[sdiy] Jupiter 4 overall tuning drifts after it gets warm

[Gil W.]

My JP4 overall tunning (the scale and the individual tuning of each card) is generally ok. How ever, after about an hour of work the overall tuning starts to move up and down a few semitones...
The tuning of all voices "moves" as one piece, so I guess the problem doesn't lay at any of the voice cards but somewhere else in the circuit ??  From my experience this can happen when a precise capacitor (usually a polypropelene) goes bad, but I couldn't find any capacitor of that type other than on the voice boards. Any suggestions please ?

Thanks  !