Troubleshot Microkorg's dead keys - confusing results

microkorgy · Post by **microkorgy** » Thu Oct 04, 2012 4:00 am

Ok, so my MK's first few adjacent keys stopped working seemingly out of the blue.

Me and an electrician troubleshot it all the way from keys to the interior of the circuit board with a multimeter and careful probing.

No detectable culprit was found! The keys still don't work..

BUT, the notes do work using an external midi keyboard.

I've tried using my old MK keyboard to see if it was keyboard related, but the same keys remained dead. So it seems it's not a keyboard based problem. Yet, on the other hand, given the external keyboard made those notes sound, it seems to indicate that the keyboard Is the problem

(otherwise no sound would sound regardless right, if it was the circuit board itself...)

I'd really like to get the keys working again. Even though 'only' 5 keys don't work, they ruin the playability of the MK, yet it also seems the MK's not quiet ruined enough to throw it away altogether. Selling it in also isn't likely a good option, since it's both in used condition and partially malfunctioning plus due to unidentified reasons.

The multimeter displayed no problems. No cracked or missing soldering. The circuit board has been cleaned, and the ribbon cables checked for continuity. Perhaps it's some vodoo by the Roland module? What else?

sohatyi · Post by **sohatyi** » Thu Oct 04, 2012 6:03 am

Have you tried using the keyboard as a controller to see if those five keys don't work. Controlling an external module?

I don't know anything about the internals of the MK but it could go.

Keyboard -> keyboard to midi ic -> sound processor.

If the bit that processes the signal from the keyboard is broken that'd explain why you can still process it externally.

microkorgy · Post by **microkorgy** » Sun Oct 07, 2012 9:37 am

Yes, I've tried triggering another synth with those keys, which didn't work, there was no sound still.

The only thing that makes their notes work is triggering them with an external keyboard. Like I said, which makes it seem like it's the keyboard that's the culprit, but after installing an old microkorg keyboard with some broken keys it still didn't work, which again suggested it's not the keyboard. So one thing suggests it's the keyboard, the other suggests not.

Also tried taking the circuit board for the keybed from the old keybed and mounting it to the current keybed, but it also didn't help, which makes it seem as if though the signal processor isn't the problem?

Or could it be a ribbon cable wire being broken internally, whatever.

X-Trade · Post by **X-Trade** » Sun Oct 07, 2012 10:57 am

Sounds like ribbon cable or keyboard scanning IC. I don't know the internals of the microKorg very well but on a lot of keyboards the scanning chip is on a separate board to the sound processor.. Depends how 'modular' the MK design is.

microkorgy · Post by **microkorgy** » Wed Oct 10, 2012 7:51 am

I may have posted overkill here in terms of hardware technical question. In the other post I describe a handful of hardware related malfunctions on the MK I own, such as malfunctioning release knob, vibrato and cutoff added 'out of the blue', self-copied patch, etc. Heck, this must be challenging even to a pro;)

At this point I'm getting a bit desperate... I need a synth, but don't want to get a new one only to Then find out that these malfunctions could be fixed with relative ease (has happened with other things before). Like, what if it was just the circuit board battery or something?

I'm leaning towards wondering what others would do in my shoes. Get another synth, or try to have the MK fixed, given there are so many issues with it?

As for the MK's modularity. Seems there's one main circuit board, and then a narrower one under the keybed which connects to the main CB via ribbon cables. Tried using another keybed circuit board, but the dead keys were still dead.

I'm thinking of the R3, but won't buy that or any other synth if there's still hope for my MK.

X-Trade · Post by **X-Trade** » Wed Oct 10, 2012 7:47 pm

Sounds like the keyboard scanning chip is on the main board then.. The board under the keys is just the switch contacts and diode matrix for polling the switches.

Get the R3

you'll love it!

microkorgy · Post by **microkorgy** » Sun Oct 14, 2012 10:13 am

No idea what causes the random cutoff or vibrato etc? Today a new thing happened. All editing parameters showed numeric values from 0-127 when turning knobs, even those that should show 'letters' such as the virtual patch source and destination.

WTF is happening to my microkorg?

Like I said, won't get the R3 before I know my current Microkorg is as good as deadly ill, with no salvation or unreasonably pricey to fix. Seems no other synth has all these issues based on google searches all brands combined. What.....is it??