Or a defect Opamp (Operational Amplifier), parts like LM741/LM13600/13700 blahblah....some of them use a capacitor around their circuit and, dependig on the age of the Delta, it is possible that one of them is simply dry.
I think that the Delta is some sort of Siel Cruise: Mono/Poly Section, Poly=Presets, Mono/Lead-Section=Presets and "programmable" etcetc. The Poly Section is build around a Top Octave Generator with frequency dividers (proably under the keybaord at the front side) and lots of CMOS 4xxx Chips, the Lead/Mono Section around a simple ICL8038 VCO. Are the Chips inside your Delta socked? Could you count me the chips which does -not- start with "4" or with "74"? Are there any chips which are "Korg"-labeled and -if-, with which number they are labeled?
Stef
