FW: Mysterious unsolvable Yamaha double-striking uprights

[Dean May]

> What would you guys do besides what I did to correct the problem?

> Rick Ucci/Ucci Piano

 

Here is a post from the archives that I'd recommend you try.

 

 

Dean

Dean May             cell 812.239.3359 

PianoRebuilders.com   812.235.5272 

Terre Haute IN  47802

  _____  

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Dean May
Sent: Tuesday, July 12, 2005 9:38 AM
To: 'Pianotech'
Subject: RE: Mysterious unsolvable Yamaha double-striking uprights

 

Check also the damper spring tension.  What may be happening is that if the
damper spring is excessive it will slow down the acceleration of the whippen
as the spoon contacts the lever. But the hammer will continue on. I can see
where this would show up on a slow blow. 

 

I just reset all the damper springs on a U3 with very good results. Here is
what I posted last week if you missed it:

 

FWIW, I played around with the tensions and ended up with the following
settings. Force was measured at the damper head where dowel was glued. 

 

Bass singles- 45g

Bass wedges- 25g

Tenor- 25g down to 15g at upper break

Upper treble- 15g

 

It was interesting that after training my touch with the gage I could pretty
accurately hit my targets just by feel with the finger.

 

 

Dean

Dean May             cell 812.239.3359

PianoRebuilders.com   812.235.5272

Terre Haute IN  47802

 

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Geoff Sykes
Sent: Tuesday, July 12, 2005 1:04 AM
To: Pianotech at Ptg. Org
Subject: Mysterious unsolvable Yamaha double-striking uprights

 

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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