*** M E M O R U M ***

You know the problem, the MTX keyboard switches either stop working or generate multiple characters due to tarnish on the brass spring leaves or pins in the switch.

What's the best way you've found to get them working again short of desoldering the keyboard PCB and dismantling the switches?

Hammering them time and again gets you so far, but often not good enough.


Any thoughts?

The keyboard switches are similar to those on an Acorn BBC / Master / Electron. Sometimes spraying switch cleaner into the mechanism (yes, easier said than done) helps if you exercise them as well.

Short of that, yes, desoldering and partially dismantling them would be the next step.

But do try repeatably operating them for 50 to 100 times…

It’s not so bad if you use all the keys regularly

Mark

Yes, vigorous “bashing” is the best way, if that doesn’t work, you’re into replacing the switch.

Not sure what you mean by “desoldering the keyboard PCB”? You can change individual switches

http://www.primrosebank.net/computers/ ... yboard.htm

As well as the recovered Acorn switches mentioned in the post, I also have some new, clone, switches available

Regards
Dave

I've tried removing a single switch once, it was hellishly tricky.

Bashing them lots only seems to work for a little while unfortunately. (I've found the best way to hit them is to repeatedly bash them hard pushing the keycap towards the back of the machine. I think that forces the contacts against the posts harder. Well, that's my theory anyway.)

OK, next will be better switch cleaner than I used the first time.

If I were to replace the switches on this keyboard it would likely to be practically all of them!

Maybe time to look at making a new keyboard PCB to work with Cherry MX switches. (It looks like the cut outs in the steel would it correctly and I think the sockets in the key caps would work too.) If I did design a new keyboard PCB I would put cut-outs so as to access those awkward nuts!

Dick Jannsen started a project to do this in 2014, but sadly, never finished it

http://primrosebank.net/computers/mtx/p ... yboard.htm

Obviously, it’s not ideal, but there is of course the option to use a PC keyboard

http://www.primrosebank.net/computers/ ... ps2kbd.htm

OK, well, as soon as the Amazon delivery of my new key cap pullers arrived it was off with the troublesome keys and a squirt of Electrolube EML200F down the posts...

Instantly all the keys started working perfectly. That EML200F stuff is dead good.

That's a pretty great result!

I might need to get a can of that stuff myself !