Monday, June 20, 2011

Repairing a pitch bend wheel with style

These pics are from 2008. I had a Swissonic CK490 USB MIDI keyboard. It was a super-cheap controller with a lot of pots and 49 keys. The response was never very good with these things, especially with the velocity sensitivity, and it slowly deteriorated over time. It's enough for making some computer music, but I would never use this thing live.

Here is the keyboard before the repair. Or actually it's just a similar one. Notice the kitchen studio setup...

The Swissonic CK490. In a kitchen.

The keyboard was actually made by M-Audio, the former Midiman. The same keyboard has been marketed also under the Evolution brand. It's not as good as M-Audio products in terms of quality.

Since it was very light to carry, I used it for practicing quite a lot. At some point the pitch bend wheel stopped working, and the pitch of the whole keyboard became unstable. It was basically unplayable. The potentiometer had clearly given up.

So I decided to repair the wheel. After opening the thing and ripping the wheel out, I noticed it would be hard for me to find a similar linear 10k pot that would fit in. The two important properties were the physical size of the pot and how many degrees the thing rotated. Both would have to be exactly same with the replacement pot...

Don't pay any attention to the tablecloth. Please.

The modulation and pitch bend wheels ripped off from the CK490.

Closeup of the pitch bend wheel.

The pitch bend wheel in pieces.

Both the pitch bend and the modulation wheels used a similar 10k linear pot. After a bit of thinking I decided to use the mod wheel as the pitch bend wheel, and replace the mod wheel with just a normal pot. Since there was no spring in the mod wheel, I took that from the old pitch bend.

It worked great, and the new modulation pot didn't take a long time to get used to. It also looked great, see for yourself!

The result looks so f*cking ghetto!

Some time later, I sold the thing, as I had gathered some better keyboards. I wonder if it's still in use somewhere...


  1. Awesome blog! I have a question for you. Recently I was setting up to record a band. I was in a hurry, in my hast, I accidentally hooked up my laptop power supply to my Boss BR-1180, now it won't event turn on I smelled electrical burning when it happened. How do I diagnose and fix the problem? is my e-mail if you could e-mail me back that would be great

  2. Hi,

    It sounds like some of the power circuitry in the BR-1180 is broken. You can open the BR-1180 and try to look for a fuse that's replaceable. But if that doesn't help, unfortunately I think the best way to fix it would be just to get a spare BR-1180. You can then install the old hard drive in that one and continue your recordings...

    Fixing the circuitry can be quite a job in this case, I'm afraid.

  3. Also, try checking the psu pcb for blown capacitor or blown transistor. I have fixed two keyboards recently with just locating and replacing blown components.

  4. Ilmeeni kun omistan kyseisen kiipparin : D. Löysin varastosta ja googlasin et mikäs mikäs ja löysin blogis.

  5. This comment has been removed by the author.

  6. I have Impakt LX49+ and i have similar problem the Pitchbend wheel gives bad vst sound as if out of pitch. I afraid of opening it

    1. What have you got to lose if it's broken already?
      Just open it carefully and you might learn something new in the process. Just keep in mind where each screw was.

    2. ok I will see what could be done
      The company has promised me a part if it is broken. So I will open it.

  7. No it is not broken it does not come to zero after changing So it gives any value and makes my instruments flat