Hi, I had similar. Generally power-up and fine for a little bit then these distortion sounds very randomly and also when striking a key. For me, this is what I did:
- Open it up and expose the logic board.
- Tap / press down with an INSULATED item on the main chips (sorry, it’s been a while). I used the handle of a screwdriver, but you could use the end of a wooden spoon. See if pressing down semi-gently (no more than as few pounds of force) on an edge or center of a chip helps. In my case it did…
- Try to localize where applying the pressure removes the issue and take note.
- Unplug the piano, let it sit to self discharge and remove the logic board.
- Inspect the area where applied pressure helped (use a GOOD magnifying glass), in my case the chip was not soldered well to the board so there was an intermittent connection. It might not be obvious. With a GOOD, FINE POINT soldering iron, re-touch the suspect lead(s) of the IC to the board / add very little solder if needed as you don’t want to create a short. Clean the area carefully with a lint-free cloth/alcohol (don’t drown it). Let it dry thoroughly and reassemble/test.
- Good luck. This worked for me, hopefully for you too!!!