Bolt modded Model M and liquid spills

[Winrar]

Hi.

My daily driver is a February 1990 Model M I bolt modded a year and a half ago.

I am a vaper and during the lockdown, maybe 4 or 5 months ago, I had half a bottle (about 25 ml) spilled over the keyboard. I cleaned it and forgot about it until some keys started failing (i.e. not producing any output) about a month ago.

Now I have finally been able to come to the place where all my Model M tools and stuff are and found something interesting.

I didn't remember the spill, so I started testing a different cable. Same failing keys. Also had some spare controllers and tried them without luck. In the process, I ended up with no working keys and only the Num Lock led lit. The only possible culprit left was the membrane, so I undid the 50-something nuts and got to it. There I found an insane amount of eliquid in the membrane sandwich, which seemed to explain my failing keys.

Happy about being able to fix my keyboard, I cleaned the membranes thoroughly, dried them and reassembled. Same failing keys again. I undid the nuts and got to the membrane again and found about 4-5 burnt sections in the traces which were consistent with the failing keys. Later I tested them with a multimeter and there was no current going through them.

Luckily enough, that membrane was an Unicomp one I used when I did the bold mod and I still had the original one from the keyboard. I installed it and the keyboard now works as new.

I have been wondering if it was the bolt mod itself which allowed such an insane amount of liquid to go into the membrane and whether a non modded keyboard would have resisted the spill better than this keyboard did.

I am writing this to ask if it would be advisable to use an additional layer somewhere in the membrane sandwich to prevent this. Is anyone using something like that? Are bolt modded Model Ms really more vulnerable to liquid spills than non-moded boards?

Best regards.

[ddrfraser1]

Liquid is a major weakness of any model M. I've never heard of any method of adding a layer that could protect it. I'm glad you were able to repair it!

[hvontres]

I'd say the only difference between a bolt modded and a non modded model M when it comes to liquid spills is that when you spill liquid on a non-bolt modded Model M, you end up having to do one to fix the membrane. Later models came with some drain channels to help let the liquid out, but I have no idea what they look like and if that is something that could be added later.

[fohat.digs]

Later models came with some drain channels to help let the liquid out, but I have no idea what they look like and if that is something that could be added later.

They definitely do help by preventing the longitudinal reinforcing fins from creating a series of dams. I thought that they had been added by 1990 but apparently not.

Either way, an intact barrel frame should not let liquid in (unless it was deep enough to over-top the barrels ("chimneys" in Unicomp parlance)) which would never happen.

The bolt mod penetrates the frame in 50+ places that all become entry points for liquid. That could be used as an argument for a screw mod over a bolt mod.

TL;DR don't allow liquids near your keyboard.
   

[Winrar]

The bolt mod penetrates the frame in 50+ places that all become entry points for liquid.

This is what I thought. I had spills in the past over non-modded Ms, but never as destructive as this one.

I have 20+ Model M keyboards and the oldest I have with drainage channels is a 1995 unit by Lexmark with no IBM markings and one piece keycaps. I also have a 1997 42H1292. It was my first model M and has had more spills over it than I can remember. It is now also bolt modded, and the membrane in it broke on the point where it folds under the controller, but everything was fine in the inner sandwich area, so the drainage channels seem to do a pretty good job.

BTW, everything in these keyboards is sturdy as hell. While looking for the problem, I did very bad things to keyboard, even to the point of plugging and unplugging the membrane in the controller while the keyboard was connected to the running computer, and everything keeps working as it should.