I own two PSR-S910's. I've started having an intermittent problem of no volume coming out of the microphone when I turn on the keyboard. The two times it's happened so far, it's gone away after 10 - 15 minutes of the keyboard being on. I checked that it wasn't the mic or mic cable.

I'm going to bring it to get repaired soon. Hopefully, it won't take too long. I did get it with a credit card that offers a 1 year extended warranty. The last time I tried to take advantage of this it worked. It did take some paperwork. You need the receipt and the original credit card statement.