Model F XT foam and vibration

juryduty · 29 Oct 2016, 02:21

Hi all. I have a Model F XT that I recently took apart and cleaned, also repainted the barrel plate. Some great references and tutorials out there. I did not replace the foam as it seemed to be in pretty good shape.

It seems that the keyboard is quite sensitive to vibration. For example if I poke at the spot below the space bar fairly hard with a "thud" a few times, it will register a bunch of random keypresses.

Is this an indication that the foam is worn out, or some other problem?

Thanks for any clues...

seebart · 29 Oct 2016, 02:58

juryduty wrote: Hi all. I have a Model F XT that I recently took apart and cleaned, also repainted the barrel plate. Some great references and tutorials out there. I did not replace the foam as it seemed to be in pretty good shape.

It seems that the keyboard is quite sensitive to vibration. For example if I poke at the spot below the space bar fairly hard with a "thud" a few times, it will register a bunch of random keypresses.

Is this an indication that the foam is worn out, or some other problem?

Thanks for any clues...

I'm no Model F expert but poking anywhere should not register a bunch of random keypresses IMO. You may have another problem, sure you reassembled the plates correctly? Fohat to the rescue!

fohat · 29 Oct 2016, 03:38

I was about to go to bed. How late do you stay up, anyway?

It is hard to guess, but I would wonder whether the plates are all fitted together properly.

Are all the sliding fit tabs meshed into each other and pressed tight? It sounds like something that might happen if the plates were loose somewhere and not being held snug to each other.

seebart · 29 Oct 2016, 05:00

fohat wrote: I was about to go to bed. How late do you stay up, anyway?

It is hard to guess, but I would wonder whether the plates are all fitted together properly.

Are all the sliding fit tabs meshed into each other and pressed tight? It sounds like something that might happen if the plates were loose somewhere and not being held snug to each other.

That's what I though, thanks fohat. Check that your plates are fitting properly juryduty.

I'm still awake & I'm still GMT+2 / CEST.

y11971alex · 29 Oct 2016, 06:37

Hasn't this been raised as a potential grounding issue with a F107 some time ago? That little cable running from the PCB to the back plate needs to be attached.

juryduty · 30 Oct 2016, 02:48

Thanks for the help. The source of the problem, I think, was the single screw in the PCB, wasn't in all the way. I also squeezed the tab a little more to make sure the plates were well fitted. Seems to be working now. Pic attached is the screw that wasn't tightened all the way.

: IMAG0610.jpg (629.48 KiB) Viewed 2136 times

fohat · 30 Oct 2016, 02:55

Oh, yeah. Those do need to be tightened snug.

Glad it was so simple and easy!

Chyros · 30 Oct 2016, 16:39

This is, in my opinion, virtually the only weakness of these magnificent boards. The capacitive system in these boards is deceptively complicated and EXTREMELY sensitive to breaches of the very fine tolerances in its design, much more so than those in the Model M.

fohat · 30 Oct 2016, 16:59

Chyros wrote:
The capacitive system in these boards is deceptively complicated and EXTREMELY sensitive to breaches of the very fine tolerances

For this reason, I do my "modified bolt mod" and add 3 strategic nuts and bolts around the central portion of Model Fs, because after I add a thicker and denser new foam, I fear that the plates end up farther apart and more isolated than before. And also, it just tightens up the entire assembly and ensures that it all stays snug.

alh84001 · 30 Oct 2016, 20:08

It turns out this was the issue with my non-responding 5th column as well. I disassembled the board, checked for continuity, used a finger on PCB and saw that 5th column actually registered. Then I assembled everything together and tightened the screw really well, and what do you know, it works! Lesson learned.