Mysterious unsolvable Yamaha double-striking uprights

[Geoff Sykes]

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Actually, it's the jack cycling out from under the butt that is giving =
me
that second strike.=20
=20
-- Geoff
=20

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On =
Behalf
Of David Ilvedson
Sent: Monday, July 11, 2005 11:33 PM
To: pianotech@ptg.org
Subject: RE: Mysterious unsolvable Yamaha double-striking uprights


A couple of things...the jack isn't cycling out from under the butt.  =
You
can solve this by shimming the hammer rail slightly and taking up the =
lost
motion and or increasing dip slightly.  Before doing this check blow
distance and dip and see if something is out of whack. =20

David Ilvedson





  _____ =20

Original message
From: Geoff Sykes=20
To: "Pianotech@Ptg. Org"=20
Received: Mon, 11 Jul 2005 23:04:27 -0700
Subject: Mysterious unsolvable Yamaha double-striking uprights


Greetings --
=20
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.)
=20
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.=20
=20
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.=20
=20
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.=20
=20
That's all the clues I have. Anybody have any idea what's going on, and =
what
can be done to correct it?
=20
Geoff Sykes
Assoc. Los Angeles Chapter


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