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I have a mechanical keyboard (Noppoo Choc Mini with Cherry MX Blue switches) and after a few weeks, some key presses are getting sent two times even though I press a single time. I found out that this is a common problem on mechanical keyboards and is called 'chattering' (or 'bouncing').

This comes likely from a hair inside the mechanics of the switch, so my posssibilities are limited here:

  • Replace the switch manually (soldering, reordering single parts from beyond, ...)
  • Buy a new one
  • ... or fix it on the software side.

So my question: is there a simple (or complicated, I'll take it all) way to fix this? Is there a kernel-patch, keyboard driver option, smart tool or a hidden settings in X11 to prevent my OS from registering the same key in a very short period of time?

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2 Answers 2

In X11 on the software side, you'll want to adjust the bounce key delay xkbsetbouncekeysdelay

http://linux.die.net/man/3/xkbsetbouncekeysdelay

And, as with any mechanical keyboard, a good cleaning may be in order.

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Its not a common problem for mech keyboards, and the cherry MX switch was made to stop this problem, because of the way the switch works you have to come back off the contact past the latching point to make another contact its not like a 'dome board.

That said after many years of using most types of mech 'board without ever seeing a problem, I thought I would try a diff *nix distro (arch, I'm a slackware user) on a spare box, as soon as I hit the cli I started to get multiple key presses.

I checked it with another Filco, no change, and then an older ALPS blue switched, then an g80-3000 board with diodes, but nothing stopped it until I changed the BIOS kbrd speed down to normal, it was a problem for all of the boards I used.

From what I have read the above bounce delay setting is often not perfect for cherry switched boards, but as I dont leave the cli I doubt it really matters to me, but might help other users.

It could be a controller problem, I dont use my Noshist's (Noppoos) as I call them, but I did get one of the first batch of the Filco Zero board a few years back and that had a problem with the direction and speed of scan rate so you got lots of transposition errors (like teh) and there is a trick you can do by pressing a credit card (or something like) down at a slight angle into 4 or 5 keys a few times into a basic text editor and checking the results are correct.

The main point of this post is to say that I have never seen a bad cherry switch that was not damaged by some outside force, most often spillage or force from something being dropped onto the board. I have some 30+ cherry switched boards (yeah, its not, er, cough, sniff a problem or anything man ;) going back to a 1984 g80-1000 that works as good as it was new, and never given more than a brush out with a clean paint brush every few months.

Something I have seen (in the last 5-6 years) as mech boards have moved into the realms of a fashion object, is that new users bash the keys too hard, if you do bottom out the keys it should hardly make a sound, and when you dont bottom out you will start to get the best from the board.

The blue switch is the best for a new user to learn with, never start with a red switch.

That said if you type less than a few 1000 words a day or are a gamer there is not really any point in getting a mech board. /ramble

May 02, The more I think about this, the more I seem to remember there being some talk that in the Noppoo T&C's or advert it was only guaranteed to work on windows boxes. They did some trick in the USB/controller to get past the 6KRO (6 key roll over) hard limit that USB has. So they could say it had full, or *n*KRO, which you only have over PS/2.

ISTR there were people using the Teensy USB to over come this fake USB thing. Might have just been random key press and no LEDs in Linux and *BSD, apple mac that had the bigger problems.

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