Welcome to the Piano World Piano Forums
Over 2 million posts about pianos, digital pianos, and all types of keyboard instruments
Join the World's Largest Community of Piano Lovers (it's free)
It's Fun to Play the Piano ... Please Pass It On!

Gifts and supplies for the musician

the Forums & Piano World

This custom search works much better than the built in one and allows searching older posts.
(ad) Yamaha CP4 Rebate
Yamaha CP4 Rebate
(ad) Pianoteq
(ad) Pearl River
Pearl River Pianos
(ad) P B Guide
Acoustic & Digital Piano Guide
(ad) Lindeblad Piano
Lindeblad Piano Restoration
Who's Online
111 registered (Anne'sson, Amosdoll, Anita Potter, ajames, angga888, 26 invisible), 1395 Guests and 9 Spiders online.
Key: Admin, Global Mod, Mod
(ad) Estonia Piano
Estonia Pianos
Quick Links to Useful Piano & Music Resources
Our Classified Ads
Find Piano Professionals-

*Piano Dealers - Piano Stores
*Piano Tuners
*Piano Teachers
*Piano Movers
*Piano Restorations
*Piano Manufacturers

Quick Links:
*Advertise On Piano World
*Free Piano Newsletter
*Online Piano Recitals
*Piano Recitals Index
*Piano & Music Accessories
*Music School Listings
* Buying a Piano
*Buying A Acoustic Piano
*Buying a Digital Piano
*Pianos for Sale
*Sell Your Piano
*How Old is My Piano?
*Piano Books
*Piano Art, Pictures, & Posters
*Directory/Site Map
*Virtual Piano
*Music Word Search
*Piano Screen Saver
*Piano Videos
*Virtual Piano Chords
Topic Options
#1546537 - 10/29/10 09:00 PM Problems with Yamaha MX100B with Disklavier
Rich H Offline
Junior Member

Registered: 10/24/10
Posts: 2
Loc: Delaware
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?
Richard A Holub

(ad 568) PTG Convention 2015 Denver
PTG Convention July 15 to 18 Denver
#1547032 - 10/30/10 03:40 PM Re: Problems with Yamaha MX100B with Disklavier [Re: Rich H]
Dave Lotek Offline
Full Member

Registered: 12/31/06
Posts: 78
Loc: midwest
ftp://tech:disklavier@ Try this link, (copy & paste) look under service manuals. Hope this helps.

Edited by Dave Lotek (10/30/10 03:41 PM)
Piano Sales, Piano Technician, "Tuning pianos for a song"

#1548829 - 11/01/10 09:43 PM Re: Problems with Yamaha MX100B with Disklavier [Re: Dave Lotek]
Rich H Offline
Junior Member

Registered: 10/24/10
Posts: 2
Loc: Delaware
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 A Holub

#1628696 - 02/26/11 04:59 PM Re: Problems with Yamaha MX100B with Disklavier [Re: Rich H]
Marge Offline
Junior Member

Registered: 02/24/11
Posts: 1
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

Edited by Marge (02/26/11 05:04 PM)

#1628910 - 02/27/11 12:18 AM Re: Problems with Yamaha MX100B with Disklavier [Re: Rich H]
pppat Offline
1000 Post Club Member

Registered: 08/09/08
Posts: 1195
Loc: Jakobstad, Finland
@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.
Patrick Wingren, RPT

Senior Lecturer (jazz piano, composition, music theory, conducting) @ Novia University of Applied Sciences, Jakobstad, Finland
- - - -
Dedicated to learning the craft of tuning. Getting better.

#1993276 - 12/01/12 04:55 PM Re: Problems with Yamaha MX100B with Disklavier [Re: Rich H]
chrigi Offline
Junior Member

Registered: 12/01/12
Posts: 1
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! smile

#1993329 - 12/01/12 06:17 PM Re: Problems with Yamaha MX100B with Disklavier [Re: Rich H]
David, Las Vegas Offline
Full Member

Registered: 10/07/08
Posts: 211
Loc: Las Vegas, Nevada
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.
David Chadwick RPT
Las Vegas, Nevada
1923 Steinway "M"
1931 Mason Hamlin AA

#2161082 - 10/03/13 06:56 AM Re: Problems with Yamaha MX100B with Disklavier [Re: Rich H]
jaguar8888 Offline
Full Member

Registered: 05/13/07
Posts: 27
Loc: Sydney Australia
Hi everyone.
I know it's been a couple of years since this post, but I now have a similar problem.
I have an MX101R, which seems to be the Japanese domestic version of the MX100B.
Was working perfectly and then all of a sudden, it wasn't. Wouldn't even play from a floppy!
Sometimes it will start to play a MIDI file through Cakewalk, but then it gives up after only a few bars!
All the diagnostic tests 1-9 are OK except #7 the MIDI one, which has NG, even though the MIDI cable is connected. And the notes test #8 only plays up to note #30. (LCD says Get data = 55)
Re the MIDI test #7, you can't activate the MIDI switch with the red light wheh you start the test programme, because the + and - keys held together prevents you from doing that. And when the test in running, pressing the MIDI switch does nothing.
Any clues anyone? Is this related to the 40/50v problem above? How would I know if this is the case?
I don't get the "PWM over" error message though.
Ian Griggs
Sydney Australia

#2161083 - 10/03/13 07:03 AM Re: Problems with Yamaha MX100B with Disklavier [Re: jaguar8888]
jaguar8888 Offline
Full Member

Registered: 05/13/07
Posts: 27
Loc: Sydney Australia
The frustrating thing with the Service Manual is that it doesn't tell you how to address any of the NG faults!


Moderator:  Piano World 
Shop our Store for Music Lovers!
PianoSupplies.com is Piano World's Online Store
Please visit our store today.
circle of 5ths coaster
(ad 125) Sweetwater - Digital Keyboards & Other Gear
Digital Pianos at Sweetwater
(ad) Hal Leonard Teacher VIP
Hal Leonard Teacher VIP Your Source for Piano Music
Ad (Seiler/Knabe)
Seiler Pianos
(125ad) Dampp Chaser
Dampp Chaser Piano Life Saver
New Topics - Multiple Forums
What happened to Polyphonist?
by JoelW
03/31/15 10:45 PM
Sohmer Upright piano model 34A
by dbf
03/31/15 09:25 PM
A long over due update...
by Les Koltvedt
03/31/15 09:04 PM
Piano Movers Tightened a Leg Bolt too Tightly
by pianoman9
03/31/15 08:17 PM
descending thirds with right hand
by pianu_reeves
03/31/15 06:40 PM
What's Hot!!
Trade Regrets: Gary Trafton - Piano Rep
Historic Piano Documents
Posting Pictures on the Forums
Forums Rules & Help
on Piano World

The world's most popular piano web site.
Forum Stats
78,727 Registered Members
43 Forums
162,896 Topics
2,390,932 Posts

Most users ever online: 15,252 @ 03/21/10 11:39 PM
Sheet Music Plus (125)
Sheet Music Plus Featured Sale

Visit our online store for gifts for music lovers

Help keep the forums up and running with a donation, any amount is appreciated!
Or by becoming a Subscribing member! Thank-you.
Donate   Subscribe
Our Piano Related Classified Ads
Dealers | Tuners | Lessons | Movers | Restorations | Pianos For Sale | Sell Your Piano |

Advertise on Piano World
| Subscribe | Piano World | PianoSupplies.com | Advertise on Piano World | Donate | Link to Us | Classifieds |
| |Contact | Privacy | Legal | About Us | Site Map | Free Newsletter | Press Room |

copyright 1997 - 2015 Piano World ® all rights reserved
No part of this site may be reproduced without prior written permission