Circuit Bending a Casio SK-1




This is a complete tutorial on how to circuit bend a Casio SK-1.
Only a few simple materials and minor Soldering skills are needed to create a truly unique instrument.
Case and modification layout is what I decided to do but there are so many options... Poking around the board and finding some different bends and other manipulations is welcomed and encouraged.
... that being said please message me or email me at with any questions.

There is also a video tutorial at  for more info

video of sound demo at

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Step 1: Materials, Removing Case, and Preparing to Bend

All you need to build this awesome project is a few simple components.

1x Casio SK-1
1x LTC1799
13x On/Off switch (I used one rocker switch for pitch)
22x RCA jacks
¼” (3.5mm) Stereo output jack
1x 100k Potentiometer
1x knob (for potentiometer)
1x Thin plastic plate
1x Multicolored back light
some solder
a bunch of wire...
and patience...  lots of patience.

...Remove back of keyboard and set screws aside.
Place some tape over the exposed battery compartment.
and lets get bending.

Step 2: Mapping Bends and Soldering Them Up on the Board

Here is an overview of the board.
-I like to print out a pic of the circuit board so I can mark bends easily and organize them.
-Tin (pre-solder) the wires before attaching them to the board for less contact time with the soldering iron.
-These are just some good bends that I have found. Feel free to poke around and add a few of your own.

Step 3: Soldering Controls to Board Points

Feel free to solder the controls to the points on the board as you find them. I like to color coat the wires to keep bends organized.

Step 4: Connecting Pitch Modification

Cut trace in between the two points.
Connect the left pin to the middle of switch
Connect the right pin to one of the out ends of switch
Connect other end of switch to the clock output of the LTC1799

Step 5: Marking Holes in Case and Making Room for Bends

The layout for the case can be altered to suit your bends I choose this layout.
I removed the speaker for some extra room.
Mark the inside of case with a marker so you know where the screw holes and other things are that may get in the way.
Drill from the inside and start with small holes and enlarge with bigger bits or a dremel tool.
Smooth out holes and clear away debris.

Step 6: Installing Connections and Bends

Mount switches and use hot glue to space and keep straight (if needed)
Solder up points to whatever switches you desire and clean up long wires if needed.
Mount Potentiometer and Pitch switch into case.
Mount Patchbay plate or drill holes directly into speaker area.
Assemble Patch bay into case before soldering board points.

Step 7: Alternative Mods and Goodies

Because I used a clear plastic plate, I added a color changing back light.
If you just drill into the case, the back light is unneeded.
Additional options include:
LED or back light in case
Potentiometer patchbay additions for variable bends.
controller input
video output
... etc.
As you can see the list goes on and on for durable bends and other creative ideas.

Step 8: Final Clean Up and Testing

Now that the connections are all in, start testing unit by switching on bends one at a time.
If all is working properly then begin to close case up taking note of where the wires are so you don't cause a unwanted short.
Don't force case closed... if you used this layout the case should close up very nicely with no interference

Step 9: Plug in and Get Down! Congrats!

Hopefully you have made it to this page after building a completely altered device.

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20 Discussions


3 years ago

some advice, tips or guide to do the same on a casio VL.1 ?

1 reply

Reply 3 years ago

The VL-1 is not nearly as well suited to this sort of mod. You may be able to find some basic overdrive and drum-mute points, but as I recall there's not much in there. It's also a pretty small board, so you can really just poke around and look for stuff.


3 years ago

LTC1799 Install picture has been updated. The correct way to connect is

PWR (blue)= to lower point

GND (Yellow)= upper point

.. Sorry for the confusion and thanks those those who pointed it out.


3 years ago

WARNING: Do not use the wiring diagram for the LTC1799 chip in this tutorial, use the one in the linked video. The image is wrong and will fry the chip (this happened to me). There are other, correct diagrams out there (see GetLoFi). Gook luck!

1 reply

Reply 3 years ago

Image will be updated shortly... Power is actually connected to the lower (blue) point and Ground is connected to the upper (yellow) point. Sorry for the trouble.


Reply 5 years ago on Introduction

Hi. There is a video tutorial link on the intro page and here is a sound demo of the unit


Reply 3 years ago

You have the LTC power wired the wrong way around in these images. Wiring it that way around will fry your LTC1799.

In the video its clearly wired the other way.


Reply 3 years ago

On the images in "step 4: Connecting pitch modification" you have the LTC ground wired to the lower blue point, and the +ve power wired to the upper yellow point. I just tested a SK1, and these are the wrong way round, as is also shown in your video at at around 8:45 where you say the power should be wired to the blue point and its clearly wired to the lower point where the ground is wired according to the images on this instructible.


Reply 3 years ago

Thanks for the heads up. I must have mixed them up on the image. I will update it shortly.


4 years ago on Introduction

Searching for LTC1799 only brings up the bare chip - your LTC1799 is soldiered on a board with some resistors and stuff. Any hints, where to get this from? Or can you soldier the chip directly without the buzz around?


5 years ago on Introduction

This Instructable arrived just in time...

I bought an SK-1 last weekend, planning to circuit-bend it in the future.

Then a big bag of assorted switches I'd forgotten about arrived from the Far East.

Thanks for the groundwork!

I'll probably use a (cheaper) discrete circuit for the substitute clock (It's TTL levels -the choices of oscillator are endless).

Looking forward to longer samples in weirdly dismal quality...


Reply 5 years ago on Introduction

Thanks! Yeah, there is a few video links on the first page and check out my other bent goodies on youtube or


5 years ago on Step 9

Hi Greig thanks for sharing. What modifications you did to this regarding sounds?

I have an old Buontempi hitorgan and would like to modify it. It's a triphonic organ and would like to make it multiphonic. Do you think this can be done?



Reply 5 years ago on Introduction

That's the great thing about this tutorial! If you have an SK-1 one and a few simple components, you can build one and make it sound how you want. Any questions welcomed.