Fix dead buttons on a Roland MC-303

Long time ago, my main sequencer for musical excursions were the Roland MC-303. Maybe not the best in the world but sure did function well enough to have a lot of fun with. So, when a unit appeared for sale on the second hand market, I bought it.

To my great disapointment, the Swedish Postal Service ("Posten") did it´s worst to kill the unit. But instead of going to the complaints department I ripped it open to find the fault.

What was dead? Some very important buttons were completely unresponsive. The green circles shows which ones.


The schematic clearly showed were to look if you consider which buttons that were dead. The wiring shows a normal way of scanning a lot of buttons using som logic.


And what did I find? A small crack on the PCB, just behind the "TAP"-button. It cut the PCB traces as shown above in the schematic.


And the fix (quick and dirty). The MC-303 now works perfectly.