Since last week I'm a proud owner of a Prophet 6. A few days ago I recorded some stuff. The last thing I did was playing chord and used the hold function. I recorded what I wanted and then turned the volume down. After that I totally forgot about it and I needed to leave in a hurry after that.
Long story short, I left the P6 on for about 24 hours while it was holding the same chord. When I found out, I turned everything off. This morning I turned it on and the P6 was completely out of tune. After calibration, everything seems to be fine again.
Still I can't stop wondering if have, or could have, damage the synth somehow by leaving it on like this, especially while it has continuously playing notes for a long period without a break.