IBM Model M Problem with space bar

Emre0172 · 20 Jun 2015, 01:33

Couple days ago I bought a model M from somebody. I knew it's spacebar didn't work, but I thought I'd be able to fix it anyway..

So here is a picture:

The problem;
I have to press really hard on the spacebar for it to register. I really have to put force on it, let's just say it's not possible to type properly.

In the picture you can see the end of the spring is messed up, but I don't think this is the problem. The spring is also a little longer because I stretched it while trying to fix the end.

But I don't think the spring is the problem.. It doesn't click. When I slowly press the spacebar I can only feel this VERY little resistance where there is supposed to be a click. So I assume the mechanism inside is broken?

Another thing, whats that cable thing with the metal plate on the end? I bought it like this and have no idea what it is. Is it related to the spacebar problem?

It's an IBM Model M 1396790

I assume it's going be a pain to fix.. I'd want to do it but I have no equipment for drilling or soldering.

What should I do?
I can take more picture if you tell me.

Thanks

edit: Is this the richt place?;_;

Muirium · 20 Jun 2015, 02:00

The spring *is* the mechanism.

So you have in fact identified the problem. It's that damn spring. It needs replaced, not chopped or stretched or fiddled about with. Which means you need to master the chopstick trick.

As for the metal clip, that's to earth the spacebar. It should be clipped onto a plastic ridge that lies inside the spacebar. Most Model Ms don't bother, but I've got a couple with it.

Redmaus · 20 Jun 2015, 02:01

First up that spring is a problem. You need to fix that buddy.

You can do some chopstick trick like mu said to avoid taking the whole kb apart and swap just the spring.

Next up, do you have a stabilizer wire for your spacebar? That might be why it is so hard to press. I think the wire thing could be it, but its hard to tell.

You should probably post a pic of your spacebar to make it easier for us.

wheybags · 20 Jun 2015, 02:54

(btw you can get a replacement spring here: http://www.pckeyboard.com/page/Misc/PVPLASM)
Comes with the pivot plate, but you can just pull it off

Muirium · 20 Jun 2015, 03:15

Or if you want to be cheap, you can swap with one of the keys you never use. You know, in the meantime…

Emre0172 · 20 Jun 2015, 03:39

Alright,

here is what I did with the little cable, hope I did it right. It's not the main problem tho:
https://dl.pushbulletusercontent.com/gC ... 025122.jpg

I removed the spring with the chopstick method, it felt satisfying when it came off;_;:
https://dl.pushbulletusercontent.com/xp ... 030126.jpg

Then, I took the spring from the numpad "-"-key and put in the spacebar spot:
https://dl.pushbulletusercontent.com/66 ... 030752.jpg
I did this before Muirium recommended it, therefore I give him no credit <3

**At this point I wanted to say that it still doesn't work, but as I was typing this on my other keyboard, I tried to put the spacebar on once again and it worked. Holy shit.

Thank you all!

By the way: I know the keyboard looks filthy, I'm going to make it look very pretty soon <3 Exams go first tho, or do they?

Muirium · 20 Jun 2015, 03:42

Tada. I never discovered any of those things either. Spreading knowledge like this is what DT's all about!

Redmaus · 20 Jun 2015, 03:49

Muirium wrote: ↑Tada. I never discovered any of those things either. Spreading knowledge like this is what DT's all about!

Too bad we are all too lazy to actually document all the knowledge in the wiki most of the time

Muirium · 20 Jun 2015, 03:54

No… the cold, dark mines!

kbdcraft · 20 Jun 2015, 14:25

Wow...long time no see this buckling style keyboard.
Old style but this switch aid for accuracy of typing as I remember that I used to use space saver model from IBM.
Anyway... It doesn't looks like an old one...rihgt?

1391401 · 30 Jun 2015, 10:14

I'm pretty sure the metal clip / wire that's attached to the underside of the space bar (not the stabilizer) is a ground wire. None of my M's have one, and dare I say I don't think it's necessary. Not that I'm recommending you remove it.

Chyros · 30 Jun 2015, 18:45

1391401 wrote: ↑I'm pretty sure the metal clip / wire that's attached to the underside of the space bar (not the stabilizer) is a ground wire. None of my M's have one, and dare I say I don't think it's necessary. Not that I'm recommending you remove it.

It is. Both of the two Ms I got recently what do I do with them?!) have one.

Compgeke · 30 Jun 2015, 19:55

Afaik it's only UK made boards that came with that wire, none of the US or Mexico ones.

fohat · 30 Jun 2015, 20:14

I have only seen it on a few late-1990s from Greenock. I took them off and threw them away.

Let's see, ground wire clipped to plastic, hmmm, what's that all about?

Chyros · 30 Jun 2015, 21:50

fohat wrote: ↑I have only seen it on a few late-1990s from Greenock. I took them off and threw them away.

Let's see, ground wire clipped to plastic, hmmm, what's that all about?

It connects to a clip mounted on the interface of the barrel plate and metal backplate, which in turn is grounded to the PCB (or vice-versa) with a metal wire and screw.

OleVoip · 30 Jun 2015, 22:49

This is an idea from the late 1980s, when keyboards were collocated with large cathode-ray-tube monitors, which charged the users with static electricity. TTL circuitry had just been replaced by CMOS technology, which was much more sensitive against static discharges, so means were sought to discharge the users and protect the devices. First idea were grounded pads, where the user should discharge before touching the keyboard. Then IBM constructed a space bar made of conductive plastic that was wired to ground, which had the advantage that the user touches the space bar anyway and often. The idea spread throughout the 1990s, when also KeyTronic and Cherry started making keyboards with grounded space bars. These disappeared again when chip circuitry had evolved and was less susceptible to discharge damage.

edit: Another factor might have been that the charging of the users with static electricity was considered unhealthy in Europe - at least more so than in the US. This could explain why space bar grounding is more likely to be found with IBM boards made for the European market.

Muirium · 01 Jul 2015, 00:52

Also: English commerce's unending love affair with plastic carpet.

http://deskthority.net/for-sale-f55/the ... et#p217036

Eeeeeep.

Chyros · 01 Jul 2015, 01:06

OleVoip wrote: ↑ a space bar made of conductive plastic that was wired to ground

Oooh! This explains why my two recent Ms with ground wires had space bars that were discoloured, while my (much older) other M didn't have the wires and had a normal (PBT?) spacebar.

Muirium · 01 Jul 2015, 01:10

Correct. I've only seen ABS spacebars on Greenock Model Ms with earthing wires too. Sometimes visibly yellowed, like a Greek layout model on Ebay for a while.

http://deskthority.net/post192008.html#p192008