Hello,
I've got a poly-800 here that sounds like it's having trouble staying in tune.
The more notes I play together the more it seems to go out of tune, like a detuning effect but not pleasant sounding.
I set the internal master oscillator as close as I could get it. I can play the C notes and they are all close to the correct frequency. If I change patches, play a little (it sounds out of tune now) and then go back to the patch I used for tuning (the one in the service manual) and press the C notes individually so I can check their frequency they are off a little from what they should be.
If I then press the 'Hold' button and then press a C note I can hear the note slewing back up to the correct frequency (that which I set before) and it will stay in tune for a few presses and then drift off again.
I have checked the power supplies and they are fine although I haven't measured it while I'm making the system work harder (playing notes).
I'm thinking lazy op-amp somewhere.
Anyone got a better idea?
Cheers
Martin