IBM Model F AT problem

[anmq91]

Apologies for opening a new post, but nobody here seems to have the problem I am with my F...

So I did a foam replacement today and everything went well, I got everything closed up and all the keys are working fine during normal use. I have noticed though that on the up stroke the keys vibrate quite a bit as the spring decompresses. I am not sure if that was there before.

The issue is that when I pull any key cap off, the computer reads the key as always being pressed. I've tried it on multiple keys across the board and the same thing happens. The second I put the key-cap back on it stops and works like normal. Does this indicate a problem with the keyboard? If so, any ideas on what to do to fix it? Do I need to perhaps use thicker foam or something? (Currently used 1.5mm Neoprene and had a hard time getting it closed up even with the help of clamps).

Any help/info would be much appreciated!

[Wazrach]

Apologies for opening a new post, but nobody here seems to have the problem I am with my F...

So I did a foam replacement today and everything went well, I got everything closed up and all the keys are working fine during normal use. I have noticed though that on the up stroke the keys vibrate quite a bit as the spring decompresses. I am not sure if that was there before.

The issue is that when I pull any key cap off, the computer reads the key as always being pressed. I've tried it on multiple keys across the board and the same thing happens. The second I put the key-cap back on it stops and works like normal. Does this indicate a problem with the keyboard? If so, any ideas on what to do to fix it? Do I need to perhaps use thicker foam or something? (Currently used 1.5mm Neoprene and had a hard time getting it closed up even with the help of clamps).

Any help/info would be much appreciated!

Nothing to worry about, that's completely normal. The reason keys register as always pressed when keycaps are missing is because the flippers are normally off the PCB with the keycaps on, but rest on the PCB when the keycaps are off. Since that's how the keyboard detects keypresses... you get the idea.

As for the ringing, you can quite easily introduce reverberating to keypresses after opening and reassembling the keyboard module (or it might be quieter). This is because the tension between the two metal plates is mainly responsible for how much (or little) the keyboard pings, other than spring wear or "dryness".

[Wazrach]

It's difficult to describe. The Model F assembly is extremely sensitive to variations in tension, so chances are every iteration (every foam replacement or slightly different reassembly) will produce a different sound and feel, it seems. I think Ellipse would be able to give you a more definitive answer.

[anmq91]

Thanks a lot for the quick reply Wazrach! It's good to hear that that is normal, I was afraid that the sudden presence of the reverb in the caps on the upstroke coupled with the odd behavior when the key caps are off, were a sign that I screwed up somewhere in the restoration process.

Just out of interest, is there any way to reduce the reverb in the caps? Like would something like a floss mod help?

[SneakyRobb]

Thanks a lot for the quick reply Wazrach! It's good to hear that that is normal, I was afraid that the sudden presence of the reverb in the caps on the upstroke coupled with the odd behavior when the key caps are off, were a sign that I screwed up somewhere in the restoration process.

Just out of interest, is there any way to reduce the reverb in the caps? Like would something like a floss mod help?

The floss mod will help to a degree. I find it mostly cuts down on the higher range ping noise more than dampens vibration, but it does dampen the vibration. It is time consuming, but not that difficult to do. I would try it out on a few keys to see if it cuts down on the vibration you don't like.

[anmq91]

Thanks a lot for the quick reply Wazrach! It's good to hear that that is normal, I was afraid that the sudden presence of the reverb in the caps on the upstroke coupled with the odd behavior when the key caps are off, were a sign that I screwed up somewhere in the restoration process.

Just out of interest, is there any way to reduce the reverb in the caps? Like would something like a floss mod help?

The floss mod will help to a degree. I find it mostly cuts down on the higher range ping noise more than dampens vibration, but it does dampen the vibration. It is time consuming, but not that difficult to do. I would try it out on a few keys to see if it cuts down on the vibration you don't like.

Hey Rob,

Thanks for the advice. The ping doesn't bother me that much, in fact I kind of like the sound! XD But if it does make any difference to the reverb in the key-caps then I will try it out for sure!

[SneakyRobb]

Thanks a lot for the quick reply Wazrach! It's good to hear that that is normal, I was afraid that the sudden presence of the reverb in the caps on the upstroke coupled with the odd behavior when the key caps are off, were a sign that I screwed up somewhere in the restoration process.

Just out of interest, is there any way to reduce the reverb in the caps? Like would something like a floss mod help?

The floss mod will help to a degree. I find it mostly cuts down on the higher range ping noise more than dampens vibration, but it does dampen the vibration. It is time consuming, but not that difficult to do. I would try it out on a few keys to see if it cuts down on the vibration you don't like.

Hey Rob,

Thanks for the advice. The ping doesn't bother me that much, in fact I kind of like the sound! XD But if it does make any difference to the reverb in the key-caps then I will try it out for sure!

Hey no worries. I do know that Model F, release and ping vrrrrrrrr noise. The model F is almost a living organism that is sometimes inexplicable. It needs to be in tension to bring out its best. I would definitely try the floss mod and report back what it sounds like.

[anmq91]

The floss mod will help to a degree. I find it mostly cuts down on the higher range ping noise more than dampens vibration, but it does dampen the vibration. It is time consuming, but not that difficult to do. I would try it out on a few keys to see if it cuts down on the vibration you don't like.

Hey Rob,

Thanks for the advice. The ping doesn't bother me that much, in fact I kind of like the sound! XD But if it does make any difference to the reverb in the key-caps then I will try it out for sure!

Hey no worries. I do know that Model F, release and ping vrrrrrrrr noise. The model F is almost a living organism that is sometimes inexplicable. It needs to be in tension to bring out its best. I would definitely try the floss mod and report back what it sounds like.

Yeah I'll give it a try over the weekend for sure and report back with how it turns out. Although since I've been using it for the past could of days, the reverb isnt annoying me much anymore. I've got used to it I guess. Either way, I'm going to try out the floss mod and see what comes of it!

[Fkazim]

I have floss modded my IBM Model F AT. it sounds so much better. As the vibration is dampened the feel is also much better too in my opinion. i have made a video demonstrating the floss modded AT sound.

[fohat]

I have floss modded my IBM Model F AT. it sounds so much better.

As the vibration is dampened the feel is also much better too in my opinion.

I concur with this 100%

All of my Model Fs get a floss mod as a matter of course and it makes them civilized.

[anmq91]

So I tried out the floss mod last week on the numpad keys and decided not to go ahead with doing the whole keyboard. It does certainly reduce the ping sound by a lot, but I personally noticed a change in the key-feel as well. To me is felt as if the travel distance became just a tiny bit shorter and the keys didnt feel as well balanced - It was more like the model M (a little heavier and less refined).

Weirdly enough though, it did make a difference to the reverb in the caps, but instead of removing/lessening it, it made it... 'sharper'. That's the best way I can describe it. It basically reverbs just as much, just over a much shorter period of time. So I ended up noticing it more as it was less spread out and more intense (albeit for a shorter period of time).

I've got a new project ahead of me now though, because yesterday my cat decided it would be fun to spill a bottle of NA beer all over the model F. I noticed it like 20 mins or so after it happened and the keyboard was drenched. Still works, but the keys are still as shit. Gotta open the whole thing up again and remake it *sigh*