music synths

my first attempt at synth repair

Somewhere in the outskirts of Saigon this beauty was waiting for me

Snatched a Roland Alpha Juno 1 for $50 a couple weeks ago. The condition wasn’t exactly perfect, but the semi-busted screen and a bunch of dead functional buttons don’t really bother me, I’m going to set up an external controller for it, and the Alpha Junos are notorious for their poorly designed menu-divey interface anyway. However, the keyboard also needed some repair, the C3 key was misbehaving.

Double triggers? Thanks, but I’ve already got an OP-Z.

I found a very helpful guide on keyboard disassembly and took the synth apart.

Removed the faulty key and discovered that someone has modified the keyboard by putting cotton wool under each key. It may sound weird but I decided to leave it this way for two reasons: I like the way the keyboard feels right now (and I’m not sure it would feel better if I removed the cotton wool), and I’m too lazy to remove 60 more keys.

Applied some Abro electronic contact cleaner under the membrane, and it works like a charm.

Now I have to set up my Roland A-01 to control it (which will take a lot of time), and this beast will join my setup.

music pocket operators synths

po-33 cheat sheet and resources

I have finally updated the ultimate cheat sheet. It’s much prettier now, plus I’ve fixed some mistakes and added even more useful stuff (and perhaps some new mistakes as well, please tell me if you find any). If you miss the old ugly version, you can get it here.

Note: this is not a guide. You’ll find way better guides in the resource list at the end of this post. This cheat sheet is merely a support material that is meant to be printed and stored with your K.O! so that you can always refresh what you’ve learned. It’s not very useful for learning the tracks of your K.O!, it’s useful for actually playing it.

PO-33 cheat sheet
My graphic editor of choice is Microsoft Excel. Please don’t laugh at me.
Some clarification of the cheat sheet
  • Green squares in scales mean the root note. If you’ve got a sample of note C and want to play in C Major, you need to move it to button 7 (it’s the root for Major). To do so, lower the sample by 3 semitones (that’s what +3 in the name of the scale means). Now your sample is A (on button 5 as always) and button 7 has C.
  • Grey squares are the notes that don’t fit in the chosen scale.
  • M in Major scale is useful for chords. If you’ve got a sample of a major chord at your root, then only the buttons marked with M will have major chords in this key. Same goes for m in minor key obviously.
  • Numbers (+1, -2 and so on) on the blue rectangles mean the number of semitones (aka half steps or half tones) between buttons. Your original sample is on 5, and button 6 is 2 semitones up from it. If you’ve got a melodic sample of A, it’s played “as is” on button 5. The “+2” on button 6 means that if you press it it plays sample + two semitones (half-steps). In this case that’s B. Button 7 plays +1 semitone from button 6, and that’s C. You don’t have to press any extra buttons for that, that’s just how the KO automatically changes the pitch (and the length) of your melodic sample to lay it out on the keyboard.
  • As the K.O! is a sampler, there are no absolutes, all the buttons are relative to the note of the original sample. The semitones on the buttons are relative, so they stay the same. If you’ve got a melodic sample in A, the scale of your K.O! will be A minor with a root on button 5 or C Major with a root on button 7. The numbers on buttons represent semitones between them, so button 7 is +1 semitone away from 6, button 6 is +2 semitones away from 5, so 7 is +3 semitones away from 5. Button 13 is -12 semitones (an octave) away from 5. Your sample is on button 5, everything else is pitched up or down accordingly.
  • The cheat sheet includes a picture of a piano keyboard (with note letters for those who aren’t familiar with music theory at all) to make it easier to wrap your mind around. There’s always a semitone between two neighboring keys. So from A to A# it’s 1 semitone, from A# to B it’s 1 semitone, that means that from A to B you have 2 semitones. But there is no black key between B and C (so no B#), and that means that there’s just 1 semitone between B and C.
  • What makes it even simpler, you’ve got two octaves of your scale (plus the odd buttons 4 and 12 that are out of scale) laid out on your button pads. So if you know the notes of the scale, you don’t have to count anything, you just know that the next button is the next note in the scale. For example, if the original sample is in A, your scale is A minor. You could count semitones from button 5, but if you remember that A minor is all white keys, you can just tell immediately that buttons 5/13 are A, 6/14 are B, 7/15 are C, 8/16 are D, 1/9 are E, 2/10 are F, 3/11 are G and 4/12 are out of the scale.
  • If you want to pitch your sample up or down, look at the black bars on the bottom of the screen, 2 bars = 1 semitone. So if you’ve recorded a sample in C and want to move it to button 7 to play in C Major, pitch the sample down until you’re 6 bars to the left. Button 5 will obviously become A (-3 semitones from C), and C will move to button 7.
  • If you still have no idea what I’m talking about, read a better explanation written by a smarter person here.
  • The orange rectangles are effects that are applied to all the samples being played (both melodic and drum). They can be permanent or temporary depending on the write toggle. Either way you hold the FX button and hold one of the number buttons to apply the corresponding effect.


Here are the highly recommended resources for the PO-33:

Other resources:
Other resource lists: