Mainboards for KORG MicroKEY V1?

Synth Repair
1

Sorry for making my first post a repairs question, and I hope this fits in since it’s technically not a synth, but a midi controller.

My KORG MicroKEY v1 of 9 years has been acting funny recently: When plugging it into my PC it’ll start and work fine for about seven seconds, some of the middle keys will begin firing madly until they stop working, leaving me only with the top dozen keys left.

I’ve been trying to diagnose it for the last week, confirming it is loading the driver correctly through event viewer and event ghost. MIDI-OX confirms that the lower octave of the keys stop working after several seconds of rapid firing until it gets reconnected.

Now I’m not so great at electronics: I just spent a couple hours looking at the PCB and inspecting it for blown capacitors. I’ll attach an image of the front and back of the board if anyone wants to have a look at it. I went to Jaycar and bought a replacement USB-B port which I can solder in next week if I get time, since the current one is incredibly loose. I’m nowhere near skilled enough to work with surface mounted bits, so the port replacement is as far as I’ll go before just tracking down a donor board.

Also tried separate cable with no fix.

Should be noted I’m on Windows 10, I hear this thing can be funky with drivers but it was working previously and I can replicate the issue on my laptop, too.

I can’t find replacement parts for the MicroKEY. The Mainboard PCB is KLM-3022-D and every time I search this term I just get pictures of aeroplanes unfortunately.

PCB IMAGES:

WaQpzVq.jpg1960×4032 1.19 MB

DJ01l28.jpg1960×4032 1.14 MB

If anyone has information about this PCB or where I can get a replacement without buying a full donor controller I’d be forever thankful.

Anyone with experience with this series controller or similar issues, I thank you in advance for whatever advice you have.

2

Hi. You didn’t mention the size-- have I read correctly elsewhere that the 2010 original was only available with 37 keys?

3

OK Synthtopia confirms what the big Wiki said. In the meantime, I studied the one that I have and made a schematic for the keys. Have you torn down the keybed and examined that PCB? You said the keys which autofire at first are near the middle-- that’s also where the connector and ground and power and middle keys diodes’ solder joints are semi-close together, so that’s certainly where a puddle of something’s sort-of-conductive residue could engulf enough points to create a real problem. I think that’s more likely than the ATMEGA32A being cooked since in that case, you probably shouldn’t still have all of the top octave. There are 2x 74HC138 address decoders on that PCB which may be malfunctioning-but-not-dead, and their inputs are 5 pins on the main board connector while the 74 diodes all run to another 8 pins on that connector. I can’t quite explain both symptoms (keys randomly activating and keys being inactive) except by saying liquid damage is random. So that’s my shot in the dark. HTH

edit again: I admit that a dying ATMEGA could alone be the cause for different symptoms at different times due to temperature increase. I’m curious if the ~7-second window of proper operation is any shorter after un- and re-plugging it. And of course normally you’d know if something got spilled on it, especially if you’re the only one near it, but I don’t know anything about that whole scenario.