Archive of the former Yahoo!Groups mailing list: Yamaha CS80

Hi all.

I was doing a few little repairs on a CS80 yesterday and saw some odd stuff. First, there was a VCA EG that would not calibrate. It was impossible to get the attack and release times right. Swapping out the chip and the related VCA chip did nothing! Turns out it was the .22uF cap on pin 2 of the EG. Swapped that out and it was fine!

Another problem was that portamento and glissando both stepped like glissando is supposed to. This turned out to be that the adjustments for the glissando clock (VR4 and VR5) on the KAS were way off and the oscillator was running so slow that the capacitors used to smooth out the glissando into portamento couldn't do their job. A quick adjust (although trying to calibrate 1.6s / 0.63Hz square wave is not easy on an old analog 'scope) and it works fine!

Hope you're all having a great, analog summer!

David (back to designing digital computer chips now...)