General > General Technical Chat
Spilt a drink on my keyboard - Cherry keyswitches washable?
wraper:
--- Quote from: bborisov567 on December 28, 2021, 11:19:55 pm ---A problem might occur only if high current is going through the switch, not the case with keyboards. Also with mechanical switches there is always friction between the contacts which will clean the residue from tap water.
--- End quote ---
Exactly opposite. High current can clean the contamination. Not the case with low current and voltage.
bborisov567:
--- Quote from: wraper on December 29, 2021, 08:21:30 am ---
--- Quote from: bborisov567 on December 28, 2021, 11:19:55 pm ---A problem might occur only if high current is going through the switch, not the case with keyboards. Also with mechanical switches there is always friction between the contacts which will clean the residue from tap water.
--- End quote ---
Exactly opposite. High current can clean the contamination. Not the case with low current and voltage.
--- End quote ---
High voltage cleans contamination. Current won't even go when the resistance is too high.
thm_w:
--- Quote from: bborisov567 on December 28, 2021, 11:19:55 pm ---A problem might occur only if high current is going through the switch, not the case with keyboards. Also with mechanical switches there is always friction between the contacts which will clean the residue from tap water.
--- End quote ---
Significant friction would only occur on wiping contacts, MX switch does not using wiping contacts. This is why tactile/limit switches are always kept well sealed.
http://xahlee.info/kbd/ikm/Cherry_MX_Brown_v004_j3qr3.gif
--- Quote ---The reason for this concern is that under normal operation, metal contacts have a tendency to become contaminated by oxide films which form on the surface of the contacts, and by particles of dust and other matter. When a switch is being used to control an inductive load the associated inrush currents and arcing will burn off any con- taminants present. With low energy loads the possibility exists that contaminants will not be burned away and eventually discontinuity can occur.
--- End quote ---
https://inspectapedia.com/heat/Limit-Switches-%20Basics-Eaton.pdf
https://sensing.honeywell.com/honeywell-sensing-basic-switches-general-technical-bulletin-001017-2-en2.pdf
floobydust:
I think the switch currents are the pullup value in the MCU say 30-50k ohms at 5V. At first, I had to fix some broken solder joints/dead keys. The board was covered in flux, your usual messy PC board so leakage currents aren't enough to be a problem.
After the shower scene, water deposit marks are hard to see but who knows what goes on inside the key module, if gold is involved or how much friction happens. Some are rated 100M cycle lifetime. I don't see a vent so how water vapour gets out is still a puzzle.
Good .gif's of the mech of each type.
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