IOTech Roland JX-8P / Juno-2 aftertouch repair

If you own an early Roland synth that has aftertouch you have probably experienced that the aftertouch function is not working as is should. You have to press very hard, and the response is not even over the whole keyboard length.

This is caused by oxidation of the aftertouch sensor. There were reports of this problem already when the JX-8P hit the streets  so most probably the sensor was already oxidized at delivery...

However, by doing a fairly easy, but time consuming job, the aftertouch can be restored to better than new condition!

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This diagram shows a cut through the sensor. When pressure is applied the two brass conductors will be electrically connected through the conductive rubber and the metal foil.
Problem is that the brass oxidize and the surface stops conducting. There is also a build-up of oxide on the conductive rubber strips.

PS: You might have heard that it is possible to get the aftertouch working by a modification to the sensor electronics. This only applies to the very first JX's  and it is mostly unlikely that this is necessary on your instrument. Only way to get the aftertouch fully working is by following the procedure below.


How to repair:

After completing this procedure your JX-8P aftertouch should be working better than new!