This is my first instructable.... ever. So here it goes.

I own a Kaossilator 2 (KO2). It's fun little phrase synthesizer and simple looper. But it has this awkward issue with mic button. When you want to record something from microphone you have to hold down two buttons simultaneously. First the mic button to enable built-in microphone or external input (mic in) and second the loop recording bank button. This isn't an issue until you want to connect another instrument to it and record a loop. While holding down two buttons you have only one hand free to express your self as best as you can.

Imagine that mic enable button is toggle switch. You could enable external input and hold down bank button with your foot and have both hands free. We are now one step closer to our goal. But you still need to put KO2 on the floor, record a loop and then pick it back up. This calls for an foot switch which I'll be making in my second instructable.

Since Korg is reluctant to incorporate mic input toggle functionality in software update this could be solved with a little hardware hack. There are many ways to latch a push button. It can be done with transistor circuit, logic gates, NE555 timer or an microcontroller (MCU) and probably some other ways too. My favorite is MCU since it uses least amount of components and can be soldered directly on KO2s PCB.

Step 1: Look Inside

First off let's see what we are dealing with.
We see a nicely exposed signal line from SW7 to some resistors. This is a signal path of our mic button. Since there are no other components in the way we can just break the line and solder our MCU directly on the board.
Next thing to consider is that big black chip. Finding out functionality of its pins is important for tracing out the circuit. In our case the only pin that concerns us is Vdd 3.3V power line for our MCU.
Link to CY8C3244AXI-153 PSoC: http://www.cypress.com/?mpn=CY8C3244AXI-153
In datasheet we see that closest Vdd pins to our line are 26 and 100. And GND is everywhere. Entire mesh is GND.
So now we know where all of the signals that concern us are located.

Step 2: Choosing and Programming MCU

MCU should be low pin count cause we only need two I/O pins. PIC10F series would be perfect for the job but they are not supported in mikroC PRO for PIC so I used the second best thing PIC12F series. I have few PIC12F675 chips lying around so I've used those. One in DIP package for breadboard and testing and one in SOIC package for soldering in KO2.
You could also use Atmel products:  ATtiny13, 25, 45, 85.
Or Texas Instruments products: MSP430G2210, MSP430G2230

The cheapest and best way to go is with Texas Instruments MSP430 LaunchPad flash programmer and debugger. 10$ and free shipping worldwide!

Attached source code has been modified since I took pictures of soldering so 3.3V for pullup resistor is no longer connected to GP0 I/O pin. With this new code you should connect pullup resistor directly between Vdd and GP1.

IDE I used: Mikroelektronika: mikroC PRO for PIC 5.4
MCU: PIC12F675
In project settings disable reset pin and set clock source as internal clock.
Project settings: Shift+Ctrl+E
Build project: Ctrl+F9

Lastly just flash your SOIC MCU. For flashing I used PICkit 2 programmer. Girls, you should too =P

Step 3: Preparing MCU

I've cut off unused pins so they don't touch the PCB but not completely so I can make software updates in the future. Note that pullup resistor should now be connected to the upper left 3.3V pin instead of pin 7.

Step 4: Preparing PCB and Soldering

First off put MCU on PCB and mark where pins touch the PCB traces and scrape off green solder mask to expose copper.
Then break the mic button signal path between the exposed copper pads.
Apply solder to the exposed copper pads. Applying solder is much easier if you use some flux.
Now all we need is power supply. If we trace from pin 26 we get to capacitor C8 and then to perfect soldering spot. Be sure to use insulated wire. Mine is from some inductor.

Step 5: Be Proud of Yourself

And that's it. Now you can press mic button to enable mic or external mic and press it again to disable it. Our second hand is almost free. Join me again in part two where we'll gain complete freedom of our hands.

Step 6: Extra Pictures

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<p>Hi i don't know if you look at these comments since this was done years ago but here goes: I'm so ticked at Korg and myself because 4 years ago I bought this but when I realized the mic didn't work it was out of warranty. I didn't really use it much so I forgot about it. BUT now I need to use it record a tongue drum that is amplified and when I saw this I started to &quot;Youtube videos&quot; someone posted one about the mic switch button and I decided to &quot;open &quot; my Ko 2 up. Well I couldn't believe it. that little piece that goes over the two metal thingies to make the mic turn on and off was GONE i mean I think it was NEVER there. I looked at the other side where the on/off and volume buttons are and sure enough that little tiny box (switch) is there. In doing this the damn yellow useless button broke off. In the meantime I GOT the MIC to enable both external and internal BUT I have to hold a piece of tin foil on a corn skewer to do it...this makes playing my instrument virtually impossible to play as I still have to hold the other button to record!! so now I need to figure out a way to fix this. If I bought that part I still have the problem of the button being broken. Any suggestions for someone who doesn't have the knowledge or tools for soldering etc. See the pictures for more details!! Thanks so much</p><p>Maria</p>
<p>Hi,</p><p>I'm sorry to hear that your little piece that goes over the two metal thingies is missing =) </p><p>Since this is a PCB repair work I cannot imagine a reliable solution without soldering. You can go to a music store or some electronic components store and ask them to solder two wires on for you. You can then just twist wires together when you want to record. Or you can add a big toggle switch on those wires.</p><p>Good luck!</p>
<p>Okay that's not a bad solution actually!! Now that I have a big hole where the switch should be. so let me just make sure I understand since this is totally not my forte (hence calling it a &quot;thingy&quot; lol) so, the two little tiny metal pieces that i have to have metal touching to make work will need to be soldered to a type of wire on each end that will come together like speaker wire when I need to record...and/or those two could be soldered to some kind of on/off switch. ? is that about correct? Look I also found this &quot;temporary&quot; fix..it's not perfect but a little better than the corn skewers!!~ </p><p>Thanks so much again!</p><p>Maria</p>
<p>Good information here. FYI: I picked up a broken KO2 which needs a new tactile switch for the INPUT (SW7) in the photos. After some investigation, I think it is part AMPTCFVTR from APEM (apem.com). Now trying to get a free sample from them, as DigiKey and Mouser do not stock this part for small quantity orders.</p>
<p>Hi I just wanna ask: Is there same problem with KP 2 mini? Or have KORG made mic input toggle functionality in software of KP 2mini? Thx</p>
<p>hello, this is what i am looking for and I am tired of the rubberband !. I just wonder if there is a simple way, rather than fidling around with programming a chip, cutting the pcb and what not. like replacing the existing button &quot;push on / release off&quot; with a &quot;push on / push off&quot; switch. in my thinking this should work. please confirm and i start looking for a right sized button to exchange : ) thank you.</p>
<p>Hi, Sorry for the late reply. Now I see <br>how I over complicated this rather banal modification, but I like <br>working with things that are laying around in my workshop =)</p><p>So <br>for simpler modification I would suggest buying a latching switch and a <br>stomp box. Just remove the old switch solder in some wires and connect <br>to effects pedal box. That's what I did for my effects pedal box with two switches for <br>loop banks. Details about that are coming soon in part two of this <br>&quot;hack&quot;.</p>
Sorry, for the delay, I did see your answer before!! <br>Well, the problem I have, using power supply 4,5 Vdclain or AA 3Vdc, sometimes power on, sometimes not power on. <br>Sometimes all leds are power on, but don't work anything. <br>I can make a video to explain better if is necessary. <br>Some ideia?
Sorry, can't help you here. I would have to have the unit in my hands to make some measurements. You don't have any warranty on the product? Try some electronics forum. I've seen lots of guys helping out on EEVblog forum: http://www.eevblog.com/forum
hello, realy nice your job here!! <br>I would like to do this on mine, but mine does not work very well, reading yous datasheets, I figure out that the problem Ia have can be fix. Give your idea if is possible. <br>About LTC3101, nobody can fix here in Brazil, maybe I can do a reset, but I have no experience with that. If you want to share your knowledges, please I would apreciate. <br>See you <br>
If you could describe your problem in a bit more detail and make some measurements around DC-DC converter if you believe that is the source of your KO2s problems maybe someone could help.

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