IBM model M spacebar thing

[nathanscribe]

Hello all, first post from a recent convert to the IBM clicky keyboard.  I've been using an old BT (British Telecom) keyboard for a few years that is better than the regular cheap rubber dome keys, but the buckling-spring IBM I recently bought is better still - money well spent, I think.

I am posting here because I read a lot about various M keyboard before buying, and also about cleaning them.  My keyboard wasn't too filthy, but dirty enough to warrant a wash.  I tested some mild detergent solution on some lesser-used keys and everything seemed fine, so I've been pulling the caps off and soaking them and it's come up a treat.

My question really is about the space bar.  The particular issue is something I've not seen mentioned or illustrated anywhere, so I thought I'd ask.

Beneath the space bar, before removing it, I noticed what looked like solder-removal braid - a stretch of mesh-like wire.  I tried to pull it out with tweezers but it was stuck.  On removing more caps for cleaning, and then the space bar itself, I realised the braid was attached to a clip that attached to the space bar.  Here's a photo:



I managed to fray a little of the wire while attempting (wrongly) to tweeze it, but it's not badly damaged.  Can anybody explain what it is?  I can't see any obvious purpose.

For further info, if needed, here's the label on the back of the keyboard:

[ch_123]

All Greenock (i.e. UK made) Model Ms had that bizarre contraption, with one end slotted on to the space bar, the other end on to the keyboard's internal assembly. The general consensus around here is that it's some sort of grounding element, although no one is really sure how or what it is grounding. It doesn't appear on any of the Model Ms made in the US or Mexico, so it's quite possibly something that was required to meet UK electrical safety regulations, which can be a bit arbitrary at the best of times.

[Half-Saint]

Ground wire. You should be able to remove the clip without much trouble just leave the wire attached

Cheers

[nathanscribe]

Wow, that was quick.  Thanks!

I'd suspected it was something like that.  I'll leave it in place, at least till I can get the body apart.

PS, sorry about the huge pics...

[Findecanor]

The KeyTronic "Ergoforce" keyboards from the '90s also had a space bar connected to ground. That space bar was grey and speckled with a lightning bolt symbol on it, as I recall.

[Half-Saint]

Well the money has to come from somewhere!

[dz_alias]

It's supposed to provide extra weight to the spacebar while simultaneously increasing resistance on the up and down stroke. To the layman it'd go by unnoticed, but if you're typing 400wpm here like some of us, it's a godsend.



Just kidding. Find out where it goes and either desolder it or snip it off or set it on fire. It's unnecessary. I'm pretty sure keycaps don't conduct electricity, and no one's died from 5V before either.

[Rusty Rat]

Ground wire. You should be able to remove the clip without much trouble just leave the wire attached :

Some Keytronics had a grounded spacebar and 3M even made a stick on strip version for spacebars. Even if the spacebar was not conductive there would still be some induction into the ground cable. We are not talking 5 volts here but the thousands of volts of static electricity that can build up on the user.  A local discharge would cause an RF spike which could knock down a local machine.

Trivia - some IBM PS2 models had an additional copper paint layer inside the steel chassis as a better RF shield.

For Ripster, the UK ones had the ground cords because UK typists could type four times faster than Americans and thus built up more static. This was because English was their first language.

[ch_123]

Well, it was all the keyboards made by Greenock, including the ones they made for the US market...

[nathanscribe]

Just for added info, if it's useful: I read about some M models being incompatible with some KVM units - I'm using the above keyboard with a NewLink KVM bought from Rapid here in the UK, and so far it's fine.

[dz_alias]

Some Keytronics had a grounded spacebar and 3M even made a stick on strip version for spacebars. Even if the spacebar was not conductive there would still be some induction into the ground cable. We are not talking 5 volts here but the thousands of volts of static electricity that can build up on the user. . A local discharge would cause an RF spike which could knock down a local machine.

Trivia - some IBM PS2 models had an additional copper paint layer inside the steel chassis as a better RF shield.

For Ripster, the UK ones had the ground cords because UK typists could type four times faster than Americans and thus built up more static. This was because English was their first language.

Could this possibly damage the keyboard?

Because a day after reading this, this happened.

1. Touched keyboard (home row and space bar).
2. Computer shuts off immediately.
3. Keyboard now acts strangely.

My left arrow key and z key are tied together. So if I press one, both are sent to the operating system. The same goes for . and my right arrow key (unless num-lock is on, in which case it's backspace and right arrow key), and - and my down arrow key.

I've tried power cycling my computer, other keyboards, and running the keyboard through a PS/2 to USB converter. It's definitely the keyboard.

[ch_123]

What sort of keyboard was this?

[dz_alias]

What sort of keyboard was this?

IBM KPD8923

That wasn't the problem though. It might be why my system died, but the reason it was acting funny was a misaligned membrane <_>.