Yamaha Tuning Instability

[Isaac OLEG]

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Good screwing of the plate have shown 3 cts raise and more.

Isaac OLEG
  -----Message d'origine-----
  De : pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]De la
part de Donald Mannino
  Envoye : lundi 23 septembre 2002 05:42
  A : Pianotech
  Objet : Re: Yamaha Tuning Instability


  Terry,

  There are always so many factors involved with tuning instability, it's
really hard to solve something like this.  In addition to what others have
written, keep in mind the following generalizations, which might be
contributing factors:

  - A smaller soundboard tends to react less to humidity changes than a
larger one.
  - An old soundboard tends to react less to humidity changes than a new
one.

  The pinblock gap at the plate flange is not likely to be the issue, as
Yamaha grand pinblocks in the past were not fit to the flange.  Some pianos
would go together with some contact, but many  did not contact the flange at
all.  Same is true for Kawai, by the way.    I believe Yamaha later changed
to doing a resin fit, but I am not sure what they are doing now.  In any
case, these pianos usually hold tuning just fine without having the pinblock
fit to the flange.

  If you are going to wedge the gap, I would recommend lowering tension and
tightening the plate screws first.

  Have you not already tightened the plate screws?  If not, it might be good
to simply do that and see how the piano holds before taking more elaborate
steps.

  Don Mannino RPT

  At 06:26 PM 9/22/2002 -0400, you wrote:

    My son's piano teacher has a 1983 Yamaha G5 (6' 7") grey market piano.
Other than tuning instability, the piano is in VERY good condition. She also
has a 1930ish Aeolian 4'some" microgrand in the same room. I have tuned both
pianos several times at six month intervals. The Yamaha consistently goes
out of tune significantly more quickly than the microgrand. No RH monitoring
and no DC (on either piano). The Yamaha does have business card gaps between
the pinblock and the flange.

    I will be servicing both these pianos two weeks from now. I plan to
check the rim screws and pinblock/flange fit on the Yamaha. I will shim any
pinblock/flange gaps I can find. She is going to start monitoring RH in the
room. But keep in mind, the Yamaha goes much more quickly out of tune than
the microgrand. Any other suggestions for things to look for? This is a
significant problem for this piano owner. I need to solve it. Any input will
be greatly appreciated.

    Thanks.

    Terry Farrell


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