Microkorg Dead Keys?

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Tboye96
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Microkorg Dead Keys?

Post by Tboye96 » Sat Jan 18, 2020 11:18 pm

Hello!

I bought a used Microkorg on ebay rather cheaply, because it had three dead keys and a few other problems.
There were a lot of tutorials online on cleaning the contacts and carbon pads. I cleaned them all up with cotton swabs and contact cleaner but that did nothing. Besides, I don't really see anything wrong with the pads, they seem fine to me visually... I then tried shifting the carbon pad strips around on the keyboard, and the pads on my three dead keys worked fine on other keys, while other carbon pads refused to trigger these three keys.

The keys that do not work are C#3, D3 and D#3. I admit I don't fully understand the theory behind how these switches work: why does break have two contact pads, one on each side of the make contact pad? And why are the switches two-fold (make and break) in the first place? I googled and also downloaded a few books on synthesizers, but I wasn't able to find the answers I was looking for, so please excuse the dumb questions.

I have done some electronic projects at home, so I can solder and all that, but I don't consider myself an expert, exactly.

One thing I HAVE noted however, is that I can actually trigger these three keys to work if I press E3, the key right above them, just before pressing one of these three. However, this only works with E3 and no other key.

I drew a diagram from the repair manual I found online, but I haven't drawn any especially meaningful conclusions from it.

Any advice? Thank you very much for your help.
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Rasputin
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Re: Microkorg Dead Keys?

Post by Rasputin » Tue Jan 21, 2020 3:12 pm

Tboye96 wrote:
Sat Jan 18, 2020 11:18 pm
The keys that do not work are C#3, D3 and D#3. I admit I don't fully understand the theory behind how these switches work: why does break have two contact pads, one on each side of the make contact pad? And why are the switches two-fold (make and break) in the first place?
The Microkorg checks the timing difference between the two pads to see how quickly the key was depressed. The longer the time between when one pad strikes and the other pad strikes, the slower the key must have been pressed.

Check all the diodes in the keybed PCBs. Make sure they conduct one way and only one way. If any of them conduct both ways or not at all then that's likely a problem.

Tboye96
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Joined: Sat Jan 18, 2020 10:39 pm

Re: Microkorg Dead Keys?

Post by Tboye96 » Tue Jan 21, 2020 11:37 pm

Good idea, will do!

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