Dead Keys

I picked up a cheap old keyboard today, a Yamaha PortaSound. When powered on it immediately made a continuous tone, and had two unresponsive keys (one of which corresponded to the note of the tone). Although I know nothing about electronics, I took it apart to see if there was anything obviously gunked up that I could clean.

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Sure enough, the relevant contacts looked corroded.

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A guide I Googled recommended 90% isopropyl alcohol to clean with. The best thing I could find was my girlfriend's flatmate's nail polish remover...

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Since cleaning up the contacts as best I could, the keyboard functions properly, but the dead keys haven't come to life. The contacts appear quite damaged – removing the blue-green gunk revealed a bronze surface (not obvious in the picture), rather than the black visible elsewhere. I don't know if it's worth spending an hour getting the rest of the corrosion off, or if there might be other issues at play.

Can anyone offer any advice?

Typical when Coke is spilled in it.

MikeMl said:

Typical when Coke is spilled in it.

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Yes, nasty stuff coke - the copper tracks at the top look like they may be rotted away, or it may be the black contacts themselves.

Anything I can do?

solder it, or even a conductive grease may help(not my best idea)

you can see where the node has detached, bypass the dead node with a wire to another node point, if ya hafta

use a ohmmeter to check for the open circuit if you can

your dead key is #5, and prolly #3?