We purchased a used Yamaha MX-100B (with Disklavier) last year and had it professionally moved and tuned once it arrived. It has worked fine since then, up until about 1 week ago. Part way through a playing a disk, the piano went silent and displayed "Piano Power Off - (PWM Over)!" If you power down and restart, it will again play partway through a song and display the same error. I'm curious if there is a simple fix for this or is it something to call out a pro for? I'm an electrical engineer with a heck of a background in "fixing" things, but without a maintenance manual or finding anything in the operations manual, I don't know where to begin. Any thoughts?

ftp://tech:disklavier@216.154.248.26/ Try this link, (copy & paste) look under service manuals. Hope this helps.

Many thanks. Found the error message and as I suspected, looks like it is going to be a power supply related issue. I always like to know the problem before I call in someone else - don't like not knowing what I'm asking someone else to do. Thanks again - I appreciate the link and the manuals.

Richard I have the same problem with my Disklavier MX100 II it will give me the same message Piano Power Off - (PWM Over)!" and will do the same if you restart it play one or 2 songs and stop did you ever fix the problem with yours thanks in advance Marge

@Rich H: I have a limited experience with these instruments, but at least the one we host is exposed to similar problems - albeit randomly, but still. If you cure the problem by switching/repairing the power supply, please let me know.

Hello I had the same problem and have solve it:

The power supply have a 20V-regulater (IC2 MJN78M20FA) witch is operated outside of its specification. At the entrance he receives 50V instead of the 40V allowed! Therefore, it switches off automatically.I put a strong Zener diode in series, so that it works with <40V.
Problem solved!

Check to see if the pedal solenoids are overheating. There should be pedal adjustment instructions on the inside cabinet. Sometimes the power error will be related and if the solenoid is too hot then it will terminate power to the system long enough for it to cool down to operating temps then you can prompt playback until it overheats again. Two cents.