Repairing keyboards Some time ago yet an other keyboard stopped working properly. Buying an other one again got sort of boring, and risky[1], so I did some websearch. One of the problem I have with keyboards is that buttons get stuck, unless you hit those exactly in the center, and then slowly. Removing all keys and cleaning it made it worse, not better. So oil? Google suggested people have used superlube (as it does not attack plastics). I ordered some superlube and tried it on 2 keys for a month, it works perfectly. So now I have done a whole keyboard with it, and not only does it work, it also makes the keyboard more quiet.
[1] Bought a new Logitech wireless keyboard a while back, the lettering came off, the keys got stuck too. Now I use an old Logitech.. I have ordered a foldable keyboard on ebay, waterproof.... just to try.
If it is one of those things with cheap rubber buttons with embedded conductor: The rubber tends to rupture on the outside as it loses elasticity. I do not think there's a cure for that. Then there may be the conductive layer on the pcb wearing off. also not fixable. One wonders if it may be possible to sample them capacitively and avoid most of those moving parts/contacts...
Yes, it has been done that way. The IBM keyboard that shipped with the PC a nd PC/XT circa 1982 used capacitive sensing and I think some clone keyboard s also do that. The key backs had a piece of aluminum foil stuck on that "b ridged" two pads on the pcb, except the pcb was coated in solder mask. The uProc in the keyboard strobed one set of pads and listened for ac coupling on the other pad, the circuit was no more complex than had the keys been co ntacting, I remember being impressed how neat the idea was.
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I've seen a capacitive keyboard, it was approx 1985 and I got it second-hand. instead of contatcts there were half-circles of track on the pcb. and to the base of the key-stem was attached a sponge pad carrying an aluminised plastic disc (plastic side down)
I was somewhat dissapointed.
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The one I use last few years is a Cherry Model ML4100 (a smallish one,
18mm pitch, here:
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). It has laser engraved caps and no key has failed so far. Older versions of that model were printed only and did wear off, and the buttons were worse - but still OK (a failed button once or twice per year which healed after a minute's banging). The older ones used to cost something like $50 to $80 IIRC, the new one (the one on the photo) I got as a gift from a friend so I don't know.
My old Cherry - a large on, cost me about $100 in 1989 IIRC (it was actually DM 150, I lived in Cologne back then) - has endured an unbelievable amount of beating and no button has failed, ever. I retired it around its 10-th year, had to repair the *traces* on its PCB - no solder mask at all, apparently some chemical agent from washing or from not having been washed had thinned a few connections enough to fail. I think it is still in good working order and will endure another decade of beating (beating like when you have to collect a few keycaps from the floor and insert them back...). Probably the best keyboard I have ever touched; takes a lot of space though and then I suppose I have already got used to the 18mm pitch of the smaller ones.
The rubber keyboard on the laptop is pretty good for a rubber one, may be the best rubber I have used is on that one (Acer something). Not sure I would have the nerve to work on it all day though, nowhere near a "true" mechanical keyboard. But a wintel PC is just a TV set for me and I don't expect that much from its remote control :D :D .
On Tue, 24 Dec 2013 05:21:53 -0800 (PST), dp Gave us:
My current, maxed out machine (maxed out on the frugal side, not a gaming screamer w/$1000 vid cards), which I just finished building, has a Logitech G19 keyboard. The keys are illuminated from below. Not the back drop for the keys... The Character on the key. And it is RGB, so I can make it any color I like. There is also a little full color LCD display on it, which can give various info bits about the machine. I use mine as a mere photo display, but with your "Cherry" costing you $100 back in '89, I do not feel so bad now, that mine only cost me $160 in 2013.
But after finding it to pass you guys a link, I wish I had waited. I may buy another. If any are left when I have the money again.
Well $100 then or $160 now is not very much for a tool one uses all day - especially if it lasts for decades. I looked at logitech keyboards a few years ago and I rejected them all though - they were all rubber. Look really good and perhaps are good for many people but not for someone who bangs in hundreds of kilobytes of text per month (don't know the figure, the working sources averaged over 20 years are something like 150 to 200k text per month, I suspect I bang at least twice as many keys to get to that figure, not counting emails etc.).
But the original question - how to repair a rubber keyboard - is something I would also be interested in; the remote control for the TV (not the wintel one, a real TV :D ) will likely be hard to replace. We also have a nice cordless phone, its keypad begins to fail when it gets too cold in the room (first symptom, not the first failing phone). And I do like that phone, I would rather not have to replace it by another model (it is about 10 years old, don't think I could buy the same).
Hah, that would be the day, when I cannot tell if a pair of NiMH have dropped or a keypad has failed :D .
It certainly is not the batteries (this comes from someone who has designed his fair share of NiMH chargers last two decades, you know).
It is the keypad all right. On a remote which had failed completely in the same way I checked what was going on. The PCB had been oiled and the oil had become denser over 5 or 10 years, too greasy or whatever one would call that so it took some huge pressure to perhaps make a key listen. I washed the oil off and the remote worked for another year or may be half a year, then failed again. This time there was nothing to wash to make it work though. Apparently the reason why it had been oiled in the first place had been to prevent oxidation etc. So the oil getting denser and the keys beginning to fail at lower temperature is consistent with how viscosity depends on temperature.
I think Jan already mentioned even the name of some oil, I guess this is the answer. Clean the old and put some suitable new oil should work. The rubber is not worn out at all, the phone has been used 2-3 times a week all these years.
The oil seems to be coming from the rubber somehow. I've cleaned off and rejuvenated loads of keypads on favorite gadgets by cleaning *off* the oil with alcohol, and lightly abrading the cleaned printed contact traces with paper.
Oddly, the goop comes *back* after a year or two. Silicone oil? Whatever it is, the contacts don't like it, especially going hi-z when cold.
At first I thought it was contamination--i.e., some sort of gooey soda pop spill or something, but it's not.
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