deskthority

I have an XT keyboard where some keys actuate a fraction of a second after the spring buckles. The delay is variable but on the order of a quarter second—enough that touch typing is a problem. It's the flipper that flips late: I can hear a second click. I can prevent the delay by pounding the key down hard, but even then the key sounds a bit different.

I have opened the board up a few times and replaced flippers and springs. There were no visible differences, but I replaced them anyway (with flippers and springs from the function keys, most of which I removed). That fixed it, but the problem soon reoccurred with other keys.

It started with Y, then U and I. Now O and Ctrl have the problem. G had the opposite problem: after releasing the key, it took a fraction of a second for the flipper to lift back up. Interestingly, the Ctrl key only has the problem when I press it one the top of the "hat". If I press it on either side, then the key acts as it should.

I should mention that this keyboard was poorly packed and somewhat damaged in shipping. The plastic case was cracked in three places, a flipper and barrel and a few keys were smashed, and a bunch fo keys had been knocked off.

I can, of course, continue to open up the keyboard and move flippers and springs around, but it's getting tedious, so I thought it was time to ask: what sort of damage or problem could be causing this? Is there something that I could have done wrong while reassembling? The black, sticky foam was in good condition, and I was able to slide the steel plates back together by hand force, no clamps necessary. I have tried to tighten the two screws in the back with various amount of force and also tried to type without the case; none of these make a difference.

There is some difference in sound between different parts of the board. The keyboard is pingier than I expected, but it's been 25 years since i used a Model F, so I don't have a good reference point. (I'm a longtime Model M user.)

Wow, it's hard to imagine that the flipper itself is physically delayed. Are you 100% sure it's not electrical and you're just perceiving it as a physical delay? I don't doubt you, just wanted to throw it out there.

I'm having trouble with mine right now. At first I thought it was mechanical but then I checked the voltage and realized that something was pulling it down to 4V.

Here's a video of the Ctrl key (with sound—you may have to click somewhere to turn the sound on): https://imgur.com/gallery/7bx5Iax

The ping is just the way they are. They ping significantly more than a model m. As far as the click problem, its sounds like the space between the barrel plate and back plate has been increased by the damage such that when you press a key the spring does not bend enough to buckle until it bottoms out or nearly so. You could try putting a thin sheet of something between the pcb and the back plate to increase the pressure when you reassemble it.

Engicoder wrote:
its sounds like the space between the barrel plate and back plate has been increased by the damage such that when you press a key the spring does not bend enough to buckle until it bottoms out

I assumed that it went without saying that all of the parts must be properly seated and aligned. Any key that does not feel and sound right is an indication of an alignment problem somewhere in the system, and until every key feels and sounds right you are wasting your time looking for electrical problems.