The choir which I help to run has a Technics sx-PX66 digital piano [1] which has performed extremely well over its 18 or so year life, but has now developed a fault. The problem is that if you play a scale down at the bass end, one of the notes is a bit intermittent and, when it *does* sound, it's a lot louder than the surrounding notes. This is asociated with a particular key on the keyboard (I think it's a G, but no matter). If you use the transpose function so that each key plays a higher or lower note than usual, the problem stays with this key - so the non-sounding or extra-loud note goes up and down in pitch with the transpose function. It would thus seem to be electro-mechanical problem with the key itself rather than a problem with the synthesiser.
Assuming I can get it apart non-destructively, I need to know what to look for. There must be a sensor of some sort associated with each key, which detects when the key is pressed and sends a signal to the synthesiser. It's unlikely to be just a simple on/off switch, since the keyboard is touch sensitive - if you strike a key hard it plays louder than if you press it gently. It's my guess that it's this which has failed - and is either not registering a press, or is responding as though the key had been pressed with maximum velocity.
Have any of you got any experience of repairing such an instrument which would enable you to point me in the right direction?
Alternatively, do you know of any newsgroups which would be more appropriate for this sort of query? [I *have* looked, but haven't found any obvious candidates].
[1] If you're interested, go toTIA.