A couple of months ago I purchased a used Yamaha QS300 synth workstation. The price was low, but for a reason - it was, albeit almost totally functional, in very bad condition: the case was blemished with wall paint, most panel buttons were not working, the screen retroillumination was dead, it had one physically broken key, lots of dirt, and so on.
Equipped with the service manual and lots of patience, I've been working to give the machine a new life, and I've almost succeeded The case now looks as good as it can get, given its age and lack of care, I've done an in-depth cleaning of (almost) all parts, I've placed a new EL-panel for the LCD screen (and now it looks with a very cool blue light), the contact ribbon of the keyboard is new, I've replaced the broken key, I've replaced the floppy disk drive with a usb, and (what took the longest time, because of the de-soldering and re-soldering process), I replaced ALL the button switches of the panel with new ones.
Now, the QS300 looks and works great, but I still have a problem I haven't been able to fix, regarding the keyboard. The QS300 uses the Yamaha C61K6 model, the same one as many other synths such as the DX11, V50, W7, CS6X, etc. It has a very nice feel and it's not only velocity-sensitive, but it also has aftertouch. And here it comes the problem: the aftertouch on my QS300 is far too sensitive, to the point that it's almost impossible to play normally without activating it. I also have a Studiologic SL88 Studio master keyboard with aftertouch, and in order to activate it, I have to make a quite hard pressure (as it's intended to be). This, in practice, renders the aftertouch capabilities of the QS300 quite useless, as it's very difficult to control.
So my question is: is there some way to "re-calibrate" the sensitivity of the aftertouch? I mean from a "physical" point of view, not by re-programming the sounds to make them respond differently to the aftertouch signals. I've noticed that the C61K6 keyboard has got a couple of adjustable screws at the bottom that seem to be used for calibration, but I've tried to put them in different positions and it seems to have little or no effect.