[sdiy] Oberheim Xpander Res fail

[Csaba Zvekan]

Hi Group ,

My Oberheim Expander fails to tune the resonance section but it doesn't tell me what voice. If I force pass it then the synth works just like expected. Even the percussive patches with high resonance work excellent .
I'd like to look at some schematics in particular the auto tune feature perhaps some 4xxx CMOS is bad or something. Any suggestions ?

Best regards

Csaba