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.