Disklavier

Hello,

while it is rare for a key solenoid to burn out (I've never come across a burnt out drive transistor), I have come across a few. The reason for this failure may or may not have been due to overheating through prolonged activation (it could be due to some 
windings on the coil shorting out, causing an over-current). However, as there are only one or two temperature sensors on  a key drive rail, those solenoids furthest from the sensors may conceivably overheat under certain circumstances, before the 
protection comes in. 

I have also come across a few coils, where heat has caused the inner plastic lining to buckle, causing the plunger to jam.

These things only happen very occasionally and, as I said in my ealier message, it's just something to bear in mind. Without deliberately damaging a numerous solenoids on a piano, it would be diffcult to determine exactly what sort of timeframe would be ok 
and at what point you'd risk causing damage.

Adrian Thomas
Milton Keynes
UK

On Thu, 02 Feb 2006 12:05 , Robert Welcyng <rwelcyng@...> sent:

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>While I cannot guarantee a thing, I personally do not believe that anyone
>need be concerned about damaging their Disklavier by playing extended notes.
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>Here are my fuzzy reasons:
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>It would not be difficult for a DKV owner to write a MIDI file that would
>hold a note on for hours. \ufffdThe Yamaha Disklavier designers surely did not
>overlook that eventuality.
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>I have never heard of a key solenoid, or more likely, of a solenoid-driving
>transistor burning out.
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>Consider the following statement from a technical manual: "Continuous usage
>of the DISKLAVIER MK III raises the temperature of the solenoids. Since the
>playback function of the solenoids (in particular, playback of very soft
>notes)
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> degrades as the temperature increases, playback data is automatically compensated
>(when it is decreased, the data reverts to its original values)."
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>Also consider the following related to the DGP1/DGA1 PK-CTL board protect
>function:
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>Error message: PIANO POWER OFF! or (PWM OVER)
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>Indication and reason:\ufffd The keyboard & sustain, soft /shift pedal playback
>stop. Playback function cannot be restored until the drive transistor(s)
>has/have cooled down sufficiently and the power has been turned off, then
>turned back on.  One or more key drive transistors have become too hot and
>the protect circuit has activated.
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>I would predict that a long note or notes would shut the DKV down before
>any damage is done. \ufffdWhile such shutdowns occur infrequently, they are certainly
>not unheard of.
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>Spencer_Lists wrote:
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>  Greetings Adrian,
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>To turn a note on, you use a right mouse click and the key color
>changes to an obvious purple and stays that way until the key is
>turned off. Exiting the program will send note off to each note. Does
>this sound like adequate protection? I can also make it turn off all
>notes after a fixed period of time but think that would be a little
>too "safe". I personally am tired of dealing with protection from
>doing things I want to do.
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>Thursday, February 2, 2006, 1:47:59 AM, you wrote:
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>    Hi,
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>    Just something to be aware of:
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>    If you tell a key to stay on until you cancel itand you leave it on
>for a considerable length of time (or even forget to cancel it), you
>could cause overheating and/or damage to the solenoid, even with the temperature sensors.
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>    Adrian Thomas
>Milton Keynes
>UK
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>    On Wed, 1 Feb 2006 13:17 , Spencer_Lists <lists@...> sent:
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>      Greetings Robert,
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>    <snip>
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>      Play notes with a mouse click and stop when click stops. Play notes on
>and leave them on until cancelled. Play notes for a precisely
>determined period of time. Play notes repeatedly until cancelled with
>a precise on and off time. Change the velocity for played notes.
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>-- 
>Robert Welcyng
>Anchorage, Alaska
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