| Electronics > Repair |
| Repairing carbon traces on a Casio WK-110 keyboard PCB? |
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| Agent24:
I have been looking at a friend's Casio WK-110 keyboard as one of the keys was not working. The rubber membrane part looks in good condition, but it seems there was some liquid ingress onto the keyswitch PCB which has caused a couple of carbon 'fingers' for the switch contact of the dead key, to come away from the board. Unfortunately Casio cheaped out where they could have used ENIG or such instead, I guess. Anyway, I have been researching if it's possible to repair these with some kind of conductive paint... At first I thought silver conductive paint such as https://www.synergyelectronics.co.nz/store/electrolube-scp03b-silver-conductive-paint might work, but after further research I see there is concern that such paints may tarnish over time and become non-conductive (at least, externally). This would of course make it useless for a switch contact. Another suggestion was black "Indian ink" from an art supply shop, e.g. https://www.warehousestationery.co.nz/product/W2802098.html Apparently this is conductive due to the carbon content. But has anyone used this to repair key contacts? Did it work? And what was the longevity?I also see some Indian ink advertised as "high carbon" - does anyone have information whether this is better or worse for such a repair? Or ... is there some other product which would work? I do like the sound of the Indian ink though, it's pretty cheap ;D Additionally... is there something I can safely clean the carbon contacts/PCB with before attempting repair? I only soaked up the liquid that remained with a cotton swab I don't know what it was or if it has left a residue that would hinder adhesion. |
| QOTF-Alexi:
I repaired a few carbon contacts in calculators with a relatively soft graphite pencil and they seem to hold fine over the years (although they don't see the same use as a keyboard of course), so I'd assume Indian ink would work just fine, although I'm not 100% sure how well it'll adhere to a smooth surface. As far as I'm aware, graphite does not dissolve in alcohol so you could try that for cleaning. |
| Agent24:
--- Quote from: QOTF-Alexi on July 22, 2024, 09:10:21 am ---I repaired a few carbon contacts in calculators with a relatively soft graphite pencil and they seem to hold fine over the years (although they don't see the same use as a keyboard of course), so I'd assume Indian ink would work just fine, although I'm not 100% sure how well it'll adhere to a smooth surface. As far as I'm aware, graphite does not dissolve in alcohol so you could try that for cleaning. --- End quote --- Interesting. I would have thought just the mark made using a pencil would come off quickly. I'm surprised you say it lasted years! I wondered about the smooth surface too but forgot to add it. Maybe the PCB surface could be roughened with a fiberglass pen or sandpaper etc. I guess it'd make sense to just get some of the Indian ink and do some tests. It was mentioned that some are not conductive, while most are. I also see now that some are described as waterproof https://www.whitcoulls.co.nz/fas-waterproof-indian-ink-60ml-black-5544777-black - I wonder if the waterproof version would be less or non-conductive. Does anyone know that? |
| 2N3055:
https://www.kontaktchemie.com/koc/KOCproductdetail.csp?division=&product=GRAPHIT%2033&ilang=en&plang=en |
| Agent24:
--- Quote from: 2N3055 on July 22, 2024, 09:43:20 am ---https://www.kontaktchemie.com/koc/KOCproductdetail.csp?division=&product=GRAPHIT%2033&ilang=en&plang=en --- End quote --- That looks quite good but doesn't appear to be available in New Zealand, however. |
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