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.

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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.

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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.

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

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