Here’s a little bit of a blast from the past, but I’d bet that many of us have encountered this problem. Keyboard contacts can wear out, be damaged by drink spills or that vat of acid you left by the TV. Automotive defroster repair paint should work – if have some handy. [eeun] documented a keyboard contact repair method using household aluminum foil and superglue.
28 thoughts on “Keyboard Contact Repair”
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ugh, apple stuff… bleah >_
It is not specific Apple stuff. It is usefull for even remotes for TV etc.
But I thought that aluminium wasn’t able to let the current through. Who’s telling me about that?
– Unomi –
acid? who do you think we are? kids? no, we use pudding, chocolate pudding, to be consumed during those afternoons at school
Best solution for this problem is silver based acrylic varnish, which conducts electricity. You can find this product in car stores also because is used to repair thermal metal stripes of car rear window heaters.
I repaired with it my (expansive) logitech desktop wireless keyboard!
Where can i buy this
@Unomi – aluminum is *highly* conductive. Who ever told you that needs to read this:
http://environmentalchemistry.com/yogi/periodic/electrical.html
(most conductive are at the bottom)
pragma, nice link. I’d known that both silver and copper were better conductors than gold (and why I laugh at the audiophiles that use gold as much as possible).
Does anybody know how much these vary with temperature?
gold doesn’t as easy oxidize, and that is why gold contacts last longer.
actually, the comment about aluminum is somwhat true. Aluminum oxidises very raplidy, with a clear layser of A12o2, which is a very good insulator. If you clamp the wire securley and have direct metal-metal contact aluminum is great, but for switch contacts, not so much.
But heck, if it works it works.
People use gold for connectors (it’s not just audiophiles) because both copper and silver (and aluminum) oxidize rapidly, making for extremely shitty connections. High-quality contacts are almost always gold-plated for this very reason.
golds plating on cable contacts is still prefrable to copper or silver, not becaus its more conductive, but because its much softer, facilitating a better coupling between surfaces
I had a G15 gaming keyboard that was screwed up when my friend spilt water on it. I bet this could have helped… o well.. good thing I could return it.
This is genius! I’ve tried various methods of repairing these traces using foil or wire with limited success, they always seem to fail after a while. The clamp over the superglue is great, I would just be worried that the glue would spread too fast and get in between the foil and the trace before I clamped it.
P.S. #5, it is mentioned in the article and the blurb that rear window defroster liquid would work well, it just costs a lot more and is harder to get than “stuff in your kitchen you already have”
#8, gold oxidizes too, it just happens that gold oxide (whatever, you know what i mean) is as conductive as gold, where copper, silver, aluminum, etc have poor conducting oxides.
Interesting stuff. aren’t there connector lubricants that can stave off corrosion, though? and is there anything they can do about the electrochemeistry between cu and al?
@mrblarg: that’s the problem – your lubricant could act as a dilectric, turning the cu+al into a electrochemical cell. Such ‘connector lubes’ are probably out there, but I’ve never heard of them (never looked either).
I suppose it might be possible to have a sealed reed switch with some mineral oil between the contacts. Finger pressure would just push the oil out of the way, allowing contact to be made. But it would have to be in a flexible container like silicone or rubber.
my science teacher was telling me how most modern keyboards use two plates immersed in something like mineral oil. The computer reads the capacitance of the plates (the plates get closer, the capacitance goes up) and detects which keys have been pushed. the purpose of all this being that there is no physical contact made, i.e. no damage, no corrosion, etc. is he right? if he isn’t, why hasn’t this been done?
Actually IBM Model F keyboards used capacitance, but the much-adored successor Model M did not – under the keys and buckling spring is a set of plastic membranes, not unlike what you would find in a cheap keyboard today.
Topre makes keyswitches that operate on the principle of capacitance, see https://deskthority.net/wiki/Topre_switch#Internal_components_.28Capacitive_switch.29
Most high quality keyswitches (Cherry MX, etc.) use conductive metal contacts.
A newer option for a high endurance switch today would be optical keyswitches, in theory, but I have no direct experience with them.
See A4tech LK, Adomax/Flaretech https://www.tomshardware.com/news/what-are-optical-keyboard-switches,32352.html
Has your teacher ever taken apart a keyboard? Have you? Most keyboard are built *very* cheap, with rubber dome switches. A good keyboard has real mechanical switches, like the famous collapsing spring of the IBM Model M, or the Alps switches in the Apple Extended Keyboard II. I’ve yet to see an oil immersion keyboard. If your keyboard starts to leak the oil, then what happens if the plates short out or an air gap forms that vastly changes the capacitance? It’s a feasible idea, but I can see many downfalls.
Shame I didn’t check HaD for a couple of days, now you will all never know that pencil works great.
OMG those way’s to repair a contact are redicules and a pain in the ***. Here is the easiest way to fix a contact. Take a #2 pencil and whatever key is failing find it on the board and trace the contact line there your done lead is conductive and i have repaired lot’s of keyboards that way infact this one im using had like 10 bad key’s and I repaired them probably 8 months ago and they still work perfect.
use a #2 pencil and trace the bad connections! Lead is conductive and I have repaired alot of keyboards this way. I am actually using a keyboard now that had 9 or 10 bad key’s and there all fixed and it’s been like 8 months.
OMG SCOTT!
It is good to mention the pencil method, but in my experience it didn’t work for longer stretches of missing trace reliably, they always seemed to flake out after a week or two.
I like the feel of the old keyboards, so I have bought a few $2 specials from Goodwill and chucked them after being unable to repair the destroyed traces.
Pencils are made of graphite, not lead. I used a trace repair pen on my apple keyboard (coffee or soda, don’t know, bought it used). It cost about $7, but it will be used for other projects. It looks like a whiteout pen, but instead of whiteout, it has a silver-ish conductive liquid that dries in a few minutes. Put down a light trace, let it dry thoroughly, and you’re done.
Radiocrap CircuitWriter pen, http://www.radioshack.com/product/index.jsp?productId=2104395&cp=&sr=1&origkw=trace+repair&kw=trace+repair&parentPage=search
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hi,
i m working for turning point i m gating a problem
in key board membrane. is there any solution for track belting. And it should be in stacker type .
redraw with pencil. simple as that. graphites like conduc. ink only with more R so lay it down thik and wide. tried n tested a good few months ago. still working fine.
Just as Enzo said already, I think the easiest way is to use silver conductive paint to bridge faulty connections on these kinds of contact foils.
I just repaired my old Cherry keyboard using this method, works like a charm!