The Kawai & Teisco Analog Synths Group

Just a note, I found two bad 4066 chips on mine so far, it looks as 
if they are prone to fail oftenly on that instrument.




--- In kawai-teisco@yahoogroups.com, "claudio" <claudio@...> wrote:
>
> Hello,
> 
> I've got a corrupt SX-210 synth, and it wasn't the battery leakage
> issue . Ok, battery is defective, too but seems, there's something
> wrong with the sound board.
> 
> When I press a note on the keyboard, a the sound is somehow 
digitally
> distorted, I can identify the instrument selected, but it sounds
> awful. This phenomenon reduces but doesn't vanish, when I change the
> LFO speed to nearly "00".
> I took my oscilloscope to the test points of the single voices: 
noise
> is  white, filters are working and each oscillator seems okay (clear
> sine or triangle... wave), the voices downmix from oscillator 
section
> is fine, too. 
> BUT: If I measure the sound output before it reaches the "Ensemble"
> board (the brown one left to the syn42) it is disorted. The waveform
> looks, as if the audio-signal is modulated upon some random 
amplitude
> rectangle pulse waveform at a continously changing frequency between
> about 10 to 50 Hz. This looks very digital... and changes with
> LFO-depth and speed. 
> Where the F*ck is the LFO section? the only sections left on sound
> board are four TC4051 multiplexers with opamps... guess they do some
> signal mixing and switching...
> 
> Anyone schematics or ideas?
> 
> thank and best regs,
> 
> claudio
>