When I switch on the synth it works for about 1-5 min. after that there's no sound anymore on all outputs (1/L,2/R,3,4 and phones). The display is working O.K., I can change programms e.t.c. just no sound! If I turn it off and restart it works again for a short time. Can someone help me??? Thank you!

I think that you should take it to a repair service,

Same thing happened to me once, except that it didn't sound at all, I took it to the korg dealer and they repaired it for about 150.00 dollers, and it worked fine after that.

Peace