i opened it up but couldn't find the problem. all of the undersides of the buttons looked good, clean, with no carbon residue on the traces beneath them. i cleaned them carefully anyway, put it back together and tried again, with no luck. this has gone on for some time, so to keep things from getting worse, i decided to use the EMX less and less, preserving the buttons until i could find a more permanent solution. about a week ago, the buttons stopped working almost altogether!
i took the EMX apart again and carefully examined the button strips inside. they're very typical: silicone button strips with a conductive carbon backing. pressing the keys down causes the carbon strips to complete the circuits on the PCB beneath them. occasionally, this carbon wears off after hundreds, or thousands of button-presses, and the key stops working. the carbon strips on my EMX looked fine, but indeed were worn out. (if you look carefully in the second picture, you can see a light patch on one of the carbon strips: that's where it had worn almost completely off)
i e-mailed Korg asking about a replacement part and the price, but i thought in the meantime i would investigate my own solution. after a bit of searching i found a few products that were made for this purpose, but most of them involved two chemicals that you mix together -- once they're mixed, the resultant conductive paint is only good for a few hours or days, and then the remainder must be discarded. i thought that was kinda crappy, but couldn't see any other choice. just when i was about to give up and buy some, i found a product called Caikote 44, from a company i recognized, Caig. Caig sells all sorts of cleaning and restorative products for electronics, and i'm already a big fan of their DeOxit cleaner (if you ever open a synth or similar electronics, you should own a can of this!). Caikote 44 comes in a single vial, and lasts up to a year after it's been opened. it includes all the tools you need to prepare, clean, and then repair your buttons. and this stuff works on all kinds of similar electronics, not just your Electribes. you can use it to repair cell phones, TV remotes, just about anything that uses those flexible, carbon-backed buttons. several places online sell it, and i paid 8 bucks.
this stuff works exactly as advertised. i cleaned the buttons, dipped the included swab into the vial, and "painted" a small coat onto the two offending keys. a tiny bit goes a long way too -- i ended up having a lot of product left on the swab, so i painted all the excess on to the other keys, until it ran out (i didn't have to, but i figured, why waste it?). i dipped the swab exactly once, mind you. there is still plenty left to do this on dozens of other items, so i'm pretty pleased at the value of this stuff. anyhow, as instructed, i held a light bulb to the buttons and let it "cure" for 5-7 minutes, and then just let it all sit for an hour, just to be sure everything was bone dry. i put everything back together, plugged it in, and presto! all buttons work again like new.
i don't know the long-term properties of Caikote once it's applied, but it's meant to be somewhat flexible, as well as permanent, so i'm pretty confident it'll last. either way, i am certain that this product costs considerably less than a replacement button strip from Korg, and you can use it on all kinds of things, so that's a big plus as well. hopefully this'll help someone else who runs into the same problem. thanks for reading!
