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#1546537 - 10/29/10 08:00 PM Problems with Yamaha MX100B with Disklavier  
Joined: Oct 2010
Posts: 2
Rich H Offline
Junior Member
Rich H  Offline
Junior Member

Joined: Oct 2010
Posts: 2
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
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#1547032 - 10/30/10 02:40 PM Re: Problems with Yamaha MX100B with Disklavier [Re: Rich H]  
Joined: Dec 2006
Posts: 78
Dave Lotek Offline
Full Member
Dave Lotek  Offline
Full Member

Joined: Dec 2006
Posts: 78
midwest
ftp://tech:disklavier@216.154.248.26/ Try this link, (copy & paste) look under service manuals. Hope this helps.

Last edited by Dave Lotek; 10/30/10 02:41 PM.

Piano Sales, Piano Technician, "Tuning pianos for a song"
#1548829 - 11/01/10 08:43 PM Re: Problems with Yamaha MX100B with Disklavier [Re: Dave Lotek]  
Joined: Oct 2010
Posts: 2
Rich H Offline
Junior Member
Rich H  Offline
Junior Member

Joined: Oct 2010
Posts: 2
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]  
Joined: Feb 2011
Posts: 1
Marge Offline
Junior Member
Marge  Offline
Junior Member

Joined: Feb 2011
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

Last edited by Marge; 02/26/11 05:04 PM.
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#1628910 - 02/27/11 12:18 AM Re: Problems with Yamaha MX100B with Disklavier [Re: Rich H]  
Joined: Aug 2008
Posts: 1,205
pppat Offline
1000 Post Club Member
pppat  Offline
1000 Post Club Member

Joined: Aug 2008
Posts: 1,205
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
Wingren Pianistik
https://facebook.com/wingrenpianistik
Concert Tuner at Schauman Hall, Jakobstad, Finland
Musician, arranger, composer

- - - -
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]  
Joined: Dec 2012
Posts: 1
chrigi Offline
Junior Member
chrigi  Offline
Junior Member

Joined: Dec 2012
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]  
Joined: Oct 2008
Posts: 219
David, OHIO Offline
Full Member
David, OHIO  Offline
Full Member

Joined: Oct 2008
Posts: 219
Newark, Ohio
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
Newark, Ohio
1931 Mason Hamlin AA
#2161082 - 10/03/13 05:56 AM Re: Problems with Yamaha MX100B with Disklavier [Re: Rich H]  
Joined: May 2007
Posts: 27
jaguar8888 Offline
Full Member
jaguar8888  Offline
Full Member

Joined: May 2007
Posts: 27
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 06:03 AM Re: Problems with Yamaha MX100B with Disklavier [Re: jaguar8888]  
Joined: May 2007
Posts: 27
jaguar8888 Offline
Full Member
jaguar8888  Offline
Full Member

Joined: May 2007
Posts: 27
Sydney Australia
The frustrating thing with the Service Manual is that it doesn't tell you how to address any of the NG faults!

#2610978 - 02/02/17 04:15 PM Re: Problems with Yamaha MX100B with Disklavier [Re: Rich H]  
Joined: Dec 2016
Posts: 9
MikeOregon Offline
Junior Member
MikeOregon  Offline
Junior Member

Joined: Dec 2016
Posts: 9
Gresham, OR
Has anyone had any luck with finding a replacement power supply for their Yamaha Disklavier piano? My MX100II power supply failed with several of the electrolytic capacitors leaking fluid and damaging the board. The unit is not viably repairable and Yamaha advised there is no replacement power supply available. It would be a shame to render this instrument, which I paid over $15,000 for, only partially useful.

I am hopeful that some combination of off-the-shelf power supplies and some custom circuitry could replace this.

Since a fine piano should be a viable instrument for many decades, I am disappointed that Yamaha has decided to drop support for this piano.

#2611744 - 02/05/17 02:35 AM Re: Problems with Yamaha MX100B with Disklavier [Re: MikeOregon]  
Joined: Nov 2004
Posts: 97
Pro-TAC Offline
Full Member
Pro-TAC  Offline
Full Member

Joined: Nov 2004
Posts: 97
Japan
I have power unit for Disklavier .(WC769209)
I'v confirmed that operation.
If you are interested, please sent me a private message.

https://goo.gl/photos/8QtExRhvqvZ5Y7bo9
https://goo.gl/photos/LReTaQ2K4TzxM1p99
https://goo.gl/photos/enXkCyqiooq1X7Pn9



--------------------------------------
Pro-TAC tuning and repair service.

http://pro-tac.jpn.org/english.html
https://www.facebook.com/protac.jp/
https://plus.google.com/b/111654612048157812408/
--------------------------------------


#2612894 - 02/09/17 11:41 AM Re: Problems with Yamaha MX100II Disklavier Power Supply [Re: Pro-TAC]  
Joined: Dec 2016
Posts: 9
MikeOregon Offline
Junior Member
MikeOregon  Offline
Junior Member

Joined: Dec 2016
Posts: 9
Gresham, OR
I sent an email with photos of my power supply and details of parts I replaced. I'm looking forward to your reply.


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