Hello all, first I want to thank you for your answers and I just wabt to say that my english is not very good.
I recently came across the same issue (speaker, headphone not working and a click 4 second after turning the piano ON)
I ordered 20x capacitor (16v 100uf) to change the C216 and c217 but the problem persisted.
After reading more answer I decided to replacing the capacitor c408 (I choose it randomly) and after after replacing it the speakers started working !!!
So if anyone has the problem persisting after changing c216 and c217 just test the other capacitor with a multimeter and try changing them !!
One more time thank you all, thanks to you I fixed my keyboard for only 15€.
I recently came across the same issue (speaker, headphone not working and a click 4 second after turning the piano ON)
I ordered 20x capacitor (16v 100uf) to change the C216 and c217 but the problem persisted.
After reading more answer I decided to replacing the capacitor c408 (I choose it randomly) and after after replacing it the speakers started working !!!
So if anyone has the problem persisting after changing c216 and c217 just test the other capacitor with a multimeter and try changing them !!
One more time thank you all, thanks to you I fixed my keyboard for only 15€.