Moedl F AT - strange behaviour of letter before E an after C

[ed_avis]

Just got a Moedl F AT keyboar but a certain key on the keyboar behaves weir.  Most of the time it oesn't o anything, but if I type ed then it works, and if I type those two letters the other way around they get turned into ed instead of de.  Some of the time.  So when I type the D key nothing happens, and on hitting E the characters 'ed' are sent.  Microcontroller bug or something?

I previously had a Model M plugged in and I switched over to the F without rebooting - maybe a reboot will fix it.  As you can see, it seemed to fix itself while typing this post.

[ed_avis]

It doesn't look like a physical problem - what possible wonky spring could cause the D keypress to wait in limbo until E is pressed a few seconds later, at which point the D comes immediately afterwards?  It looks like some oddity in the keyboard controller or the way the PC decodes the protocol.

Physically, the only problem with the keyboard is that the spacebar's a bit stiff.  I have to whack it harder than I'd like.  Any quick fix for that?  Can I pop off the Model F spacebar to have a look, as I would with the M?

[ed_avis]

Apparently no, you can't just pop off the spacebar - this tutorial shows how to modify the spring: http://geekhack.org/showwiki.php?title=Island:8865

[ed_avis]

Looks like you were right, since I found a small dust bunny roughly underneath the D key, and since removing it the odd effects have stopped.  I never experienced anything like this with my Ms, but the F is like a double dose of buckling spring weirdness.  The awkward position of the left Alt key is bugging me though - it makes Emacs shortcuts hard to type.  DesktopJinx listed the problems with the AT layout in another thread but this is one thing he didn't mention: Alt is hard to hit with your left thumb.  I have a 122-keyer on the way so after some soldering with a Teensy I may get a better layout.

[ed_avis]

Problem recurs - that key now oes not work reliably at all - any suggestions?  Can I exchange the barrel with some unuse other key?

[ed_avis]

Or is it the capacitative switch unedr the key - oes that need cleaning somehow?

[Soarer]

Sounds like it's worth taking it apart to check for dirt, and while you're there swap the hammer and spring of the d key with some other key. (And do the space bar mod). You can test as soon as you've slid the two halves together, no need to fold the tab back for testing, just stick a couple of keys on where you've swapped the springs and see how it is then.

[ed_avis]

Thanks Soarer, I was dreading taking it apart after the stories of disintegrating foam rubber and how hard it is to make sure every hammer and spring is in place when you put it back.  But I guess it can't be avoided - and I would certainly like to loosen the spacebar at the same time.  I guess everything I need to know is on the wiki?

[Soarer]

It's not very hard to do at all, actually. Getting the hammers in place is OK, you just have to make sure, as you pick the assembly up to slide the two plates back together, that the two stay firmly together - usually, you can slide the plates together a little way into the tabs before picking it up to do the final shove (and it is a shove!).

The rubber may or may not be a problem. I haven't had a really bad one, so I don't know quite how bad it gets, or how common that actually is. However, if it is bad, it could be contributing to your problem already!

edit: fohat.digs made a very nice replacement foam mat for his 122-key.

Just remember when you remove the keys, to leave the spacebar on.

[ed_avis]

OK, will do.  BTW the spacebar advice does not apply to the 122-key Model F I have seen, which has an easy to remove Model M-style spacebar.  I think only the XT and AT Model Fs may have this awkward spacebar.  Anyway I'll try it out, and post about the 122-key in a separate thread.

[Soarer]

Yes, that's right. As a rule of thumb, I think it's only the super-wide spacebars that are the troublesome ones.

In other respects though, including the foam rubber mat, all Model Fs are constructed in pretty much the same ways.

[ed_avis]

Rule of thumb... I see what you did there

[ed_avis]

FTR, a thread about the terminal Model F keyboard is here: http://geekhack.org/showthread.php?29425