline Maledicted

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  • Location: Wisconsin, United States
Re: IBM Model M "Stuck" Keys
« Reply #7 on: Tue, 30 June 2020, 10:52:26 »
It does seem like this could be a USB adapter issue. Here's the one I've been using, for anyone curious: https://www.amazon.com/UCEC-Mouse-Keyboard-Converter-Cable/dp/B00X9QX9MS/ref=sr_1_2_sspa. Many reviews for that converter say that it worked for Model Ms, so I may want to purchase another (or try a different converter, like the Monoprice one mentioned) and see if that works.

I haven't even seen that exact one yet. I think I have a very similar one with different-colored cable jacketing. If I find it, I should test it with an M

Regarding under-powered USB ports: That shouldn't be an issue if the USB converter is plugged in directly to my computer (not through a USB hub), right?

I have found plenty of onboard USB controllers that were pretty flaky actually, myself. They say the Model M requires more power than most USB, or even ps2 keyboards.

Online yui

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Re: IBM Model M "Stuck" Keys
« Reply #8 on: Wed, 01 July 2020, 00:45:44 »
Regarding under-powered USB ports: That shouldn't be an issue if the USB converter is plugged in directly to my computer (not through a USB hub), right?

I have found plenty of onboard USB controllers that were pretty flaky actually, myself. They say the Model M requires more power than most USB, or even ps2 keyboards.

also some adapters will not negotiate for the full 500mA and will only get 100mA so maybe not quite enough for the M+adapter and then there is motherboards that will not quite adhere to the usb specs like macs with their lack of protection so who knows.
vi vi vi - the roman number of the beast (Plan9 fortune)