Author Topic: Corsair K95 key not working, switch OK  (Read 1315 times)

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Offline SolfDoernplop

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Corsair K95 key not working, switch OK
« on: Mon, 07 December 2020, 04:13:22 »
I have a Corsair K95 LED monochrome mechanical keyboard with red switches and have the strangest defect that I can't fix.
I spilled a tiny little bit of water on it. I dried it, cleaned it, but the space key does not work anymore, no matter what I do. It is just the space key, all other keys work. I took the keyboard apart and found that the switch actually works (checked with a multi meter)

What could this be? That just one key does not work? Any suggestions how to fix this?

I don't want to throw away the keyboard just for one single key, but I need the space key.

Possible workaround?:
I figured if I could wire the space key switch to another key (like right alt or the context key (left of the right Ctrl key. I definitely never use that key) and then remap that key to space in the keyboard layout, it could make it work.

What are your thoughts about it?

Offline suicidal_orange

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Re: Corsair K95 key not working, switch OK
« Reply #1 on: Mon, 07 December 2020, 06:42:09 »
If somehow during cleaning you damaged the trace to that switch you should be able to solder a jumper wire to reconnect it properly.

Also have you checked the diode connected to that switch (if there is one) - It should have continuity one way but not when you swap the probes.

Post picture of the area around that switch, if the PCB is black or white you'll need to get the traces to show up in the shine (hopefully it's not as this is not fun!)
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Offline SolfDoernplop

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Re: Corsair K95 key not working, switch OK
« Reply #2 on: Mon, 07 December 2020, 13:46:59 »
I most definitely did not hurt any traces, I work with electronics a lot and I was super gentle. The only thing that could have happened was that the liquid damaged something like the diode (why do you need a diode?), will check that, there are these tiny little component and every key has one.

What about redirecting the key? Does anybody know if that works? I have a few keys on the keyboard that I never use. I figure I can just solder leads to the space key and connect that to the other key and then remap space on that key.

Offline suicidal_orange

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Re: Corsair K95 key not working, switch OK
« Reply #3 on: Mon, 07 December 2020, 14:45:13 »
The diodes are there to stop the controller getting confused when you press multiple keys at the same time.

You could desolder the space switch and insulate the pins from the PCB then solder both pins to another switch and remap the other key in software but 99% sure you have somehow killed the diode and replacing it will bring the switch back.

Whatever has happened you have not killed either of the pins space is (should be) connected to so you can make it work good as new.
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Offline SolfDoernplop

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Re: Corsair K95 key not working, switch OK
« Reply #4 on: Mon, 07 December 2020, 19:57:18 »
I can check out the diode. Why would I need to desolder the key? it is not connected right now as it is, I could just wire it to another key I figure.

Offline suicidal_orange

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Re: Corsair K95 key not working, switch OK
« Reply #5 on: Tue, 08 December 2020, 00:24:39 »
It is probably half connected, connecting two places into one will result in two keys being pressed.

If the board was wired friendlily like a DIY one you could connect two rows or columns (depending which way the diodes are connected) so pressing B or . could type both.  If you posted a pic I'd (hopefully) add some dots and suggest places to connect but it seems a requirement for designing keyboard PCBs professionally is to be an addict as they are rarely as sensible or organised as those first timers here create.

Search for'switch matrix if you're interesed :)
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Offline SolfDoernplop

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Re: Corsair K95 key not working, switch OK
« Reply #6 on: Mon, 01 February 2021, 16:08:08 »
I will make a picture of the PCB, there seem to be no diodes, the multimeter does not show what looks like diodes are actually diodes.

I don't have much experience with keyboards, but wow, next time I buy one, i will definitely shun corsair and never buy a keyboard from them again, they are too expensive to not be repairable and such a pain in the butt to fix.

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Re: Corsair K95 key not working, switch OK
« Reply #7 on: Tue, 02 February 2021, 06:47:08 »
if it is in series with the switch you can always try to short that diode-not-diode and see if your space start working again before starting rerouting keys, in circuit diodes can behave strangely to being tested, especially if damaged, and yeah pics would help
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Offline SolfDoernplop

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Re: Corsair K95 key not working, switch OK
« Reply #8 on: Mon, 22 February 2021, 18:02:35 »
Here is a picture of the board, the black circle is around the switch that is relevant (space key). This is a LED keyboard (not RGB), with one LED per key backlighting.
I'm curious what you guys make of this PCB, what the little thing is that looks like a Diode.
« Last Edit: Mon, 22 February 2021, 21:57:38 by SolfDoernplop »

Offline suicidal_orange

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Re: Corsair K95 key not working, switch OK
« Reply #9 on: Mon, 22 February 2021, 18:27:02 »
It's a nice colour and at least semi sane :eek:  This is actually one of the best looking commercial PCBs I've seen for repairing with visible traces and diodes not attached at random (at least in this bit...)

The thing that looks like a diode is indeed a diode, it should only allow current to flow one way so on a multimeter it should continuity beep with the probes one way round but not the other. 

Or the brute force test without a multimeter is shorting purple to green to bypass the switch and diode, if that types a space the diode is dead and needs replacing.

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