Yamaha bobbling

David Graham dcgrpt@earthlink.net
Tue, 13 Apr 2004 23:05:00 -0500


Hi all: I tune a LOT of new Yamaha uprights, and they all do this  to some
extent. You have to check two things: the lost motion-as soon as there is
more than enough,the problem will occur; and you have to weaken the damper
return springs. They are too tight, and "push back" on the key at the bottom
of the stroke, jamming the jack as it tries to escape. I don't see too many
U#s, but it certainly happens a lot on P22s,U1s and the T series pianos. I
weaken the spring by pushing it against the damper lever with the Hart
spring tool. Well, now that I think of it, there is one other potential
cause- many times the shoe at the bottom of the balance hole is too thick,
and the key will bind as it rocks, even though it seems free when you lift
it. Pianotek makes a chisel tool that goes inside the key and removes some
of the wood.
-- 
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David Graham <dcgrpt@earthlink.net>



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