Mysterious unsolvable Yamaha double-striking uprights

[Susan Kline]

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Interesting about the plastic jacks, though I don't see what difference it 
would make.

For some kind of relief, you might try repinning the hammer flanges firmer. 
Also make sure there isn't a rail set up to stop the motion of the jacks 
too soon.

If it's still driving you crazy, you might widen the letoff a hair, and 
maybe strengthen the hammer springs a little bit.

Good luck - I've seen this on Yamaha big uprights and also on Kawai big 
uprights, though not all of them, or this bad. For some reason, I haven't 
found it on consoles or short uprights. Maybe I just didn't look ...

Susan

At 11:04 PM 7/11/2005 -0700, you wrote:
>Greetings --
>
>I did a dealer prep on a brand new, fresh out-of-the-box, Yamaha MX500 P 
>upright today. Every single note double-struck when played softly. I 
>checked regulation and had to adjust lost motion on every key. Let-off 
>also needed to be adjusted, but only on about 10 keys. When I finished 
>these two adjustments the regulation may not have been perfect but it was 
>certainly close enough. Still, every single note was double striking when 
>played softly. (Definition of "softly": Playing the note faster then when 
>you are checking let-off but slower than it takes to actually check.)
>
>What I am witnessing is this: When I play the note, just before the jack 
>releases from under the butt the hammer jumps off the jack prematurely and 
>strikes the string. After striking the string the hammer then bounces back 
>onto the jack, which is still in it's pre-release position. Continuing 
>through the keystroke results in the hammer striking the note a second 
>time as the jack finally releases from under the butt.
>
>This was something new to the store manager so I called an associate. He 
>suggested I go through the routine I had just completed, but otherwise 
>could offer no further suggestion. OK, so I decided to tune the thing 
>while I pondered the matter further.
>
>Aha! Tuning finished. Let's see what the other Yamaha uprights are doing. 
>I checked six other, (not used), Yamaha uprights on the floor, (none of 
>which I had prepped, but all of them allegedly prepped), and every single 
>one of them exhibited the same double-strike behavior. For comparison I 
>then checked some NON Yamaha uprights and they all behaved properly. I 
>finally checked the showroom Yamaha action model, and it, too, was 
>behaving correctly. BUT... It was then that I noticed that all the Yamahas 
>used in this test had plastic jacks. The Yamaha action model, as well as 
>the non-Yamaha uprights used in this test, all had wooden jacks.
>
>That's all the clues I have. Anybody have any idea what's going on, and 
>what can be done to correct it?
>
>Geoff Sykes
>Assoc. Los Angeles Chapter

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