[sdiy] Cs-60 Touch Response

[The Old Crow]

On Mon, 2 Sep 2002, crystal wizard wrote:

> Is anybody out there familiar with the touch response circuit on the
> Yamaha CS-60.  This one just doesn't work, maybe old CMOS chips?  I
> spent a while acquainting myself with the CS-80 touch response only to
> open up the CS-60 and find the "TRG" board is nowhere to be found.  
> Perhaps they improved the Touch response for the CS-80? Also a pointer
> in the direction of any CS-60 Touch Response schematics would be great.

  First thing to check: the light bulb in the optical shutter housing 
underneath the keyboard.  It is probably dead.  It is  a "type 47" bayonet 
mount type as found at ratshak and hardware stores.  I used a 24V one on 
the CS-50 and it works fine.

  FWIW, touch response on the 50 & 60 is done differently than on the 80.  
The 50 & 60 use a rocker-arm that any key down will push on and open a 
metal shutter that is blocking a light source (the above bulb) path to a 
photoresistor.  The more force on the key(s), the wider the shutter opens 
to affect the photoresistor.  This sort of action works out very well for 
quick/sharp brass 'hits'.

  The CS-80 uses resistive pressure sensors under each key, along with 
multiplexing circuitry to route the correct key-down sensor to the correct 
synthesizer voice cards.  The CS-80 keyboard has a lot more weight to it, 
so the sharp, crisp 'hit' type of response is not nearly so easy to do.

Crow
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