I had the similar problem during one live gig with rock group 32 years ago, and the reason were weak batteries. I had to compensate it by tuning pot, and when it was not enough near the end of the show, by transposing the music. Which was not so comfortable for the person with perfect pitch :-)
Since that I have always used new batteries for each gig, or when using Poly 800 on the stand, always with power supply.
So maybe check everything around power supply, voltage regulators...
Daniel Forro
On Oct 6, 2015, at 2:00 PM, ian r ianpoly800@... [korgpolyex] wrote:
Hi, I've searched and haven't found anyone else posting with this problem. Hopefully I'm not just posting in the wrong places.My poly 800 drifts out of tune over time, often just over the span of a day, and it's usually too far to use the tuning slider on the face of the keyboard to correct it. I have opened it up and tuned it using the trimpots VR1 and VR4, but the problem persists, and opening the keyboard up before each gig is a hassle.Does anyone have experience with this issue? I don't know enough to judge whether it's a problem with caps, heat, or some other type of shenanigan.Thanks for reading!Ian